Alfentanil supplemented anaesthesia for short procedures

Thirty-nine unpremedicated patients who presented for cystoscopy were given either alfentanil or saline in a random double-blind fashion immediately before anaesthesia with etomidate, nitrous oxide and enflurane. Alfentanil significantly reduced myoclonus associated with etomidate. During anaesthesia, patients who received alfentanil had smaller minute volumes, lower respiratory frequencies, and smaller increases in heart rate. The incidence of apnoea was not significantly increased. After operation, patients who received alfentanil were prescribed significantly more analgesia, possibly because of their reduced uptake of volatile anaesthetic agent. It is concluded that supplementation with alfentanil improves the quality of anaesthesia induced with etomidate.     

Alfentanil infusions. Comparison of bolus administration of fentanyl with three alfentanil infusion regimens

Three different dosage regimens of alfentanil were compared with boluses of fentanyl in 80 patients who underwent a variety of surgical procedures. Alfentanil given by infusion at a rate of 7.5 micrograms/kg/minute for 10 minutes followed by 0.75 micrograms/kg/minute, was shown to provide a stable anesthetic which minimises the use of a volatile agent for surgery that lasts more than 45 minutes.     

Alfentanil used to supplement propofol infusions for oesophagoscopy and bronchoscopy

This randomised double-blinded study compared the cardiovascular stability and rate of recovery when propofol infusions with or without alfentanil were used to provide anaesthesia for rigid oesophagoscopy and (or) bronchoscopy. Forty-six patients were allocated randomly to receive either alfentanil 10 micrograms/kg or saline just before a rapid sequence induction with propofol. Suxamethonium 1 mg/kg was given and infusions of suxamethonium 10 mg/minute and propofol (10 mg/kg/hour for 10 minutes, 8 mg/kg/hour for 10 minutes and then 6 mg/kg/hour thereafter) were started. There were 23 patients in each group with no significant demographic differences between the groups. A significantly mean lower induction dose of propofol was needed in the alfentanil group (1.7 mg/kg compared to 2.2 mg/kg). Cardiovascular measurements were made on the ward pre-operatively, just before induction, just after induction, just after intubation, and at 3-minute intervals thereafter. Arterial pressure was significantly lower during the procedure in the patients who received alfentanil and there was a significant incidence of hypotension. There was no significant difference between the groups in respect of heart rate, with a significant increase in both groups just after intubation compared to the baseline values. Recovery from anaesthesia was assessed using the critical flicker fusion threshold. No differences were found between the groups and patients in both groups had returned to baseline values by 60 minutes. No patient had any recall of intra-operative events, and there were no other adverse effects of any significance.     

Alfentanil in short procedures

Ninety patients, premedicated with temazepam 20 mg, undergoing suction termination of pregnancy, were studied. Forty patients received alfentanil (500 micrograms), and thirty halothane (1.5%) as supplements to either etomidate or methohexitone-nitrous oxide-oxygen anaesthesia. A further 20 patients received alfentanil 250 micrograms at induction of anaesthesia with methohexitone, followed by a further 250 micrograms immediately prior to the onset of surgery. Recovery was assessed by the time patients took to open eyes on command, to giving their correct date of birth, and to performing the 'p' deletion test. Satisfactory operating conditions were not obtained with the combination of etomidate and halothane. Faster recovery was seen in patients with either etomidate or methohexitone and receiving alfentanil (p less than 0.01) Testing by the 'p' deletion test showed impaired psychomotor performance at 30 minutes after cessation of anaesthesia in all groups compared with the pre-operative scores. Side effects leading to unsatisfactory anaesthesia were more frequent in patients who had received etomidate (p less than 0.01).     

Gastric emptying after minor gynaecological surgery

Gastric emptying was measured using the paracetamol absorption method in 30 patients immediately after a general anaesthetic for minor gynaecological surgery and in 10 female controls. Anaesthesia was induced with either propofol alone, propofol and alfentanil (4.5 micrograms.kg-1) or propofol and fentanyl (1.4 micrograms.kg-1) and maintained with intermittent propofol and 66% nitrous oxide in oxygen. Gastric emptying was delayed significantly in all patient groups when compared with volunteers. However, the delay in gastric emptying was similar in the three patient groups.     

