Acute Bronchiolitis Flashcards
What is the mortality of acute bronchiolitis?
What is the defining clinical measure of hypoxemia?
O2 sat of
What are the most common etiologies of acute bronchiolitis (in order of most to least common)?
RSV (50-75%), rhinovirus, hMPV, parainfluenza (2 at beginning of winter, 3 is late winter/beginning of spring), influenza (outcompetes RSV), adenovirus (
What is the most common cause of summertime acute bronchiolitis?
Adenovirus
Why are newborns at an increased risk of acute bronchiolitis
Greater peripheral airway resistance, Affects ventilatory distribution. Increases vulnerability to hypoxemia. Lack collateral ventilation through the Pore of Kohn’s (airway obstructed by mucus leads to entire distal airway obstruction)–>atelectasis and abnormal gas exchange, especially with LRTIs. More obstruction.
Pathophysiology of acute bronchiolitis
Mucous plugging mucosal edema necrosis of bronchiolar epithelium airway inflammation mucociliary destruction, Retractions air trapping wheezing tachypnea, causing: Decreased compliance Increased resistance Increased Work of Breathing (increased effort with accessory muscles, air trapping showing hyperventilation, some wheezing, increased respiratory rate) Hypoxemia (caused by decreased compliance and V/Q mismatch) Hypocarbia/Normocarbia (with fatigue means imminent respiratory failure).
What is the timeline of RSV?
2-8 days. Illness 3-7 days (months for immunocompromised). Recovery 1-2 weeks.
How is RSV diagnosed?
History, wheezing, physical exam, Xrays (hyperinflation, flattened diaphragms, atelectasis, air trapping in upper lobe), confirmation by fluorescent Ab, PCR and Elisa (sensitivity >95%).
Risk factors for RSV
Low birth weight, siblings, crowded living, daycare, smoke exposure, air pollution, male sex, multiple births, low maternal education, family asthma history, lack of breastfeeding
What are risk factors for severe RSV?
Chronic lung disease (BPD), congenital HD, immunocompromise, prematurity, hypotonia (insufficient cough), genetic syndromes (trisomy 21). Passive immunization targets.
What else can RSV cause?
Bronchiolitis/pneumonitis in infants. Apnea (most common). Sepsis like syndrome. SVT. Post-infection wheezing/childhood asthma. Severe disease in the institutionalized elderly. Giant cell pneumonia in persons with deficient T cell immunity. Vaccine-enhanced disease.
What other diseases are differential diagnoses with RSV?
Acute myocarditis (high HR, low perfusion, CHF, metabolic acidosis. danger of CHF after bronchodilator administration).
Indications for hospitalization with RSV?
Saturation on room air < 92% Unable to maintain hydration. Markedly increased RR (>70). Hx underlying cardiorespiratory disease. Unavailability for qualifying primary care. Recurrent visits to ED.
Supportive care for RSV
Administer humidified oxygen. Keep room air saturation above 92%. Nasal suctioning – to clear upper airway. Monitor for apnea, hypoxemia, and impending respiratory failure. Normalize body temperature. Rehydrate with oral or intravenous fluids. Monitor hydration status.
