(Pediatrics in Review. 1997;18:361-366.)
© 1997 American Academy of Pediatrics
Consultation with the Specialist: Respiratory Failure
Dennis C. Stokes, MD*
*
Associate Professor of Pediatrics, Clinical Director,
Pediatric Pulmonary Medicine, Vanderbilt Children's Hospital, Vanderbilt University School of Medicine, Nashville, TN.
Dr. Stokes is an Advisory Board Consultant for the Genentech, Inc-sponsored Epidemiologic Study of Cystic Fibrosis.
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Introduction
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Respiratory failure represents the failure of compensatory
mechanisms that attempt to preserve gas exchange in the face of lung disease,
chest wall disease, or respiratory muscle weakness. Respiratory failure is
not strictly defined by a specific set of blood gas values, but usually
represents the final stage of these compensatory mechanisms that presents as
increasing respiratory distress. Respiratory failure may occur primarily
because of inability to provide either adequate oxygenation, as in adult
respiratory distress syndrome (ARDS) or pneumonia, or because of the
inability to ventilate adequately, as in neuromuscular weakness or upper
airway obstruction. The adequacy of ventilation is determined by minute
ventilation, which is a product of tidal volume and respiratory rate.
Reduction in either tidal volume (eg, chest wall disease) or respiratory
rate (eg, central nervous system disease) can lead to respiratory failure.
In addition, overall ventilation is reduced by the ventilation of poorly
perfused lung units ("deadspace" ventilation) seen in diffuse lung
disease. In most situations of severe hypoxemia, the predominant mechanism
of hypoxemia is mismatching between ventilation and perfusion, resulting in
severe intrapulmonary shunting. Infants and young children are particularly
prone to respiratory failure because of smaller airways, mechanical
instability of the chest wall, and rapid fatigue of respiratory muscles and
diaphragm.
A child who is in respiratory distress but has good air
movement, color, and tone is "compensated" and usually can be
watched carefully while supplemental oxygen is begun and attention is turned
to assessment and diagnostic studies. The overall goal is to preserve gas
exchange and prevent sudden and catastrophic development of cardio-pulmonary
arrest while treating the underlying condition.
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Case Histories
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Three cases illustrate the spectrum of respiratory failure. The first is a 6-month-old
who has croup and presented with acute respiratory symptoms and dramatic
inspiratory stridor. Despite loud stridor, he was feeding well and . . . [Full Text of this Article]
Copyright © 1997 by the American Academy of Pediatrics.