[Remifentanil analgesia for aspiration of follicles for oocyte retrieval]

Remifentanil is an esterase-metabolized ultra-short acting mu-agonist opioid with a rapid clearance. The aim of this study was to determine the efficacy of remifentanil infusion for the short-lasting, but painful, transvaginal puncture for oocyte retrieval. Eighty consenting adult women (ASA I and II) aged 30.5 +/- 5 years and with a body weight of 69.1 +/- 9.1 kg were enrolled in this prospective study. After an oral premedication with 7.5 mg midazolam, all patients received 3 l/min oxygen. Subsequently, the remifentanil infusion was started with a rate of 0.3 microg/kg/min. Remifenanil doses were adjusted as needed for painless puncture and sufficient oxygen saturation in steps of 0.05 microg/kg/min. Dosage requirements, blood pressure, heart rate, oxygen saturation (pulse oxymetry, SaO2) and the level of analgesia were recorded every 3 minutes. Follicular aspiration lasted 11.8 +/- 4.1 min and the time of remifentanil infusion was 18.7 +/- 4.6 min. Dosage requirements of remifentanil were 0.3 microg/kg/min in 48.7% of all patients, but 27.8% needed only 0.25 microg/kg/min and 16.6% needed only 0.2 microg/kg/min. However, 4.2% of patients needed 0.35 microg/kg/min and 2.7% of all cases needed 0.4 microg/kg/min. Vital parameters remained nearly unchanged. Oxygen saturation decreased significantly from 99.2 +/- 0.7% to 98.2 +/- 2.4% after 3 min and to 94.9 +/- 7.2% after 10 min. Nine women showed motoric reactions to puncture. In many cases, the infusion of remifentanil after premedication with midazolam provided a suitable and satisfying anaesthesia for oocyte retrieval. Some patients, however, showed motoric reactions to vaginal puncture, while in other cases significant and clinical relevant decreases in Hb-oxygen saturation occurred. Therefore, we no longer carry out remifentanil infusion for transvaginal oocyte retrieval. We now prefer a remifentanil infusion of 0.2 microg/kg/min and propofol (1 mg/kg initially with intermittent doses of 0.5 mg/kg) combined with assisted ventilation by mask.