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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.