Respiratory Glossary
341+ medical terms and definitions for respiratory therapy professionals.
Showing 341 of 341 terms
A20 terms
Aorticopulmonary septum
A septum formed by ridges that develop between the bulbus cordis and the truncus arteriosus during embryonic heart development, dividing the outflow tract into the aorta and the pulmonary trunk.
Apgar Score
A standardized assessment performed at 1 and 5 minutes after birth evaluating five criteria: heart rate, respiratory effort, muscle tone, reflex irritability, and skin color. Each criterion is scored 0-2 for a maximum total of 10.
Apnea
A pathological cessation of breathing lasting greater than 20 seconds, or a shorter pause accompanied by oxygen desaturation, cyanosis, or bradycardia.
Apnea of infancy (AOI)
An unexplained episode of cessation of breathing for 20 seconds or longer, or a shorter respiratory pause associated with bradycardia, cyanosis, pallor, or hypotonia, occurring in an infant born at 37 weeks gestational age or greater.
Apnea of prematurity (AOP)
Cessation of breathing for more than 20 seconds, or a shorter pause accompanied by oxygen desaturation or bradycardia, in an infant born at less than 37 weeks gestational age. It is caused by immaturity of the respiratory control center in the brainstem.
ALTE (Apparent life-threatening event)
A frightening episode characterized by some combination of apnea, color change (cyanosis or pallor), marked change in muscle tone (limpness), choking, or gagging. The observer fears the infant has died.
Arachidonic acid
A polyunsaturated omega-6 fatty acid found in cell membrane phospholipids that serves as a precursor for the synthesis of prostaglandins, thromboxanes, and leukotrienes involved in inflammatory and immune responses.
Arterial blood gas (ABG)
A laboratory test performed on arterial blood that measures partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2), pH, bicarbonate (HCO3-), and oxygen saturation to assess pulmonary gas exchange and acid-base status.
Assist control ventilation (A/C)
A mode of mechanical ventilation in which the ventilator delivers a preset tidal volume or pressure with every patient-triggered breath, and provides mandatory breaths at a set rate if the patient fails to initiate spontaneous breaths.
Asthma
A chronic reversible obstructive lung disease characterized by airway inflammation, bronchospasm, and mucus hypersecretion leading to episodic wheezing, shortness of breath, chest tightness, and coughing.
Asthma action plan
A written, individualized management plan developed with a healthcare provider that outlines daily medications, how to recognize worsening symptoms using a zone system (green, yellow, red), and specific instructions for adjusting treatment.
Asthma education
A structured program designed to teach patients and caregivers about asthma pathophysiology, trigger avoidance, proper medication use, self-monitoring techniques, and when to seek emergency care.
Asthma triggers
Environmental or physiological factors that can provoke or worsen asthma symptoms, including allergens (dust mites, pollen, mold, pet dander), irritants (tobacco smoke, air pollution), respiratory infections, exercise, cold air, and emotional stress.
Atelectasis
The absence of air (gas) in part or all of the lung parenchyma resulting in collapse of the alveoli. It may be caused by obstruction (resorption atelectasis), compression, surfactant deficiency, or loss of contact between the visceral and parietal pleurae.
Atelectrauma
Lung injury caused by the repetitive opening and collapse (recruitment and derecruitment) of atelectatic alveoli during mechanical ventilation, generating shear stress forces that damage the alveolar epithelium.
Atomizer
A device that uses a high-velocity gas stream or mechanical energy to break a liquid medication into a spray of small droplets for inhalation or topical application.
Atrial bulge
An outward protrusion or enlargement of the atrial wall, often visible on echocardiography, that may indicate atrial dilation secondary to volume or pressure overload in congenital heart disease.
Atrioventricular septal defect (AVSD)
A congenital heart defect characterized by a deficiency of the atrioventricular septum, resulting in a common atrioventricular valve and communication between the atria and ventricles. It is commonly associated with Down syndrome.
Atypical BPD
Bronchopulmonary dysplasia that develops in infants who initially had minimal or no lung disease and did not require significant ventilatory support in the first days of life, but later develop chronic lung disease often triggered by sepsis or a PDA.
Azoospermia
The complete absence of spermatozoa in the ejaculate. It may be obstructive (blockage of the reproductive tract) or non-obstructive (impaired sperm production). In neonatal medicine, it may be considered in the context of genetic syndromes.
B13 terms
B2 agonist
A class of bronchodilator medications that selectively stimulate beta-2 adrenergic receptors in airway smooth muscle, causing relaxation and bronchodilation. Short-acting examples include albuterol; long-acting examples include salmeterol and formoterol.
Baffle
A surface or structure within an aerosol delivery device (such as a nebulizer or metered-dose inhaler) that serves as a target for aerosol deposition, removing large particles and allowing only appropriately sized particles to reach the patient.
Ballard Score
A standardized assessment tool used to estimate the gestational age of a newborn by evaluating six neuromuscular and six physical maturity criteria, with scores ranging from -10 to 50 corresponding to gestational ages of 20 to 44 weeks.
Barium swallow
A fluoroscopic radiographic examination in which the patient swallows a barium sulfate contrast agent, allowing visualization of the pharynx, esophagus, and stomach to detect structural abnormalities, swallowing dysfunction, or gastroesophageal reflux.
Barotrauma
Lung injury caused by excessive pressure (high transpulmonary pressure) during mechanical ventilation, resulting in alveolar rupture and potentially leading to pneumothorax, pneumomediastinum, pneumopericardium, or subcutaneous emphysema.
Benchmarking
The process of comparing an organization's clinical outcomes, processes, and performance metrics against best practices or standards from leading institutions to identify areas for improvement in healthcare quality.
Betamimetic
A pharmacological agent that mimics the effects of beta-adrenergic stimulation, used as tocolytics (e.g., terbutaline) to relax uterine smooth muscle and delay preterm labor, or as bronchodilators to treat airway obstruction.
Bilateral choanal atresia
A congenital condition in which both posterior nasal passages (choanae) are blocked by bony or membranous tissue, preventing nasal breathing. Since neonates are obligate nasal breathers, this is a life-threatening emergency requiring immediate oral airway placement.
Biophysical profile (BPP)
A prenatal assessment that uses ultrasound to evaluate fetal well-being by scoring five parameters: fetal breathing movements, gross body movements, fetal tone, amniotic fluid volume, and non-stress test reactivity, each scored 0 or 2 for a total of 10.
Blastocyst
An early stage of embryonic development (approximately 5-6 days after fertilization) consisting of an inner cell mass (which becomes the embryo), a fluid-filled cavity (blastocoel), and an outer cell layer (trophoblast) that forms the placenta.
Breath-actuated nebulizer (BAN)
A nebulizer device that generates aerosol only during the inspiratory phase of breathing, reducing medication waste during exhalation and increasing the proportion of drug delivered to the lungs.
Breath-enhanced nebulizers
A type of jet nebulizer that increases aerosol output during inspiration by drawing additional air through the nebulizer using one-way valves, improving drug delivery efficiency compared to conventional constant-output nebulizers.
Bronchial fremitus
A palpable vibration felt on the chest wall during breathing, produced by the movement of air through airways containing secretions or by narrowing of the bronchi. It may also be detected during auscultation as a coarse rumbling sound.
E2 terms
ELBW infant (Extremely Low Birth Weight)
An infant with a birth weight of less than 1000 grams (approximately 2.2 pounds). These infants are at the highest risk for complications of prematurity including intraventricular hemorrhage, necrotizing enterocolitis, BPD, and ROP.
Exudative effusion
A pleural effusion characterized by high protein content (>3 g/dL) and high LDH levels, resulting from increased capillary permeability or decreased lymphatic drainage, typically caused by infection, inflammation, or malignancy.
F13 terms
FMEA (Failure Mode and Effects Analysis)
A systematic, proactive quality improvement method used to identify potential failures in a process, assess their severity, likelihood, and detectability, and prioritize corrective actions to prevent patient harm before errors occur.
Fetal alcohol syndrome (FAS)
A constellation of physical, behavioral, and cognitive abnormalities resulting from maternal alcohol consumption during pregnancy, characterized by facial dysmorphism (smooth philtrum, thin upper lip, short palpebral fissures), growth restriction, and central nervous system dysfunction.
Fetal fibronectin (fFN)
A glycoprotein found at the interface of the fetal membranes and the uterine lining. Its presence in cervicovaginal secretions between 22 and 34 weeks of gestation is a marker for increased risk of preterm delivery.
Fetal lung fluid
A chloride-rich liquid actively secreted by the fetal pulmonary epithelium that fills the airways and alveoli in utero, playing a critical role in normal lung growth and development. It is absorbed during labor and delivery.
Fine-particle fraction (FPF)
The proportion of aerosolized drug particles with an aerodynamic diameter of less than 5 micrometers, representing the fraction most likely to deposit in the lower respiratory tract and exert therapeutic effect.
Flexible fiberoptic bronchoscopy
A diagnostic procedure using a thin, flexible bronchoscope with a fiberoptic light source to visualize the upper and lower airways, obtain specimens for culture or biopsy, and assess airway patency and anatomy.
Flow-volume loop
A graphical representation of airflow (plotted on the y-axis) versus lung volume (plotted on the x-axis) during forced inspiration and expiration, used to diagnose obstructive, restrictive, and upper airway disorders.
Focal biliary cirrhosis
A localized form of liver cirrhosis occurring around bile ducts, commonly seen in patients with cystic fibrosis due to inspissated (thickened) bile secretions blocking the intrahepatic bile ducts, leading to progressive liver damage.
Fontanel
A soft membranous gap between the incompletely ossified cranial bones of an infant. The anterior fontanel (diamond-shaped) typically closes by 18 months of age, while the posterior fontanel (triangular) closes by 2-3 months.
Fontan procedure
A palliative surgical procedure for patients with single-ventricle physiology in which systemic venous blood is directed to the pulmonary arteries without passing through a ventricular pump, typically performed as the final stage of surgical palliation.
