ABP Pediatric Pulmonology key terms

The volume of air remaining in the lungs at the end of a quiet expiration. It reflects the balance between outward chest-wall recoil and inward lung elastic recoil, and it helps prevent alveolar collapse.

A mixture of lipids and proteins secreted by alveolar type II cells that lowers surface tension. By reducing surface tension, it stabilizes alveoli, prevents collapse at low lung volumes, and decreases the work of breathing.

A measure of how easily the lungs or chest wall expand for a given change in pressure. Higher compliance means greater volume change per unit pressure; lower compliance means the system is stiffer and harder to inflate.

The opposition to airflow through the conducting airways, determined mainly by airway caliber and gas viscosity. Small reductions in radius greatly increase resistance, making resistance clinically important in obstructive airway disease.

The volume of fresh gas reaching functioning alveoli per minute. It equals respiratory rate times the difference between tidal volume and dead space, and it determines effective carbon dioxide removal.

The portion of each breath that does not participate in gas exchange. Anatomic dead space fills the conducting airways; physiologic dead space also includes alveoli that are ventilated but poorly perfused.

A protective reflex in which pulmonary arteries constrict when alveolar oxygen tension falls. It redirects blood from poorly ventilated lung regions toward better-ventilated areas, improving ventilation-perfusion matching but raising pulmonary vascular resistance when widespread.

A chronic lung disease of premature infants, usually born very early, characterized by impaired alveolar and vascular growth. It causes prolonged oxygen need, respiratory symptoms, and increased risk of later airway disease.

A chronic inflammatory airway disorder marked by variable airflow obstruction, bronchial hyperresponsiveness, and symptoms such as wheeze, cough, and dyspnea. Symptoms and obstruction often improve spontaneously or with bronchodilator treatment.

Excessive airway narrowing in response to stimuli that cause little or no response in healthy people, such as methacholine, exercise, cold air, or allergens. It is a central physiologic feature of asthma.

A pulmonary function test that measures how much air a person can forcefully exhale and how quickly. It provides forced vital capacity, forced expiratory volume in one second, and ratios used to identify and grade obstructive or restrictive patterns.

The maximum speed of forced exhalation, usually measured with a small portable meter. It reflects large-airway function and is used for monitoring asthma, though it is effort-dependent and less informative than full spirometry.

The improvement in spirometric airflow after inhaling a short-acting bronchodilator. Significant improvement supports variable airway obstruction and asthma, whereas fixed obstruction suggests remodeling, bronchiectasis, or another chronic process.

An infection of the lung parenchyma acquired outside a hospital setting. In children it commonly presents with fever, cough, tachypnea, and focal crackles, and common pathogens vary substantially by age.

A viral lower respiratory infection of infants, most often caused by respiratory syncytial virus, producing small-airway inflammation, wheeze, crackles, and increased work of breathing. Management is mainly supportive, with attention to hydration and oxygenation.

An infection caused by Mycobacterium tuberculosis, most often affecting the lungs. In children it frequently follows household exposure, may present with chronic cough, fever, weight loss, or extrapulmonary disease, and requires multidrug treatment.

An autosomal recessive disorder caused by mutations in the CFTR chloride channel. Thickened secretions lead to chronic airway infection, bronchiectasis, pancreatic insufficiency, and multisystem complications, with wide variability in severity.

The diagnostic standard for cystic fibrosis, performed by pilocarpine iontophoresis. Elevated sweat chloride concentrations reflect impaired CFTR function; results near the diagnostic threshold may require repeat testing or genetic analysis.

Failure of the pancreas to supply enough digestive enzymes, common in cystic fibrosis. It causes malabsorption of fats and proteins, steatorrhea, poor weight gain, and fat-soluble vitamin deficiency, often requiring enzyme replacement and nutritional support.

Irreversible widening and destruction of bronchi, usually from chronic infection and inflammation. It causes chronic cough with purulent sputum, recurrent exacerbations, and impaired airway clearance; cystic fibrosis is an important pediatric cause.

