Small doses of remifentanil or sufentanil for blunting cardiovascular changes induced by tracheal intubation: a double-blind comparison

BACKGROUND AND OBJECTIVE: To compare the effects on cardiovascular changes induced by tracheal intubation when small doses of either remifentanil or sufentanil are used in the presence of midazolam. METHODS: Thirty normotensive, ASA physical status I-II patients, receiving general anaesthesia for major abdominal surgery, received an intravenous midazolam premedication (0.05 mg kg-1) 10 min before induction. They were randomly allocated to receive in a double-blind fashion an intravenous bolus of either (a) remifentanil given as a bolus dose 1 microgram kg-1 (n = 15), or else (b) sufentanil 0.1 microgram kg-1 infused over 60 s (n = 15). In each instance this loading dose was followed by a continuous intravenous infusion (0.1 microgram kg-1 min-1 or 0.01 microgram kg-1 min-1 of remifentanil or sufentanil, respectively). General anaesthesia was induced with propofol (2 mg kg-1), followed by atracurium besilate (0.5 mg kg-1) to facilitate tracheal intubation. Following intubation, the lungs were mechanically ventilated with a 60% nitrous oxide in oxygen mixture and a 1% inspired sevoflurane. RESULTS: Arterial pressure and heart rate were recorded before induction of anaesthesia (baseline), immediately before intubation, immediately after tracheal intubation and every minute for the first five minutes thereafter. No differences in systolic and diastolic arterial pressures were observed between the two groups. At the end of the study period, systolic and diastolic pressures slightly decreased from preinduction values in both groups. Four patients in the remifentanil group (26%) and five patients in sufentanil group (33%) showed at least one systolic pressure value < 90 mmHg during the study period (P = not significant); however, the observed decreases in systolic pressure were transient and did not require treatment. Heart rate values were not affected by tracheal intubation in either group. CONCLUSIONS: In healthy normotensive patients without cardiovascular disease the use of a relatively small dose of either remifentanil or sufentanil after standard midazolam premedication results in a similar and clinically acceptable effectiveness in blunting the cardiovascular changes induced by tracheal intubation.     

Use of a continuous infusion of propofol in maintaining anesthesia

This open, non comparative study was designed to establish a suitable dose regime for propofol when used as the main anaesthetic agent and given as a continuous infusion. Thirty patients (ASA I and II) were studied; five received muscle relaxants and were excluded from the analysis of maintenance and recovery. Immediately after an i.v. bolus dose of fentanyl (2 micrograms X kg-1), anaesthesia was induced in all patients with a mean dose of 2.03 mg X kg-1 propofol. Apnoea at induction was seen in 14 patients, with a mean duration of 151 s (range: 20 to 360 s). Mean, systolic and diastolic arterial pressures and heart rate decreased slightly but statistically significantly following induction. Fourteen patients, four of whom received propofol into a vein of the hand, noted pain on the injection site without venous sequelae immediately nor 24 h after anaesthesia. The mean duration of anaesthesia from induction to the patient ability to obey a simple command was approximately 40 min (range: 10 to 95 min). The mean infusion rate of propofol during maintenance was 0.86 +/- 0.04 mg X kg-1 X min-1. During maintenance, a satisfactory depth of anaesthesia was achieved in 23 patients without any further bolus injection of propofol. The mean time from stopping the infusion to eye opening on verbal command was 6.2 min, whilst that for orientation was 8.4 min. The anaesthesist assessed the quality of recovery as good or adequate in all the patients, who all were satisfied by the anaesthesia. No major adverse reactions occurred during or after anaesthesia and the incidence of minor side-effects was low.     

Alfentanil infusions: relationship between pharmacokinetics and pharmacodynamics in man

Fourteen fit young patients undergoing body surface surgery received an infusion of alfentanil at either 50 or 100 micrograms kg-1 hr-1 to supplement nitrous oxide anaesthesia. The alfentanil infusion was continued for two hours post-operatively at the lower rate of 20 micrograms kg-1 hr-1. Resting ventilation, carbon dioxide responsiveness and pain scores were measured post-operatively. Values for clearance and elimination half life were similar to data following single doses of alfentanil but showed considerable interindividual variation. However, there was a greater systemic clearance (P = 0.02) when determined using the post-infusion decay data compared with that calculated during anaesthesia (527 ml min-1 compared with 434 ml min-1). This is in accord with observations for other intravenous drugs.     

