EQUIVALENCE OF POSTOPERATIVE ANALGESIA WITH PATIENT-CONTROLLED INTRAVENOUS OR EPIDURAL ALFENTANIL

The analgesia and the frequency and severity of oxyhemoglobin desaturation related to alfentanil administration were compared in 32 patients randomly selected to receive patient-controlled analgesia (PCA) by either the epidural (EPI) or intravenous (IV) route for a mean period of 16 h after major abdominal surgery. Bolus increments of 250 mug of alfentanil with a lockout interval of 5 min for IV and of 1 0 min for EPI route were administered by a programmable pump. Oxygen saturation (Spo2) was monitored for 16 h, using a pulse oximeter; data were collected continuously and stored every 30 s via an interface connected to a computer. For the purpose of analysis, Spo2 was divided into six categories: 95%-100%, 90%-94%, 85%-89%, 80%-84%, 75%-79%, and 70%-74%. Both routes provided similar degrees of analgesia at rest and on coughing. Maximum pain relief was obtained earlier in the IV group (P < 0.01). The total consumption of alfentanil was 13,141 +/- 3471 mug (mean +/- SD) in the IV group and 8000 +/- 4213 mug in the EPI group (p < 0.001). The effects on Spo2 were not statistically different between the two groups. Cumulative time spent in each saturation category was similar for the EPI and IV groups. Severe desaturation episodes, defined as Spo2 less-than-or-equal-to 85% for at least 60 s, occurred in 69% of patients in the EPI group and 56% in the IV group. The authors conclude that alfentanil EPI PCA was no more effective than IV PCA and that it was associated with the same incidence of oxyhemoglobin desaturation, emphasizing no clinical advantage to administering alfentanil by the epidural route over the intravenous route despite the use of PCA.