Summary

Background and objective: Extremity surgery with tourniquet to provide a bloodless field may be a good human model for ischaemia reperfusion (IR) injury. The aim of this study was to investigate the effects of three different modes of propofol use on tourniquet induced IR injury in lower extremity operations. Methods: Thirty-three consecutive ASA Grade I and II patients were randomized into three groups of 11 patients each. In the spinal group (Group S), after intrathecal anaesthesia, sedation was given with a propofol infusion at 2 mg kg−1 h−1 after a 0.2 mg kg−1 bolus dose and fentanyl 100 μg. In the general (Group G) and TIVA (Group T) groups, general anaesthesia was induced with propofol 2 mg kg−1 with fentanyl 100 μg and maintained with inhalation of halothane or infusion of propofol respectively. Venous blood samples were obtained at different time points for measurements of plasma malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) levels. Results: Plasma MDA levels were increased significantly in the Group G at 1 min before tourniquet release and 5 and 20 min after tourniquet release compared with before induction of general anaesthesia (baseline). Before intrathecal anaesthesia and before induction of general anaesthesia significantly decreased levels of MDA were observed both before and after tourniquet release compared to baseline. Plasma SOD and CAT concentrations were decreased significantly only at tourniquet release in the Group G compared with baseline. In the Groups S and T these enzymes were not changed significantly. Plasma GPx levels were not altered in any groups. Conclusion: Propofol administration may inhibit lipid peroxidation and restore antioxidant enzyme levels in extremity surgery requiring tourniquet application.

Summary

Background and objective: Propofol has been shown to inhibit a variety of functions of neutrophils in vitro, but there is a lack of in vivo data. To analyse the effects of propofol on neutrophil function in vivo we chose to investigate cataract surgery since it represents a small surgical procedure with minimal immunomodulatory effects induced by surgery. We sought to analyse any immunosuppressive effects of propofol after short-term administration in vivo in comparison to local anaesthesia as well as to in vitro effects of propofol. Methods: The study was designed as an open randomized trial enrolling 20 patients undergoing general or local anaesthesia. The neutrophil oxidative response and propofol plasma concentration were assessed prior, during and after anaesthesia. Neutrophil function was determined flow cytometrically based on dihydrorhodamine 123 oxidation. Results: Propofol concentrations which yielded a marked suppression in vitro did not alter the neutrophil oxidative response during cataract surgery in vivo. However, after local anaesthesia the neutrophil oxidative response declined to 37%, compared to the control response prior to anaesthesia. Conclusions: Although we could detect the well established suppression of neutrophil function by propofol in vitro it was not evident in vivo. This may be due to compensating effects on neutrophil function during surgery in vivo. The decline in the neutrophil oxidative response in the local anaesthesia group might be due to increased stress and catecholamine concentrations or a direct interaction of local anaesthetics with neutrophil intracellular signalling.

Summary

Background and objective: Following strabismus surgery, immediate postoperative ophthalmic evaluation may be desired. Thus, an anaesthetic technique allowing rapid recovery of ocular motility is required. Saccadic eye movements is a biophysical monitor of ocular motility and may be used to assess recovery from anaesthesia. The aim of this study is to compare the time to the recovery of saccadic eye movements in patients, following one of two anaesthetic techniques: Propofol–remifentanil-based anaesthesia vs. sevoflurane–fentanyl-based anaesthesia. Methods: Fifty adult patients undergoing strabismus surgery were randomly assigned to one of two groups: patients in Group R received induction and maintenance of anaesthesia with propofol and remifentanil, while patients in Group S received induction of anaesthesia with propofol and fentanyl and maintenance of anaesthesia with sevoflurane. Recovery from anaesthesia was measured from the time all anaesthetics were turned off and was assessed every 2 min. Recovery time was attained when patients were able to generate brisk saccadic eye movements. At recovery time, the ophthalmic evaluation was started. Results: The mean recovery time of saccadic eye movements was significantly shorter in the Group R when compared to the Group S (12.1 ± 4.3 min vs. 21.5 ± 4.7 min, respectively, P < 0.0001). More patients in Group S experienced nausea and vomiting postoperatively as compared to Group R (9/25 vs. 2/25, respectively, P = 0.037). Conclusions: Propofol–remifentanil-based anaesthesia may be a useful technique in strabismus surgery when immediate postoperative ophthalmic evaluation is desired. When compared to sevoflurane maintenance of anaesthesia, it allows for a more rapid recovery from anaesthesia as judged by recovery of saccadic eye movements and a decreased incidence of postoperative nausea and vomiting.