Effect of total intravenous anaesthesia with midazolam/alfentanil on the adrenocortical and hyperglycaemic response to abdominal surgery

The effect of anaesthesia on the hyperglycaemic and adrenocortical response induced by surgery was studied in patients undergoing abdominal hysterectomy. The study group was anaesthetized with midazolam and alfentanil using a totally intravenous anaesthetic technique. A reference group received anaesthesia with thiopentone, alfentanil and nitrous oxide. Midazolam 0.42 mg.kg-1 was given as a loading infusion followed by a maintenance infusion of 0.125 mg.kg-1.h-1. Alfentanil was given as a bolus dose of 0.075 mg.kg-1 in both groups, followed by a loading infusion of 0.3 mg.kg-1.h-1 for 15 min and a maintenance infusion of 0.065 mg.kg-1.h-1. Increments of alfentanil were given whenever heart rate or systolic blood pressure exceeded pre-induction values by more than 10%. During anaesthesia mean arterial pressure and heart rate were similar in both groups and there was no difference in alfentanil requirement. An immediate increase in blood glucose concentrations was seen following incision, but maximum concentrations were measured in the early postoperative period. Serum cortisol concentrations decreased after induction of anaesthesia. During surgery they returned to pre-induction values, and in the postoperative period they increased to about twice the pre-induction values. It is concluded that midazolam/alfentanil anaesthesia is as effective as anaesthesia induced by thiopentone, alfentanil and nitrous oxide in suppressing the stress-response to surgery until the postoperative period. No signs of prolonged adrenocortical depression were observed.     

Preinduction atropine or glycopyrrolate and hemodynamic changes associated with induction and maintenance of anesthesia with propofol and alfentanil

Total intravenous anesthesia by infusions of propofol and alfentanil may be associated with decreases in heart rate and blood pressure. The effects of two vagolytic agents on these hemodynamic changes were studied in 24 ASA physical status 1 patients undergoing body surface surgery. Patients were randomly allocated to receive atropine 10 micrograms/kg, glycopyrrolate, 5 micrograms/kg, or 0.9% sodium chloride, intravenously, 5 min before induction of anesthesia with loading doses of alfentanil, 50 micrograms/kg and propofol 1 mg/kg. Anesthesia was maintained with infusions of alfentanil 50 micrograms.kg-1.hr-1, and propofol 10 mg.kg-1.hr-1 for the first 10 min, 8 mg.kg-1.hr-1 for the next 10 min, and 6 mg.kg-1.hr-1 thereafter. Patients given glycopyrrolate before anesthesia had significantly higher arterial pressures than did patients receiving either atropine or saline, even though heart rates increased equally after glycopyrrolate and atropine.     

Maintenance of anaesthesia with propofol--a comparative study of a stepdown infusion of propofol and a low dose infusion supplemented by incremental doses.

Forty-four patients, ASA Grade I or II, had anaesthesia induced with propofol at 100 mg min-1 followed by a maintenance rate of 6 mg kg-1 h-1 or a stepdown regimen of 10 mg kg-1 h-1 for 10 min, 8 mg kg-1 h-1 for the next 10 min and at 6 mg kg-1 h-1 thereafter. Anaesthesia was maintained with propofol infused using an Ohmeda 9000 pump supplemented by nitrous oxide and oxygen (2:1) in a Bain circuit with spontaneous ventilation. Incremental doses of 20 mg of propofol were given to both groups as clinically indicated to maintain anaesthesia. Both methods provided satisfactory maintenance of anaesthesia but significantly more incremental doses were required in the group receiving the steady rate infusion. However, a lower cumulative dose was required up to 30 min in this group but not by 40 min. A comparable fall in systolic and diastolic blood pressure and heart rate was seen in both groups. There was no difference in the recovery times between the groups and the total dose did not correlate with time to recovery.     

Propofol versus propanidid for the conduction of suspension laryngoscopy

Forty patients who where to undergo suspension laryngoscopy were randomly assigned to two groups, the first receiving 1 microgram . kg-1 fentanyl and a bolus of 2.5 mg . kg-1 propofol followed by 5 to 10 mg . kg-1 . h-1 propofol infusion, and the second 1 microgram . kg-1 fentanyl and 0.2 mg . kg-1 flunitrazepam with 8 mg . kg-1 propanidid in a bolus followed by 40 to 50 mg . kg-1 propanidid infusion. The following parameters were studied: length of apnoea, quality of anaesthesia, the time between stopping giving the anaesthetic and the moment when the patient opens the eyes, gives his name and date of birth, the heart rate, the systolic, diastolic and mean blood pressures, blood gases, before induction, during suspension and at stopping the infusion. Anaesthetic quality was the same for both protocols, and the variations of the haemodynamic parameters were very similar for both groups. Apnoea lasted twice as long with propofol as with the flunitrazepam-propanidid association (p less than 0.001), whereas recovery was twice as quick (p less than 0.001). This seemed to confirm that propofol is better indicated for this type of surgery than the previously used flunitrazepam-propanidid association.     

