[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 4.14 mg for alfentanil. Blood pressure, respiratory frequency, and blood gases were investigated postoperatively until the 240th min under spontaneous breathing of room air. Blood pressure varied less than 10% from initial values in both groups. The respiratory rate decreased by 13% in the alfentanil group and by 20% in the fentanyl group until the 120th min. The blood gases (paCO2, paO2) showed a slow increase of about 10% in the paCO2 in both groups. The paO2 lay at 5.8% below the baseline after 240 min in the fentanyl group and there was roughly 3% below the baseline after 60 min in the alfentanil group.