Summary

Background and objective: Magnesium administered before anaesthesia induction results in a significant reduction in intravenous anaesthetic consumption. The purpose of this study was to evaluate whether the dose of intravenous magnesium sulphate reduces the minimum alveolar anaesthetic concentration of sevoflurane for endotracheal intubation (MACEI) and skin incision (MAC), and attenuates haemodynamic responses. Methods: We studied 60 patients who were scheduled for elective surgery. Patients were not premedicated before induction of anaesthesia and were randomly assigned to receive intravenous saline 0.9% (Group I, n = 20) or magnesium sulphate 30 mg kg−1 bolus + 10 mg kg−1 h−1 continuous infusion (Group II, n = 20) or 50 mg kg−1 bolus + 10 mg kg−1 h−1 continuous infusion (Group III, n = 20). Results: Median and 95% confidence limits for sevoflurane MACEI were 2.68 (2.48–2.85), 2.88 (2.70–3.06) and 2.96 (2.70–3.16), and for sevoflurane MAC were 2.08 (1.76–2.40), 2.26 (2.08–2.47) and 2.40 (2.19–2.68) in Groups I, II and III, respectively. The differences in MACEI and MAC among groups were not statistically significant, except Group III in MAC study (P < 0.05). Mean arterial pressures and heart rate did not increase in Groups II and III after endotracheal intubation and skin incision. Conclusions: Magnesium sulphate administered before induction of anaesthesia increases MAC of sevoflurane and reduces cardiovascular responses to intubation.

Summary

Background and objectives: The On-Line Electronic Help (OLEH) is a point-of-care information system for anaesthesia providers prepared by the European Society of Anaesthesiologists. In this preliminary study the effect of the OLEH availability on the incidence of knowledge-based errors during the management of case scenarios and participants' subjective evaluation of the OLEH were evaluated. Methods: After a short training session, 48 anaesthesiologists (24 junior residents, 12 senior residents and 12 board-certified) were presented randomly with six computer screen-based case scenarios with, and six without, the option of using the OLEH. Two reviewers evaluated the answers independently according to preconfigured guidelines. Results: The availability of the OLEH was associated with higher scores in 11 of the 12 scenarios, and with a decrease in the incidence of critical errors in 10 scenarios. Time to task completion was increased in one scenario only when the OLEH was used. The degree of professional experience was associated with better scores in five of the scenarios and with a reduced occurrence of critical errors in three scenarios. Forty-two out of 48 participants stated that finding information in the OLEH software was easy and that the system was helpful in managing the scenarios. Conclusions: This preliminary study demonstrates the potential value of the OLEH in decreasing the number of knowledge-based errors made by anaesthesiologists. According to the encouraging results, the OLEH system is currently under evaluation using full-scale simulation scenarios in an operating room environment.

Summary

Background and objective: The level of performance in junior and senior anaesthetists was investigated after 24-h shift working and on-call duties. Methods: Pre- and post-duty psychomotor function, influence on response time, cognitive function and well-being in 23 individuals (13 junior and 12 senior anaesthetists) was assessed before and after 24-h in-house on-call duty. Subjective perception of tiredness and concentration abilities was estimated by applying a visual analogue scale. Results: The self-assessed tiredness prior to duty was high in both age groups and significantly increased in senior anaesthetists after night duty (P = 0.01). Post-duty impairment of concentration abilities was reported in both groups. Comparing results from pre- and post-duty psychometric testing showed a comparable decline in junior and senior anaesthetists as well. Assessment of burnout showed a significant lack of personal accomplishment in junior anaesthetists as compared to their older colleagues (P = 0.038). Senior anaesthetists judged their contribution to patient well-being significantly higher than did their younger colleagues (P = 0.035). Conclusions: Although tiredness and subjective impairment of concentration abilities was high in senior anaesthetists after 24-h in-house on-call duty, performance assessed by psychometric testing does not support the hypothesis that senior colleague's performance cannot keep up with routine hospital shift work.