Propofol auto-co-induction as an alternative to midazolam co-induction for ambulatory surgery

We propose the use of an intravenous propofol/propofol auto-co-induction technique as an alternative to propofol/midazolam for induction of anaesthesia. We have studied 54 unpremedicated ASA 1 or 2 patients undergoing day-stay anaesthesia for minor orthopaedic surgery. All received 10 micrograms.kg-1 or alfentanil before induction, followed by either midazolam 0.05 mg.kg-1, propofol 0.4 mg.kg-1 or saline, and 2 min later, a propofol infusion at a rate of 50 mg.kg-1.h-1 until loss of eyelash reflex. We compared pre- and postinduction haemodynamic changes, complications at insertion of a laryngeal mask airway and recovery from anaesthesia in the three groups. Both co-induction techniques showed less postinduction hypotension and significant reduction of the total induction dose of propofol when compared to the control group. In the propofol/propofol group there was a decreased incidence of apnoea during induction of anaesthesia. These patients were discharged from hospital 2 h after the end of anaesthesia whereas patients in the midazolam/propofol group were discharged after 2 1/2 h (p < 0.001).     

Total intravenous anaesthesia with propofol or etomidate

In combination with fentanyl, propofol was compared with etomidate for total intravenous anaesthesia in 21 women (ASA Grades I-II) admitted for elective hysterectomy. They received either propofol (bolus 1.5 mg kg-1, infusion 9 mg kg-1 h-1 for 10 min thereafter 6 mg kg-1 h-1) or etomidate (bolus 0.10 mg kg-1, infusion 3 mg kg-1 h-1 reduced to 0.6 mg kg-1 h-1). Fentanyl 10 micrograms kg-1 was given for induction followed by an infusion of 30 micrograms kg-1 h-1 for 10 min reduced to 6 micrograms kg-1 h-1 for the first hour and successively reduced over time. Induction was smooth and maintenance easy to manage in both groups. There was no difference in time from end of infusion until extubation, but the time until the patients could report their date of birth was significantly shorter in the propofol group. Nausea and vomiting were more pronounced in the etomidate group, and mental side-effects were only seen after etomidate. After 3 months, more patients in the etomidate group complained of reduced power of concentration. We conclude that total intravenous anaesthesia with either propofol or etomidate is equally easy to manage, but in the recovery situation propofol was advantageous in time and quality.     

Propofol versus etomidate in short-time urologic surgery]

Thirty patients, scheduled for short urological surgical procedures and ranked ASA 1 or 2, were randomly assigned to two homogenous groups. In group P, they were given a 2 mg.kg-1 bolus of propofol and 10 micrograms.kg-1 of alfentanil, followed by a continuous infusion of propofol (5 mg.kg-1.h-1) and 5 micrograms.kg-1 doses of alfentanil. In group E, they were given a 0.3 mg.kg-1 bolus of etomidate, followed by an infusion (1.5 mg.kg-1.h-1). The doses of alfentanil were the same as in group P. Further doses of either propofol (0.5 mg.kg-1) or etomidate (0.2 mg.kg-1) were used should anaesthesia prove not to be deep enough. The patients were not intubated, and breathed spontaneously. Surgery lasted a mean of 18.3 +/- 11.8 min (group P) and 18.8 +/- 9.4 min (group E). The following parameters were studied: the amount of each agent required for maintenance of anaesthesia, the duration of apnoea at induction, the quality of anaesthesia and of muscle relaxation, adverse effects (coughing, trismus, restlessness, nausea, vomiting), the time required for recovery, and its quality. In group P, there was a 27% decrease in arterial pressure, without any tachycardia or hypoxia, together with a quick recovery of excellent quality. On the other hand, in group E, there was little or no haemodynamic alteration, but there often was a trismus at induction. Hypoxia also occurred during induction with etomidate, being severe enough in one case to require tracheal intubation and artificial ventilation. The reasons for this hypoxia seemed to be the apnoea and the trismus, which tends to hinder assisted ventilation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vomiting after alfentanil anesthesia: effect of dosing method.

