Pulmonary vascular tone improves pulmonary gas exchange in the adult respiratory distress syndrome.
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.
Melot
C
C
Department of Intensive Care, Erasme University Hospital, Belgium.
Naeije
R
R
Mols
P
P
Hallemans
R
R
Lejeune
P
P
Jaspar
N
N
D000328:Adult; D000368:Aged; D004110:Diltiazem / Q000494:pharmacology; D005260:Female; D006801:Humans; D006976:Hypertension, Pulmonary / Q000209:etiology / Q000503:physiopathology*; D008168:Lung / Q000098:blood supply* / Q000187:drug effects; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D012128:Respiratory Distress Syndrome / Q000150:complications / Q000503:physiopathology*; D014655:Vascular Resistance / Q000187:drug effects; D014692:Ventilation-Perfusion Ratio / Q000187:drug effects
D004110:Diltiazem; D010100:Oxygen