Introduction: Transvaginal puncture for oocyte retrieval is a short-lasting but painful procedure. We hypothesized that a sole infusion of the ultra-short acting mu-agonist remifentanil may be a suitable and well-controllable single-agent analgesic technique that can dose-dependently be applied to spontaneously breathing patients.
Methods: Fifty consenting adult women were enrolled in this prospective trial. A sedative premedication was omitted, all patients received 3 L/min of inhaled oxygen, and a sole remifentanil infusion was started with 0.25 microg/kg/min. Remifentanil was adjusted as needed for pain relief (in steps of 0.05 microg/kg/min) and finished after the last puncture. Dosage requirements, vital functions, oxygen saturation (as achieved by pulse oximetry, psO(2)), adverse drug effects and the level of sedation (LOS 1-5; 1 = asleep/unarousable, 4 = calm/awake) were recorded. Remifentanil plasma concentrations were achieved by STANPUMP pharmacokinetic simulation. Data are presented as mean +/- SD.
Results: A total of 50 women (31.8 +/- 5.1 yr, 67.3 +/- 14. ASA I or II ) were investigated. Follicular aspiration lasted 10.8+/-5.2 min, and remifentanil was infused for 19.7+/-8.3 min. Dosage requirements were 0.25 microg/kg/min in 70% of all patients, 0.3 microg/kg/min in 22%, 0.2 microg/kg/min in 6%, and 0.4 microg/kg/min in 2% of all cases. Vital signs (baseline, after 1(st) puncture, end of surgery) nearly remained unchanged: heart frequency = 85 +/- 15, 87 +/- 17, 90 +/- 17 bpm, systolic blood pressure = 129 +/- 12, 132 +/- 13, 131 +/- 14 mmHg; respiratory rate = 116 +/- 4, 15 +/- 4 breaths/min; psO(2) = 99 +/- 1, 99 +/- 1, 99 +/- 2%. LOS was 4.0 (all), 3.9 +/- 0.3, 3.9 +/- 0.3. Remifentanil plasma concentrations were 5.0 +/- 1.3 ng/mL at the start, 6.6 +/- 1.3 at the end of surgery and 1.2 +/- 0.5 at PACU arrival. Adverse drug effects: 54% itching, no muscle rigidity. 94% of all women would choose this technique again.
Conclusions: The sole infusion of remifentanil is a suitable and satisfying single-agent monitored anaesthesia care technique for oocyte retrieval. However, close anaesthetic observation - especially of the respiratory function - is mandatory.