Hypoxaemia after premedication in cardiac patients. Glycopyrronium compared with hyoscine.

Arterial blood gases were analysed before and approximately one hour after premedication in two groups of 10 patients awaiting cardiac surgery. One group received intramuscular papaveretum and hyoscine, the other papaveretum and glycopyrronium. Similar, small but statistically significant reductions in mean arterial oxygen tension and oxygen saturation, and increases of arterial carbon dioxide tension occurred in both groups. Hypoxaemia in individual patients was unpredictable and in some was clinically relevant.