[Opioid analgesia--an alternative to general anesthesia]

The use of opioid analgesia in the awake, spontaneously breathing patient has not yet been published as an alternative to general anaesthesia or epidural analgesia. 297 patients were treated by injecting on demand up to 0.9 mg of fentanyl intravenously to abolish the considerable pain which is caused by extracorporal shock wave lithotripsy. In contrast to its alternatives, fentanyl analgesia had no effect on circulatory parameters when the patients were immersed in a bath at 37 degrees C. Arterial gas analysis showed only a slight increase in paCO2 values and a remarkably constant paO2 if oxygen was added to inhaled air. Breathing of pure air caused a dramatic decrease of paO2 6 to 15 minutes after the administration of the loading dose of fentanyl. The method is only practicable if the patient stays awake and is awakened whenever he is at the point of falling asleep.