Enhancement of hypoxic pulmonary vasoconstriction by low dose almitrine bismesylate in normal humans.
The effect of almitrine bismesylate on hypoxic pulmonary vasoconstriction (HPV) remains controversial. We therefore investigated in a double-blind, placebo-controlled, randomized design the effects of low dose of almitrine bismesylate (4 micrograms/kg/min given intravenously) on blood gases, pulmonary hemodynamics, and ventilation-perfusion (VA/Q) distributions in normal subjects breathing a hypoxic mixture (FIO2, 0.125), room air (FIO2, 0.21), and oxygen (FIO2, 1.0) in a random sequence. In the placebo group (7 subjects), no change was recorded. In the almitrine group (10 subjects), arterial PO2 improved during hypoxia (from 42 +/- 2 to 47 +/- 1 mm Hg, p less than 0.05, mean +/- SEM) and normoxia (from 99 +/- 3 to 104 +/- 2, p less than 0.05). Pulmonary arterial mean pressure and pulmonary vascular resistance index increased with almitrine during hypoxia, respectively, from 20 +/- 1 to 23 +/- 1 mm Hg (p less than 0.01) and from 207 +/- 22 to 283 +/- 35 dyne.s.cm-5.m2 (p less than 0.01), and during normoxia, respectively, from 12 +/- 1 to 14 +/- 1 mm Hg (p less than 0.05) and from 90 +/- 11 to 137 +/- 13 dyne.s.cm-5.m2 (p less than 0.05). The VA/Q distribution improved during hypoxia, with a shift of the blood flow distribution to better oxygenated lung units with higher VA/Q ratios. We conclude that in normal humans low dose of almitrine improves gas exchange by an enhancement of HPV.
Mélot
C
C
Intensive Care Department, Erasme University Hospital, Brussels, Belgium.
Dechamps
P
P
Hallemans
R
R
Decroly
P
P
Mols
P
P
D000328:Adult; D015765:Almitrine; D001794:Blood Pressure / Q000187:drug effects; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000503:physiopathology*; D008297:Male; D010100:Oxygen / Q000097:blood; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*; D011652:Pulmonary Circulation / Q000187:drug effects*; D011897:Random Allocation; D014655:Vascular Resistance / Q000187:drug effects; D014661:Vasoconstriction / Q000187:drug effects*; D014692:Ventilation-Perfusion Ratio / Q000187:drug effects
D010879:Piperazines; D015765:Almitrine; D010100:Oxygen