Foramen ovale
An opening in the interatrial septum of the fetal heart that allows oxygenated blood from the placenta to pass from the right atrium to the left atrium, bypassing the pulmonary circulation. It normally closes functionally at birth.
Functional residual capacity (FRC)
The volume of air remaining in the lungs at the end of a normal passive exhalation. It serves as the baseline lung volume for tidal breathing and is important for maintaining alveolar stability and gas exchange.
Funnel chest (Pectus excavatum)
A congenital chest wall deformity in which the sternum is displaced posteriorly, creating a sunken or funnel-shaped appearance of the anterior chest. Severe cases may compress the heart and lungs, impairing cardiopulmonary function.
G9 terms
Gastroschisis
A congenital abdominal wall defect, usually to the right of the umbilicus, through which bowel and sometimes other abdominal organs herniate directly into the amniotic fluid without a protective membrane covering.
Gentle ventilation
A lung-protective ventilation strategy for neonates that uses low tidal volumes, permissive hypercapnia, and minimal mean airway pressures to reduce ventilator-induced lung injury while maintaining acceptable gas exchange.
Geometric standard deviation (GSD)
A statistical measure of the spread or variability of particle sizes in an aerosol distribution. A GSD of 1.0 indicates a monodisperse (uniform) aerosol; values greater than 1.22 indicate a heterodisperse (variable) aerosol.
Germinal matrix
A highly vascularized region of the developing brain located in the subependymal zone of the lateral ventricles in premature infants. Its fragile capillary network is the source of intraventricular hemorrhage (IVH), the risk decreasing after 32 weeks.
Glasgow Coma Scale (GCS)
A neurological assessment tool that evaluates the level of consciousness by scoring three components: eye opening (1-4), verbal response (1-5), and motor response (1-6), with scores ranging from 3 (deep coma) to 15 (fully alert).
Glenn procedure
A palliative cardiac surgical procedure (bidirectional cavopulmonary shunt) in which the superior vena cava is connected directly to the right pulmonary artery, used as an intermediate stage in the management of single-ventricle heart defects.
Global Lung Initiative (GLI)
An international collaborative project that developed multi-ethnic reference equations for spirometry, providing standardized normal values for forced expiratory volume (FEV1), forced vital capacity (FVC), and other pulmonary function parameters across diverse populations.
Group B Streptococcus (GBS)
Streptococcus agalactiae, a gram-positive bacterium that colonizes the maternal genital and gastrointestinal tracts and is a leading cause of early-onset neonatal sepsis, pneumonia, and meningitis. Intrapartum antibiotic prophylaxis is used to prevent transmission.
Grunting
A characteristic sound produced by a neonate exhaling against a partially closed glottis, creating positive end-expiratory pressure to prevent alveolar collapse. It is a sign of respiratory distress and is seen in conditions such as RDS and pneumonia.
H23 terms
Head bobbing
A sign of increased work of breathing in infants in which the head moves up and down with each breath due to the use of the sternocleidomastoid and other accessory muscles of respiration, indicating significant respiratory distress.
HFMEA (Healthcare Failure Mode and Effects Analysis)
A proactive risk assessment tool adapted for healthcare settings that systematically evaluates processes to identify potential failure modes, assess their impact on patient safety, and develop strategies to eliminate or mitigate identified risks.
High-frequency percussive ventilation (HFPV)
A mode of mechanical ventilation that delivers small, rapid bursts of gas (percussive breaths) at high frequencies superimposed on conventional pressure-limited breaths, providing both ventilation and secretion mobilization simultaneously.
High-frequency ventilation (HFV)
A mechanical ventilation strategy that delivers very small tidal volumes at rates greater than 150 breaths per minute (typically 300-900 bpm), reducing the risk of volutrauma and barotrauma while maintaining adequate gas exchange through enhanced gas mixing.
High position (UAC)
The recommended placement of an umbilical arterial catheter (UAC) with the tip positioned between thoracic vertebrae T6 and T8, above the diaphragm, to minimize the risk of renal and mesenteric artery vasospasm.
HRO (High Reliability Organization)
An organization that operates in complex, high-hazard domains while maintaining consistently safe operations through a culture of preoccupation with failure, reluctance to simplify, sensitivity to operations, commitment to resilience, and deference to expertise.
Hila (Hilum)
The medial aspect of each lung where the bronchi, pulmonary arteries and veins, lymphatics, and nerves enter and exit. On chest radiograph, the hila appear as shadows created by the pulmonary vasculature and lymph nodes.
Hirsutism
Excessive growth of dark, coarse hair in androgen-dependent areas (face, chest, back, abdomen) in females, often caused by elevated androgen levels from conditions such as polycystic ovary syndrome or congenital adrenal hyperplasia.
Home assessment
An evaluation of the home environment conducted before discharge of a medically complex infant (especially those requiring home oxygen or monitoring) to ensure adequate resources, safety, caregiver competency, and appropriate follow-up services are in place.
Horizontal fissure
An anatomical landmark on the right lung that separates the right upper lobe from the right middle lobe, extending from the oblique fissure anteriorly to the lung border at approximately the level of the fourth costal cartilage.
HIV (Human Immunodeficiency Virus)
A retrovirus that attacks CD4+ T lymphocytes, leading to progressive immune deficiency. Perinatal transmission can occur in utero, during delivery, or through breastfeeding; antiretroviral therapy during pregnancy significantly reduces mother-to-child transmission.
Humidified high-flow nasal oxygen
A non-invasive respiratory support modality that delivers heated and humidified oxygen at flow rates exceeding the patient's inspiratory demand through nasal cannulae, providing a low level of continuous positive airway pressure and reducing work of breathing.
Hydrofluoroalkane (HFA)
An environmentally safer propellant (replacing chlorofluorocarbons) used in pressurized metered-dose inhalers to generate the aerosol for drug delivery. HFA propellants produce a softer, warmer spray with a smaller particle size distribution.
Hydrops fetalis
A serious fetal condition characterized by abnormal accumulation of fluid in two or more body compartments (ascites, pleural effusion, pericardial effusion, skin edema). It may be immune (Rh incompatibility) or non-immune (cardiac, chromosomal, infectious causes).
Hygromas (Cystic hygroma)
Congenital malformations of the lymphatic system presenting as soft, fluid-filled masses, most commonly found in the posterior triangle of the neck. They are often detected prenatally on ultrasound and may be associated with chromosomal abnormalities such as Turner syndrome.
Hyperinflation therapy
A respiratory technique involving the delivery of breaths larger than the patient's normal tidal volume using a manual resuscitation bag or ventilator to recruit collapsed alveoli, improve gas exchange, and facilitate secretion mobilization.
Hypertonic
A solution with a higher osmolarity than body fluids (greater than approximately 310 mOsm/L). Hypertonic saline (3-7%) is used in respiratory care to induce sputum production, improve mucociliary clearance, and reduce airway edema.
Hypochloremic metabolic alkalosis
An acid-base disturbance characterized by elevated blood pH and bicarbonate concentration with decreased serum chloride levels, commonly caused by prolonged nasogastric suctioning, diuretic use, or persistent vomiting (e.g., pyloric stenosis in infants).
Hypoplastic left heart syndrome (HLHS)
A severe congenital heart defect in which the left-sided cardiac structures (mitral valve, left ventricle, aortic valve, ascending aorta) are critically underdeveloped, rendering the left ventricle incapable of supporting systemic circulation. Requires staged surgical palliation.
HPA axis (Hypothalamic-pituitary-adrenal axis)
A complex neuroendocrine feedback system involving the hypothalamus, pituitary gland, and adrenal glands that regulates cortisol production and the body's response to stress. Chronic corticosteroid use can suppress this axis.
Hypothermia
A core body temperature below 35 degrees Celsius (95 degrees Fahrenheit). In neonates, hypothermia significantly increases oxygen consumption, metabolic acidosis, and mortality risk. Therapeutic hypothermia (33.5 degrees Celsius) is used to treat hypoxic-ischemic encephalopathy.
Hypoxemia
An abnormally low level of oxygen in the arterial blood, defined as a PaO2 less than 60 mmHg or an arterial oxygen saturation less than 90%. It may result from hypoventilation, V/Q mismatch, shunt, diffusion impairment, or low inspired oxygen.
Hypoxia
A condition in which the body tissues or a specific region does not receive an adequate supply of oxygen to meet metabolic demands. It can result from hypoxemia, anemia, impaired circulation, or cellular inability to utilize oxygen.
I10 terms
Ileus
A temporary cessation of normal intestinal peristalsis in the absence of mechanical obstruction, resulting in abdominal distension, vomiting, and inability to pass flatus or stool. In neonates, it may be associated with sepsis, NEC, or electrolyte imbalances.
Impulse oscillometry (IOS)
A non-effort-dependent pulmonary function testing technique that uses sound waves (oscillations) superimposed on tidal breathing to measure respiratory system resistance and reactance, particularly useful in young children unable to perform spirometry.
Indirect calorimeter
A device that measures oxygen consumption (VO2) and carbon dioxide production (VCO2) through analysis of inspired and expired gases to calculate resting energy expenditure, respiratory quotient, and substrate utilization for nutritional assessment.
Inhaled mass
The total amount (mass) of aerosolized drug that is actually inhaled by the patient during aerosol therapy, representing the portion of the nominal dose that enters the respiratory tract and is available for deposition.
Inhaled nitric oxide (iNO)
A selective pulmonary vasodilator administered by inhalation at concentrations of 5-20 ppm to treat persistent pulmonary hypertension of the newborn (PPHN) and hypoxic respiratory failure by relaxing pulmonary vascular smooth muscle and improving V/Q matching.
IPAP (Inspiratory Positive Airway Pressure)
The higher pressure level delivered during the inspiratory phase of bilevel positive airway pressure (BiPAP) ventilation, providing ventilatory support by augmenting tidal volume and reducing work of breathing.