Summary

Background and objective: Anaesthesiology is considered a stressful occupation. Our purpose was to assess stress and burnout among Portuguese anaesthesiologists. Methods: A cross-sectional survey based on an anonymous questionnaire was sent to all Portuguese anaesthesiologists registered by the Portuguese Medical Association. Data on patient characteristics and professional variables, perceived stress (Perceived Stress Scale), the subscale of work satisfaction of the Pressure Management Indicator scale, burnout (Maslach Burnout Inventory) and main stress factors were collected. The proportion of participation was 31.8%. Results: The average value of perceived stress scale was 24.0 (range: 0–56). Among the 263 anaesthesiologists, 57.9% experienced emotional exhaustion, 44.8% lack of personal accomplishment and 90.9% depersonalisation. Lack of personal accomplishment increased with number of children among women but not among men; depersonalisation was more frequent among anaesthesiologists working in community hospitals and anaesthesiologists with leadership functions experienced less professional stress. Conclusion: There are stress conditions and burnout amongst Portuguese anaesthesiologists. The prevalence of depersonalisation was extremely high in the studied sample. Emotional exhaustion is partially explained by high perceived-stress and low satisfaction with organisation in the job according to Pressure Management Indicator scale.

Summary

Background and objective: Astrocytes exposed to hypoxia produce pro-inflammatory cytokines and upregulate intercellular adhesion molecule-1 on cerebral endothelium. This study investigated the effects of midazolam on this response. Methods: Mouse astrocytes were exposed to 4 h of hypoxia and 24 h of reoxygenation. Astrocyte-conditioned medium were applied to mouse cerebral endothelial cell cultures for 4 h and 24 h in normoxia. Endothelial cells were pre-incubated for 1 h with midazolam (0, 5, 50 μg L−1). Flow cytometry was used to estimate endothelial ICAM-1 expression. IL-1β concentrations were measured with ELISA. Repeated comparisons were made using ANOVA and post hoc Tukey Test as appropriate. Data are mean (SD). Results: Mouse cerebral endothelial cell ICAM-1 expression was greater after 24 h exposure to hypoxia–reoxygenation astrocyte-conditioned medium compared to normoxic astrocyte-conditioned medium (mean channel flouresence 112.5 (9.5) vs. 81.5 (7.5), P = 0.01). ICAM-1 expression was decreased by midazolam (5 μg L−1) compared to control (mean channel flouresence 81.35 (7.5) vs. 112.5 (9.5), P = 0.01). Supernatant IL-1β concentrations (pg mL−1) in astrocytes exposed to hypoxia–reoxygenation were greater than those exposed to normoxia (16.41 (2.35) vs. 10.5 (2.13), P = 0.01). Conclusion: We conclude that decreased cerebral endothelial ICAM-1 expression in response to activated glial cell compartment by midazolam may decrease post ischaemic brain inflammation and secondary brain injury.

Summary

Background and objective: A randomized double-blind controlled trial was performed to determine if there was a difference in discomfort on injection between two preparations of propofol. A long-chain triglyceride preparation (LCT-propofol (Fresenius)) was compared against a medium- and long-chain triglyceride preparation (MCT/LCT-propofol (BBraun)). Methods: One hundred and twenty ASA I–II patients listed for elective procedures were consented and randomized to receive either induction agent. A standard rate of infusion was used for induction of anaesthesia and subjects were questioned about discomfort until contact was lost. Discomfort was recorded as none, mild, moderate or severe. Incidence of postoperative nausea and vomiting and anti-emetic requirements were recorded in the postanaesthetic care unit. Results: There was seen to be a 54% reduction in moderate/severe discomfort with MCT/LCT-propofol compared with LCT-propofol (P < 0.006). There was a 70% reduction in severe discomfort with MCT/LCT-propofol compared with LCT-propofol (P < 0.04). The term discomfort was used during the study because there is a wide array of unpleasant sensations felt by patients during propofol induction which are not always reported as pain. There was no significant difference in the incidence of postoperative nausea and vomiting or anti-emetic use between the two groups. Conclusions: There is a significant decrease in the incidence of discomfort with MCT/LCT-propofol compared with LCT-propofol. This difference is more marked in subjects reporting severe discomfort.

Summary

Background and objective: We conducted a study investigating the effectiveness of four face mask designs in the bag-mask ventilation of a special manikin adapted to simulate a difficult airway. Methods: Forty-eight anaesthetists volunteered to bag-mask ventilate the manikin for 3 min with four different face masks. The primary outcome of the study was to calculate mean percentage leak from the face masks over 3 min. Anaesthetists were also asked to rate the face masks using a visual analogue score. Results: The single-use scented intersurgical face mask had the lowest mean leak (20%). This was significantly lower than the mean leak from the single-use, cushioned 7000 series Air Safety Ltd. face mask (24%) and the reusable silicone Laerdal face mask (27%) but not significantly lower than the mean leak from the reusable anatomical intersurgical face mask (23%). Conclusions: There was a large variation in both performance and satisfaction between anaesthetists with each design. This highlights the importance of having a variety of face masks available for emergency use.

