Summary: A patient receiving cyclophosphamide suffered apnoea and respiratory insufficiency after two anaesthetics in which suxamethonium had been used whilst an anaesthetic without suxamethonium was uneventful; the plasma was found to have a lowered activity of plasma cholinesterase. Accordingly eight patients being treated with cyclophosphamide were tested for plasma cholinesterase activity; in seven there was a significantly depressed level, of the acquired type, as compared with control groups of healthy subjects and patients with comparable diseases not receiving cyclophosphamide. In two patients a fall in cholinesterase activity was demonstrable after cyclophosphamide was begun. Thus appropriate precautions should be taken with patients receiving cyclophosphamide and requiring general anaesthesia: withdrawal of cyclophosphamide, avoidance if possible of depolarising relaxant drugs, or the giving of fresh blood preoperatively to raise the level of plasma cholinesterase.

No abstract