[Hyperoxia test during attempts to withdraw artificial ventilation].

A 30 minute test of hyperoxia (10 l.min-1) was conducted in patients (n = 21) with chronic obstructive lung disease during the weaning trials from mechanical ventilation. Two groups were formed according to whether the occlusion pressure at 100 ms (PO.1), index of central stimulation, decreased or not during the test. The first group lowered PO.1 and increased PaCO2 by decreasing VE (minute-ventilation), VA (alveolar ventilation) and increasing the VD/VT ratio; the others had a lower PO.1 and did not modify it after administration of 02 despite a lowered PaO2 initially identical to that in the first group. They held PaCO2 constant by increasing VE and by maintaining VA in relationship with an improvement in diaphragm contractility and/or a better response to hypercapnia stimulus. All the patients is this group were successfully weaned eight days after the study period.