This double-blind study correlated the association of nausea and vomiting after alfentanil with its method of administration (bolus dose vs continuous infusion). Of 40 women undergoing lower abdominal gynecologic or laparoscopic surgery, 20 received an intravenous alfentanil (30 micrograms/kg) bolus dose for induction of anesthesia, with subsequent bolus doses of 10 micrograms/kg every 10 min, and 20 received the same induction dose delivered over 1 min, followed by an intravenous infusion at 1.0 micrograms.kg-1.min-1. The infusion group experienced more frequent nausea and vomiting than the bolus dose group (50% vs 30%, respectively; P = 0.0001). Laparoscopic surgery affected the incidence of nausea and vomiting independently of the method of alfentanil administration (75% for laparoscopic vs 17% for incisional procedures; P = 0.0001). Laparoscopy and alfentanil infusion combined synergistically to worsen the incidence of nausea and vomiting. We conclude that alfentanil infusion for laparoscopic surgery entails a high risk for nausea and vomiting.     

Total intravenous anaesthesia without muscle relaxants in a child with diagnosed Duchenne muscular dystrophy

The case of a 3 year old child, affected by Duchenne muscular dystrophy, who underwent adenoidectomy and bilateral myringotomy, is reported. Total intravenous anaesthesia (propofol 1% infusion (160 micrograms kg-1min-1) and remifentanil (0.55 microgram kg-1min-1) without any muscle relaxants was used. The postoperative period was uneventful.     

An open, randomized comparison of alfentanil, remifentanil and alfentanil followed by remifentanil in anaesthesia for craniotomy

We studied 52 adults undergoing elective craniotomy, allocated randomly to one of three opioid treatments: alfentanil 50 micrograms kg-1 followed by 0.833 microgram kg-1 min-1 until dural closure (group Alf.); alfentanil 50 micrograms kg-1 followed by 0.833 microgram kg-1 min-1 for 2 h, then remifentanil 0.25 microgram kg-1 min-1 (group Alf.- Remi.); or remifentanil 1 microgram kg-1 followed by 0.5 microgram kg-1 min-1 reducing to 0.25 microgram kg-1 min-1 after craniotomy (group Remi.). Anaesthesia was maintained with infusion of propofol and 66% nitrous oxide in oxygen. Infusions of propofol and remifentanil were stopped at head bandaging. Group Remi. had the least intraoperative haemodynamic responses and group Alf. the most (P < 0.05). Times to tracheal extubation and obey commands were similar in all groups. In all patients in group Alf.-Remi. and group Remi., the trachea was extubated 27 min from the end of anaesthesia; three patients in group Alf. were slower to recover. Use of analgesia in the recovery room and time to transfer to the neurosurgical unit were similar in the three groups.      

Use of propofol in anesthesia in cardiac surgery. Preliminary results

Nine patients, all NYHA class III and IV, who were to undergo surgery with cardiopulmonary bypass, were divided into two groups. All nine were premedicated with 2 mg flunitrazepam orally 90 min before surgery. Group A consisted in five men, mean age 53 years (extremes: 43 and 73), with no significant difference in weight and body surface area, who were to undergo aortic valve replacement (2), mitral valve replacement (2), and aortic and mitral valve replacement (1). They were given 1.5 mg X kg-1 propofol as a bolus at induction, followed by an infusion of 50 micrograms X kg-1 X min-1 propofol. Group B consisted in four patients, two men and two women, mean age 60 years (extremes: 49 and 76), with no significant difference in weight and body surface area, who were to undergo aortic valve replacement (3) and corrective surgery for left ventricular aneurysm (1). They were given 2 mg X kg-1 propofol as a bolus at induction, followed by an infusion of 100 micrograms X kg-1 X min-1 propofol. All the patients were intubated after 0.1 mg X kg-1 pancuronium; they were given 10 micrograms X kg-1 before intubation and 10 micrograms X kg-1 before skin incision. Repeat doses of fentanyl and pancuronium were given as required. The haemodynamic parameters studied were: heart rate, systolic, diastolic and mean blood pressures, central venous pressure, mean pulmonary pressure, wedge pressure, and cardiac output measured by thermodilution. The following indices were calculated: cardiac index, systolic index, right and left systolic work indices, and pulmonary and systemic vascular resistances.(ABSTRACT TRUNCATED AT 250 WORDS)     