Summary

Background: This study was designed to evaluate the feasibility of propofol infusion by a closed-loop system for the titration of anaesthetic induction guided by Bispectral Index. Methods: Forty patients were prospectively and randomly allocated into two groups: the target control infusion (TCI) group, where propofol titration was performed manually guided by the Bispectral Index using a commercial pharmacokinetic model (Diprifusor device) and the closed-loop group where titration was performed using a proportional differential algorithm. For both groups, the objective was to achieve a Bispectral Index of 50. Remifentanil TCI was infused at a target of 2 ng mL−1 and was maintained constant throughout the study. Feasibility of automatic induction was evaluated with performance error and haemodynamic data. Results: Bispectral Index overshoot (−9 ± 13% vs. −16 ± 20%, P = 0.035) and mean duration of induction (381 ± 106 s vs. 490 ± 131 s, P = 0.004) were lower in the closed-loop group than in the TCI group. Haemodynamic data were similar between groups with a similar use of ephedrine bolus. Conclusion: The system was able to allow induction clinically for all patients. Automated titration guided by Bispectral Index for propofol infusion was feasible without increase in haemodynamic adverse effects.

Summary

Backgrounds: The purpose of this study was to evaluate the effect of ephedrine and phenylephrine on propofol concentrations and bispectral index during propofol anesthesia. Methods: General anaesthesia was induced with propofol and was maintained with propofol (4 mg kg−1 h−1) and fentanyl. Vecuronium was used to facilitate the artificial ventilation of the lungs. Patients with systolic blood pressure > 90 mmHg were defined as the control group (n = 16). Patients who had to be treated for larger decreases in arterial blood pressure (systolic blood pressure <90 mmHg) were randomly assigned to receive ephedrine 0.1 mg kg−1 (n = 20) or phenylephrine 2 μg kg−1 (n = 20). Propofol concentrations were determined before (baseline) and at 3 and 10 min after the administration of ephedrine or phenylephrine. Bispectral index was monitored continuously. Cardiac output was determined using a pulmonary arterial catheter. Results: Ten minutes after drug injection, bispectral index in the ephedrine group increased significantly compared with the baseline and was significantly larger than that in the control or phenylephrine group. Eight patients in the ephedrine group had bispectral index >60, whereas no patient in the control or phenylephrine groups had bispectral index >60. There were no significant differences in propofol concentrations or cardiac output relative to baseline at 3 or 10 min after the administration of ephedrine or phenylephrine. Conclusions: Ephedrine increases bispectral index values without decreasing propofol concentrations during general anesthesia.

Summary

Background and objective: We examined the efficacy of intraoperative propofol administration to prevent pruritus induced by epidural morphine. Methods: Seventy patients ASA I–II undergoing combined epidural and general anaesthesia for hysterectomy were randomly assigned to two groups, Group P where anaesthesia was induced with propofol and fentanyl and maintained with propofol-nitrous oxide and Group S in which anaesthesia was induced with thiopental and fentanyl and maintained with sevoflurane-nitrous oxide. All patients received a ropivacaine epidural bolus with 3 mg morphine 1 h before the end of surgery. The incidence and severity of pruritus were evaluated every 4 h for the first 12 h postoperatively by blinded observers. Results: The total incidence of pruritus was significantly higher (P = 0.024) in Group S (65.6%) compared to Group P (29%) between 4 and 8 h postoperatively. There were also significantly more patients (P = 0.03) reporting severe pruritus in Group S (22%) compared to Group P (0). Conclusion: Propofol-based general anaesthesia compared to thiopental–sevoflurane-based anaesthesia reduces the incidence and severity of pruritus induced by a single injection of 3 mg epidural morphine with ropivacaine.

