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protective airway reflexes with loss of airway tone or pulmonary aspiration Alternatively, neurologic disease may directly affect the peripheral nerves or muscles, leading to either airway obstruction or inadequate excursion of the chest wall and diaphragm The result is inadequate gas exchange and ventilation– perfusion (V/Q) mismatch Finally, numerous other nonpulmonary diseases may precipitate respiratory failure Though with varied underlying pathophysiology, the diseases listed in Table 99.1 may alter the balance of O2 consumption and CO2 production such that gas exchange cannot be maintained by the respiratory system, leading to secondary respiratory failure Goals of Treatment The goals of management of acute respiratory failure are correction of hypoxia and sufficient support of ventilation Immediate efforts should be directed toward both lifesaving maneuvers and appropriate diagnostic testing, as establishing a diagnosis will inform disease-specific management Clinical Considerations Clinical Recognition Acute respiratory failure represents the severe end of the spectrum of respiratory disease Though the onset can be hyperacute (e.g., complete airway obstruction from foreign-body aspiration or traumatic injury to phrenic nerve with complete loss of respiratory effort), respiratory failure more commonly results from a progression of respiratory illness and distress The differential diagnosis is broad, though the underlying causes vary by age While congenital anomalies are likely to present in the first several months of life, some may present in older infants and toddlers Some progressive neurologic conditions may present in older children It is important to appreciate that normal ranges of respiratory rate differ by age ( Table 99.2 ) Some cases may involve patients without concerning medical history who have a severe acute condition such as upper airway obstruction from aspirated foreign body or swelling due to infection Some cases may involve progressive deterioration of a chronic condition such as cystic fibrosis (CF) Details of management differ according to acute diagnosis and pathophysiology of underlying condition