The haemodynamic effects of bronchoscopy Comparison of propofol and thiopentone with and without alfentanil pretreatment

The haemodynamic response to bronchoscopy under general anaesthesia was investigated. Forty patients were allocated at random to receive either thiopentone or propofol; half the patients in each group received in addition 18 micrograms/kg of alfentanil one minute before induction of anaesthesia. The heart rate, noninvasive blood pressure and Holter ECG was monitored in all patients. Significant increases in heart rate (p less than 0.05), systolic and diastolic arterial pressures (p less than 0.01) occurred in the thiopentone only group, following bronchoscopy. Systolic and diastolic arterial pressure decreased in patients receiving thiopentone plus alfentanil, following induction of anaesthesia and laryngoscopy (p less than 0.05). No significant haemodynamic changes were seen in either of the groups which received propofol. ST segment changes on subsequent Holter analysis were seen in four patients, but there were no significant differences between the groups. Anaesthesia with propofol alone provides adequate haemodynamic stability for bronchoscopy and the addition is superfluous.     

The optimum concentration for epidural fentanyl

A randomised, double-blind study comparing a variety of different concentrations of fentanyl with and without 1:200 000 adrenaline is described. It was shown that the quality and duration of analgesia with epidural fentanyl was concentration-dependent below 10 micrograms/ml, but that the addition of adrenaline abolished this phenomenon. The rate of failure to achieve any analgesia was very high with the more dilute solutions, but adrenaline reversed this problem. In general the incidences of side effects were related to the concentrations of fentanyl used and apart from itching, the incidences of these side effects were reduced by the addition of adrenaline.     

The effects of remifentanil on haemodynamic stability during rigid bronchoscopy

We examined the effect of remifentanil on the haemodynamic response to rigid bronchoscopy in 22 adult ASA 2-4 patients, randomly allocated to receive 1.0 microg.kg-1 remifentanil over 1 min followed by 0.5 microg.kg-1.min-1 (remifentanil group) or 2.0 microg.kg-1 fentanyl followed by a saline infusion (control group). Following the initial infusion, all patients received a sleep dose of propofol followed by rocuronium 0.6 mg.kg-1 and their lungs were ventilated using a Sander's injector attached to the rigid bronchoscope. Direct arterial blood pressures, heart rate and ST segment changes on the CM5 lead configuration of the electrocardiograph were measured at 1-min intervals from before induction of anaesthesia until the end of bronchoscopy. Arterial pressures and heart rate were similar in the two groups before and after induction of anaesthesia. Remifentanil attenuated the haemodynamic response to bronchoscopy (p < 0.05 for increases in arterial pressures and heart rate). Four patients in the remifentanil group had ST segment depression compared with eight patients in the control group, but this was not statistically significant.     

Epidural versus intramuscular fentanyl

In a randomised double blind trial, 36 patients in the first stage of labour received either epidural or intramuscular fentanyl at the same time as the epidural test dose of bupivacaine. Analgesia was more rapid in onset and more complete in the epidural fentanyl group. Supplementary doses of bupivacaine were required within the first hour in 62% of the intramuscular fentanyl group compared with only 16% in the epidural group. Plasma fentanyl concentrations showed wide interindividual variation, but after epidural fentanyl the peak occurred earlier. There was no correlation between analgesia and plasma fentanyl concentration, and epidural fentanyl produced superior analgesia but a systemic contribution to this effect cannot be ruled out.     

Epidural fentanyl in labour

In a randomized double-blind trial in the first stage of labour, 20 patients given fentanyl 80 micrograms in the epidural test dose of bupivacaine, were compared with 20 patients receiving an intravenous infusion designed to produce comparable plasma fentanyl concentrations, at the same time as their epidural test dose. Despite slightly higher plasma fentanyl concentrations in the intravenous fentanyl group, epidural fentanyl produced analgesia which was more complete, more rapid in onset and slightly longer lasting. Supplementary doses of bupivacaine were needed to produce analgesia in 75% of the intravenous and 30% of the epidural fentanyl group. It is clear that epidural fentanyl produces satisfactory pain relief when added to the epidural test dose, but that the presence of fentanyl in the systemic circulation makes a negligible contribution to analgesia.     

Epidural fentanyl and perineal pain in labour

Perineal pain during the course of routine epidural analgesia with bupivacaine was treated with a 10-ml top-up of either bupivacaine 25 mg, fentanyl 100 micrograms or fentanyl 100 micrograms plus bupivacaine 10 mg, in 46 women in the first stage of labour. Only fentanyl plus bupivacaine produced consistently reliable analgesia which was quicker in onset and longer in duration (140, SD 26 minutes) than either fentanyl (114, SD 26 minutes) or bupivacaine (99, SD 44 minutes) alone. Side effects, itching and drowsiness, which were not troublesome, were more frequent in the groups given fentanyl.     

A comparison of the effects of alfentanil/droperidol or fentanyl/droperidol on intra-ocular pressure

The influence of two intravenous sedative regimens on intra-ocular pressure was investigated in conjunction with retrobulbar local anaesthesia. Forty patients were allocated randomly to either group A (alfentanil and droperidol) or group F (fentanyl and droperidol). Measurements of intra-ocular pressure, arterial pressure and oxygen saturation were made before operation, after premedication, after intravenous sedation and after surgery. Paco2 was also measured before and after operation. Each sedation technique caused a similar reduction in intra-ocular pressure. There was less effect on Paco2 and oxygenation in group A.     

