[Comparative studies of the postoperative phase following opioid analgesia using fentanyl and alfentanil within the scope of extracorporeal shockwave lithotripsy].

30 patients (ASA Class I-III) received opioid analgesia with fentanyl and alfentanil for extracorporeal shock wave lithotripsy. Average doses were 0.41 mg for fentanyl and 4.