Summary

Background and objective: Remifentanil boluses are used in different clinical situations and the effects on bispectral index monitoring are unclear. We analysed the effect of a remifentanil bolus on the bispectral index of the electroencephalogram (bispectral index) under total intravenous anaesthesia with propofol and remifentanil. Methods: ASA I–III patients were included in this study. All patients received a 2 μg k g−1 remifentanil bolus in a period free from stimuli. Bispectral index and haemodynamic data were collected from an A-2000XP bispectral index monitor (every second) and an AS/3 Datex monitor (every 5 s). Bispectral index data were analysed using the area under the curve. Mean arterial pressure and heart rate were averaged at each 30-s period and analysed using analysis of variance. Results: A total of 240 bispectral index values were obtained per patient. The area under the curve between 90 and 120 s after the bolus was significantly lower than the basal area under the curve (average of all areas before the bolus, P < 0.05). Mean arterial pressure and heart rate were significantly reduced from 96.4 ± 19.9 mmHg at the time of the bolus to 74.2 ± 16.6 mmHg 120 s after, and from 70 ± 16.4 bpm at the time of the bolus to 61 ± 13.6 bpm after (P < 0.001), respectively. Conclusions: There was a significant reduction in the areas under the curve between 90–120 s following the bolus. Heart rate and blood pressure also showed significant reductions. Thus, remifentanil bolus given under total intravenous anaesthesia with propofol and remifentanil decreases bispectral index, an effect independent of intubation and surgical stimuli.

Summary

Background and objective: We compared the dose requirement and side effect profile of total intravenous anaesthesia using Diprivan® to generic propofol at a specific anaesthetic target level utilizing the bispectral index monitor to determine efficacy differences between the two products. Methods: Sixty women undergoing abdominal hysterectomy were induced with propofol 2 mg kg−1 and maintained with infusion (20–200 μg kg−1 min−1) adjusted to maintain a bispectral index of 50–65. Plasma propofol concentration was measured at 1 and 2 h post induction in 25 patients. Results: Mean (SD) drug doses adjusted for weight and time were similar in the Diprivan® and generic propofol groups: 90 (30) μg kg−1 min−1 vs. 90 (20) μg kg−1 min−1 respectively. Mean (SD) plasma propofol levels at 1 and 2 h were also similar (3.0 (1.0) μg mL−1 vs. 3.6 (1.4) μg mL−1, P = 0.2 and 3.0 (1.9) μg mL−1 vs. 3.4 (1.6) μg mL−1, P = 0.58). Conclusions: Diprivan® and generic propofol have similar efficacy at a specified, bispectral index-defined, depth of anaesthesia.

Summary

Background and aim: The neuromuscular effects of a bolus dose of rocuronium 0.6 mg kg−1 under propofol anaesthesia in renal failure patients are prolonged compared to healthy patients. The present study aims to describe the neuromuscular effects of 0.3 mg kg−1 rocuronium under propofol anaesthesia in patients with renal failure and to compare these effects with healthy control patients. Methods: With institutional approval and informed consent, 18 healthy patients and 18 patients with renal failure took part in this prospective open label study. The renal failure patients were undergoing either renal transplantation or insertion of a shunt. Rocuronium 0.3 mg kg−1 was given intravenously after induction of anaesthesia with propofol 1–2 mg kg−1 and fentanyl 2 μg kg−1. Propofol 6–12 mg kg−1 h−1 was used for maintenance of anaesthesia. Four acceleromyographic responses of the thumb after supramaximal stimulation of the ulnar nerve using surface electrodes at 2 Hz every 15 s were measured and recorded. The onset time, the time to recovery of the first twitch to 25% recovery and the time to a train-of-four ratio of 0.7 were all recorded. Wilcoxon rank sum testing was used to compare the pharmacodynamics and to see if medication, gender or electrolytes influenced the duration of the block. P < 0.05 was significant. Results: No statistical differences were seen in the neuromuscular blocking effects of rocuronium between the two groups but there was a significant difference (P < 0.00001) in the variability of the total duration of the block. Conclusions: Rocuronium 0.3 mg kg−1 is suitable for use in patients with renal failure when endotracheal intubation and neuromuscular block for a short period of time are needed. Tracheal intubation is facilitated within 4 min and the block can be antagonized within 20 min.

