British journal of anaesthesia
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We describe a system for monitoring and controlling i.v. anaesthesia in rats using burst suppression ratio (BSR) detection in the extradural EEG. After bolus injection, peak BSR values of 95% were achieved with propofol 8 mg kg-1, etomidate 3.5 mg kg-1 and alphaxalone 4.5 mg kg-1. Thiopental 32 mg kg-1 produced a peak BSR of 70% (larger doses were not tolerated). ⋯ During these experiments the infusion rates were found to decrease with time, more so with etomidate (approximately 40%) than with propofol (approximately 20%). Recovery times were 2-3 times longer with etomidate than with propofol. This model demonstrated differences between i.v. anaesthetics and may be useful in screening new compounds in preclinical development.
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Randomized Controlled Trial Clinical Trial
Effect of preoperative extradural bupivacaine and morphine on stump sensation in lower limb amputees.
We have examined the effect of preoperative extradural bupivacaine and morphine on postoperative stump sensation in 31 patients undergoing amputation of the lower limb in a prospective, randomized, double-blind study. Patients were allocated randomly to one of two groups: group 1 received extradural 0.25% bupivacaine 4-7 ml h-1 and morphine 0.16-0.28 ml h-1 before and during operation; group 2 received extradural saline before and during amputation and conventional analgesics for pain treatment. All patients received general anaesthesia for the amputation and extradural bupivacaine and morphine after operation. ⋯ The following were measured: pressure pain thresholds (pressure algometry), touch and pain detection thresholds (von Frey hairs), thermal sensibility (thermal rolls), and allodynia and wind-up-like pain. There were no differences between the two groups at any of the postoperative assessments for mechanical and thermal sensibility or rate of allodynia and wind-up-like pain. Our study suggests that preoperative and intraoperative extradural block had no long-term prophylactic effect on hyperalgesia, allodynia or wind-up-like pain.
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Randomized Controlled Trial Clinical Trial
Influence of timing of morphine administration on postoperative pain and analgesic consumption.
We have investigated if a pre-emptive dose of morphine, given 30 min before skin incision, influenced postoperative pain and morphine consumption after hysterectomy. In a prospective, randomized, double-blind, placebo-controlled clinical study, patients received morphine 0.3 mg kg-1 at induction of anaesthesia or 30 min later at skin incision. The primary endpoint was defined as 24-h morphine consumption via patient-controlled analgesia. We could not demonstrate any difference between the two groups in morphine consumption or pain scores, and we conclude that there was no evidence of pre-emptive analgesia in this study.