IOM (Institute of Medicine)
Now the National Academy of Medicine, an independent organization that provides evidence-based recommendations on public health and medical practice, including landmark reports on medical errors (To Err Is Human) and quality improvement (Crossing the Quality Chasm).
Intimal mounds
Small proliferative cushions of intimal tissue found in neonatal pulmonary arterioles that contribute to the physiologic elevation of pulmonary vascular resistance at birth and normally regress as the pulmonary vasculature remodels postnatally.
IUGR (Intrauterine growth restriction)
A condition in which a fetus fails to achieve its expected growth potential in utero, resulting in an estimated fetal weight below the 10th percentile for gestational age. Causes include placental insufficiency, maternal hypertension, infections, and chromosomal anomalies.
IVH (Intraventricular hemorrhage)
Bleeding into the cerebral ventricles, graded I-IV by severity, most commonly occurring in premature infants due to the fragility of the germinal matrix vasculature. Higher grades (III-IV) carry significant risk of neurodevelopmental impairment and hydrocephalus.
J1 term
Just culture
A healthcare organizational philosophy that distinguishes between human error (consoled), at-risk behavior (coached), and reckless behavior (disciplined), promoting open reporting of safety events without fear of punitive action for unintentional mistakes.
K2 terms
Kaizen
A Japanese quality improvement philosophy meaning 'change for the better,' applied in healthcare to encourage continuous, incremental process improvements involving all staff members at every level of the organization.
Kyphosis
An excessive outward curvature of the thoracic spine, producing a rounded or hunched appearance of the upper back. Severe kyphosis can restrict lung expansion and impair respiratory function by reducing thoracic volume.
L19 terms
Lamellar bodies
Intracellular organelles within type II alveolar cells that store and secrete pulmonary surfactant. The lamellar body count in amniotic fluid is used as a marker of fetal lung maturity; counts above 50,000/microliter suggest mature lungs.
Laminaria tent
A device made from dried seaweed (Laminaria japonicum) or synthetic material inserted into the cervical canal, where it absorbs moisture and gradually expands to achieve slow, atraumatic cervical dilation for induction of labor or surgical procedures.
Lanugo
Fine, soft, unpigmented hair that covers the body of the fetus beginning around 16 weeks of gestation. It is typically shed by 36-40 weeks; its presence at birth suggests prematurity.
Laryngeal web
A congenital or acquired membrane of tissue that spans part or all of the laryngeal lumen, most commonly at the level of the vocal cords (glottis), causing varying degrees of airway obstruction and voice abnormalities ranging from hoarseness to aphonia.
Laryngomalacia
The most common congenital laryngeal anomaly, characterized by supraglottic collapse during inspiration due to immature or flaccid laryngeal cartilages, causing inspiratory stridor that typically worsens with feeding and resolves by 12-18 months of age.
Lean method
A quality improvement methodology adapted from the Toyota Production System that focuses on eliminating waste (non-value-added steps), improving workflow efficiency, and enhancing patient value in healthcare processes.
Left-to-right shunt
An abnormal blood flow pattern in which oxygenated blood from the left side of the heart or systemic circulation crosses to the right side through a defect (e.g., VSD, ASD, PDA), resulting in increased pulmonary blood flow and potential heart failure.
Leukocytosis
An elevated white blood cell count, generally defined as greater than 25,000/microliter in neonates. It may indicate bacterial infection, stress response, or leukemoid reaction, though normal neonatal WBC ranges are higher than in older children and adults.
Leukopenia
An abnormally low white blood cell count, generally less than 3,500/microliter, indicating decreased bone marrow production or increased peripheral destruction. In neonates, leukopenia may be a sign of overwhelming sepsis and carries a poor prognosis.
Listeria monocytogenes
A gram-positive, facultatively anaerobic bacterium that can cause severe neonatal infection (sepsis, meningitis, pneumonia) acquired in utero via transplacental transmission from maternal ingestion of contaminated foods (soft cheeses, deli meats, unpasteurized dairy).
LBW infant (Low Birth Weight)
An infant with a birth weight of less than 2,500 grams (approximately 5.5 pounds) regardless of gestational age. LBW may result from preterm birth, intrauterine growth restriction, or a combination of both.
Lower airway
The portion of the respiratory tract below the larynx, including the trachea, main bronchi, lobar bronchi, segmental bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, and alveoli.
Lower inflection point (LIP)
The point on the pressure-volume curve of the respiratory system where compliance begins to improve, indicating the pressure at which significant alveolar recruitment begins. It is used to guide optimal PEEP settings during mechanical ventilation.
Low-flow oxygen
Supplemental oxygen delivered at flow rates less than or equal to 2 liters per minute through a nasal cannula, providing a variable FiO2 depending on the patient's respiratory pattern. It is the most common method of oxygen supplementation.
Low-frequency ventilation
Mechanical ventilation delivered at rates less than 150 breaths per minute, encompassing conventional ventilation modes (assist control, SIMV, pressure support) as distinguished from high-frequency ventilation strategies.
Low position (UAC)
Placement of an umbilical arterial catheter (UAC) with the tip positioned between lumbar vertebrae L3 and L4, below the aortic bifurcation origin of renal arteries, as an alternative to the high position when high placement is not achievable.
Low tidal volume ventilation
A lung-protective mechanical ventilation strategy that uses tidal volumes of 4-6 mL/kg of ideal body weight to minimize alveolar overdistension (volutrauma) and reduce the risk of ventilator-induced lung injury, particularly in patients with ARDS.
Lung compliance
A measure of the lung's ability to expand in response to a change in pressure, expressed as the change in volume per unit change in transpulmonary pressure (mL/cmH2O). Decreased compliance indicates stiffer lungs, as seen in RDS, pulmonary fibrosis, and ARDS.
Lung transplantation
A surgical procedure in which one or both diseased lungs are replaced with healthy lungs from a deceased donor, considered for end-stage lung diseases such as cystic fibrosis, idiopathic pulmonary fibrosis, and pulmonary hypertension unresponsive to medical therapy.
M29 terms
Macrosomia
A condition in which a newborn has an excessively high birth weight, generally defined as greater than 4,000 grams (8 pounds 13 ounces) or above the 90th percentile for gestational age. It is associated with maternal diabetes, obesity, and birth injuries.
Mainstream capnography
A method of continuous CO2 monitoring in which the infrared sensor is placed directly in the ventilator circuit (in-line) at the airway adapter, providing real-time breath-by-breath measurement of end-tidal CO2 without gas sampling.
Major fissures (Oblique fissures)
The primary anatomical divisions of the lungs: the oblique fissure separates the upper and lower lobes of the left lung, and separates the upper/middle lobes from the lower lobe of the right lung.
Malpractice
Professional negligence by a healthcare provider in which treatment falls below the accepted standard of care, resulting in harm or injury to the patient. It requires proof of duty, breach, causation, and damages.
Mass effect
The displacement or compression of adjacent structures by a space-occupying lesion such as a tumor, hemorrhage, abscess, or tension pneumothorax, potentially compromising blood flow, airway patency, or organ function.
MMAD (Mass Median Aerodynamic Diameter)
The aerodynamic diameter at which 50% of the aerosol mass is contained in smaller particles and 50% in larger particles. An MMAD of 1-5 micrometers is optimal for lower respiratory tract deposition.
Maximal respiratory pressures (MIP/MEP)
Measurements of maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP) generated by the respiratory muscles against an occluded airway, used to assess respiratory muscle strength and predict weaning readiness.
Medial basal segment
One of the five bronchopulmonary segments of the lower lobe of the right lung (and four in the left), situated medially and bordered by the cardiac impression, supplied by a segmental bronchus from the right lower lobe bronchus.
Medical errors
Preventable adverse events or near-misses in healthcare resulting from failures in planning or execution of a plan of care, including medication errors, diagnostic errors, procedural mistakes, communication failures, and system-level breakdowns.
Medical home
A model of primary care delivery that provides comprehensive, coordinated, patient-centered, accessible care with a sustained partnership between the patient/family and their personal physician, emphasizing continuity and quality improvement.
Medication reconciliation
The process of comparing a patient's current medication orders against all medications the patient has been taking to identify and resolve discrepancies, typically performed at transitions of care (admission, transfer, discharge).
MAS (Meconium Aspiration Syndrome)
A respiratory condition occurring when a newborn aspirates meconium-stained amniotic fluid into the lungs, causing airway obstruction, chemical pneumonitis, surfactant inactivation, and persistent pulmonary hypertension, typically in term or post-term infants.
Mesoderm
The middle of the three primary germ layers formed during gastrulation that gives rise to the musculoskeletal system, circulatory system, urogenital system, connective tissues, and the serous linings of body cavities.
Metabolic rate
The rate at which the body converts chemical energy from nutrients into heat and mechanical work, expressed as calories per unit time. Basal metabolic rate (BMR) represents the minimum energy required to maintain vital functions at rest.
Methemoglobin
An oxidized form of hemoglobin in which the iron molecule is in the ferric (Fe3+) state rather than the normal ferrous (Fe2+) state, rendering it unable to bind and transport oxygen. Levels above 1-2% are considered abnormal.
Methemoglobinemia
A condition characterized by elevated levels of methemoglobin in the blood (>1-2%), causing functional anemia and tissue hypoxia. It may be congenital or acquired (from exposure to nitric oxide therapy, dapsone, local anesthetics, or nitrites).
Micrognathia
An abnormally small lower jaw (mandible) that may cause airway obstruction by posterior displacement of the tongue, particularly in neonates. It is associated with Pierre Robin sequence, Treacher Collins syndrome, and other craniofacial anomalies.
Microvascular permeability
The ability of the walls of small blood vessels (capillaries and post-capillary venules) to allow the passage of fluid, proteins, and cells into the interstitial space. Increased permeability is a hallmark of inflammation and contributes to pulmonary edema.
