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,alfentanil, and oxygen-air: three different dosage schemes

Three different dosage schemes of propofol infusions combined with a fixed-rate alfentanil infusion were investigated in total intravenous anaesthesia. In 30 premedicated patients, divided at random into three groups, anaesthesia was induced with propofol 2 mg.kg-1 immediately followed by an alfentanil infusion 10 micrograms.kg-1.min-1 as a loading dose which was decreased after ten minutes to a maintenance dose of 1 microgram.kg-1.min-1. Vecuronium bromide 0.1 mg.kg-1 was used as the muscle relaxant. After induction of anaesthesia a propofol infusion 2 mg.kg-1.hr-1 was started in group A, 3 mg.kg-1.hr-1 in group B and 4 mg.kg-1 hr-1 in group C. At signs of light anaesthesia supplementary bolus doses of 20 mg propofol and 1 mg alfentanil were given. The patients' lungs were ventilated with air-oxygen (FIO2 0.35). The mean systolic and diastolic blood pressures showed no statistical significant differences between the three groups. A significant (P less than 0.01) decrease of the mean systolic and diastolic blood pressures was present after induction of anaesthesia and tracheal intubation. Recovery was uneventful in all but one patient, who had ventilatory depression that responded to naloxone (0.2 mg IV). Awareness did not occur in any patient. The only difference between the three groups was the higher number of supplementary bolus doses of propofol and alfentanil needed in group A (P less than 0.01). In total intravenous anaesthesia propofol 3 and 4 mg.kg-1.hr-1 as a maintenance dose combined with a two-step fixed-rate alfentanil infusion provided smooth anaesthesia and uneventful rapid recovery.     

右美托咪啶与丙泊酚用于小儿心导管术麻醉维持的比较

目的 右美托咪啶(dexmedetomidine,DEX)为α2肾上腺素受体激动剂,目前较多研究正在探索其用于小儿麻醉的可行性.研究比较了DEX与丙泊酚用于小儿心导管术的维持麻醉的药效学.方法 选择40例ASA Ⅱ～Ⅲ级、22月～67月、体重11 kg～28 kg导管介入治疗患儿,进入导管室后静注氯胺酮2 mg/kg,...     

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.     

Effects of propofol, propofol-nitrous oxide and midazolam on cortical somatosensory evoked potentials during sufentanil anaesthesia for major spinal surgery

Recording of cortical somatosensory evoked potentials (CSEP) enables monitoring of spinal cord function. We studied the effects of propofol, propofol-nitrous oxide or midazolam during sufentanil anaesthesia on CSEP monitoring during major spinal surgery. Thirty patients with normal preoperative CSEP were allocated randomly to one of the following anaesthesia regimens: propofol (2.5 mg kg-1 followed by 10-6 mg kg-1 h-1) with or without nitrous oxide, or midazolam (0.3 mg kg-1 followed by 0.15 mg kg-1 h-1) combined with sufentanil 0.5 microgram kg- 1 h-1 in the propofol and midazolam groups, or 0.25 microgram kg-1 h-1 in the propofol-nitrous oxide group. CSEP were elicited by alternate right and left tibial posterior nerve stimulation and recorded before and after induction (15 min, 1, 2 and 3 h), and during skin closure. CSEP latencies were not significantly modified in the three groups. CSEP amplitude decreased significantly in the propofol-nitrous oxide group (from mean 2.0 (SEM 0.3) to 0.6 (0.1) microV; P < 0.05) but not in the propofol (from 1.8 (0.6) to 2.2 (0.3) microV) or midazolam (1.7 (0.5) to 1.6 (0.5) microV) groups. The time to the first postoperative voluntary motor response (recovery) delay was significantly greater in the midazolam group (115 (19) min) compared with the propofol and propofol-nitrous oxide groups (43 (8) and 41 (3) min, respectively). Consequently, the use of propofol without nitrous oxide can be recommended during spinal surgery when CSEP monitoring is required.      

Atracurium infusion in total intravenous anesthesia

The neuromuscular blocking effect of atracurium given as a bolus dose (0.5 mg X kg-1) followed by a maintenance infusion was studied during two different anesthetic techniques. It has been reported that benzodiazepines interact with non-depolarising neuromuscular blockers. In this study no difference was found in the effect of atracurium given with conventional fentanyl/nitrous oxide anesthesia when compared to total intravenous anesthesia using midazolam/alfentanil. More than 90% twitch depression was achieved after 123 and 137 s, respectively. Recovery time to 10% twitch height following the bolus dose was around 32 min. The dosage range for atracurium given by infusion (0.29-0.44 mg X kg-1 X h-1) was confirmed.     