Techniques that help patients mobilize and remove retained airway secretions. Examples include chest physiotherapy, oscillating positive expiratory pressure devices, high-frequency chest wall oscillation, and assisted coughing, chosen according to age and disease severity.

Respiratory distress in a newborn after meconium-stained amniotic fluid is inhaled. Meconium obstructs airways, inactivates surfactant, and causes chemical pneumonitis, often producing hypoxemia and persistent pulmonary hypertension.

A birth defect in which abdominal organs move into the chest through a diaphragmatic opening, compressing the developing lungs. It causes pulmonary hypoplasia and pulmonary hypertension, often requiring immediate neonatal intensive care.

A developmental lung abnormality characterized by abnormal cystic or solid lung tissue. It may be asymptomatic or cause respiratory distress, infection, or pneumothorax, and management depends on size, symptoms, and progression.

A condition of premature infants caused by surfactant deficiency and immature lungs. It produces tachypnea, grunting, retractions, and hypoxemia shortly after birth and is treated with oxygen, respiratory support, and exogenous surfactant.

A developmental pause in breathing lasting at least 20 seconds, or shorter if accompanied by bradycardia or desaturation, in an infant born prematurely. It reflects immature respiratory control and usually resolves with maturation.

A sleep-related breathing disorder in which repeated upper-airway collapse causes obstructed breathing, intermittent hypoxemia, and sleep disruption. In children, it often presents with snoring, mouth breathing, restless sleep, and daytime behavioral or learning problems.

A comprehensive sleep study that records brain activity, eye movements, breathing, oxygen saturation, heart rhythm, and limb movements. It quantifies apneas, hypopneas, and hypoxemia and is the reference standard for diagnosing obstructive sleep apnea.

Enlargement of the adenoids and tonsils, common in children. It can narrow the upper airway, causing snoring, mouth breathing, obstructive sleep apnea, and recurrent middle-ear or sinus problems.

A noninvasive method that estimates arterial oxygen saturation by measuring light absorption through tissue. It detects hypoxemia rapidly but can be inaccurate with poor perfusion, motion, nail polish, or abnormal hemoglobin species.

Continuous measurement of carbon dioxide in exhaled gas, displayed as a waveform and end-tidal value. It helps assess ventilation, confirm tracheal intubation, and detect hypoventilation or cardiac arrest, but it does not directly measure oxygenation.

A blood test that measures pH, partial pressures of oxygen and carbon dioxide, bicarbonate, and oxygen saturation. It assesses acid-base status and ventilation and is central to managing severe respiratory failure.

Breathing support delivered through a mask or nasal interface without an invasive artificial airway. It can reduce work of breathing and improve ventilation in selected children with neuromuscular weakness, obstructive sleep apnea, or acute respiratory failure.

A severe form of acute lung injury with diffuse inflammation, increased capillary permeability, and noncardiogenic pulmonary edema. It causes refractory hypoxemia and reduced lung compliance and requires intensive supportive care.

A respiratory support device that delivers heated, humidified oxygen at flows higher than conventional nasal cannula. It provides modest positive pressure, washes out nasopharyngeal dead space, and is used for hypoxemic respiratory failure and bronchiolitis.

Inability of the respiratory system to maintain adequate oxygenation, carbon dioxide removal, or both. Type I is primarily hypoxemic; type II is hypercapnic, often reflecting alveolar hypoventilation or pump failure.

The most common cause of infant stridor, caused by floppy supraglottic structures that collapse inward during inspiration. It typically worsens with crying and feeding and usually resolves without surgery.

Weakness of the tracheal cartilage causing excessive airway collapse, especially during expiration. It produces wheezing, barking cough, or respiratory distress and may be congenital or acquired after prolonged intubation or airway surgery.

A viral upper-airway infection, usually caused by parainfluenza virus, producing laryngeal edema and a barking cough. Inspiratory stridor and hoarseness are typical, and treatment often includes corticosteroids and sometimes nebulized epinephrine.

Acute inflammation of the epiglottis and surrounding supraglottic structures, now uncommon because of vaccination. It can rapidly obstruct the airway and presents with fever, drooling, muffled voice, and positional preference; airway management is urgent.