Epidural fentanyl and 0.5% bupivacaine for elective Caesarean section

Either 100 micrograms fentanyl or 2 ml saline was added to 0.5% bupivacaine administered epidurally for elective Caesarean section in 30 patients, in a double-blind randomised study. Bupivacaine 0.5% was administered until a complete sensory block was established extending to the 4th thoracic dermatome. One of the patients who received epidural fentanyl required intravenous alfentanil and Entonox and another, Entonox only briefly during surgery, compared with seven in the control group who required intravenous alfentanil and Entonox and one who required Entonox only. Postoperative analgesia was of longer duration in those who received epidural fentanyl (p less than 0.01). There were no deleterious effects on neonatal or maternal outcome.     

Epidural fentanyl and monoamine oxidase inhibitors

The successful use of continuous epidural fentanyl infusion to control postoperative pain in a patient treated with monoamine oxidase inhibitors is described. The use of epidural opioids may be a safe technique for the management of such patients.     

Antagonism of fentanyl and alfentanil by intravenous plus subcutaneous naloxone

Twenty patients undergoing microlaryngoscopy were anaesthetized with thiopentone. Half received fentanyl supplementation (about 8.5 micrograms/kg) and the other half alfentanil (about 65 micrograms/kg). Both groups were given naloxone 0.4 mg intravenously plus 0.4 mg subcutaneously shortly after the procedure which lasted some 12 minutes. The degree of ventilatory depression was assessed by a CO2 rebreathing test. The ventilation at an end-tidal PCO2 of 8.0 kPa (V8.0) was noted, and the findings related to a control value obtained on the day before anaesthesia. In the fentanyl group, V8.0 was significantly (p less than 0.05) less one hour after naloxone than 15 minutes after, and remained significantly below the control value for the first 8 hours after microlaryngoscopy. A second peak in plasma fentanyl concentration was observed four hours postoperatively in three patients. Respiratory depression in the alfentanil group was less pronounced and of shorter duration than in the fentanyl group. Postoperative plasma alfentanyl concentration decreased progressively with time in every patient.     

Large dose epidural sufentanil

The postoperative analgesic management of a patient who was intolerant of morphine and pethidine is described. An epidural infusion of fentanyl up to 1 microgram/kg/hour was ineffective for analgesia in the first 18 hours. Subsequently, 50-micrograms boluses and an infusion of 0.5 microgram/kg/hour sufentanil provided satisfactory analgesia with minimal side effects for 28 hours.     

Alfentanil infusion in the elderly

The use of a computer-assisted infusion of alfentanil, combined with 66% nitrous oxide in oxygen, for induction and maintenance of anaesthesia was evaluated in 18 elderly patients. The target alfentanil concentration for induction was varied between 300 and 475 ng/ml, to be achieved in 2 minutes. During maintenance, the alfentanil concentration was increased or decreased according to each patient's responses. Arterial blood samples were taken for measurement of alfentanil concentration. There were high incidences of muscle rigidity, bradycardia and hypotension during induction. Hypotension was dose- and concentration-dependent. Signs of light anaesthesia during maintenance were controlled rapidly by increasing the target plasma concentration. Nine patients required naloxone at the end of surgery. Ventilatory depression recurred in three of these. The use of published alfentanil pharmacokinetic data from elderly patients to predict plasma concentrations during prolonged infusion resulted in significant prediction errors, notably in the higher concentration range.     

Ventilatory effects of subarachnoid fentanyl in the elderly

Twenty-eight elderly patients scheduled for urological surgery were randomly assigned to receive, in a double-blind study, subarachnoid hyperbaric bupivacaine 15 mg with 50 micrograms (group A, n = 7), 25 micrograms (group B, n = 7), or 12.5 micrograms (group C, n = 7) of fentanyl or 1 ml of saline (group D, n = 7) in a total volume of 4 ml. The pattern of breathing and the ventilatory response to CO2 were studied before and 90, 150 and 480 min after the subarachnoid injection. In group A, mild pruritus and sedation occurred in five patients, while nausea, vomiting and periodic breathing occurred in two. In group B, mild pruritus and sedation were observed in four patients, while nausea and vomiting occurred in two. No significant differences in minute ventilation, respiratory drive and respiratory timing were observed between the groups. Patients receiving fentanyl 50 micrograms showed a percentual change from baseline values as function of time (slope VE/PE'CO2) significantly below baseline at 90 and 150 min (p less than 0.05). However, the baseline values in this group reverted after 480 min. No side effects were observed in groups C or D. It is concluded that subarachnoid fentanyl 50 micrograms can cause an early respiratory depression and its use as a postoperative analgesic should be avoided in the elderly.     

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.     

Comparison of effects of fentanyl and alfentanil on intra-ocular pressure

The effects of fentanyl and alfentanil on intra-ocular pressure during anaesthesia were investigated in 50 consecutive patients in a double-blind controlled trial. Both drugs produced a significant reduction in intraocular pressure (p less than 0.01). Alfentanil produced significantly greater reduction (48.5 percent) than fentanyl (28.6 percent) (p less than 0.01). A small but statistically significant reduction in arterial pressure (15 percent approximately) and heart rate (18 percent approximately), were observed with both agents, but no significant differences between them were noted. It is suggested that alfentanil may be a suitable alternative to fentanyl in ophthalmic anaesthesia.