ABP Pediatric Pulmonology cheat sheet

At birth, lung fluid is absorbed through ENaC-mediated sodium transport and lymphatic drainage; failure of clearance contributes to transient tachypnea of the newborn.

Surfactant is produced by type II pneumocytes; phosphatidylcholine is the main phospholipid, and surfactant deficiency causes neonatal respiratory distress syndrome.

Airway resistance is inversely proportional to the fourth power of airway radius (R ∝ 1/r^4), so small reductions in infant airway caliber cause large resistance increases.

Infant functional residual capacity is maintained by laryngeal braking and postinspiratory muscle activity because the chest wall is highly compliant.

Alveolar septation begins in fetal life and continues into early childhood; the adult lung contains roughly 300 million alveoli.

Alveolar ventilation is VA = (tidal volume − dead space) × respiratory rate; PaCO2 is inversely proportional to alveolar ventilation.

Compliance is C = ΔV/ΔP; elastance is the reciprocal of compliance, and surfactant increases compliance by reducing surface tension.

Hypoxic pulmonary vasoconstriction diverts blood from hypoventilated alveoli but can cause pulmonary hypertension when alveolar hypoxia is widespread.

Asthma is characterized by chronic airway inflammation, variable expiratory airflow obstruction, and bronchial hyperresponsiveness.

Spirometric obstruction is a reduced FEV1/FVC ratio; a ≥12% increase in FEV1 after a short-acting beta-agonist supports bronchodilator reversibility.

Inhaled corticosteroids are first-line controller therapy for persistent pediatric asthma; montelukast is an alternative but has neuropsychiatric warnings.

Acute severe asthma treatment includes oxygen to SpO2 94–98%, repeated inhaled salbutamol, systemic corticosteroids, and ipratropium for severe exacerbations.

Croup treatment is dexamethasone 0.15–0.6 mg/kg once; nebulized epinephrine is used for moderate or severe stridor, with observation for recurrence after its effect wanes.

Foreign-body aspiration causes sudden cough, unilateral wheeze, or asymmetric aeration; rigid bronchoscopy is both diagnostic and therapeutic.

Tracheomalacia causes expiratory collapse of the trachea, often with barking cough and wheeze; flexible bronchoscopy confirms dynamic collapse.

Vocal cord dysfunction produces inspiratory stridor and a flattened inspiratory flow-volume loop, often without reversible obstruction.

Community-acquired bacterial pneumonia in children most commonly involves Streptococcus pneumoniae; viral causes include RSV, rhinovirus, and influenza.

RSV bronchiolitis management is supportive with suctioning, hydration, and oxygen for hypoxemia; routine bronchodilators, steroids, and antibiotics are not indicated.

Pertussis has catarrhal, paroxysmal, and convalescent phases; azithromycin treats infection and eradicates carriage.

Mycoplasma pneumoniae is a common atypical pneumonia in school-age children; macrolides are first-line, and extrapulmonary manifestations can occur.

Complicated parapneumonic effusion is suggested by pleural fluid pH <7.20, glucose <40 mg/dL, or loculation, and these features favor drainage.

Bacterial tracheitis presents with toxic appearance and purulent tracheal secretions; Staphylococcus aureus is a common pathogen.

Pneumocystis jirovecii pneumonia in immunocompromised children causes hypoxemia and diffuse ground-glass opacities; trimethoprim-sulfamethoxazole is treatment.

Tuberculosis in young children often requires gastric aspirate or induced sputum; interferon-gamma release assays can be negative in active disease.

CF diagnosis requires characteristic clinical features plus sweat chloride ≥60 mmol/L on two tests, or two disease-causing CFTR mutations, or abnormal nasal potential difference.

Newborn screening uses immunoreactive trypsinogen with DNA mutation analysis; a positive screen requires confirmatory sweat testing.

Pancreatic insufficiency is indicated by fecal elastase <200 µg/g; treatment is pancreatic enzyme replacement with meals and snacks.

Airway clearance in CF includes chest physiotherapy, oscillating positive expiratory pressure, hypertonic saline, and dornase alfa for many patients.

Chronic Pseudomonas aeruginosa infection is treated with inhaled tobramycin or colistin; early eradication often adds oral ciprofloxacin.

A CF pulmonary exacerbation is treated by increasing airway clearance and giving antibiotics guided by prior sputum cultures, often intravenously for severe disease.

Bronchiectasis is irreversible airway dilation with loss of tapering; high-resolution CT shows dilated airways larger than adjacent vessels.

