Étude en double insu de l'effect de l'almitrine sur les malades porteurs de polyglobulie pathologique d'altitude

Abstract

ABSTRACT. Chronic polycythaemia in people living at high altitude is associated with hypoxaemia due to a marked reduction in hypoxic and hypercapnie drives. The effect of almitrine, a chemoreceptor stimulant, was evaluated in 40 patients, with haematocrit values over 57 %, living in La Paz (3,600-4,000 m). Two studies were carried out. The aim of the first was to assess the ventilatory response, and the increase in Pao₂, due to almitrine in a double blind, placebo controlled protocol including 40 patients (mean haematocrit 66.8%). Almitrine was given orally at a dose of 3 mg. kg-1. Variance analysis showed that three hours later there was a significant increase in Pao₂, (+ 0.46 kPa), pH and respiratory frequency, with a significant reduction in Paco₂, (-- 0.4 kPa). The increase in ventilation (+ 17 %) was not significant. The aim of the second study was to assess the effect of almitrine on the polycythaemia. It was given orally at a dose of 1.5 mg• kg-1. day-1 to twelve patients over a four week period. Blood gases, ventilation (VE), oxygen consumption (VO₂), carbon dioxide production (VCO₂) and haematocrit were measured every week. There was a slight but significant reduction in haematocrit (-- 3.5 %). Pao₂, and all the other measured parameters (VE, Paco₂, pH, VO₂ Vco₂,) remained constant. The reduction in haematocrit was not therefore due to an increase in diurnal Pao₂, but is perhaps due to the improvement in pulmonary ventilation during sleep.