Comparison of the effects of intravenous almitrine and positive end-expiratory pressure on pulmonary gas exchange in adult respiratory distress syndrome

Abstract

The effects of almitrine on pulmonary gas exchange and haemodynamics were compared to those of positive end-expiratory pressure (PEEP) in 10 patients with a severe adult respiratory distress syndrome (ARDS) who required continuous mechanical ventilation. Haemodynamic and gas exchange measurements were made before and after 30 min of PEEP at a level of 10 cmH2O, then 30 min later, before and at the end of the intravenous infusion of almitrine at a dose of 0.25 mg · kg-1 in 30 min. There was no significant difference between baseline gas exchange and haemodynamic parameters. PEEP and almitrine increased PaO2 (p = 0.001) from 10.9 to 12.6 kPa and from 10.6 to 12.6 kPa (1 kPa = 7.5. mmHg), respectively, and ratio of venous admixture to total blood flow (Q̇s/Q̇T) decreased (p < 0.001) from 34 to 29% and from 33 to 29%, respectively, the effects of PEEP and almitrine being not significantly different. Neither PEEP nor almitrine caused a significant change in arterial carbon dioxide tension (PaCO2). The haemodynamic parameters did not change significantly with almitrine, whereas mean systemic arterial pressure decreased from 85.4 to 81.1 mmHg (p < 0.05) with PEEP. These results are consistent with the hypothesis that both treatments improve ventilation/perfusion (V̇A/Q̇) distributions, by an increase in functional residual capacity in the case of PEEP and a redistribution of pulmonary perfusion in the case of almitrine.