CF-related diabetes screening uses annual oral glucose tolerance testing beginning at age 10 years in patients with CF.

Respiratory distress syndrome: prematurity and surfactant deficiency cause low lung volumes, ground-glass opacities, and air bronchograms; exogenous surfactant is treatment.

Transient tachypnea of the newborn follows delayed fetal lung fluid clearance; chest radiograph shows perihilar streaking and fluid in fissures.

Congenital diaphragmatic hernia causes pulmonary hypoplasia and pulmonary hypertension; immediate intubation and nasogastric decompression are required.

Congenital pulmonary airway malformation may be asymptomatic; symptomatic lesions or those with concerning features are managed surgically.

Meconium aspiration syndrome causes patchy infiltrates and air leak in term or post-term infants; routine intrapartum suction is not recommended.

Persistent pulmonary hypertension of the newborn causes refractory hypoxemia from right-to-left shunting; inhaled nitric oxide is a first-line pulmonary vasodilator.

Bronchopulmonary dysplasia is defined by oxygen or respiratory support at 36 weeks postmenstrual age in preterm infants.

Choanal atresia causes cyclic cyanosis relieved by crying; a nasal catheter cannot be passed on the affected side.

Pediatric obstructive sleep apnea is most often caused by adenotonsillar hypertrophy and presents with snoring, mouth breathing, and restless sleep.

Polysomnography is the gold standard for diagnosing OSA; the obstructive apnea-hypopnea index quantifies severity.

Adenotonsillectomy is first-line therapy for OSA with adenotonsillar hypertrophy; persistent symptoms require reevaluation and possibly positive airway pressure.

Apnea of prematurity is defined as a respiratory pause >20 seconds or shorter with bradycardia or cyanosis; caffeine citrate is standard therapy.

Caffeine citrate for apnea of prematurity uses a loading dose of 20 mg/kg and maintenance of 5–10 mg/kg/day.

Children with Down syndrome have high OSA risk due to midface hypoplasia, hypotonia, and large tonsils; polysomnography screening is recommended.

Obesity hypoventilation syndrome causes daytime hypercapnia with sleep-disordered breathing and often requires noninvasive ventilation.

A brief resolved unexplained event in an infant requires risk assessment; low-risk events may not need extensive testing.

Spirometry measures FVC, FEV1, and FEV1/FVC; obstruction shows a reduced ratio, while restriction shows reduced FVC with a normal or high ratio.

Bronchodilator response is a ≥12% increase in FEV1 after a short-acting beta-agonist; it supports asthma but a negative test does not exclude it.

Lung volumes by plethysmography confirm restriction when total lung capacity is reduced; spirometry alone cannot confirm restriction.

Diffusing capacity for carbon monoxide is reduced in parenchymal lung disease and is typically normal in asthma.

Sweat chloride ≥60 mmol/L confirms CF; 30–59 mmol/L is intermediate and requires further CFTR testing.

Fractional exhaled nitric oxide is elevated in eosinophilic asthma and may help monitor adherence and inflammation.

Pulse oximetry estimates arterial oxygen saturation; normal is ≥95% at sea level, and values <90% indicate significant hypoxemia.

Arterial blood gas in respiratory acidosis shows low pH and elevated PaCO2; metabolic compensation raises bicarbonate over time.

Respiratory failure: type 1 is hypoxemia with PaO2 <60 mm Hg and normal or low PaCO2; type 2 adds PaCO2 >50 mm Hg.

For children older than 1 year, uncuffed endotracheal tube size in mm ≈ age/4 + 4; cuffed tube size ≈ age/4 + 3.5.

Pediatric ARDS ventilation uses low tidal volumes around 6 mL/kg predicted body weight and adequate PEEP while avoiding barotrauma.

High-flow nasal cannula provides heated humidified oxygen at flow rates up to 2 L/kg/min and can reduce work of breathing in bronchiolitis.

Severe asthma exacerbation treatment includes continuous inhaled albuterol, systemic corticosteroids, oxygen, and IV magnesium sulfate 25–50 mg/kg as an adjunct.

Noninvasive ventilation can support respiratory distress in cooperative children; contraindications include unprotected airway and severe agitation.

ECMO is considered for refractory hypoxemic or hypercapnic respiratory failure when conventional ventilation fails.

Permissive hypercapnia may be tolerated in severe asthma to avoid excessive ventilation and air trapping.