The influence of esmolol on the dose of propofol required for induction of anaesthesia.

Cardiac output may be an important determinant of the induction dose of intravenous anaesthetic. Esmolol is known to reduce cardiac output, and we examined its effect on the propofol dose required for induction of anaesthesia. The size of the effect seen with esmolol was compared with midazolam co-induction. Sixty patients were randomly allocated to placebo (saline), esmolol (1mg x kg(-1) bolus, followed by an infusion at 250 microg x kg(-1)min(-1)) or midazolam (0.04 mg x kg(-1)) groups. Induction of anaesthesia commenced 3 min following the administration of the study drug, using a Diprifusor set to achieve plasma propofol concentrations of 10 microg x ml(-1) at 5 min. The primary end point used was the propofol dose per kg at loss of response to command. The mean (SD) propofol dose for each group was 2.38 (0.48) mg x kg(-1) for placebo, 1.79 (0.36) mg x kg(-1) for esmolol and 1.34 (0.35) mg x kg(-1) for midazolam (all means significantly different; p < 0.0005). We found that predosing with esmolol reduces the propofol requirements for induction of anaesthesia by 25%.

The use of tramadol following day--case oral surgery.

This prospective, randomised double-blinded study was designed to assess the analgesic efficacy and occurrence of nausea when tramadol is added to a nonsteroidal anti-inflammatory drug to provide analgesia following day-case third molar teeth extraction. All patients received oral diclofenac pre-operatively and one of four treatments intra-operatively: fentanyl and metoclopramide, tramadol and metoclopramide, fentanyl and ondansetron, or tramadol and ondansetron. There were no significant differences between groups in scores for pain in the early postoperative period. However, there were significant differences in nausea scores at this time, with the fentanyl-ondansetron group having the lowest and the tramadol-ondansetron group having the highest scores. There were no significant differences in the incidence of pain or nausea in the following 24 h. We conclude that the addition of tramadol to diclofenac results in no useful improvement in analgesic effect, and that the use of ondansetron fails to reduce the nausea associated with tramadol.

Intravenous tenoxicam for analgesia following laparoscopic cholecystectomy.

In a double-blind, placebo-controlled clinical trial (power of 80% to detect a 30% reduction in morphine consumption, P < 0.05) we have determined that intraoperative intravenous administration of tenoxicam 40 mg during laparoscopic cholecystectomy, when compared with placebo, was associated with a significant reduction in consumption of morphine at 6 hours and 12 hours (P < 0.05) but not at 24 hours, when assessed by patient-controlled analgesia. Furthermore there was a significantly greater requirement for "rescue" analgesia with intramuscular morphine in the placebo group during the period of the study. There was no difference between the groups in pain scores, either at rest or on movement, nor in the incidence of nausea and vomiting. No patient in either group suffered a respiratory rate less than 8/min or oversedation at any time, and there were no other adverse effects.

Effectiveness and sequelae of very low-dose suxamethonium for nasal intubation.

We have studied the effectiveness and sequelae of low-dose suxamethonium in 60 day-case oral surgery patients requiring nasal intubation. Anaesthesia was induced with propofol and alfentanil; 60 patients were allocated randomly to three groups of 20 patients and received no suxamethonium, suxamethonium 0.25 mg kg-1 or 0.5 mg kg-1. All patients received i.v. fentanyl and diclofenac 100 mg rectally for analgesia. Good intubating conditions were produced in all 20 patients receiving suxamethonium 0.25 mg kg-1, in 19 patients receiving suxamethonium 0.5 mg kg-1 and in 11 patients not receiving a neuromuscular blocker. The incidence of postoperative myalgia after suxamethonium 0.25 mg kg-1 (20%) did not differ significantly from the incidence after propofol and alfentanil alone (28%).

Towards a standardized anaesthetic state using isoflurane and morphine.

In 34 patients undergoing major surgery, the inspired isoflurane concentration was adjusted by a control system designed to maintain systolic arterial pressure at a predetermined value. An empirical rule allowed additional morphine administration if the demand of the system for isoflurane was excessive. Satisfactory control of systolic arterial pressure was achieved in 31 patients and the anaesthetic state was clinically acceptable to an independent observer; no awareness was reported and the mean recovery time was 9.6 min. In these patients, control of systolic arterial pressure produced a pattern of clinical signs recognizable as general anaesthesia.

Towards a standardized anaesthetic state using enflurane and morphine.

General anaesthesia was maintained in 22 patients undergoing major surgery using a proportional-plus-integral control system. The system automatically adjusted the dose of enflurane according to the systolic arterial pressure (SAP). Additional morphine was administered if the system's demand for enflurane exceeded preset limits. In 21 patients, satisfactory control of SAP was achieved and anaesthesia was clinically adequate; no awareness was reported and the mean recovery time was 6.7 min (SD 3.5 min).