The changes in hemodynamics and dose requirements in total intravenous anesthesia using propofol and buprenorphine

A retrospective study was performed to evaluate the changes in hemodynamics and dose requirements in total intravenous anesthesia (TIVA) using propofol and buprenorphine without (Group S: spinal surgery (3-6 h), n = 8, 28-79 Y) or with (Group A: abdominal surgery (5-10 h), n = 15, 36-83 Y) epidural anesthesia. All patients were premedicated with midazolam i.m. (2-5 mg). Anesthesia was maintained with a single dose of buprenorphine (Group S: 1.9 +/- 0.4 micrograms.kg-1, Group A: 2.0 +/- 0.5 micrograms.kg-1), propofol infusion and vecuronium with 40% oxygen in air. Group A was supplemented with continuous epidural anesthesia using 2% mepivacaine. In Group A, mean arterial pressure (MAP) and heart rate remained stable after the start of surgery. However, in Group S, 2 hours after the start of surgery MAP increased (P < 0.05) and remained elevated (P < 0.05) at higher levels than those in Group A. The maintenance dose of propofol in Group A (4.0 +/- 1.1 mg.kg-1.h-1) was significantly smaller than in Group S (6.5 +/- 0.9 mg.kg-1.h-1). In both groups, infusion rates of propofol were unchanged from 1 hour after the start to the end of surgery. Infusion rates of mepivacaine (5.2 +/- 0.9 ml.h-1) were unchanged following the increase 2 hours after the start of surgery. Awakening times were within 25 min (Group S 11.3 +/- 7.2 min vs Group A 14.7 +/- 7.3 min). There was no awareness during anesthesia in either group. The results suggest that additional continuous epidural anesthesia in TIVA would be useful to reduce propofol dose, to stabilize hemodynamic state and to obtain rapid recovery in anesthesia of long duration.     

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.     

Midazolam-flumazenil vs. propofol in ambulatory ENT endoscopic procedures.

Two total intravenous anaesthesia techniques were compared in an open study of 80 ambulatory patients undergoing ENT endoscopic procedures randomly assigned to two groups: Group I midazolam-flumazenil n = 40, Group II propofol n = 40. The mean doses including induction were 0.75 +/- 0.31 mg kg-1 h-1 for midazolam and 171 +/- 64 micrograms kg-1 min-1 for propofol for 46.3 +/- 17.7 min and 50.3 +/- 24.8 min respectively. At the end of the procedure flumazenil 8.1 +/- 1.9 micrograms kg-1 was administered to Group I patients followed by a flumazenil continuous infusion at a minimal arousal rate (MAR) of 0.24 +/- 0.1 micrograms kg-1 min-1, and propofol discontinued in Group II patients. Baseline mean arterial pressure (MAP) and heart rate (HR) were similar in both groups and remained so during the procedure and recovery. In patients with cardiovascular disease, large variations (greater than or equal to 40% of baseline values) occurred more frequently in the propofol group whereas large variations in patients with no cardiovascular disease occurred more frequently in the midazolam group (P less than 0.05). Early recovery was more rapid after midazolam (P less than 0.05) whereas late criteria for recovery (maze and ambulation tests) were met more rapidly after propofol (P less than 0.05). It is concluded that with the midazolam-flumazenil sequence, early recovery is faster and haemodynamic stability better maintained in poor cardiovascular risk patients, whereas with propofol, street-fitness is more rapidly obtained, and haemodynamic stability better maintained in good risk patients.     

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.     

