USE OF ALFENTANIL FOR IN-VITRO FERTILIZATION OOCYTE RETRIEVAL

Study Objectives: To determine alfentanil levels with a specific radio immunoassay in serum and ovarian follicular fluid. Design: Observation al study. Setting: University hospital. Patients: 14 ASA status 1 wome n undergoing oocyte retrieval for in vitro fertilization. Intervention s: General anesthesia was induced with alfentanil 15 mu g/kg and midaz olam 2 mg and maintained with alfentanil 0.5 mg, 60% nitrous oxide (N2 O) in oxygen (O-2) and midazolam up to a total of 4 mg. Oocyte retriev al was performed using a transvaginal ultrasound guided technique, 34 to 36 hours after human chorionic gonadotrophin administration. Measur ements and Main Results: Mean procedure time for oocyte retrieval was 18 +/- 2.4 (SEM) minutes. All patients were fully awake within 5 minut es and all patients except one were able to move from the operating ta ble to the stretcher with minimal help. Mean total protein concentrati on in the follicular fluid was 3.8 +/- 0.4 mg%. Maximal serum alfentan il concentrations (Cmax) were attained 5 minutes after start of the pr ocedure (tmax) and were 92 +/- 20 ng/ml. In contrast, alfentanil conce ntrations in the follicular fluid increased constantly throughout the procedure up to 8.9 +/- 0.8 ng/ml at 15 minutes. Clinical pregnancy ra te was 3 of 14 patients. Conclusion: It is evident that during the ooc yte retrieval procedure, the alfentanil concentrations in the follicul ar fluid are about ten-fold smaller than the serum alfentanil concentr ations at the same time points. Similar pharmacokinetics have been sho wn when propofol was used as anesthetic. The low accumulation of alfen tanil in the follicular fluid increases the attractiveness of alfentan il for anesthesia during oocyte retrieval for in vitro fertilization.