Summary

Background and objective: Data from several studies implicate that pre-treatment with non-selective cyclooxygenase inhibitors such as aspirin or diclofenac may decrease the incidence of postoperative succinycholine-related myalgia. We tested the influence of a preoperatively administered selective cyclooxygenase 2 inhibitor, parecoxib, on postoperative myalgia. Methods: After Ethics Committee approval, 68 patients were randomized into two groups (n = 34 each). Group 1 received parecoxib 40 mg intravenously 3 min before induction of anaesthesia, and Group 2 received saline (in a double-blinded manner). Incidence and severity of myalgia was evaluated systematically with a standardized questionnaire 24, 48 and 72 h after anaesthesia. We also the assessed the number of patients who felt limited in their activity due to myalgia. Results: Seven patients in the parecoxib-treated group complained of myalgia compared with 11 in the control group (not significant). No significant difference in the severity of myalgia or in the limitation of patients activity was found between the groups. Conclusion: Intravenous parecoxib 40 mg, when administered before induction of anaesthesia, did not reduce incidence and severity of postoperative myalgia and did not improve activity in those who suffered from myalgia.

Summary

Background: Short-acting agents for neuromuscular block (NMB) require frequent dosing adjustments for individual patient's needs. In this study, we verified a new closed-loop controller for mivacurium dosing in clinical trials. Methods: Fifteen patients were studied. T1% measured with electromyography was used as input signal for the model-based controller. After induction of propofol/opiate anaesthesia, stabilization of baseline electromyography signal was awaited and a bolus of 0.3 mg kg−1 mivacurium was then administered to facilitate endotracheal intubation. Closed-loop infusion was started thereafter, targeting a neuromuscular block of 90%. Setpoint deviation, the number of manual interventions and surgeon's complaints were recorded. Drug use and its variability between and within patients were evaluated. Results: Median time of closed-loop control for the 11 patients included in the data processing was 135 [89–336] min (median [range]). Four patients had to be excluded because of sensor problems. Mean absolute deviation from setpoint was 1.8 ± 0.9 T1%. Neither manual interventions nor complaints from the surgeons were recorded. Mean necessary mivacurium infusion rate was 7.0 ± 2.2 μg kg−1 min−1. Intrapatient variability of mean infusion rates over 30-min interval showed high differences up to a factor of 1.8 between highest and lowest requirement in the same patient. Conclusions: Neuromuscular block can precisely be controlled with mivacurium using our model-based controller. The amount of mivacurium needed to maintain T1% at defined constant levels differed largely between and within patients. Closed-loop control seems therefore advantageous to automatically maintain neuromuscular block at constant levels.

Summary

Background and objective: Low flow desflurane and sevoflurane anaesthesia were administered to children and compared for haemodynamic response, renal and hepatic function, recovery time and postoperative nausea and vomiting. Methods: Eighty ASA I–II patients aged 5–15 yr were included in the study. Midazolam was given for premedication. Anaesthesia induction was performed with fentanyl, propofol and atracurium. After intubation, the first group received desflurane, oxygen and nitrous oxide at 6 L min−1 and the second sevoflurane, oxygen and nitrous oxide at 6L min−1. Ten minutes after induction the flow was decreased to 1L min−1 in both groups. Haemodynamic parameters, preoperative and postoperative renal and hepatic function, the times of operation and anaesthesia, and early recovery data were recorded. Modified Aldrete scores were noted at the 10th and 30th minutes postoperatively and postoperative nausea, and vomiting were assessed. Results: There were no significant differences in haemodynamic parameters, renal and hepatic functions, postoperative recovery and postoperative nausea and vomiting between groups. The recovery time was shorter in the desflurane group compared to the sevoflurane group. Conclusion: Low flow desflurane and sevoflurane anaesthesia do not adversely affect haemodynamic parameters, hepatic and renal function in children. Desflurane may be preferred when early recovery from anaesthesia is warranted.