Midline catheter
A peripheral intravenous catheter (8-20 cm in length) inserted into a vein of the upper arm with the tip positioned below the axillary vein, providing intermediate-duration venous access (1-4 weeks) for non-vesicant infusions.
Minimal leakage technique
A method of endotracheal tube cuff inflation in which the cuff is inflated until no air leak is heard during positive pressure ventilation, then a small amount of air is removed until a minimal audible leak is detected at peak inspiration.
Mitochondrial myopathy
A group of neuromuscular disorders caused by dysfunction of the mitochondrial respiratory chain, resulting in impaired energy production and affecting primarily tissues with high metabolic demands such as skeletal muscle, brain, and heart.
SvO2 (Mixed venous oxygen saturation)
The oxygen saturation of hemoglobin in blood returning to the right side of the heart (pulmonary artery), normally 60-80%. It reflects the balance between oxygen delivery and consumption and is used to assess global tissue oxygenation.
Mode of ventilation
The specific pattern of breath delivery during mechanical ventilation, defined by the trigger variable (time or patient effort), control variable (pressure or volume), cycling criteria, and relationship between mandatory and spontaneous breaths.
Morbidity
The incidence or prevalence of disease, illness, or complications within a population. In neonatology, common morbidities include BPD, IVH, NEC, ROP, and neurodevelopmental impairment.
Mortality
The incidence of death within a population over a specified time period, expressed as a rate (e.g., deaths per 1,000 live births). Neonatal mortality specifically refers to deaths within the first 28 days of life.
MDRO (Multidrug-resistant organism)
A microorganism (bacterium, virus, or fungus) that has developed resistance to multiple antimicrobial agents, making infections difficult to treat. Examples include MRSA, VRE, ESBL-producing organisms, and carbapenem-resistant Enterobacteriaceae.
Myasthenia gravis
An autoimmune neuromuscular disorder caused by antibodies against acetylcholine receptors at the neuromuscular junction, resulting in fluctuating muscle weakness and fatigability. Neonatal myasthenia may occur transiently due to maternal antibody transfer.
Myopathy
A broad term for any disease of muscle tissue, characterized by muscle weakness, cramping, stiffness, or spasm. Congenital myopathies presenting in neonates can cause hypotonia, feeding difficulties, and respiratory insufficiency.
Myotonic dystrophy
A genetic (autosomal dominant) multisystem disorder characterized by progressive muscle wasting and weakness with myotonia (delayed relaxation after contraction). The congenital form presents with severe hypotonia, respiratory failure, and feeding difficulties at birth.
N14 terms
NG tube (Nasogastric tube)
A flexible tube inserted through the nose, passed down the esophagus, and into the stomach for enteral feeding, medication administration, or gastric decompression. Proper placement is verified by radiograph or pH testing of aspirate.
NAS (Neonatal Abstinence Syndrome)
A withdrawal syndrome occurring in newborns exposed to addictive substances (most commonly opioids) in utero, presenting with irritability, tremors, high-pitched cry, feeding difficulties, seizures, and autonomic instability. Scored using the Finnegan Neonatal Abstinence Scale.
NICU (Neonatal Intensive Care Unit)
A specialized hospital unit equipped with advanced technology and staffed by neonatologists, neonatal nurses, and respiratory therapists to provide comprehensive critical care for premature, low-birth-weight, and critically ill newborn infants.
Neonatology
A subspecialty of pediatrics devoted to the medical care of newborn infants, particularly those who are premature, low birth weight, or critically ill, typically encompassing the first 28 days of life (neonatal period).
Nephrocalcinosis
The deposition of calcium salts in the renal parenchyma, commonly seen in premature infants receiving prolonged furosemide therapy or parenteral nutrition. It may lead to impaired renal function and is detected by renal ultrasound.
Neurodevelopmental
Pertaining to the growth and maturation of the central nervous system and the acquisition of developmental milestones (motor, cognitive, language, social). Neurodevelopmental follow-up is critical for high-risk NICU graduates.
Neurofibromatosis
A group of genetic disorders (NF1 and NF2) characterized by the growth of tumors on nerve tissue. NF1 (von Recklinghausen disease) presents with cafe-au-lait spots, neurofibromas, and skeletal abnormalities. It may be associated with pulmonary involvement.
NMBA (Neuromuscular blocking agent)
A class of medications (e.g., vecuronium, pancuronium, rocuronium) that block neuromuscular transmission at the motor end plate to produce skeletal muscle paralysis, used in neonates to facilitate mechanical ventilation or surgical procedures.
Neuroplasticity
The brain's ability to reorganize its structure and function in response to experience, injury, or environmental stimuli. It is particularly robust in neonates and young infants, forming the basis for early intervention and rehabilitation programs.
Neutropenia
An abnormally low absolute neutrophil count (ANC), typically less than 1,500/microliter (or <500 for severe neutropenia), increasing susceptibility to bacterial and fungal infections. In neonates, it may indicate sepsis, maternal preeclampsia, or bone marrow suppression.
NO (Nitric oxide)
A naturally occurring gaseous signaling molecule produced by endothelial cells that causes vascular smooth muscle relaxation. When administered by inhalation (iNO), it acts as a selective pulmonary vasodilator without systemic effects.
NIV (Non-invasive ventilation)
Ventilatory support delivered without an endotracheal tube or tracheostomy, using interfaces such as nasal prongs, nasal masks, or full-face masks. Modalities include CPAP, BiPAP, NIPPV, and high-flow nasal cannula.
NST (Non-stress test)
A prenatal assessment that monitors fetal heart rate in response to fetal movement using external cardiotocography. A reactive (normal) NST shows two or more accelerations of at least 15 bpm lasting 15 seconds within a 20-minute window.
Norwood procedure
The first stage of surgical palliation for hypoplastic left heart syndrome, performed in the first week of life, which reconstructs the aorta using the pulmonary artery, creates a reliable source of pulmonary blood flow, and ensures unobstructed systemic outflow.
O11 terms
Oblique fissure
The major fissure present in both lungs that separates the lower lobe from the upper lobe (left lung) or from both the upper and middle lobes (right lung), running obliquely from the posterior aspect superiorly to the anterior aspect inferiorly.
Oligohydramnios
A deficiency of amniotic fluid (amniotic fluid index <5 cm or deepest vertical pocket <2 cm), associated with fetal renal anomalies, IUGR, post-term pregnancy, PROM, and placental insufficiency. It can cause pulmonary hypoplasia and limb deformities.
Omphalocele
A congenital midline abdominal wall defect in which abdominal contents (intestines, liver, other organs) herniate into the base of the umbilical cord, covered by a protective membrane (peritoneum and amnion). Often associated with chromosomal and cardiac anomalies.
Open lung strategy
A mechanical ventilation approach that uses recruitment maneuvers and optimized PEEP to open collapsed alveoli and maintain them open throughout the respiratory cycle, minimizing atelectrauma while avoiding overdistension.
Oxygen consumption (VO2)
The volume of oxygen utilized by the body per minute, reflecting metabolic demand. Normal neonatal oxygen consumption is approximately 6-8 mL/kg/min, higher than adults due to the relatively higher metabolic rate.
Oxygen delivery (DO2)
The total amount of oxygen transported from the lungs to the peripheral tissues per minute, calculated as the product of cardiac output and arterial oxygen content (CaO2). Adequate oxygen delivery is essential to meet tissue metabolic demands.
Oxygen hood
A clear plastic enclosure placed over an infant's head to deliver a controlled concentration of humidified oxygen, allowing precise FiO2 regulation without direct nasal or oral interface. It provides oxygen without positive pressure.
Oxygen therapy
The administration of supplemental oxygen at concentrations greater than ambient air (21%) to treat or prevent hypoxemia, using delivery devices ranging from nasal cannula and oxygen hood to CPAP and mechanical ventilation.
Oxygenation index (OI)
A calculated measure of oxygenation impairment defined as (FiO2 x mean airway pressure x 100) / PaO2. An OI greater than 25 indicates severe hypoxemic respiratory failure, and values above 40 may indicate the need for ECMO.
Oxyhemoglobin
Hemoglobin that is bound to oxygen (HbO2), giving arterial blood its bright red color. The percentage of hemoglobin in this form is measured by pulse oximetry (SpO2) and reported as oxygen saturation on arterial blood gas analysis (SaO2).
Oxytocin
A hormone produced by the hypothalamus and released from the posterior pituitary gland that stimulates uterine contractions during labor and promotes milk ejection (let-down reflex) during breastfeeding. Synthetic oxytocin (Pitocin) is used for labor induction.
P59 terms
Papilledema
Swelling of the optic disc caused by increased intracranial pressure, visible on fundoscopic examination. In neonates and infants, it may be a sign of hydrocephalus, intracranial hemorrhage, or meningitis.
Parenteral
A route of medication or nutrition administration that bypasses the gastrointestinal tract, including intravenous, intramuscular, subcutaneous, and intradermal delivery. Parenteral nutrition (TPN) provides nutrients directly into the bloodstream.
Parietal pleura
The outer layer of the pleural membrane that lines the inner surface of the thoracic cavity, diaphragm, and mediastinum. It is richly innervated with somatic nerves, making pleural inflammation (pleurisy) painful.
PaCO2 (Partial pressure of carbon dioxide in arterial blood)
The measure of carbon dioxide dissolved in arterial blood, normally 35-45 mmHg. Elevated PaCO2 (hypercapnia) indicates hypoventilation or increased CO2 production; decreased PaCO2 (hypocapnia) indicates hyperventilation.
PaO2 (Partial pressure of oxygen in arterial blood)
The measure of oxygen dissolved in arterial blood, normally 80-100 mmHg in room air. It reflects the efficiency of pulmonary gas exchange; values below 60 mmHg define hypoxemia and indicate the need for supplemental oxygen.