Ambulatory anesthesia and induced abortion. Comparative study of propofol-alfentanyl and ketamine-midazolam combinations

The use of propofol alone or with alfentanil in the day-case anaesthesia for abortion was compared with that of ketamine with midazolam. Two hundred young women were assigned to two successive series of two groups each. The four groups were: group 1 (2 mg . kg-1 propofol only); group II (0.5 mg . kg-1 ketamine with 0.25 mg . kg-1 midazolam); group III (2 mg . kg-1 propofol with 4 micrograms . kg-1 alfentanil); group IV (1 mg . kg-1 ketamine with 0.1 mg . kg-1 midazolam). All the patients were premedicated one hour before anaesthesia with 0.25 mg . kg-1 midazolam orally. All the patients were asleep at the end of the propofol injection (60 s), and 10 to 15 s later for the ketamine-midazolam groups. The haemodynamic parameters did not vary much during induction with ketamine-midazolam. In the propofol groups, the heart rate remained steady, with an 8 to 12% fall in blood pressure. A fall of the mandible was seen in 40 and 84% of the patients in the propofol groups, with a short apnoea in 32 and 48% of these same patients. Clinical recovery was very quick, less than 12 min for all groups. The four psychomotor and sensory tests were carried out at the 30th min by 95% of the patients in the propofol groups, whereas only 50% of those in the ketamine-midazolam groups did so. Speed and quality were significantly better in the propofol groups. The most frequent adverse effect of propofol was pain during injection in 32 and 14% of patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of intravenous hypnotics on the actions of pipecuronium.

Seventy-five ASA Grades I-III patients (18-85 years, 45-90 kg) were randomized into five groups. All patients received N2O/O2 (2/1) and alfentanil: loading dose (LD) 0.015 mg kg-1 and maintenance dose (MD) 0.045 mg kg-1 h-1 (groups 1-4). Group 1 received propofol (LD 2 mg kg-1 and MD 6 mg kg-1 h-1); Group 2 etomidate (LD 0.3 mg kg-1 and MD 0.6 mg kg-1 h-1); Group 3 midazolam (LD 0.2 mg kg-1 and MD 0.120 mg kg-1 h-1); Group 4 methohexitone (LD 1.5 mg kg-1 and MD 4 mg kg-1 h-1); Group 5 dehydrobenzperidol 0.05-0.23 mg kg-1 and alfentanil (LD 0.100 mg kg-1 and MD 0.060 mg kg-1 h-1). The neuromuscular block induced by pipecuronium (50 micrograms kg-1) was evaluated. No statistically significant differences were found between the five groups as concerned degree of block (expressed as % twitch amplitude in response to the first of the TOF stimuli (Ta1) at intubation, T1 minimum and recovery to Ta1 = 20%, 25% and 75%. Slightly faster intubation was possible when midazolam was used in comparison with propofol, methohexitone or NLA and when etomidate was used in comparison with propofol. A wide range of individual values of maximal neuromuscular blocking activity was found.     

Haemodynamic comparison of propofol-fentanyl anaesthesia with midazolam-fentanyl anaesthesia in CABG patients without preoperative heart failure

This study was designed to compare prebypass haemodynamics under total intravenous anaesthesia (TIVA) using midazolam-fentanyl (group M) and propofol-fentanyl (group P) combinations. Sixteen adult patients undergoing CABG were studied with patients in group M and P (n = 8 each) given intravenous midazolam 0.1 mg.kg-1.h-1 and propofol 4 mg.kg-1.h-1 with fentanyl 25 micrograms.kg-1 until sternotomy, respectively. Following induction of anaesthesia, cardiac index and heart rate decreased significantly (30% and 20% in both groups, p < 0.05) these variables returned to baseline on completion of sternotomy. In addition, in group P mean arterial pressure decreased significantly (about 15%) following induction and there were no ischaemic signs. Overall for MAP there was no significant difference between the two groups. LVSWI and RVSWI were reduced by around 25% in both groups. Only the change in LVSWI reached statistical significance (p < 0.05). This reduction may have exert a caridioprotectant action by decreasing myocardial oxygen consumption. We conclude that both TIVA techniques represent an acceptable anaesthetic regimen for use in cardiac anaesthesia.     

