Respiratory failure other diagnostic studies

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hadeel Maksoud M.D.[2]

Despite most patients being unable to perform a pulmonary function test during acute respiratory failure, pulmonary function testing may be useful with chronic respiratory failure. Chronic respiratory failure is usually due to an underlying restrictive disease, pulmonary function test findings include a decrease in FEV1 and a significant decrease in FVC with an overall increase in the FEV1/FVC ratio. It is unlikely that an obstructive lung disease would cause respiratory failure. In respiratory failure with significant cardiac function compromise, a right side cardiac catheter may be used. Catheterization is controversially used to assess those patients with acute hypoxemic respiratory failure where cardiac function is uncertain.

• Pulmonary function test may be helpful in the diagnosis of chronic respiratory failure. Findings suggestive of chronic respiratory failure include:^[1]
  • A decrease in FEV1
  • A significant decrease in FVC
  • An increase in FEV1/FVC ratio
• Right side cardiac catheterization can distinguish cardiogenic from non-cardiogenic respiratory failure.

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