PDA (Patent Ductus Arteriosus)
A congenital cardiac condition in which the ductus arteriosus (a fetal blood vessel connecting the pulmonary artery to the aorta) fails to close after birth, resulting in a left-to-right shunt and increased pulmonary blood flow. Common in premature infants.
Pectus carinatum
A congenital chest wall deformity in which the sternum protrudes anteriorly, creating a 'pigeon chest' appearance. It rarely affects cardiopulmonary function but may cause cosmetic concerns and chest discomfort.
Pedunculated
Attached by a narrow stalk or pedicle, as opposed to sessile (broad-based). The term is used to describe polyps, tumors, or other growths that project from a surface and are connected by a stalk of tissue.
PALS (Pediatric Advanced Life Support)
An American Heart Association certification course that teaches healthcare providers a systematic approach to pediatric assessment, recognition, and management of respiratory emergencies, shock, cardiac arrest, and arrhythmias in infants and children.
PEFR (Peak Expiratory Flow Rate)
The maximum speed of expiration measured during a forced exhalation, used to monitor airway obstruction in asthma. It is measured with a peak flow meter and compared to personal best or predicted values.
PIP (Peak Inspiratory Pressure)
The highest pressure measured in the airway during the inspiratory phase of mechanical ventilation. Excessive PIP increases the risk of barotrauma and volutrauma; lung-protective strategies aim to minimize PIP.
Pericardial effusion
An abnormal accumulation of fluid in the pericardial sac surrounding the heart, which may cause hemodynamic compromise (cardiac tamponade) if the fluid accumulates rapidly or in large volume, compressing the heart chambers.
Perinatal
The period surrounding birth, generally defined as from 22 weeks of gestation (or viability) through 7 days after birth. Perinatal medicine addresses the care of both the mother and the fetus/neonate during this critical period.
PICC (Peripherally Inserted Central Catheter)
A long, thin catheter inserted through a peripheral vein (usually in the arm) and advanced until the tip lies in a central vein (superior vena cava), providing reliable central venous access for prolonged IV therapy, TPN, and blood sampling.
PAD (Peripheral Arterial Disease)
A circulatory condition in which narrowed arteries reduce blood flow to the extremities, most commonly the legs. In neonates, peripheral arterial compromise may occur from catheter-related vasospasm or thrombosis.
Peripheral cyanosis
A bluish discoloration of the extremities (hands and feet) caused by increased oxygen extraction in poorly perfused peripheral tissues, while central oxygen saturation remains adequate. It is common and often benign in newborns (acrocyanosis).
Permissive hypercapnia
A ventilatory strategy that accepts higher-than-normal PaCO2 levels (typically 45-55 mmHg) to allow the use of lower tidal volumes and airway pressures, reducing the risk of ventilator-induced lung injury while maintaining an acceptable pH (>7.25).
PPHN (Persistent Pulmonary Hypertension of the Newborn)
A condition in which pulmonary vascular resistance remains abnormally elevated after birth, causing right-to-left shunting through the foramen ovale and/or ductus arteriosus, resulting in severe hypoxemia refractory to supplemental oxygen.
Pharyngeal
Pertaining to the pharynx (throat), the musculomembranous passage extending from the base of the skull to the esophagus, serving as a common pathway for both the respiratory and digestive systems.
Pharmacodynamics
The study of the biochemical and physiological effects of drugs on the body, including mechanisms of action, dose-response relationships, therapeutic effects, and adverse reactions at the receptor and cellular level.
Pharmacokinetics
The study of how the body processes drugs, encompassing absorption, distribution, metabolism (biotransformation), and excretion (ADME). Neonatal pharmacokinetics differs significantly from adults due to immature organ systems.
Pharmacology
The scientific discipline concerned with the study of drugs, including their composition, properties, mechanisms of action, therapeutic uses, toxicology, and interactions with biological systems.
Pharyngitis
Inflammation of the pharynx causing sore throat, typically caused by viral or bacterial (Group A Streptococcus) infection. Symptoms include throat pain, difficulty swallowing, erythema, and exudates on the pharyngeal mucosa.
Phlebitis
Inflammation of a vein, characterized by pain, redness, warmth, and swelling along the course of the affected vessel. It commonly occurs at peripheral IV insertion sites and may be mechanical, chemical, or infectious in origin.
Physiologic dead space
The total volume of gas in the respiratory system that does not participate in gas exchange, comprising anatomic dead space (conducting airways) plus alveolar dead space (ventilated but unperfused alveoli). Normally equals approximately 2 mL/kg.
Physiologic shunt
The portion of cardiac output that passes through the lungs without participating in gas exchange, including blood flowing through non-ventilated alveoli (true shunt) and blood in the bronchial and thebesian circulations. Normally 2-5% of cardiac output.
Picrotoxin
A non-competitive GABA receptor antagonist and central nervous system stimulant that has been studied as a potential respiratory stimulant for neonatal apnea, though it is not in routine clinical use due to its narrow therapeutic index.
Piperacillin
A broad-spectrum semisynthetic penicillin antibiotic with activity against gram-negative organisms including Pseudomonas aeruginosa, commonly combined with tazobactam (a beta-lactamase inhibitor) for treatment of serious neonatal and pediatric infections.
Pleurisy (Pleuritis)
Inflammation of the pleural membranes causing sharp, stabbing chest pain that worsens with breathing or coughing. It may result from infection, autoimmune disease, pulmonary embolism, or as a complication of pneumonia.
Pneumomediastinum
The presence of free air in the mediastinal space, often resulting from alveolar rupture with air tracking along bronchovascular sheaths. It may present as chest pain, subcutaneous emphysema, and a crunching sound with heartbeats (Hamman sign).
Pneumonia
An infection of the lung parenchyma causing inflammation and consolidation of the alveoli with inflammatory exudate. In neonates, it may be acquired congenitally, during delivery, or postnatally, and is a significant cause of neonatal sepsis and mortality.
Pneumopericardium
The presence of air within the pericardial sac, a potentially life-threatening air leak complication of mechanical ventilation in neonates. It may cause cardiac tamponade requiring emergency pericardiocentesis.
Pneumoretroperitoneum / Pneumoperitoneum
Pneumoperitoneum is the presence of free air in the peritoneal cavity, often indicating bowel perforation (e.g., from NEC). Pneumoretroperitoneum is air in the retroperitoneal space, which may result from duodenal perforation or tracking of mediastinal air.
Pneumothorax
The accumulation of air in the pleural space between the visceral and parietal pleura, causing partial or complete lung collapse. It may be spontaneous, traumatic, or iatrogenic (complication of mechanical ventilation or central line placement).
Poliomyelitis
An infectious disease caused by the poliovirus that attacks motor neurons in the spinal cord, potentially causing irreversible paralysis and respiratory failure. Vaccination has largely eradicated this disease in most of the world.
Polyhydramnios
Excessive amniotic fluid (amniotic fluid index >24 cm or deepest vertical pocket >8 cm), associated with fetal conditions that impair swallowing (esophageal atresia, neurological disorders), increased fetal urine output (diabetes), or idiopathic causes.
Portal hypertension
Elevated pressure in the hepatic portal venous system (>5 mmHg), most commonly caused by cirrhosis. It leads to complications including esophageal varices, splenomegaly, and ascites. In children, it may result from cystic fibrosis or biliary atresia.
Position
In respiratory care, the therapeutic arrangement of a patient's body to optimize ventilation-perfusion matching, promote secretion drainage, reduce work of breathing, or improve comfort. Includes prone, supine, lateral, and upright positions.
PEP therapy (Positive Expiratory Pressure therapy)
An airway clearance technique in which the patient exhales against a fixed or oscillating resistance (10-20 cmH2O), splinting airways open to promote collateral ventilation behind mucus plugs and facilitating secretion mobilization.
Postductal
Referring to the region of the aorta distal (downstream) to the insertion of the ductus arteriosus, typically supplied by the descending aorta. Postductal blood may have lower oxygen saturation when right-to-left ductal shunting is present.
Postductal oxygen saturation
Oxygen saturation measured from a site supplied by blood distal to the ductus arteriosus, typically the lower extremities (foot). A difference of greater than 5-10% between pre- and postductal saturations suggests right-to-left ductal shunting.
Potter's syndrome
A pattern of abnormalities resulting from severe oligohydramnios, characterized by pulmonary hypoplasia, limb deformities, and distinctive facial features (flattened nose, recessed chin, low-set ears). It is commonly caused by bilateral renal agenesis.
Precipitous delivery
An extremely rapid labor and delivery lasting less than 3 hours from onset of contractions to birth, which may result in complications including maternal lacerations, uterine atony, neonatal trauma, hypothermia, and inadequate preparation for resuscitation.
Precursor
A substance from which another is formed through a chemical or biological process. In pulmonary medicine, phospholipid precursors such as choline and glycerol are necessary for surfactant synthesis by type II alveolar cells.
Preductal
Referring to the region of the aorta proximal (upstream) to the insertion of the ductus arteriosus, supplied by the ascending aorta and aortic arch branches. Preductal blood typically has higher oxygen saturation than postductal blood when ductal shunting exists.
Preductal oxygen saturation
Oxygen saturation measured from a site supplied by blood proximal to the ductus arteriosus, typically the right hand or right upper extremity. It is used in the pre/postductal saturation comparison to assess for ductal shunting.
Preeclampsia
A pregnancy-specific hypertensive disorder characterized by new-onset hypertension (blood pressure >140/90 mmHg) and proteinuria or other end-organ dysfunction after 20 weeks of gestation, potentially leading to eclampsia, HELLP syndrome, and fetal compromise.
Premature delivery
Birth occurring before 37 completed weeks of gestation. Classified as late preterm (34-36 weeks), moderately preterm (32-33 weeks), very preterm (28-31 weeks), and extremely preterm (<28 weeks). It is the leading cause of neonatal morbidity and mortality.
