Reduced neuromuscular blocking potency of atracurium in patients with a purulent intrathoracic disease

Objective: Based on personal observations the neuromuscular blocking potenc y of atracurium was supposed to be diminished in purulent intrathoracic dis eases. This hypothesis was tested in a prospective clinical trial. Methods: 52 adult patients undergoing general anaesthesia (methohexitone, s ufentanil,flunitrazepam, N2O enflurane) for elective thoracic surgery were investigated. After the intubation dose of 0.6 mg/kg atracurium was applied continuously to maintain a 90% suppression of the evoked compound electrom yogram. According to the intraoperatively established diagnosis patients we re allocated to three categories: 1) non-malignant tumor as the control gro up (n=15), 2) lung cancer (n=22), 3) purulent intrathoracic process without tumor (n=15). The groups were compared regarding onset time, DUR 10% and m aintenance dose of atracurium. Results: Patients with lung cancer did not differ significantly from the co ntrols regarding efficiency of atracurium. In contrast, patients with a pur ulent intrathoracic process showed a significantly longer onset time (6.3+/ -2.5 vs. 2.9+/-0.8 min,p<0.001),and a significantly shorter DUR 10% (23+/-6 vs. 36+/-10 min,p<0.001) compared to the control group. Mean infusion rate of atracurium to maintain a 90% suppression of the evoked compound electro myogram was significantly higher in patients with a purulent process compar ed to the controls (10.5+/-3.2 vs. 6.0+/-1.2 mu g/kg.min,p<0.001). Conclusion: Our results support the hypothesis that patients with a purulen t intrathoracic disease show a clear reduction in neuromuscular blocking po tency of atracurium.