The Pulmonary Haemodynamic Effects of Almitrine Infusion in Men with Chronic Hypercapnia

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Abstract
Almitrine, an agonist of peripheral chemoreceptors, is effective in lowering PaCO2 [arterial partial pressure of CO2] in patients with chronic obstructive lung disease. The pulmonary hemodynamic response to almitrine was investigated in clinically stable patients with chronic airflow obstruction and chronic hypercapnia (PaCO2 7.1 .+-. 0.5 kPa [pascals], mean .+-. SD). Seven men, aged from 55 to 64 yr, had the following values for pulmonary functions (means .+-. SD): FEV1.0 [forced expiratory vol in 1 s] 0.67 .+-. 0.16 l; VC [ventilatory capacity] 2.12 .+-. 0.52 l; FEV1.0/VC 33 .+-. 8%. They had hemodynamic monitoring during 1 h of almitrine (1 mg/kg i.v.) and solvent (placebo) in a random fashion while receiving 28% O2. Before infusion, 6 patients had evidence of pulmonary hypertension and the mean pulmonary artery pressure %w%000004%% for all 7 patients was 4.3 .+-. 1.6 kPa (mean .+-. SD); the pulmonary vascular resistance (PVR) was 0.61 .+-. 0.22 kPa l-1 s (mean .+-. SD). There were no significant changes from baseline values during placebo. During almitrine the .**GRAPHIC**. and right ventricular stroke work (mean .+-. SD) increased significantly at 30 min (6.0 .+-. 2.1 kPa, P < 0.001, 0.38 .+-. 0.12 J, P < 0.05, respectively) with maximum increase of PVR at 45 min (1.01 .+-. 0.34 kPa l-1 s, P < 0.001, mean .+-. SD). The lowest PaCO2 (mean .+-. SD) was observed at the end of the infusion (5.7 .+-. 0.5 kPa, P < 0.001). These results confirm the benefit of almitrine in lowering PaCO2 in patients with chronic airflow obstruction who have chronic hypercapania but also demonstrate significant pulmonary vasoconstriction.