PROM (Premature Rupture of Membranes)
Rupture of the fetal membranes (amniotic sac) before the onset of labor. Preterm PROM (PPROM) occurs before 37 weeks and is associated with increased risk of infection (chorioamnionitis), cord prolapse, placental abruption, and preterm delivery.
Pressure ventilation
A mode of mechanical ventilation in which the ventilator delivers gas flow until a preset pressure is reached, with the resulting tidal volume varying depending on the patient's lung compliance and airway resistance.
pMDI (Pressurized Metered-Dose Inhaler)
A handheld aerosol device that delivers a precisely measured dose of medication propelled by a liquefied gas (HFA propellant) with each actuation. Use with a spacer/valved holding chamber is recommended for optimal drug delivery.
Primary germ layers
The three fundamental embryonic tissue layers (ectoderm, mesoderm, and endoderm) established during gastrulation from which all body tissues and organs develop. The endoderm gives rise to the respiratory epithelium.
Pulmonary compliance
The measure of the distensibility of the lung tissue, defined as the change in volume per unit change in pressure (mL/cmH2O). Neonatal lung compliance is much lower than adult values, particularly in premature infants with surfactant deficiency.
PE (Pulmonary Embolism)
Obstruction of a pulmonary artery or one of its branches by a blood clot (thrombus), fat, air, or other material that has traveled from another site in the body. It increases dead space ventilation and can cause hemodynamic collapse.
PFTs (Pulmonary Function Tests)
A group of diagnostic tests that measure lung volumes, capacities, flow rates, and gas exchange to assess respiratory function. In neonates and infants, specialized techniques (raised volume RTC, plethysmography) are used due to inability to cooperate.
Pulmonary hypertension
Abnormally elevated pressure in the pulmonary arterial system (mean PAP >20 mmHg), which increases right ventricular afterload and may lead to right heart failure. In neonates, it may be persistent (PPHN) or secondary to lung disease.
Pulmonary surfactant
A complex mixture of phospholipids (primarily dipalmitoylphosphatidylcholine) and surfactant-associated proteins (SP-A, SP-B, SP-C, SP-D) produced by type II alveolar cells that reduces alveolar surface tension, preventing atelectasis at end-expiration.
Pulse oximetry
A non-invasive method of measuring arterial oxygen saturation (SpO2) by detecting the differential absorption of red and infrared light by oxygenated and deoxygenated hemoglobin in pulsatile arterial blood through a sensor placed on the skin.
Pyrexia
An elevation of body temperature above the normal range (>38 degrees Celsius or 100.4 degrees Fahrenheit), commonly known as fever. In neonates, pyrexia may indicate infection, dehydration, or environmental overheating.
Q1 term
Quiet sleep
A behavioral state in neonates characterized by minimal body movements, regular respiration, and absence of eye movements (NREM sleep). During quiet sleep, oxygen consumption and metabolic rate are at their lowest, and respiratory patterns are most regular.
R18 terms
Radiant warmer
An open bed with an overhead radiant heat source used to maintain thermoregulation in neonates, particularly useful during resuscitation, procedures, and initial stabilization when ready access to the infant is needed.
Radiography
A diagnostic imaging technique that uses X-rays to produce images of internal body structures. Chest radiography is the most common imaging study in the NICU for evaluating lung disease, line placement, and cardiopulmonary anatomy.
Receptor
A protein molecule on or within a cell that binds to a specific substance (ligand, neurotransmitter, hormone, drug) and initiates a cellular response. Drug-receptor interactions form the basis of pharmacological therapy.
Reflux (Gastroesophageal reflux)
The retrograde flow of gastric contents into the esophagus. Gastroesophageal reflux (GER) is physiologic in infants; gastroesophageal reflux disease (GERD) occurs when reflux causes troublesome symptoms or complications such as esophagitis, aspiration, or failure to thrive.
Respiratory acidosis
An acid-base disturbance caused by retention of carbon dioxide (elevated PaCO2 >45 mmHg), resulting in a decrease in blood pH (<7.35). It occurs in conditions causing hypoventilation such as respiratory depression, airway obstruction, or severe lung disease.
Respiratory alkalosis
An acid-base disturbance caused by excessive elimination of carbon dioxide (PaCO2 <35 mmHg) through hyperventilation, resulting in elevated blood pH (>7.45). Causes include anxiety, pain, fever, hypoxia, and excessive mechanical ventilation.
Respiratory arrest
The complete cessation of breathing requiring immediate intervention with positive pressure ventilation and/or intubation. Without treatment, respiratory arrest rapidly progresses to cardiac arrest and death.
RDS (Respiratory Distress Syndrome)
A common neonatal lung disease caused by surfactant deficiency in premature infants, characterized by progressive atelectasis, impaired gas exchange, tachypnea, grunting, retractions, and cyanosis. Treated with exogenous surfactant and respiratory support.
RSV (Respiratory Syncytial Virus)
A highly contagious RNA paramyxovirus that is the most common cause of bronchiolitis and pneumonia in infants and young children. Premature infants and those with BPD or congenital heart disease are at highest risk for severe disease.
Reticulocyte
An immature red blood cell that still contains remnants of ribosomal RNA, representing newly released erythrocytes from the bone marrow. The reticulocyte count reflects the rate of erythropoiesis and is used to assess bone marrow response to anemia.
ROP (Retinopathy of Prematurity)
A vasoproliferative disorder of the developing retinal blood vessels in premature infants, primarily caused by oxygen exposure and immature retinal vasculature. Severe cases can lead to retinal detachment and blindness. Screened by ophthalmologic examination.
Retropharyngeal cellulitis
An infection of the retropharyngeal space (the potential space posterior to the pharynx and anterior to the prevertebral fascia), which can progress to retropharyngeal abscess causing airway obstruction and requiring urgent drainage.
Rh isoimmunization
A condition in which an Rh-negative mother develops antibodies against Rh-positive fetal red blood cells after sensitization, potentially causing hemolytic disease of the fetus and newborn (erythroblastosis fetalis) with anemia, jaundice, and hydrops.
Right atrial pressure (RAP)
The blood pressure within the right atrium, reflecting right ventricular preload and central venous pressure (CVP). Normal neonatal RAP is 0-5 mmHg. Elevated RAP may indicate right heart failure, volume overload, or cardiac tamponade.
Right-to-left shunt
An abnormal blood flow pattern in which deoxygenated blood from the right side of the heart crosses to the left side through a defect (e.g., PFO, PDA, VSD) without passing through the pulmonary capillary bed, causing systemic arterial desaturation.
Roller pump
A type of positive displacement pump used in extracorporeal membrane oxygenation (ECMO) and cardiopulmonary bypass circuits that propels blood through tubing by compressing it between rollers rotating on a track, providing continuous non-pulsatile flow.
RCA (Root Cause Analysis)
A structured investigation method used to identify the underlying system-level causes of adverse events or near-misses in healthcare, aiming to develop corrective actions that prevent recurrence rather than assigning individual blame.
Rule of nines
A clinical tool used to estimate the total body surface area (TBSA) affected by burns. In infants, the head represents 18% (not 9% as in adults), and the lower extremities each represent 14%, reflecting the different body proportions of neonates.
S48 terms
Saccules
Primitive thin-walled air spaces that develop during the saccular stage of lung development (26-36 weeks gestation), representing the precursors to mature alveoli. Gas exchange becomes possible during this stage.
Safe harbor
A legal or institutional provision that protects healthcare professionals from disciplinary action when they report in good faith their concerns about unsafe conditions, assignments beyond their competence, or staffing levels that may endanger patients.
Saline lock
An intravenous catheter that is flushed with normal saline and capped (without continuous infusion) to maintain venous access for intermittent medication administration, reducing the need for repeated venipuncture.
Saturation
In respiratory care, the percentage of hemoglobin binding sites occupied by oxygen (oxygen saturation). Arterial saturation (SaO2) is measured by blood gas analysis; peripheral saturation (SpO2) is estimated by pulse oximetry.
Saxagliptin
A dipeptidyl peptidase-4 (DPP-4) inhibitor used as an oral antidiabetic medication to improve glycemic control in type 2 diabetes mellitus by enhancing incretin hormone activity, thereby increasing insulin secretion and decreasing glucagon levels.
Scaphoid abdomen
A concave or sunken appearance of the anterior abdominal wall, seen in neonates with congenital diaphragmatic hernia (CDH) where abdominal contents have herniated into the thorax, and in malnourished or dehydrated infants.
Scapula
The large, flat, triangular bone (shoulder blade) located on the posterior thoracic wall overlying ribs 2-7. It serves as an attachment point for numerous muscles of the upper extremity and is used as a landmark in chest assessment.
Scarlet fever
An illness caused by erythrogenic toxin-producing Group A Streptococcus (GAS) characterized by a diffuse, fine, sandpaper-like erythematous rash, strawberry tongue, pharyngitis, and fever. It is treated with antibiotics to prevent rheumatic heart disease.
Scarring
The formation of fibrous connective tissue (scar tissue) as part of wound healing, replacing normal functional tissue. Pulmonary scarring (fibrosis) can result from chronic inflammation, infection, or ventilator-induced lung injury.
Sclera
The tough, white, opaque outer coat of the eyeball. Scleral icterus (yellowing of the sclera) is an important clinical sign of hyperbilirubinemia/jaundice, and blue sclerae may indicate osteogenesis imperfecta.
Scoliosis
An abnormal lateral curvature of the spine, which when severe can compromise pulmonary function by restricting thoracic expansion and reducing lung volumes, potentially leading to restrictive lung disease and respiratory failure.
Screening
The systematic application of a test or procedure to an apparently healthy population to identify individuals at increased risk for a specific disease or condition, enabling early detection and intervention. Neonatal screening includes hearing, metabolic, and cardiac screens.
Scrotum
The external pouch of skin and muscle that contains the testes, epididymides, and lower portions of the spermatic cords. In premature males, the scrotum may be undeveloped with undescended testes, which is assessed as part of the Ballard score.