Alfentanil v. isoflurane for outpatient arthroscopy

Alfentanil by continuous intravenous infusion and isoflurane have been compared as anaesthetic agents for outpatient arthroscopy. In 42 patients, divided at random into two groups, anaesthesia was induced with methohexitone and vecuronium bromide, and, after intubation, maintained with nitrous oxide 66% in oxygen combined with alfentanil or isoflurane. Alfentanil was given before intubation (1 mg), as a loading dose before starting surgery (50 micrograms kg-1) and by a continuous infusion at a rate of 1 microgram kg-1 min-1. Isoflurane was given in a concentration of 0.9% as a maintenance dose. Awakening from anaesthesia was more rapid with alfentanil than with isoflurane. Recovery tests were applied in the recovery room. Both anaesthetic techniques provided satisfactory anaesthesia and rapid recovery. All patients but one were content with the anaesthesia. The patients who received isoflurane scored better in the recovery tests in the first 3 h, but after 3 h there was no difference between the groups. The alfentanil group showed a higher incidence of nausea and/or vomiting: 45% compared to 14% in the isoflurane group.     

Continuous propofol infusion versus enflurane in children operated on for strabismus. Comparison of the quality of anesthesia and recovery conditions

In children, the use of a continuous infusion of propofol has not yet been reported. A study was therefore designed to compare the characteristics of anaesthesia and recovery when either propofol or enflurance was used as the main anaesthetic agent. All 42 children (14 girls, 28 boys), ASA I and scheduled for corrective squint surgery under general anaesthesia, received 350 micrograms.kg-1 midazolam and 40 micrograms.kg-1 atropine intrarectally 20 min before induction, which was carried out with 3 mg.kg-1 propofol intravenously in 20 s. The patients were then randomly assigned to two groups, according to the drug used for maintenance: group P (n = 21) received a continuous intravenous infusion of propofol, 18 mg.kg-1.h-1 for the first 30 min and 15 mg.kg-1.h-1 thereafter; group E (n = 21) received 2.5%, then, after 30 min, 2% enflurane. Both groups were given 15 micrograms.kg-1 dextromoramide and 0.09 mg.kg-1 vecuronium. During anaesthesia, the following parameters were monitored: systolic (Pasys), diastolic (Padia) and mean arterial (Pa) pressures, heart rate (fc), the presence or not of an oculocardiac reflex with or without a 20% fall in fc which responded to 10-15 micrograms.kg-1 atropine, the appearance of a cardiac dysrhythmia, duration of anaesthesia and the delay before extubation. Recovery was assessed 1, 2, 4 and 6 h postoperatively by using both clinical and psychomotor criteria, the latter being adapted to children having one or both eyes occluded.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effects of intravenous anesthetics, propofol, fentanyl and ketamine on the excitability of spinal motoneuron in human: an F-wave study

We have investigated the effects of various intravenous anesthetics, propofol, fentanyl and ketamine on the excitability of spinal motoneuron using an F-wave analysis in a total of 28 patients. All patients were divided randomly into three groups as follows; 2 mg.kg-1 intravenous bolus injection followed by 6 mg.kg-1.h-1 infusion of propofol (P group), 1 mg.kg-1 intravenous bolus injection followed by 1 mg.kg-1.h-1 infusion of ketamine (K group), and 5 micrograms.kg-1 injection of fentanyl (F group). The F-wave was determined after supramaximal electrostimulation of the median nerve in distal point. After establishing stable baseline values, intravenous injection of one of the three anesthetics was applied. The F-wave was recorded 3 minutes after the time of bolus administration. We found a significant (P = 0.018) reduction of the persistence from 77.5 +/- 15.2 to 40.9 +/- 16.8% in the propofol group. On the other hand, no significant changes in F-wave parameters were found in ketamine, or fentanyl group. These results suggested that motoneuron excitability in spinal cord could be inhibited by anesthetic dose of propofol, but not by ketamine or fentanyl.     