Influence of bispectral index monitoring on fentanyl requirements during total intravenous anesthesia for major gynecological surgery]

OBJECTIVE: To determine the influence that bispectral index (BIS) monitoring of hypnosis might have on need for analgesia during surgery under total intravenous anesthesia provided by bolus administration of fentanyl. PATIENTS AND METHOD: Prospective, randomized and partially double-blind study of 40 patients undergoing major gynecological surgery under total intravenous anesthesia with propofol and fentanyl. In the BIS group (n = 20) propofol administration was adjusted to maintain BIS between 40 and 60. In the control group (n = 20) standard doses were given: 10 mg/kg-1/h-1 after anesthetic induction and for 5 minutes, 8 mg/kg-1/h-1 over the next 5 minutes and 6 mg/kg-1/h-1 throughout the rest of the operation. All patients received intravenous bolus administration of 150 or 75 microg of fentanyl to maintain analgesia whenever systolic blood pressure and heart rate increased 20% over baseline. We compared propofol and fentanyl requirements, intraoperative changes in BIS, and awakening from anesthesia. RESULTS: Patient and surgical characteristics were similar in both groups. BIS monitoring allowed propofol administration to be decreased a mean 24% during maintenance of anesthesia, and this in turn was associated with a significant increase in mean dose of fentanyl (415 microg versus 253 microg in the BIS and control groups, respectively; p = 0.01). Mean values of BIS were higher in the BIS group (46.4 versus 42.2; p = 0.04) and patients in the BIS group awoke sooner (in 7.7 min versus 11.1 min; p = 0.01) and tended to report less pain upon arrival at the postanesthetic recovery room, although the difference was not statistically significant. CONCLUSIONS: BIS monitoring of depth of hypnosis can influence requirements for fentanyl during total intravenous anesthesia by bolus dosing for maintenance of analgesia. This is probably due to changes in the administration of propofol made possible by BIS monitoring.     

Epidural Clonidine or Bupivacaine as the Sole Analgesic Agent during and after Abdominal Surgery: A Comparative Study

Background: The rationale of this study was to compare high-dose epidural clonidine with a more commonly used agent, such as bupivacaine. This was performed to give a more objective idea of the relative analgesic potency of epidural clonidine.

Methods: Sixty patients undergoing intestinal surgery during propofol anesthesia were studied. At induction, the patients received epidurally a dose of 10 mg/kg clonidine in 7 ml saline followed by an infusion of 6 mg [middle dot] kg-1 [middle dot] h-1 (7 ml/h) (group 1, n = 20), a dose of 7 ml bupivacaine, 0.5%, followed by 7 ml/h bupivacaine, 0.25% (group 2, n = 20), or a dose of 7 ml bupivacaine, 0.25%, followed by 7 ml/h bupivacaine, 0.125% (group 3, n = 20). Intraoperatively, increases in arterial blood pressure or heart rate not responding to propofol (0.5 mg/kg) were treated with intravenous alfentanil (0.05 mg/kg). Additional doses of propofol were given to maintain an adequate bispectral index. The epidural infusions were maintained for 12 h. In cases of subjective visual analogue pain scores up to 5 cm at rest or up to 8 cm during coughing, the patients were given access to a patient-controlled analgesia device.

Results: During anesthesia, patients in group 1 required less propofol than those in groups 2 and 3 (78 [36-142] mg vs. 229 [184-252] mg and 362 [295-458] mg; P < 0.05) and less alfentanil than patients in group 3 (0 [0-0] mg vs. 11 [6-20] mg; P < 0.05). Analgesia lasted 380 min (range, 180-645 min) in group 1 versus 30 min (range, 25-40 min) in group 2 and 22 min (range, 12.5-42 min) in group 3 (P < 0.05). There was no suggestion of a hemodynamic difference among the three groups except for heart rates that were significantly reduced in patients in group 1. Sedation scores were significantly higher in this group during the first 2 h postoperatively.     

A comparison of fentanyl and buprenorphine in total intravenous anesthesia using propofol during spinal surgery

A retrospective study was performed to compare the hemodynamic effect and postoperative pain relief of fentanyl (Group F, n = 11) and buprenorphine (Group B, n = 11) in total intravenous anesthesia (TIVA) using propofol during spinal surgery. All patients were premedicated with midazolam (3-5 mg) i.m. Anesthesia was maintained with propofol infusion, and increments of fentanyl or single dose of buprenorphine with 40% oxygen in air. Total doses of fentanyl and buprenorphine were 7.6 +/- 1.0 micrograms.kg-1 and 2.0 +/- 0.4 micrograms.kg-1, respectively. Maintenance doses of propofol (Group F: 5.5 +/- 0.8 mg.kg-1.h-1, Group B: 5.9 +/- 1.1 mg.kg-1.h-1) and vecuronium were not significantly different. Mean arterial pressures from 2 hours after incision to the end of surgery were elevated significantly in Group F than in Group B. Recovery time (Group F 12.5 +/- 6.1 min vs Group B 11.8 +/- 6.1 min) and extubation time (Group F 19.5 +/- 10.3 min vs Group B 15.0 +/- 7.0 min) were not different. At the end of anesthesia, seven patients in Group F and one patient in Group B (P < 0.01) complained of severe pain. All patients in Group F, and only two in Group B (P < 0.02) received analgesics within 20 hours. Neither nausea nor respiratory depression was found in both groups. This study suggests that buprenorphine would provide a more stable hemodynamic state and better postoperative pain relief than fentanyl in TIVA using propofol.     