A comparison of nalbuphine and morphine as premedication agents for minor gynaecological surgery

Nalbuphine 10 mg and morphine 10 mg were compared in a randomised double-blind trial as intramuscular premedication in 50 patients undergoing minor gynaecological surgery. Both nalbuphine and morphine produced significant sedation without anxiolysis as assessed by patient linear analogue scales, but there were no significant differences between the two drugs. Observer ratings demonstrated that nalbuphine produced calm/sleepy patients to a greater extent than morphine. There were no differences in untoward effects produced by each drug.     

A comparison of alfentanil, halothane and enflurane for day-case gynaecological surgery

Sixty patients received either alfentanil, halothane or enflurane for maintenance of anaesthesia during short day-case gynaecological procedures. The alfentanil group recovered more rapidly but there was no difference between halothane and enflurane in terms of recovery time. Apnoea and movement during surgery only occurred in the patients who received alfentanil. The incidence of other side effects was the same in each group, including late subjective feelings of drowsiness and unsteadiness.     

Alfentanil in daycase anaesthesia

The effect of the addition of a single dose of 7 μg.kg⁻¹ of alfentanil to a propofol/enflurane anaesthetic on the quality of anaesthesia and recovery was assessed. A total of 53 ASA grade 1 or 2 patients who underwent daycase dental surgery were allocated randomly to receive either alfentanil or saline. The study was blinded so that neither the anaesthetist nor the assessor was aware of which solution had been given. Patients in the alfentanil group took signficantly longer to recommence spontaneous ventilation (p = 0.035). Both techniques provided good quality of anaesthesia. Postoperative morbidity was common (45% of patients), but there was no difference between the groups. The rate of recovery was similar in the two groups and no patient required hospital admission after the final assessment at 3 h. Drowsiness was only mild to moderate in both groups at 24 h. A single dose of alfentanil can be administered safely as part of a daycase anaesthetic without increasing morbidity, although there appears to be little advantage in doing so.     

Total intravenous anaesthesia with etomidate-fentanyl

A total intravenous anaesthetic technique using etomidate, fentanyl and neuromuscular blocking drugs with artificial ventilation of the lungs has been used in 90 patients undergoing elective general and gynaecological surgery. A two-step schedule was used, based on a pharmacokinetic model for rapidly eliminated, intravenously administered drugs. Etomidate 100 micrograms/kg/minute with fentanyl 1 microgram/kg/minute were given for 10 minutes, followed by a maintenance dose at a rate of one-tenth this amount. Concurrent evaluation of the technique led to variations in the adjuvant drugs used (atropine, droperidol and neuromuscular blocking agent). The basic dose schedule provided adequate surgical anaesthesia for 76% of patients (although dose adjustments were used in the remainder), with recovery times of 10 minutes or less in 57% of patients. No further opiate analgesia was needed in 40% of patients postoperatively. Those patients given atropine intravenously prior to induction had a significantly lower incidence of nausea and vomiting postoperatively.     

A comparison between isoflurane and alfentanil supplemented anaesthesia for short procedures

Sixty unpremedicated patients undergoing short urological and gynaecological procedures were randomly allocated to three groups to receive either methohexitone, alfentanil, nitrous oxide and oxygen, methohexitone, isoflurane and oxygen or methohexitone, isoflurane, nitrous oxide and oxygen. The group receiving methohexitone, isoflurane and oxygen was abandoned after 11 patients had been studied, due to poor conditions during induction of anaesthesia. Therefore, data from only 51 patients are presented. Early recovery was assessed by time to opening eyes, giving correct name and date of birth; later, recovery was assessed by using the postbox test and deletion of 'p's. During anaesthesia and surgery, there was a high incidence of coughing and laryngospasm in the isoflurane groups. The patients in the alfentanil group opened their eyes and gave their names and dates of birth significantly faster postoperatively (p less than 0.01) than those in the isoflurane groups. However, there were no significant differences between the three groups regarding the later tests of recovery. The late recovery after isoflurane was equal to that obtained using an intravenous technique with alfentanil, although the peroperative complication rate was higher.     