Summary

Background and objective: Opioids and especially fentanyl are widely used during the intensive care unit management of intracranial pressure in fulminant hepatic failure patients as well as during and after liver transplantation. The newer synthetic opioid remifentanil is also increasingly being used in critical care patients. Due to a lack of data relating to the influence of acute hepatic failure on remifentanil and fentanyl pharmacokinetics, this study was designed in order to determine the impact of this condition on the blood levels of these opioids using a pig model. Methods: Twenty pigs were randomly assigned to one of two groups: A group with surgically induced acute hepatic failure by hepatic devascularization (acute hepatic failure, n = 10) and a control group (SHAM, n = 10), subjected to a SHAM operation. Postoperatively, five animals in each group were administered remifentanil (1 μg kg−1 min−1) or fentanyl (0.2 μg kg−1 min−1) by continuous intravenous infusion. Blood samples for determination of drug concentrations were withdrawn at 0 h and 0.5, 1, 5, 7, 9 h after initiation of dosing. Results: Significantly higher blood concentrations were found in animals with acute hepatic failure compared to SHAM-operated animals receiving remifentanil at 5 h (P = 0.003), 7 h (P = 0.007) and 9 h (P = 0.004) and fentanyl at 7 h (P < 0.0005) and 9 h (P = 0.05). The small number and the great variability in drug concentrations did not allow a detailed kinetic analysis to be performed. Approximate clearance values were found to be greater for the SHAM compared with the acute hepatic failure animals for both fentanyl and remifentanil. Conclusions: Hepatic devascularization in our porcine acute hepatic failure model, appears to have significantly altered the disposition of fentanyl and unexpectedly remifentanil. These changes were thought to be brought about by severe disruption of blood flow and biotransformation in the liver, as well as by haemodynamic changes in the acute hepatic failure animals.

Summary

Background and objective: The best place for the electrode of transcutaneous measurement of oxygen tension (tcPO2) and carbon dioxide tension (tcPCO2) during general anaesthesia was investigated in three different locations. Methods: Fifteen patients for major abdominal surgery in the supine position were studied. The electrode of the TCM4™ (Radiometer, Copenhagen, Denmark) was put on the chest, upper arm or forearm. TcPO2, tcPCO2, end-tidal carbon dioxide tension (etCO2), percutaneous oxygen saturation (SaO2), arterial oxygen tension (PaO2 ) and arterial carbon dioxide tension (PaCO2) were simultaneously measured at four different etCO2 concentrations and inhaled oxygen percentages and the location of the electrode was changed to other places to repeat the same measurement. In total, 12 measurements for each patient and 60 measurements for each place were performed. Results: TcPO2 correlated better than SaO2 (R2 = 0.58) with PaO2 (R2 = 0.76), and tcPCO2 correlated well with PaCO2 (R2 = 0.76) and etCO2 (R2 = 0.74) when the electrode was put on the chest, while not on the upper arm or forearm (R2 < 0.5). However, limits of agreement were too big to use tcPO2 (bias, −67.9; limits of agreement, 16.5, −152.3) and tcPCO2 (bias, −0.47; limits of agreement, 8.7, −9.64) as surrogate measures of PaO2 and PaCO2, respectively even when the electrode was put on the chest. Conclusions: When the electrode was put on the chest, tcPO2 and tcPCO2 might be available as non-invasive monitors of oxygenation and CO2 status during general anaesthesia, while the absolute values were not interchangeable with PaO2 and PaCO2, respectively.

Summary

Background and objective: The present study was designed to compare cerebral oxygenation measured with near infrared spectroscopy and local brain tissue oxygen partial pressure, respectively, in pigs during cardiopulmonary resuscitation. Since tissue overlying the brain may have an impact on near infrared spectroscopy readings, we tested whether optode placement on intact skin or on the skull yielded comparable results. Methods: Twelve healthy pigs were anaesthetized and subjected to continuous haemodynamic, near infrared spectroscopy and brain tissue oxygen partial pressure monitoring. After 4 min of untreated ventricular fibrillation, cardiopulmonary resuscitation was started and arginine vasopressin was administered repeatedly three times. Near infrared spectroscopy values recorded were both the tissue oxygenation index and the tissue haemoglobin index as well as relative changes of chromophores (haemoglobin and cytochrome oxidase). Four animals served as control and were measured with both near infrared spectroscopy optodes mounted on the intact skin of the forehead, while in the remaining eight animals, one near infrared spectroscopy optode was implanted directly on the skull. Results: Near infrared spectroscopy readings at the skin or at the skull differed consistently throughout the study period. After arginine vasopressin administration, near infrared spectroscopy values at the different locations showed a transient dissociation. In contrast to near infrared spectroscopy measured on intact skin, near infrared spectroscopy readings obtained from skull showed a significant correlation to brain tissue oxygen partial pressure values (r = 0.67, P < 0.001). Conclusion: Near infrared spectroscopy readings obtained from skin and skull differed largely after vasopressor administration. Near infrared spectroscopy optode placement therefore may have an important influence on the tissue region investigated.