异丙酚或咪达唑仑复合麻醉下心脏手术患者心肌细胞凋亡及术后早期恢复的比较

Objective To compare the cardiomyocyte apoptosis and early postoperative recovery in patients undergoing cardiac valve replacement under propofol-or midazolam-combined anesthesia.Methods Forty NYHA class Ⅱ or Ⅲ patients (aged 48-64 yr and weighing 45-78 kg) undergoing cardiac valve replacement with cardiopulmonary bypass (CPB) were randomly divided into midazolam group (Group M) and propofol group (Group P) (n=20each). The patients were premedicated with morphine 0.1 mg/kg i.v. and scopolamine 0.3 mg i.v. Anesthesia was induced with midazolam 0.2 mg/kg (in Group M) or propofol 2 mg/kg (in Group P) combined with fentanyl 10 μg/kg and vecuronium 0.1 mg/kg, and maintained with propofol 5 mg. kg-1·h-1 (in Group P) or midazolam 0.1 mg·kg-1·h-1(in Group M) and intermittent i.v. boluses of fentanyl and vecuronium after tracheal intubation. The patients were mechanically ventilated with PETCO2 maintained at 35-45 mm Hg. Myocardial tissues were obtained from the right atrium before and after CPB for determination of apoptosis in cardiomyocytes (by TUNEL). The apoptotic index was calculated. The expression of caspase-3 and caspase-9 was determined by immunohistochemical avidin-biotin-peroxidase complex (ABC) technique staining. The mean airway pressure (MAP) and heart rate (HR) were monitored. Aortic cross-clamping time, surgical and CPB times, spontaneous recovery of normal heart beat, emergence from anesthesia, extubation time and duration of ICU stay were recorded and compared between the two groups.Results The percentage of spontaneous recovery of normal heart beat after release of aortic cross clamp was significantly higher and the need for dobutamine support was significantly less in Group P than in Group M ( P ＜ 0.05). The emergence from anesthesia was significantly more rapid, the extubation time and the ICU stay were significantly shorter in Group P than in Group M (P＜0.05). There were no significant differences in apoptosis index and expression of caspase-3 and caspase-9 before CPB between the two groups. The apoptosis index and expression of caspase-3 and caspase-9 were significantly increased after CPB in Group M and significantly higher than those after CPB in Group P (P＜0.05).Conclusion Cardiomyocyte apoptosis in patients undergoing CPB can be inhibited and the postoperative recovery is more rapid under propofol-combined anesthesia.     

Patient-controlled drug administration during local anesthesia: A comparison of midazolam, propofol, and alfentanil

Study Objective: To evaluate the perioperative effects of alfentanil, midazolam, and propofol when administered using a patient-controlled analgesia (PCA) device during local anesthesia.

Design: Randomized, single-blind comparative study.

Setting: Outpatient surgery center at a university teaching hospital.

Patients: Ninety outpatients undergoing minor elective surgical procedures with local anesthetic infiltration were assigned to one of three treatment groups.

Interventions: After premedication with midazolam 1 mg intravenously (IV) and fentanyl 50 μg IV, patients were allowed to self-administer 2 ml bolus doses of either alfentanil 250 μg/ml, midazolam 0.4 mg/ml, or propofol 10 mg/ml at minimal intervals of 3 minutes to supplement a basal infusion rate of 5 ml/hr.