Seborrheic dermatitis
A common chronic inflammatory skin condition characterized by erythematous patches with greasy, yellowish scales, often affecting the scalp (cradle cap in infants), face, and skin folds. It is benign and typically self-limited in infancy.
Sedation
The administration of pharmacological agents (e.g., midazolam, fentanyl, morphine, dexmedetomidine) to reduce anxiety, agitation, and pain in critically ill neonates, facilitating tolerance of mechanical ventilation and invasive procedures.
Seizure
A transient episode of abnormal, excessive, or synchronous neuronal electrical activity in the brain causing clinical signs such as tonic or clonic movements, subtle automatisms, or apnea. Neonatal seizures often indicate hypoxic-ischemic encephalopathy, infection, or metabolic disorder.
Sepsis
A life-threatening systemic inflammatory response to infection. Neonatal sepsis is classified as early-onset (within 72 hours, typically from vertical transmission) or late-onset (after 72 hours, often nosocomial), requiring empirical antibiotic therapy and supportive care.
Serum
The liquid portion of blood that remains after coagulation, containing electrolytes, proteins (albumin, immunoglobulins), hormones, metabolic waste products, and other dissolved substances, but lacking fibrinogen and clotting factors (unlike plasma).
SCID (Severe Combined Immunodeficiency)
A group of rare genetic disorders characterized by the absence of functional T lymphocytes and B lymphocytes, resulting in profound immune deficiency and life-threatening susceptibility to infections. Newborn screening via TREC assay enables early detection.
STI (Sexually Transmitted Infection)
An infection transmitted through sexual contact, including chlamydia, gonorrhea, syphilis, herpes, HIV, and human papillomavirus. Maternal STIs can cause congenital infections, preterm labor, PROM, and neonatal complications.
Shunt
An abnormal pathway allowing blood flow between two compartments. In the cardiovascular system, intracardiac shunts (L-to-R or R-to-L) allow blood to bypass normal circulation through septal defects, PDA, or other anomalies.
Sickle cell disease
A group of inherited hemoglobin disorders caused by a mutation in the beta-globin gene producing hemoglobin S (HbS), which polymerizes under low oxygen conditions causing red blood cells to assume a rigid sickle shape, leading to vaso-occlusion and hemolysis.
Simple face mask
An oxygen delivery device that covers the nose and mouth, providing FiO2 of 35-55% at flow rates of 6-10 L/min. Exhaled gas exits through side ports. Minimum flow of 5 L/min is required to prevent CO2 rebreathing.
Sinusitis
Inflammation of the paranasal sinuses caused by viral, bacterial, or fungal infection, resulting in mucosal edema, obstruction of sinus drainage, and accumulation of purulent secretions. In pediatric patients, the maxillary and ethmoid sinuses are most commonly involved.
Six Sigma
A data-driven quality improvement methodology that uses statistical tools and a structured approach (DMAIC: Define, Measure, Analyze, Improve, Control) to reduce defects, minimize variability, and improve processes to achieve near-perfection (3.4 defects per million).
Spacer
A tube-shaped device (with or without a one-way valve) attached to a pressurized metered-dose inhaler that acts as a holding chamber, slowing aerosol velocity, reducing oropharyngeal deposition, and eliminating the need for hand-breath coordination.
Specific airway conductance (sGaw)
Airway conductance (the reciprocal of airway resistance) normalized to lung volume, measured by body plethysmography. It provides a volume-independent assessment of airway caliber and is used to detect airway obstruction.
SMA (Spinal Muscular Atrophy)
A genetic (autosomal recessive) neuromuscular disorder caused by degeneration of anterior horn cells in the spinal cord, resulting in progressive muscle weakness and atrophy. Type 1 (Werdnig-Hoffmann) is the most severe form, presenting in infancy.
Spine sign
A radiographic finding on lateral chest X-ray in which the vertebral bodies become progressively less visible (whiter) from superior to inferior due to a posterior pleural effusion or consolidation obscuring the normal increasing lucency.
Spirometry
The most common pulmonary function test, measuring the volume and flow rate of air that can be inhaled and exhaled. Key parameters include FEV1 (forced expiratory volume in 1 second), FVC (forced vital capacity), and FEV1/FVC ratio.
Status epilepticus
A neurological emergency defined as continuous seizure activity lasting more than 5 minutes or two or more sequential seizures without full recovery of consciousness between episodes, requiring urgent pharmacological intervention to prevent brain injury.
Steatorrhea
The presence of excess fat in the stool, producing bulky, foul-smelling, pale, floating stools. It indicates fat malabsorption, commonly seen in cystic fibrosis (pancreatic insufficiency), celiac disease, and other malabsorptive conditions.
Sternocleidomastoids
Paired muscles in the neck originating from the sternum and clavicle and inserting on the mastoid process of the temporal bone. They are accessory muscles of respiration; their visible use in neonates indicates significant respiratory distress.
Strabismus
A condition in which the eyes are not properly aligned and do not look in the same direction simultaneously. Esotropia (inward deviation) and exotropia (outward deviation) may be congenital or acquired. Early treatment prevents amblyopia.
Stertor
A low-pitched, snoring-like sound produced during breathing, originating from vibration of tissues in the nasopharynx or oropharynx. It suggests upper airway obstruction at or above the level of the oropharynx.
Stridor
A high-pitched, musical sound heard during breathing, caused by turbulent airflow through a narrowed airway. Inspiratory stridor suggests supraglottic or glottic obstruction; expiratory stridor suggests subglottic or tracheal obstruction; biphasic stridor suggests fixed obstruction.
Subcutaneous emphysema
The presence of air trapped in the subcutaneous tissue, palpable as crepitus (crackling sensation) under the skin. It may result from alveolar air leak, pneumothorax, pneumomediastinum, or trauma.
Subgaleal hemorrhage
Bleeding into the potential space between the periosteum of the skull and the scalp galea aponeurosis. It can accumulate large volumes of blood rapidly, presenting as a fluctuant, progressively enlarging mass crossing suture lines, and may cause life-threatening hypovolemic shock.
Suctioning
The procedure of using negative pressure to remove secretions, blood, or other material from the airway, either through the nose, mouth, or an artificial airway (endotracheal tube, tracheostomy). It should be performed only when clinically indicated.
SIDS (Sudden Infant Death Syndrome)
The sudden, unexplained death of an apparently healthy infant under 1 year of age that remains unexplained after thorough investigation including autopsy, death scene review, and clinical history. Safe sleep practices (supine, firm surface, no loose bedding) reduce risk.
Support ventilation
Mechanical ventilation modes that augment the patient's spontaneous breathing effort (e.g., pressure support ventilation), where the patient triggers each breath and the ventilator provides additional pressure or volume to assist ventilation.
Surface tension
The cohesive force at the air-liquid interface within the alveoli that tends to collapse them. Pulmonary surfactant reduces surface tension, lowering the work of breathing and preventing atelectasis according to the law of LaPlace.
Surfactant
A surface-active lipoprotein complex produced by type II alveolar cells, composed primarily of dipalmitoylphosphatidylcholine (DPPC) and surfactant proteins (SP-A, B, C, D), that reduces alveolar surface tension and maintains alveolar stability.
Surfactant proteins
Four surfactant-associated proteins (SP-A, SP-B, SP-C, SP-D): SP-A and SP-D are large hydrophilic proteins involved in innate immune defense and surfactant metabolism; SP-B and SP-C are small hydrophobic proteins essential for surfactant surface activity.
SRT (Surfactant Replacement Therapy)
The administration of exogenous surfactant (natural bovine or porcine-derived, or synthetic) directly into the trachea through an endotracheal tube to treat or prevent respiratory distress syndrome in premature infants.
Sweep gas
The flow of gas (a mixture of oxygen and nitrogen/air) passed through the membrane oxygenator in an ECMO circuit. Adjusting sweep gas flow rate primarily controls carbon dioxide removal, while FiO2 of sweep gas controls oxygenation.
Sympathomimetic
A pharmacological agent that mimics the effects of the sympathetic nervous system by stimulating adrenergic receptors. In respiratory care, sympathomimetic bronchodilators (beta-2 agonists like albuterol) are used to treat bronchospasm.
Syphilis
A sexually transmitted infection caused by the spirochete Treponema pallidum. Congenital syphilis (transplacental transmission) can cause stillbirth, hydrops, hepatosplenomegaly, rash, osteochondritis, and multisystem involvement in the newborn.
T17 terms
Tactile fremitus
A palpable vibration felt on the chest wall when a patient speaks or cries, transmitted through the bronchial tree and lung parenchyma. It is increased over areas of consolidation (pneumonia) and decreased over pleural effusion or pneumothorax.
Tension pneumothorax
A life-threatening emergency in which air enters the pleural space through a one-way valve mechanism, progressively accumulating with each breath, causing mediastinal shift, compression of the contralateral lung, and cardiovascular collapse. Requires immediate needle decompression.
Tension time index (TTI)
A measure of respiratory muscle energy demand calculated as the product of the ratio of mean inspiratory pressure to maximum inspiratory pressure and the duty cycle (Ti/Ttot). Values above 0.15 indicate risk of respiratory muscle fatigue.
Teratogen
Any agent (chemical, infectious, physical, or metabolic) that can cause structural or functional abnormalities in the developing embryo or fetus. Examples include alcohol, certain medications (thalidomide, valproic acid), radiation, and infections (TORCH).
Tetralogy of Fallot
A congenital cyanotic heart defect consisting of four abnormalities: ventricular septal defect (VSD), overriding aorta, right ventricular outflow tract obstruction (pulmonary stenosis), and right ventricular hypertrophy. It is the most common cyanotic heart defect.
Therapeutic gas mixtures
Specialized gas blends used in respiratory care, including heliox (helium-oxygen mixture to reduce airway resistance), nitric oxide (pulmonary vasodilator), carbogen (CO2-oxygen mixture), and various oxygen-nitrogen combinations for controlled FiO2 delivery.
