Buprenorphine as premedication and as analgesic during and after light isoflurane-N2O-O2 anaesthesia. A comparison with oxycodone plus fentanyl

Sixty patients undergoing gynaecological laparotomies under isoflurane anaesthesia received 0.4 mg of buprenorphine sublingually or 0.12 mg/kg of oxycodone intramuscularly in random order for preanaesthetic medication. Patients premedicated with buprenorphine were given buprenorphine before, during and after anaesthesia and patients premedicated with oxycodone received fentanyl before and during anaesthesia and oxycodone after anaesthesia. Buprenorphine premedication produced less drowsiness and sedation and alleviated patients' apprehension significantly (P less than 0.05) less than oxycodone. Systolic and diastolic blood pressure and heart rate were significantly (P less than 0.05 to P less than 0.01) higher after intubation in the buprenorphine group when compared with the oxycodone plus fentanyl group. After anaesthesia, spontaneous respiration started rapidly; the return of consciousness and immediate recovery occurred at the same rate in both groups. In the recovery room moderate to severe pain was more common (P less than 0.05) in the oxycodone plus fentanyl group than in the buprenorphine group. The respiratory rate in the recovery room was lower among patients given buprenorphine, and two patients given buprenorphine developed severe respiratory depression. In the ward (2 to 24 h after operation) sublingual buprenorphine provided pain relief as good as intramuscularly administered oxycodone. No differences were noted in the incidence or severity of emetic symptoms between the groups. It is concluded that buprenorphine can provide good postoperative pain relief for gynaecological laparotomies performed under light isoflurane anaesthesia, but patients need to be monitored carefully after operation because of the possibility of respiratory depression.     

The stability of preservative-free morphine in plastic syringes

The stability of preservative-free morphine in plastic syringes over 36 hours in the range of concentrations commonly used in our hospital to provide continuous morphine infusions was investigated. The morphine concentration remained at 100% (SD 1.5 percent) of the control values over 36 hours and demonstrates that the concentration of morphine is not reduced with time in these circumstances.     

Sedation in the ICU

The effect of midazolam on the induction dose-response curve for alfentanil was studied in non-premedicated ASA physical status I or II patients. The response to the verbal command was used as an end point of anaesthesia. Dose-response curves for midazolam, alfentanil, and their combination were determined with a probit procedure, and compared with algebraic (fractional) analysis of drug interaction. Interaction between midazolam and alfentanil was found to be synergistic (supra-additive). The results suggest that the use of this combination is advantageous not only because it helps to achieve different anaesthetic goals with specific drugs (a benzodiazepine for unconsciousness and an opioid for blockade of the responses to noxious stimulation), but also because its components are complementary for unconsciousness.     

Propofol and alfentanil infusion

In 42 patients undergoing major surgery, anaesthesia was induced by intravenous alfentanil 10 micrograms/kg together with methohexitone 1.5 mg/kg or propofol 2 mg/kg. An infusion of six times these doses per hour was then started; the rate was varied subsequently as indicated by the monitoring of arterial blood pressure, heart rate, EEG and frontalis electromyogram. The mean duration of infusion was 76.7 minutes for propofol and 74.5 minutes for methohexitone and the infusion was stopped about 10 minutes before the end of surgery in each group. The induction dose differed, but the total dose requirement for the two drugs was similar. In every case, anaesthesia was satisfactory. Methohexitone caused a significant rise in mean pulse rate throughout anaesthesia (p less than 0.05, paired t-test). There was no change in mean pulse rate during propofol infusion. The dose of alfentanil used provided excellent control of autonomic reflexes, with negligible respiratory depression. Naloxone was not required. Propofol provided better anaesthesia than methohexitone, with fewer side effects (p less than 0.05, Chi squared test), easier control of the level of narcosis and faster recovery (p less than 0.001, t-test after log transformation).     

Papaveretum infusions in infants under 6 months of age

The effectiveness of a continuous low dose papaveretum infusion for the relief of postoperative pain was assessed in 29 infants aged 1-6 months nursed on the infant surgical ward following major abdominal surgery. Trained nursing staff were able to adjust the dosage within prescribed guidelines and satisfactory analgesia was obtained with a regimen which delivered up to 0.0375 mg/kg/hour, approximately half the dose recommended in children older than 12 months. There was one case of clinically significant respiratory depression.     