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: We recently demonstrated that intrathecal bupivacaine before or after acute photochemical spinal injury improved functional outcome in rats. However, the closest model to spinal trauma is the contusive weight-drop method. The aim of this study was to evaluate functional, electrophysiological and anatomical consequences of a contusive spinal-cord lesion in rats with or without an intrathecal injection of bupivacaine. Methods: Fifteen minutes before a contusive spinal lesion, 18 rats received intrathecally either 0.5% bupivacaine (Group T) or saline (Group C). During an 18-days period, motor and sensory functions were evaluated, and bladder voiding dysfunction was noted. Somatosensory evoked potential testings were performed at day 18. Then, the intact spinal cord area at the epicentre of the lesion and the extent of the lesion were measured. Results: Motor deficit was less and inclined-plane stability was better in treated animals at all times, the scores were statistically different from day 7. There were no differences concerning the sensory test. Despite no significant difference, there were less spinal bladders in the T group from day 7. Somatosensory evoked potential latencies were longer in T group, but only the first negative component (N1) was statistically significant. Amplitudes were higher in T group, but were not statistically different. The spinal cord intact area at the epicentre of the lesion was higher in the T group (1.23 ± 0.8 mm2 vs. 0.81 ± 0.39 mm2; P < 0.05). The extent of the lesion was higher in the C group (9.4 ± 2.9 mm vs. 6.4 ± 3.4 mm; P < 0.05). Conclusion: Intrathecal 0.5% bupivacaine provide a neuroprotective effect by decreasing functional, electrophysiological and anatomical consequences after a contusive spinal cord injury.

Summary

Background: Propofol and dexmedetomidine are widely used for sedation in the intensive care unit yet there are limited data on its effects on gastric motility. In our preliminary study, we examined whether or not any effect of propofol and dexmedetomidine on gastric emptying is preserved in critically ill patients. Methods: Twenty-four critically ill, enterally fed adult patients each received enteral feeding via a nasogastric tube at 50 mL h−1 throughout the 5-h study period. Either propofol 2 mg kg−1 h−1 (n = 12, Group P) or dexmedetomidine 0.2 μg kg−1 h− (n = 12, Group D) was given intravenously over 5 h. Gastric motility was measured indirectly by analysis of the absorption over time of 1.5 g of paracetamol administered into the stomach at the start of the study period. At the beginning and end of the study, residual gastric volume and pH of residual gastric fluid were measured. Results: Gastric residual volume measured at the end of propofol infusion (19.33 ± 11.33) was found to be higher when compared with the volume measured before infusion (11.33 ± 4.84) and after dexmedetomidine infusion (9.17 ± 4.54). But, there was no difference between groups in gastric emptying time (AUC120 894.53 ± 499.39 vs. 1113.46 ± 598.09 propofol and dexmedetomidine groups, respectively). Conclusion: In our study, gastric residual volume measured at the end of propofol infusion was found to be higher when compared with the volume measured before infusion and after dexmedetomidine infusion. There was no difference between groups in gastric emptying time.

Summary

Background: The purpose of this study was to assess whether the addition of intravenous magnesium sulphate (Mg) at the induction of anaesthesia to a balanced anaesthetic protocol including wound infiltration, paracetamol and tramadol resulted in improved analgesic efficiency after radical prostatectomy. Methods: We conducted a randomized, double-blind, controlled study. Thirty ASA I or II males scheduled to undergo radical retropubic prostatectomy with general anaesthesia were prospectively assigned to one of the two groups (n = 15 each). The Mg group (Gr Mg) received 50 mg kg−1 of MgSO4 in 100 mL of isotonic saline over 20 min immediately after induction of anaesthesia and before skin incision. The patients in the control group (Gr C) received the same volume of saline over the same period. At the time of abdominal closure, wound infiltration with 190 mg (40 mL) of ropivacaine was performed in both groups. Pain was assessed by a 10-point visual analogue scale in the recovery room starting from the time of tracheal extubation. Standardized postoperative analgesia included paracetamol and tramadol administered via a patient-controlled analgesia device. Results: In the postoperative period, both groups experienced an identical pain course evolution. Cumulative mean tramadol dose after 24 h was 226 mg in the magnesium group and 446 mg in the control group (P < 0.001). Postoperative nausea occurred in two patients in each group. Two vs. eight patients required analgesic rescue in magnesium and control groups, respectively (P = 0.053). Conclusions: This study shows that intravenous magnesium sulphate reduces tramadol consumption when used as a postoperative analgesic protocol in radical prostatectomy.