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.

Abstract

Background: Postoperative nausea and vomiting still represents a major problem after surgery. Although risk factors for postoperative nausea and vomiting and procedures to reduce postoperative nausea and vomiting have been described, the incidence of postoperative nausea and vomiting remains high. The aim of the present study was to investigate the potential role of the proton pump inhibitor esomeprazole to reduce postoperative nausea and vomiting after elective surgery. Methods: In a randomized, double-blind trial, ASA I–III patients at high risk for postoperative nausea and vomiting received esomeprazole tablets 3 × 40 mg or matching placebo the evening before surgery, 2 h preoperatively and 24 h postoperatively. Total intravenous anaesthesia with propofol and remifentanil without nitrous oxide (FiO2 0.5) was used. Patients were interviewed using a standardized postoperative nausea and vomiting questionnaire at discharge from the post-anaesthesia care unit, 6 h and 24 h later. The severity of nausea was estimated on a 0–100 point numerical scale (0 = no nausea, 100 = maximum nausea). Results: The incidence of vomiting was similar in the esomeprazole (n = 45) and the placebo (n = 48) groups (64.4% vs. 60.5%, P > 0.05). The average nausea score was 17.8 with esomeprazole and was 18.7 with placebo (P > 0.05). Only 24.7% of all patients (esomeprazole 24.4%, placebo 25.0%) did not experience any nausea or vomiting. Conclusion: There is no evidence that prophylactic esomeprazole reduces the incidence of postoperative nausea and vomiting or the degree of postoperative nausea.

Summary

Background and objective: Inhalation induction with sevoflurane provides acceptable conditions for tracheal intubation. Opioids significantly decrease the alveolar concentration needed to achieve tracheal intubation. The purpose of this study was to determine the target concentration of remifentanil providing excellent conditions for tracheal intubation with sevoflurane at 1 minimum alveolar concentration without muscle relaxant. Methods: Twenty-four consecutive patients, aged 18–50 yr, ASA I or II, were studied. Induction of anaesthesia was performed with sevoflurane at age-adjusted minimum alveolar concentration. Remifentanil was simultaneously administered using target-controlled infusion with the Minto model. Target plasma concentration of remifentanil was selected for each patient according to an up-and-down method. Results: The mean target concentration of remifentanil for successful tracheal intubation was 3.3 ng mL−1 (95% confidence interval: 2.6–3.9 ng mL−1). Arterial pressure, heart rate and bispectral index did not increase after tracheal intubation in the group of patients with successful intubation. Conclusions: Remifentanil at 3.3 ng mL−1 together with sevoflurane at 1 minimum alveolar concentration provides excellent conditions for tracheal intubation in 50% of patients.

Summary

Background and objective: Inhalational anaesthetics have been associated with hepatotoxicity. Even desflurane, with its low solubility in blood and tissues, and its minimal hepatic biotransformation, is known to affect hepatic integrity. The effects of propofol on hepatic function are, however, a matter of controversy. Alpha-glutathione S-transferase (α-GST), a sensitive and specific biomarker for hepatic integrity, was measured to assess the influence of total intravenous anaesthesia (TIVA) with propofol vs. anaesthesia with desflurane.

Methods: Forty-two patients scheduled for elective prostatectomy were randomly allocated to receive either desflurane, fentanyl and thiopental (desflurane group) or propofol and remifentanil (TIVA group). Depth of anaesthesia was guided by bispectral index. Plasma concentrations of α-GST and aminotransferases were measured before induction of anaesthesia (T0), at the end of surgery (T1), as well as 2 h (T2) and 24 h (T3) postoperatively. Haemodynamic parameters and bispectral index values were documented.

Results: α-GST increased significantly in the desflurane group from T0 (3.0 ± 2.2 μg L−1) to T1 and T2 (5.5 ± 4.3 and 5.6 ± 3.7 μg L−1, respectively), whereas no changes were seen in the TIVA group. α-GST values above the normal upper limit (>7.5 μg L−1) were seen in 24% of the patients receiving desflurane. Aminotransferases remained unchanged in both groups throughout the study period.

Conclusions: The use of propofol as part of a TIVA regimen seems to have no influence on hepatocellular function during and after surgery. In contrast, patients receiving desflurane showed a transient slight, but significant, increase of α-GST to above the normal upper limit after anaesthesia, although this was without further clinical relevance.

Summary

Background: This study was designed to investigate the impact of patient age on propofol consumption and recovery time using a propofol–remifentanil anaesthetic standardized with Narcotrend™ EEG monitoring. The Narcotrend is a monitor for measuring the depth of anaesthesia based upon a six-letter classification from A (awake) to F (increasing burst suppression) including 14 substages.

Methods: In 200 patients scheduled for minor orthopaedic surgery Narcotrend EEG electrodes were positioned on the patient's forehead as recommended by the manufacturer. Anaesthesia was induced with remifentanil 0.4 μg kg−1 min−1 and 2 mg kg−1 propofol. Immediately after intubation remifentanil was reduced to a constant rate of 0.2 μg kg−1 min−1 whereas a propofol infusion was now started at 3 mg kg−1 h−1 and then adjusted accordingly to achieve a target Narcotrend stages of D0–2 indicating general anaesthesia. At the end of surgery the propofol and remifentanil infusions were stopped without tapering, the time to unstimulated opening of eyes was determined, and the propofol consumption (given as mg kg−1 h−1) was calculated from the total amount of infused propofol but without the induction bolus, from the actual body weight and the duration of propofol infusion. Furthermore, a linear regression analysis was applied for propofol consumption vs. age.

Results: The ages of the patients studied ranged from 16 to 83 yr old and patients were classified as ASA I–III. Propofol consumption significantly decreased with the patients' age: 30 yr of age or below the propofol consumption was calculated as 5.9 ± 1.7 mg kg−1 h−1, for 31–50 yr as 5.4 ± 1.8 mg kg−1 h−1, for 51–70 yr as 4.5 ± 1.7 mg kg−1 h−1 and above 70 yr as 3.5 ± 1.4 mg kg−1 h−1. Linear regression analysis revealed propofol (mg kg−1 h−1) = 9.136 − (0.0597 × age (yr)); R = 0.53. Concomitantly, the recovery time to opening of eyes increased with the patients' age: ≤30 yr, 7.4 ± 3.7 min; 31–50 yr, 9.5 ± 4.0 min; 51–70 yr, 9.8 ± 4.1 min; and ≥71 yr, 14.9 ± 12.1 min.

Conclusions: We conclude that with Narcotrend guidance, mean propofol consumption and recovery times are age dependent. However, as a result of large inter-individual variability, age per se does not allow a prediction of individual propofol need or recovery time.