Measurements and Main Results: The total intraoperative dosages of alfentanil, midazolam, and propofol were 2.7 ± 1.1 mg, 4.7 ± 2.7 mg, and 114 ± 42 mg, respectively, for procedures lasting 48 ± 28 minutes to 51 ± 19 minutes (means ± SD). Propofol produced more pain on injection (39% vs. 4% and 6% in the alfentanil and midazolam groups, respectively). Episodes of arterial oxygen saturation less than 90% were more frequent with alfentanil (28%) than with midazolam (3%) or propofol (13%). Using the visual analog scale, patients reported comparable levels of discomfort, anxiety, and sedation during the operation in all three treatment groups. Postoperative picture recall was significantly decreased with midazolam versus alfentanil and propofol. Finally, postoperative nausea was reported more frequently in the alfentanil group (29%) than in the midazolam (10%) or propofol (18%) groups, contributing to a significant prolongation of the discharge time in the alfentanil-treated patients.

Conclusions: When self-administered as adjuvants during local anesthesia using a PCA delivery system, alfentanil, midazolam, and propofol were equally acceptable to patients. However, propofol and midazolam were associated with fewer perioperative complications than was alfentanil.     

Mixed-effects Modeling of the Influence of Alfentanil on Propofol Pharmacokinetics

Background: The influence of alfentanil on the pharmacokinetics of propofol is poorly understood. Therefore, the authors studied the effect of a pseudo-steady state concentration of alfentanil on the pharmacokinetics of propofol.

Methods: The pharmacokinetics of propofol were studied on two occasions in eight male volunteers in a randomized crossover manner with a 3-week interval. While volunteers breathed 30% O2 in air, 1 mg/kg intravenous propofol was given in 1 min, followed by 3 mg [middle dot] kg-1 [middle dot] h-1 for 59 min (sessions A and B). During session B, a target-controlled infusion of alfentanil (target concentration, 80 ng/ml) was given from 10 min before the start until 6 h after termination of the propofol infusion. Blood pressure, cardiac output, electrocardiogram, respiratory rate, oxygen saturation, and end-tidal carbon dioxide were monitored. Venous blood samples for determination of the blood propofol and plasma alfentanil concentration were collected until 6 h after termination of the propofol infusion. Nonlinear mixed-effects population pharmacokinetic models examining the influence of alfentanil and hemodynamic parameters on propofol pharmacokinetics were constructed.

Results: A two-compartment model, including a lag time accounting for the venous blood sampling, adequately described the concentration-time curves of propofol. Alfentanil decreased the elimination clearance of propofol from 2.1 l/min to 1.9 l/min, the distribution clearance from 2.7 l/min to 2.0 l/min, and the peripheral volume of distribution from 179 l to 141 l. Scaling the pharmacokinetic parameters to cardiac output, heart rate, and plasma alfentanil concentration significantly improved the model.     

依托咪酯和异丙酚复合麻醉对腹部手术患者脑氧代谢影响的比较

目的 比较依托咪酯和异丙酚复合麻醉对腹部手术患者脑氧代谢的影响.方法 择期全麻下拟行腹部手术患者36例,ASA Ⅰ或Ⅱ级,随机分为异丙酚复合麻醉组(P组)和依托咪酯复合麻醉组(E组),每组18例.两组均静脉注射咪达唑仑0.08 mg/kg、芬太尼3μg/kg、维库溴铵0.1 mg/kg,P组静脉注射异丙酚1.5 mg/kg、E组静脉注射依托咪酯0.3 mg/kg行麻醉诱导,P组静脉输注异丙酚4～6mg·kg-1·h-1、E组静脉输注依托咪酯0.4～0.7 mg·kg-1·h-1,术中均间断注射维库溴铵和芬太尼维持麻醉.分别于麻醉前(T1)、气管插管后即刻(T2)、手术开始30 min(T3)及术毕即刻(T4)时监测HR、MAP和SpO2,抽取桡动脉血和颈内静脉球部血样行血气分析,测定乳酸浓度,计算动脉血氧含量(CaO2)、颈内静脉氧含量(cjvO2)、脑氧摄取率(CERO2).结果 两组HR、MAP和SpO2均在正常范围内.与T1时相比,两组SaO2、SjvO2、PaO2、PjvO2升高,T2-4时Da-jvO2和CERO2降低(P<0.01);两组问比较各时点SaO2、SjrO2、PaO2、PjvO2、CaO2、CjvO2、Da-jvO2、CERO2及乳酸水平差异均无统计学意义(P>0.05).结论 依托眯酯和异丙酚复合麻醉均可降低腹部手术患者的脑氧代谢率,且无明显差别.