Day case laparoscopy: a survey of postoperative pain and an assessment of the value of diclofenac

A randomised, controlled study was undertaken to assess the postoperative pain and side effects experienced by patients undergoing day case diagnostic laparoscopy and laparoscopic sterilisation, and to evaluate the effectiveness in these patients of peroperative diclofenac. Patients undergoing laparoscopic sterilisation had significantly higher pain scores at one hour postoperatively, and at discharge, than patients undergoing diagnostic laparoscopy (p less than 0.01) but there were no significant differences in pain scores 24 hours after discharge. The incidence of postoperative side effects following discharge from hospital was high, but there were no significant differences between the groups. Diclofenac had no significant effect in either group on the severity of postoperative pain, or the incidence of postoperative side effects.     

Myoclonic spasms after epidural diamorphine infusion

A case is presented in which myoclonus occurred after epidural diamorphine infusion. Reports of this phenomenon following other epidural drugs and possible mechanisms are discussed.     

Influence of perioperative nalbuphine and fentanyl on postoperative respiration and analgesia

In a double-blind study the relative postoperative respiratory and analgesic effects of perioperatively administered nalbuphine and fentanyl were compared in 60 females undergoing gynecological surgery under i.v. anesthesia. One milliliter (10 mg) nalbuphine was considered equipotent to 1 ml (100 micrograms) fentanyl. In the recovery period pain was assessed by visual analog score (VAS) and recovery by Pegboard scoring. Respiratory function was evaluated by continuous monitoring of respiratory frequency and end-tidal CO2 (ETCO2) and by frequent arterial blood gas analyses. The total volume of analgesic required for surgical analgesia was similar in the two groups. Patients in the nalbuphine group showed mild to moderate increases in pulse rate during the intubation phase and in blood pressure during surgery. Fentanyl was more effective in suppressing these cardiovascular responses. Within the first 15 min following recovery, increasing PaCO2 and ETCO2 as well as respiratory rates below 10/min were noted in 8 patients, who all belonged to the fentanyl group; in 4 of these patients i.v. naloxone had to be administered to reverse respiratory depression. Prolonged sedation was a common feature in patients receiving nalbuphine. It was concluded that fentanyl was superior to nalbuphine in attenuating the pressor responses to intubation and surgery. However, fentanyl was associated with respiratory depression in a considerable number of patients. The quality and duration of postoperative analgesia were similar in the two groups.     

Effect of sufentanil on intracranial pressure in neurosurgical patients

The effects of sufentanil on intracranial pressure, mean arterial pressure, cerebral perfusion pressure and heart rate were studied in 20 neurosurgical intensive care unit patients. Epidural intracranial pressure probes were implanted in patients who suffered head injury, intracerebral haemorrhage or underwent tumour resection. Sufentanil was given intravenously in sequential doses of 0.5, 1.0 and 2.0 micrograms/kg. Fifteen minutes elapsed after each dose. The patients were allocated to either group 1 (baseline intracranial pressure less than 20 mmHg) or group 2 (baseline intracranial pressure greater than 20 mmHg). Intracranial pressure did not change significantly in either group. Therefore the falls in mean arterial pressure with the highest dose in both groups and with 1.0 micrograms/kg in group 2, closely reflect corresponding reductions in cerebral perfusion pressure. As sufentanil in itself exerts no effects on intracranial pressure, concomitant haemodynamic changes are the critical factor for an adequate cerebral perfusion pressure.     

Patient-controlled on-demand epidural fentanyl

A prospective, open, clinical trial is described in which 20 patients having upper abdominal surgery were randomly allocated to receive fentanyl for postoperative analgesia by patient-controlled demand analgesic computer by either the epidural or intravenous route. Hourly pain, sedation and nausea scores were very similar in the two groups during the first 24 hours after surgery. What few differences there were favoured the epidural group. There was a highly significant difference in fentanyl consumption between the two groups, with the intravenous group demanding consistently more than twice as much as the epidural group.