DETECTION OF INSPIRATORY RESISTIVE LOADS AFTER ANESTHESIA FOR MINOR SURGERY

We measured the ability to detect inspiratory resistances in 22 patien ts undergoing minor gynaecological surgery, using linear resistances o f 1.2-24.4 cm H2O litre(-1) s, and ranked 1-9. The rank that could be detected was measured before surgery, approximately 10 min after recov ery from anaesthesia, and then 25 min later. After anaesthesia there w as a significant increase (P<0.001) in the rank number by 2, which ret urned to preoperative values 25 min later. Minute ventilation was redu ced by 25% after operation and this may partly explain this change; ho wever, we believe the transient decrease in ability to sense resistanc e indicates residual effects of anaesthetics and may explain in part t he incidence of hypoxia caused by airway obstruction in patients after anaesthesia.