Effects of sodium-nitroprusside and urapidil on gas exchange and ventilation-perfusion relationships in patients with congestive heart failure.
Vasodilators usually decrease arterial PO2 in patients with congestive heart failure (CHF) because of alteration in ventilation-perfusion (Va/Q) relationships. The effects of sodium nitroprusside (SNP) and urapidil (U), a new selective alpha 1-receptor antagonist, were investigated in seven patients with CHF. The distribution of ventilation and perfusion was examined using the multiple gas elimination technique. The haemodynamic responses to SNP and U were similar, cardiac index increasing by 25% with SNP and by 31% with U. Despite a similar increase of mixed venous oxygen tension, the arterial PO2 decreased from 11.3 +/- 0.8 to 9.6 +/- 0.6 kPa (p less than 0.01) with SNP but remained unchanged (11.0 +/- 0.9 vs 11.4 +/- 0.8 kPa, NS) with U. SNP and U both increased perfusion to lung units with Va/Q ratios of 0.1 or less with no change in shunt fraction. The fractional perfusion to total low Va/Q ratios (low Va/Q + shunt) was higher with SNP than with U (14.1 +/- 2.6 vs 9.5 +/- 2.3%, p less than 0.01). The results suggest that gas exchange and Va/Q relationships are altered less with U than with SNP in patients with CHF.
Adnot
S
S
Dépt de Physiologie, Hôpital Henri Mondor, Créteil, France.
Radermacher
P
P
Andrivet
P
P
Dubois-Rande
J L
JL
Dupeyrat
A
A
Lemaire
F
F
D000317:Adrenergic alpha-Antagonists / Q000627:therapeutic use*; D005260:Female; D006333:Heart Failure / Q000188:drug therapy*; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D009599:Nitroprusside / Q000627:therapeutic use*; D010879:Piperazines / Q000627:therapeutic use*; D011652:Pulmonary Circulation / Q000187:drug effects; D011659:Pulmonary Gas Exchange / Q000187:drug effects; D014692:Ventilation-Perfusion Ratio / Q000187:drug effects
D000317:Adrenergic alpha-Antagonists; D010879:Piperazines; D009599:Nitroprusside; C015568:urapidil