Depression of cardiac output is a mechanism of shunt reduction in the therapy of acute respiratory failure

Chest. 1980 May;77(5):636-42. doi: 10.1378/chest.77.5.636.


The relationship between changes in cardiac output and intrapulmonary shunt associated with mechanical ventilation was evaluated in 20 patients with the adult respiratory distress syndrome (ARDS). The distribution of ventilation-perfusion (VA/Q) ratios and the level of intrapulmonary shunt was determined by the multiple inert gas technique. Pulmonary blood flow was distributed predominantly to either effective gas-exchanging units or shunt units. Positive end-expiratory pressure (PEEP) or high tidal volume ventilation led to decreases in shunt and cardiac output without altering the overall pattern of VA/Q distributions. Changes in shunt and cardiac output were quantitatively and qualitatively silimar and a strong correlation was found between changes in shunt and cardiac output with both PEEP and high tidal volumes (r = 0.76). Cardiac output depression associated with tese modes of ventilation appears to be a mechanism of shunt reduction in ARDS. Interpretation of improvements in gas exchange in ARDS must take into account concomitant hemodynamic changes.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Blood Pressure
  • Cardiac Output*
  • Humans
  • Oxygen / blood
  • Positive-Pressure Respiration
  • Pulmonary Circulation*
  • Respiratory Distress Syndrome / therapy*
  • Tidal Volume
  • Ventilation-Perfusion Ratio*


  • Oxygen