Disposition of propofol infusions for caesarean section

The disposition of propofol was studied in women undergoing elective Caesarean section. Indices of maternal recovery and neonatal assessment were correlated with venous concentrations of propofol. After induction of anaesthesia with propofol 2.0 mg.kg-1, ten patients received propofol 6 mg.kg-1.hr-1 with nitrous oxide 50 per cent in oxygen (low group) and nine were given propofol 9 mg.kg-1.hr-1 with oxygen 100 per cent (high group). Pharmacokinetic variables were similar between the groups. The mean +/- SD Vss = 2.38 +/- 1.16 L.kg-1, Cl = 39.2 +/- 9.75 ml.min-1.kg-1 and t1/2 beta = 126 +/- 68.7 min. At the time of delivery (8-16 min), the concentration of propofol ranged from 1.91-3.82 micrograms.ml-1 in the maternal vein (MV), 1.00-2.00 micrograms.ml-1 in the umbilical vein (UV) and 0.53-1.66 micrograms.ml-1 in the umbilical artery (UA). Neonates with high UV concentrations of propofol at delivery had lower neurologic and adaptive capacity scores 15 minutes later. The concentrations of propofol were similar between groups during the infusion but they declined at a faster rate in the low group postoperatively. Maternal recovery times did not depend on the total dose of propofol but the concentration of propofol at the time of eye opening was greater in the high group than the low group (1.74 +/- 0.51 vs 1.24 +/- 0.32 micrograms.ml-1, P less than 0.01). The rapid placental transfer of propofol during Caesarean section requires propofol infusions to be given cautiously, especially when induction to delivery times are long.     

Comparative evaluation of propofol and thiopentone for total intravenous anaesthesia

Sixty unpremedicated ASA physical status I or II patients scheduled for surgical procedures of intermediate duration (15 to 60 min) were studied to evaluate the safety and efficacy of propofol, to measure recovery times and to compare the return of psychomotor and cognitive function with thiopentone. Patients were randomly allocated into two groups. Anaesthesia was induced and maintained by either propofol (2.0-2.5 mg.kg-1 followed by a continuous infusion 0.1-0.2 mg.kg-1.min-1) or thiopentone (4.0-5.0 mg.kg-1, and infusion rate 0.16-0.32 mg.kg-1.min-1), titrated to patient response. Succinylcholine was administered to facilitate tracheal intubation and maintain neuromuscular blockade. Induction of anaesthesia was slightly longer with propofol than thiopentone (42.2 vs 29.8 sec) and was smooth with both drugs. Post-intubation increases in heart rate, and systolic and diastolic blood pressures were attenuated by propofol when compared with thiopentone. After the administration of propofol, times to eye opening (6.4 +/- 4.3 vs 13.9 +/- 15.9 min), response to verbal command (7.6 +/- 6.3 vs 15.4 +/- 16.6 min) and orientation (22.7 +/- 12.8 vs 36.2 +/- 23.1 min), were significantly shorter. Psychomotor and cognitive function returned earlier with propofol and fewer side effects were noted. At 24 hr there was no distinguishable difference between groups. Propofol is a safe anaesthetic agent with the potential for early patient discharge and street fitness after outpatient procedures.     

Assessment of Depth of Anesthesia and Postoperative Respiratory Recovery after Remifentanil-versus Alfentanil-based Total Intravenous Anesthesia in Patients Undergoing Ear-Nose-Throat Surgery

Background: The authors investigated whether total intravenous anesthesia (TIVA) with precalculated equipotent infusion schemes for remifentanil and alfentanil would ensure appropriate analgesia and that remifentanil would result in better recovery characteristics.

Methods: Forty consenting patients (classified as American Society of Anesthesiologists physical status I-III) scheduled for microlaryngoscopy were randomized to receive, in a double-blind manner, either remifentanil (loading dose 1 [mu]g/kg; maintenance infusion, 0.25 [mu]g [middle dot] kg-1 [middle dot] min-1) or alfentanil (loading dose, 50 [mu]g/kg; maintenance infusion, 1 [mu]g [middle dot] kg-1 [middle dot] min-1) as the analgesic component of TIVA. They were combined with propofol (loading dose, 2 mg/kg; maintenance infusion, 100 [mu]g [middle dot] kg-1 [middle dot] min-1). To insure an equal state of anesthesia, the opioids were titrated to maintain heart rate and mean arterial pressure within 20% of baseline, and propofol was titrated to keep the bispectral index (BIS) less than 60. Neuromuscular blockade was achieved with succinylcholine. Drug dosages and the times from cessation of anesthesia to extubation, verbal response, recovery of ventilation, and neuropsychological testing, orientation, and discharge readiness were recorded.

Results: Demographics, duration of surgery, and anesthesia were similar between the two groups. Both groups received similar propofol doses. There were no difference in BIS values preoperatively (mean, 96), intraoperatively (mean, 55), and postoperatively (mean, 96). Recovery of BIS and times for verbal response did not differ. At 20, 30, and 40 min after terminating the opioid infusion, the peripheral oxygen saturation and respiratory rate were significantly higher in the remifentanil group compared with the alfentanil group.