Summary

Background and objective: The aim of this study was to assess postoperative patients' self-evaluation after xenon anaesthesia compared to total intravenous anaesthesia with propofol. Methods: 160 patients aged 18–60 yr, ASA I–II undergoing elective surgery took part in this randomised-controlled trial. After approval by the local Ethics Committee and as soon as the patients had given their written informed consent, they were randomly allocated to either the xenon (n = 80) or propofol (n = 80) group. In both groups remifentanil was used as opioid. The postoperative patients' self-evaluation was assessed with a double-blind telephone poll. Early spatial orientation, patients' self-evaluation of anaesthesia, choice of the same anaesthesia for future operations and recall of uncomfortable feelings after anaesthesia were determined. Results: 116 Patients were analysed, 63 in the xenon and 53 in the propofol group. The two study groups were comparable with respect to age, weight, height, gender and ASA classification. The two groups indicated similar values in the early spatial orientation at the onset of recovery and thereafter. Patients' self-evaluation of anaesthesia with main emphasis at high marks and repetition of the same anaesthesia if necessary were similar in both groups. Recalls of uncomfortable feelings were comparable but not for postoperative pain and appetite/thirst which appeared with a significantly higher incidence in the xenon group. Conclusions: Patients' self-evaluation and memory of early spatial orientation following xenon anaesthesia are comparable to propofol.

Summary

Background and objective: High doses of opioid associated with low doses of hypnotic is a popular anaesthetic technique since the use of remifentanil has become widespread. This type of anaesthesia could result in a higher incidence of implicit memory.

Methods: Ten patients were anaesthetised with a target-controlled infusion of remifentanil (target concentration of 8 ng mL−1) combined with a target-controlled infusion of propofol with progressive stepwise increases until loss of consciousness was reached. A tape containing 20 words was then played to the patients. Bispectral index (BIS, Aspect Medical Systems, Newton, MA, USA) was continuously monitored during the whole study period. Implicit and explicit memories were tested between 2 and 4 h after recovery.

Results: Loss of consciousness was obtained with a mean calculated propofol plasma concentration of 1.3 ± 0.4 μg mL−1. At this low hypnotic concentration no implicit or explicit memory was found in the three postoperative memory tests. Median (range) BIS value during word presentation was 93 (80–98).

Conclusions: In our group of young American Society of Anesthesiologists (ASA) I/II patients, no explicit or implicit memory was found when the calculated concentration of propofol combined with a high concentration of remifentanil was maintained at the level associated with loss of consciousness with high BIS values.

Summary

Background and objective: We conducted a prospective randomized study to evaluate whether the duration of action of a single bolus dose of rocuronium is influenced by maintenance of anaesthesia with sevoflurane, desflurane or propofol infusion.

Methods: Fifty-seven ASA I–II patients undergoing elective abdominal surgery were enrolled in this study. Anaesthesia was induced with thiopental 3–5 mg kg−1 or propofol 2.5 mg kg−1 and fentanyl 5 μg kg−1 and tracheal intubation was facilitated with rocuronium 0.9 mg kg−1. Thereafter patients were randomly allocated to three different groups to receive sevoflurane, desflurane or propofol for maintenance of anaesthesia. Recovery of neuromuscular function was monitored by single twitch stimulation of the ulnar nerve and by recording the adductor pollicis response using accelerometry. Intergroup recovery times to 5% of control value of single twitch were analysed using analysis of variance with Bonferroni correction.

Results: The mean (95% confidence interval) recovery time to 5% of control value of single twitch during desflurane anaesthesia was 90.18 (86.11–94.25) min. Significantly shorter recovery times were observed during sevoflurane or propofol anaesthesia, 58.86 (54.73–62.99) min and 51.11 (45.47–56.74) min, respectively (P < 0.001). There were also significant differences in the recovery time between groups receiving desflurane vs. sevoflurane (P < 0.001) and desflurane vs. propofol (P < 0.001).

Conclusions: Desflurane anaesthesia significantly prolongs the duration of action of rocuronium at 0.9 mg kg−1 single bolus dose, compared to sevoflurane or propofol anaesthesia maintenance regimens.

Summary

This study reports a review of all comparative published studies of adult day case anaesthesia in the English language up to December 2000. Ten databases were searched using appropriate keywords and data were extracted in a standardized fashion. One hundred-and-one published studies were examined. Recovery measurements were grouped as early, intermediate, late, psychomotor and adverse effects. With respect to induction of anaesthesia, propofol was superior to methohexital, etomidate and thiopental, but equal to sevoflurane and desflurane. Desflurane and sevoflurane were both superior to thiopental. There was no detectable difference between sevoflurane and isoflurane. With respect to the maintenance of anaesthesia, isoflurane and halothane were the worst. There were no significant differences between propofol, desflurane, sevoflurane and enflurane. Propofol is the induction agent of choice in day case patients. The use of a propofol infusion and avoidance of nitrous oxide may help to reduce postoperative nausea and vomiting.