Pulmonary vascular tone improves pulmonary gas exchange in the adult respiratory distress syndrome

Am Rev Respir Dis. 1987 Nov;136(5):1232-6. doi: 10.1164/ajrccm/136.5.1232.


Hemodynamics, blood gases, lung mechanics, and the distributions of ventilation-perfusion ratios (VA/Q) were studied before and after iv diltiazem, 0.5 mg/kg over 30 min, in 6 patients with pulmonary hypertension secondary to the adult respiratory distress syndrome (ARDS) ventilated with 7 to 20 cm H2O positive end-expiratory pressure (PEEP). Diltiazem decreased systemic and pulmonary arterial pressures without changes in cardiac output and in filling pressures of the heart, and with a slowing of heart rate. Pulmonary vascular resistances decreased from 401 +/- 59 to 329 +/- 58 dyne.s.cm-5.m2 (mean +/- SEM), p less than 0.01. Arterial Po2 decreased from 87 +/- 10 to 80 +/- 11 mm Hg (p less than 0.02) without changes in arterial PCO2, mixed venous PO2, and O2 consumption. Lung compliance and airway resistances did not change. Diltiazem increased true shunt from 23 +/- 5 to 30 +/- 7% of total blood flow (p less than 0.02) without other modification in the pattern of VA/Q distribution as measured by the multiple inert gas elimination technique. These results suggest that pulmonary vascular tone contributes to the maintenance of VA/Q matching in patients with ARDS.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Diltiazem / pharmacology
  • Female
  • Humans
  • Hypertension, Pulmonary / etiology
  • Hypertension, Pulmonary / physiopathology*
  • Lung / blood supply*
  • Lung / drug effects
  • Male
  • Middle Aged
  • Oxygen / blood
  • Respiratory Distress Syndrome / complications
  • Respiratory Distress Syndrome / physiopathology*
  • Vascular Resistance* / drug effects
  • Ventilation-Perfusion Ratio* / drug effects


  • Diltiazem
  • Oxygen