Supported by two case reports we show that resistance to atracurium ca
n develop postoperatively. Both patients had septic complications afte
r elective thoracic surgery. A 39-year-old patient developed a bronchi
al fistula and a superinfection of the remaining thoracic cavity after
pneumonectomy. At the time of rethoracotomy the neuromuscular blockin
g potency of atracurium had changed drastically: onset time was length
ened (7 vs. 3.5 min), recovery period (DUR 10%) was reduced (14 vs. 28
min) and the maintenance dose had to be trippled (14.3 vs. 5.0 mu g/k
g per minute). Following superior robe resection in a 56-year-old pati
ent, middle robe gangrene occurred which had to be removed. ln contras
t to the first anaesthesia the intubation dose of atracurium had to be
increased significantly (70 vs. 40 mg), and even with this amount the
neuromuscular blocking effect was not complete. Furthermore to accomp
lish a convenient state of relaxation the maintenance dose had to be r
aised considerably (11.8-16.5 vs. 5.5 mu g/kg per minute). These repor
ts show that even within a short period of time resistance to atracuri
um can develop and we must suppose that the severe inflammatory reacti
ons caused these changes.