Tocolytic
A class of medications used to suppress premature uterine contractions and delay preterm delivery, allowing time for corticosteroid administration for fetal lung maturity. Examples include magnesium sulfate, nifedipine, indomethacin, and terbutaline.
Tolerance
A pharmacologic phenomenon in which repeated exposure to a drug leads to a decreased physiologic response, requiring higher doses to achieve the same effect. Commonly occurs with opioids and benzodiazepines in the NICU setting.
TPN (Total Parenteral Nutrition)
A method of providing complete nutritional requirements (amino acids, dextrose, lipids, electrolytes, vitamins, trace elements) intravenously, bypassing the gastrointestinal tract. Used in neonates who cannot tolerate enteral feeding.
Tracheitis
Infection and inflammation of the trachea, often bacterial (Staphylococcus aureus), presenting with high fever, stridor, and thick purulent tracheal secretions. Bacterial tracheitis is a pediatric airway emergency that may require intubation.
Tracheostomy
A surgical procedure creating an opening (stoma) in the anterior wall of the trachea to establish an artificial airway, indicated for prolonged mechanical ventilation, upper airway obstruction, or airway protection in patients requiring long-term respiratory support.
TCOM (Transcutaneous monitoring)
Non-invasive continuous monitoring of partial pressures of oxygen (TcPO2) and carbon dioxide (TcPCO2) through heated electrochemical sensors applied to the skin, providing trend data that correlates with arterial blood gas values in neonates.
Transcutaneous pacemaker
A non-invasive temporary cardiac pacing device that delivers electrical impulses through electrode pads placed on the chest wall to stimulate cardiac contraction in patients with symptomatic bradycardia or heart block.
TGA (Transposition of the Great Arteries)
A congenital cyanotic heart defect in which the aorta arises from the right ventricle and the pulmonary artery from the left ventricle, creating parallel (rather than series) circulations. Survival depends on mixing through ASD, VSD, or PDA.
Tricuspid atresia
A congenital heart defect in which the tricuspid valve fails to develop, preventing direct blood flow from the right atrium to the right ventricle. Survival requires an ASD for right-to-left shunting and a VSD or PDA for pulmonary blood flow.
Truncus arteriosus
A congenital heart defect in which a single arterial trunk arises from the heart, receiving blood from both ventricles through a ventricular septal defect and giving rise to the coronary, pulmonary, and systemic arteries, rather than separate aortic and pulmonary outflows.
Tympanometry
An objective test of middle ear function that measures the compliance (mobility) of the tympanic membrane in response to controlled air pressure changes in the external ear canal. It is used to detect middle ear effusions and eustachian tube dysfunction.
U7 terms
UAC (Umbilical Arterial Catheter)
A catheter inserted through one of the two umbilical arteries into the aorta for continuous blood pressure monitoring and arterial blood gas sampling in critically ill neonates. Tip position is verified radiographically (high: T6-T8; low: L3-L4).
UVC (Umbilical Venous Catheter)
A catheter inserted through the umbilical vein and advanced through the ductus venosus into the inferior vena cava or right atrium for administration of fluids, medications, TPN, and blood products. Correct position is confirmed by chest radiograph.
Unilateral choanal atresia
A congenital condition in which one posterior nasal passage (choana) is blocked by bony or membranous tissue. It is less immediately life-threatening than bilateral atresia and may present later in life with unilateral nasal obstruction and rhinorrhea.
Upper airway
The portion of the respiratory tract above the larynx, including the nose, nasal cavity, paranasal sinuses, nasopharynx, oropharynx, hypopharynx (laryngopharynx), and the supraglottic larynx. It functions to warm, humidify, and filter inspired air.
Ureterocele
A congenital cystic dilation of the distal (intravesical) portion of the ureter that can cause urinary obstruction and is often associated with a duplex collecting system. It may be detected on prenatal ultrasound.
UPJ (Ureteropelvic Junction obstruction)
A blockage of urine flow at the junction of the renal pelvis and the ureter, the most common cause of neonatal hydronephrosis. It may be congenital (intrinsic narrowing) or extrinsic (crossing vessel), often detected on prenatal ultrasound.
Urethritis
Inflammation of the urethra, most commonly caused by sexually transmitted infections (Neisseria gonorrhoeae, Chlamydia trachomatis) or non-infectious causes. Symptoms include dysuria, urethral discharge, and urethral pruritus.
V16 terms
Vaccine
A biological preparation that provides active acquired immunity to a particular infectious disease by stimulating the immune system to recognize and fight specific pathogens. NICU infants receive vaccines on a chronological age schedule.
Vagus nerve
The tenth cranial nerve (CN X), a mixed nerve with extensive distribution providing parasympathetic innervation to the heart, lungs, and gastrointestinal tract. Vagal stimulation causes bradycardia, bronchoconstriction, and increased GI motility.
Valvuloplasty
A catheter-based or surgical procedure to repair or dilate a stenotic (narrowed) heart valve using a balloon catheter (balloon valvuloplasty) or surgical techniques, restoring normal blood flow through the valve.
Vancomycin
A glycopeptide antibiotic that inhibits bacterial cell wall synthesis, used primarily to treat serious infections caused by gram-positive organisms, particularly methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative staphylococci. Requires therapeutic drug monitoring.
Vasculitis
Inflammation of blood vessel walls, which can be caused by autoimmune disorders, infections, or hypersensitivity reactions. It may affect arteries, veins, or capillaries of any size and can cause ischemia, necrosis, or organ damage.
Vasodilator
A pharmacological agent that relaxes vascular smooth muscle, causing blood vessel dilation and reducing blood pressure or pulmonary vascular resistance. Examples include nitric oxide, sildenafil, milrinone, and nitroprusside.
Vasopressor
A medication that causes vasoconstriction and increases systemic blood pressure, used to treat hypotension and shock. Examples include dopamine, epinephrine, norepinephrine, and vasopressin, each with varying alpha and beta adrenergic effects.
Venipuncture
The procedure of puncturing a vein with a needle for the purpose of drawing blood for laboratory testing, administering intravenous fluids or medications, or establishing intravenous access.
VSD (Ventricular Septal Defect)
A congenital heart defect consisting of an abnormal opening in the interventricular septum, allowing blood to flow between the left and right ventricles. It is the most common congenital heart defect. Small VSDs may close spontaneously.
Vernix caseosa
A waxy, white, cheese-like protective coating on the skin of the fetus, composed of sebum, desquamated epithelial cells, and lanugo hair. It protects the skin from the aqueous amniotic environment and has antimicrobial properties.
VLBW infant (Very Low Birth Weight)
An infant with a birth weight of less than 1,500 grams (approximately 3.3 pounds). VLBW infants are at significant risk for all complications of prematurity and require intensive neonatal care.
Vestibular system
The sensory system located in the inner ear that provides the sense of balance and spatial orientation for coordination of movement, posture, and equilibrium. Vestibular stimulation (rocking, positioning) may reduce apnea episodes in premature infants.
Viral load
The quantity of virus (measured as copies per milliliter of blood) present in an infected individual, used to monitor disease progression, treatment response, and infectivity, particularly in HIV and hepatitis infections.
Vocal cord dysfunction (VCD)
A condition in which the vocal cords adduct (close) paradoxically during inspiration, causing stridor, dyspnea, and wheezing that can mimic asthma. Diagnosis is made by direct laryngoscopy during a symptomatic episode.
VMD (Volumetric Median Diameter)
The median particle diameter of an aerosol based on volume distribution, where 50% of the total aerosol volume is contained in particles smaller than the VMD. It is used to characterize aerosol particle size distributions.
Volume ventilation
A mode of mechanical ventilation in which the ventilator delivers a preset tidal volume with each breath, with airway pressure varying depending on the patient's lung compliance and resistance to ensure consistent volume delivery.
W4 terms
Weaning
The gradual reduction of mechanical ventilatory support as the patient's respiratory status improves, transitioning toward spontaneous unassisted breathing. Parameters assessed include respiratory rate, tidal volume, blood gases, and work of breathing.
WNV (West Nile Virus)
A flavivirus transmitted by mosquitoes that can cause neuroinvasive disease (encephalitis, meningitis, acute flaccid paralysis). Perinatal and neonatal transmission has been documented through transplacental passage, breast milk, and blood transfusion.
Wheezing
A high-pitched, continuous, musical adventitious breath sound produced by airflow through narrowed or compressed airways during expiration (or inspiration in severe cases). It is characteristic of asthma, bronchiolitis, and other obstructive airway conditions.
WOB (Work of Breathing)
The energy expenditure required to move air in and out of the lungs, expressed as the product of pressure and volume. Increased WOB is indicated by tachypnea, retractions, nasal flaring, grunting, and accessory muscle use.
X2 terms
X-linked
A pattern of genetic inheritance in which the responsible gene is located on the X chromosome. X-linked recessive disorders (e.g., Duchenne muscular dystrophy, hemophilia) predominantly affect males, while females are typically carriers.
X-ray
A form of electromagnetic radiation used in diagnostic imaging to produce radiographic images of internal body structures. In neonatal care, chest and abdominal X-rays are essential for diagnosing lung disease, evaluating line placement, and detecting surgical conditions.
Y1 term
Yolk sac
An early embryonic structure that provides nutrients to the developing embryo before the placenta is fully functional, serves as the initial site of blood cell formation (hematopoiesis), and contains primordial germ cells that migrate to form the gonads.
Z2 terms
Zinc
An essential trace mineral required for numerous enzymatic reactions, immune function, wound healing, protein synthesis, and DNA synthesis. Zinc supplementation in premature infants supports growth and may reduce the incidence of necrotizing enterocolitis.
Zygote
The single diploid cell formed by the fusion of a sperm and an ovum at fertilization, containing the complete genetic complement (46 chromosomes). It undergoes cleavage divisions to form a morula, then a blastocyst, initiating embryonic development.