Respiratory effects of intraoperative alfentanil infusion in post-abdominal hysterectomy patients: A comparison of high versus low dose

A number of reports have been published describing (recurrent) respiratory depression after the use of alfentanil intraoperatively. To evaluate the severity of respiratory depression after the administration of alfentanil, 49 patients undergoing general anaesthesia for abdominal hysterectomy were randomly allocated to one of three groups and studied in a double-blind manner. During surgery patients received no opioids (group 1), low dose (group 2) or high dose of alfentanil (group 3). Postoperatively patients were monitored with pulse oximetry and respiratory inductive plethysmography. Postoperative pain was managed with PCA morphine. Thirty-nine patients completed the study. Respiratory depressant effects were found in all three groups. A higher number of apnoeas (at 60 minutes in group 1: 3.3 ± 1.6; group 2: 3.5 ± 1.8; group 3: 12.2 ± 2.8) and a higher morphine consumption was found in group 2 when compared with group 1 and 3. No differences were found among the groups in the other respiratory parameters or in terms of the number of patients with respiratory depression at any one time. No cases of clear-cut recurrent respiratory depression were identified

Pre-emptive lumbar epidural anaesthesia reduces postoperative pain and patient-controlled morphine consumption after lower abdominal surgery

The present study tested the hypothesis that patients receiving epidural bupivacaine before surgery would require less morphine postoperatively and/or report less intense pain than patients receiving epidural bupivacaine after incision but before the end of surgery. Forty-two patients (ASA class I-III) scheduled for lower abdominal surgery were randomly assigned to 1 of 2 groups of equal size and prospectively studied using a double-blind, placebo-controlled crossover design. Epidural catheters were placed in the T12-L1 or L1-L2 interspaces pre-operatively, the position of the catheter was confirmed with 3% chloroprocaine with epinephrine 1:200,000, and sensory testing was carried out until levels had receded to below T12. Group 1 received 15 ml of 0.5% epidural bupivacaine injected 35 min before incision followed by 15 ml of epidural normal saline 30 min after incision. Group 2 received 15 ml of epidural normal saline injected 37 min before incision followed by 15 ml of 0.5% epidural bupivacaine 30 min after incision. General anaesthesia was induced with thiopental (4–6 mg/kg) and maintained with N2O/O2 and isoflurane. Paralysis was achieved with pancuronium (0.1 mg/kg). Opioids were not used as pre-medication or during surgery. Postoperative analgesia consisted of patient-controlled (PCA) intravenous morphine. Visual analogue pain scores (VAS) (at rest and after standardized mobilization) did not differ significantly between the 2 groups but McGill Pain Questionnaire (MPQ) pain ratings were significantly lower in group 1 at the 24 and 72 h assessments. Group 1 used significantly less morphine than did group 2 between 12 and 24 h after surgery. Cumulative PCA morphine consumption in group 1 (55.2 ± 4.7 mg) was significantly lower than in group 2 (71.7 ± 6.1 mg) 24 h and 48 h (group 1: 86.8 ± 6.3 mg vs. group 2: 108.9 ± 9.8 mg) after surgery, but not at the 72 h assessment. Reduction in morphine dose at 24, 48 and 72 h amounted to 30%, 25% and 22%, respectively. The results suggest that single-shot pre-emptive epidural local anaesthesia is associated with a short-term morphine-sparing effect which is most pronounced between 12 and 24 h after surgery. Extending the pre-operative blockade into the postoperative period may prolong the initial advantage conferred by pre-emptive epidural local anaesthesia

High dose alfentanil pre-empts pain after abdominal hysterectomy

This study tested the hypothesis that high dose systemic alfentanil administered before and during abdominal hysterectomy would pre-empt post-operative pain to a greater extent than administration of either low dose alfentanil or no alfentanil perioperatively. Patients (ASA 1 or 2) were randomly assigned to group 1 (n = 15), no opioid; group 2 (n = 15), low dose alfentanil; or group 3 (n = 15), high dose alfentanil. Anaesthesia was induced in group 1 with midazolam and thiopentone and was maintained with isoflurane and 70% N2O in O2. Anaesthesia was induced in group 2 with midazolam, thiopentone and i.v. alfentanil (30 μg kg−1), and was maintained with isoflurane, 70% N2O in O2, and bolus doses of i.v. alfentanil (10–20 μg kg−1) every hour. Anaesthesia was induced in group 3 with midazolam and i.v. alfentanil (100 μg kg−1), and was maintained with 70% N2O in O2, and an infusion of i.v. alfentanil (1–2 μg kg−1 min−1). Blood samples were drawn at 30 and 120 min after surgery and assayed for plasma alfentanil. Morphine consumption and VAS pain scores were consistently lowest in group 3 over the 48 h study period. A composite measure of pain and morphine consumption was significantly lower in group 3 than group 2 up to 6 h after surgery, and siificantly lower than group 1 up to 12 h. No adverse effects were observed. A 6-month follow-up did not reveal any significant differences among the three groups. It is concluded that intra-operative high dose alfentanil anaesthetic pre-empts post-operative pain after abdominal hysterectomy, but the effects are small and of short duration. Surgical procedures carried out under general anaesthesia using standard (and even high) doses of opioids intraoperatively provide sub-optimal protection from the injury barrage brought about by incision and subsequent noxious surgical events