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).     

The effects of speed of injection on induction with propofol A comparison with etomidate

One hundred and eighty female patients received either propofol 2.5 mg/kg or etomidate 0.3 mg/kg injected over 20, 40 or 80 seconds for induction of anaesthesia after premedication with temazepam 20 mg. The mean induction times for both etomidate and propofol were significantly reduced with increasing speed of injection. The mean induction times for etomidate were significantly less than propofol at the slower rates of injection. At each speed of injection, the decrease in systolic, mean and diastolic arterial blood pressures with etomidate were less than with propofol. The decrease in systolic blood pressure was not significantly affected by injection speed for either drug. Apnoea occurred significantly more frequently with propofol than with etomidate at each speed of injection and the incidence of apnoea greater than 60 seconds with propofol was significantly higher when injected over 20 seconds than 80 seconds. The incidence of pain on injection was unaffected by injection speed for either drug. The incidence of myoclonus and (or) hypertonus was significantly higher following etomidate.     

Comparison of etomidate and propofol for anaesthesia in microlaryngeal surgery

Propofol and etomidate were compared as hypnotics in total intravenous anaesthesia for microlaryngeal surgery combined with jet ventilation. Two groups of 15 patients were studied. In group 1, propofol 2.0 mg/kg was used for induction. For maintenance a continuous infusion of 12 mg/kg/hour was used for the first 10 minutes, followed by 9 mg/kg/hour for the next 10 minutes and 6 mg/kg/hour thereafter. In group 2, the induction dose of etomidate was 0.3 mg/kg followed by continuous infusion of 1.8 mg/kg/hour for 10 minutes, 1.5 mg/kg/hour for the next 10 minutes and 1.0 mg/kg/hour thereafter. Alfentanil was given for analgesia and suxamethonium for muscle relaxation. The propofol group showed better surgical conditions, more stable anaesthesia and better recovery according to the Steward score. Recovery times to opening eyes on command were comparable for both groups.     

Echocardiographic assessment of the haemodynamic effects of propofol: a comparison with etomidate and thiopentone

The haemodynamic effects of propofol (2 mg/kg), etomidate (0.2 mg/kg) and thiopentone (4 mg/kg) were studied in 30 ASA 1 and 2 patients in whom anaesthesia had been induced with midazolam 0.1 mg/kg, fentanyl 5 micrograms/kg, vecuronium 0.1 mg/kg and atropine 10 micrograms/kg, and maintained with nitrous oxide in oxygen. Arterial pressure was measured directly and left ventricular diameters were determined by transoesophageal echocardiography. Systolic blood pressure after propofol and thiopentone and the end-systolic quotient (systolic pressure/end-systolic diameter), a measure of inotropy, decreased. Fractional shortening (end-diastolic-end-systolic diameter/end-diastolic diameter) decreased only in the thiopentone group. Diastolic blood pressure and end-diastolic diameter (a measure of preload) did not change in any of the groups, and the etomidate group showed no changes in the haemodynamic variables measured. Propofol shows simultaneous negative inotropy and afterload reduction, while thiopentone is exclusively negatively inotropic.     

Assessment of alfentanil by intravenous infusion as long-term sedation in intensive care

The use of an alfentanil infusion for sedation of critically ill patients in intensive care was investigated in 16 patients who were entered consecutively into the study. The mean duration of stay was 8 days. Supplements of Diazemuls and muscle relaxants were administered if required. The success of the technique was judged by nursing and medical staff and, in particular, the wakefulness of patients was noted. No patient could recall events that occurred during their infusion. An outline protocol is described.