Summary

Background and objective: ProSeal™ Laryngeal Mask Airway (PLMA) and Laryngeal Tube Suction™ (LTS), supraglottic airway devices allowing gastric drainage, were compared in this prospective, randomized study for airway management under conditions with elevated intra-abdominal pressure induced by capnoperitoneum.

Methods: Fifty patients undergoing elective gynaecological laparoscopic surgery were randomized to two groups of 25 each. After induction of general anaesthesia, devices were inserted, correct placement was verified, airway leak pressure was measured, and a gastric tube was inserted. Ease of insertion, quality of airway seal, risk of gastric insufflation and patient comfort were investigated.

Results: There were no differences in patient characteristics data for both groups. First-time insertion success rates were comparable for both groups: 92% – first attempt, 8% – second attempt for PLMA and LTS. Time until delivery of the first tidal volume for PLMA and LTS was 23.2 ± 6.1 and 23.5 ± 6.6 s, airway leak pressure was 45.4 ± 4.9 cmH2O and 45.6 ± 6.7 cmH2O with cuff pressures adjusted to 60 cmH2O. No gastric insufflation, gas loss or signs of regurgitation were detected. Placement of a gastric tube was successful in all patients. Patients were questioned for sore throat and dysphagia after removal of devices. Sore throat was stated in 1%/0% (PLMA) and 8%/4% (LTS) after 6/24 h, dysphagia in 4%/4% (PLMA) and 12%/4% (LTS).

Conclusions: Both devices provide a secure airway even under conditions of elevated intra-abdominal pressure. In this pilot study, no differences concerning handling or quality of airway seal were detected between PLMA and LTS.

Laudanosine is a metabolite of the neuromuscular-blocking drugs atracurium and cisatracurium with potentially toxic systemic effects. It crosses the blood-brain barrier and may cause excitement and seizure activity. Its interest in recent years has increased because of the recognized interaction with γ-aminobutyric acid, opioid and nicotinic acetylcholine receptors. It has been shown to produce analgesia in animals. In the cardiovascular system, high plasma concentrations produce hypotension and bradycardia. In hepatic failure, its elimination halflife is prolonged but only moderate accumulation occurs in adults, whereas in infants and children plasma concentration are greater. In patients undergoing liver transplantation, laudanosine concentrations are increased during preanhepatic, anhepatic and postanhepatic stages. Patients with renal failure have higher plasma concentrations and a longer mean elimination half-life. In pregnancy, laudanosine crosses the placental barrier. The mean transplacental transfer is 14% of maternal blood concentrations. Except for prolonged administration of atracurium in intensive care units, laudanosine accumulation and related toxicity seem unlikely to be achieved in clinical practice. When cisatracurium is used, plasma concentrations of laudanosine are lower. Further studies are needed, especially around the interactions with γ-aminobutyric acid, opioid and nicotinic acetylcholine receptors.

The efficacy of an integrated autotransfusion regimen, including pre-donation and perioperative salvage of autologous blood, was prospectively evaluated in 2884 patients undergoing total hip (n=2016) or knee arthroplasty (n = 480), and hip revision (n = 388) with either balanced general, regional, or integrated epidural/general anaesthesia. Allogenic concentrated red blood cells were transfused in the presence of symptomatic anaemia or when haemoglobin concentration was < 6gdL−1 (10gdL−1 in patients affected by cerebrovascular or coronary artery disease) after all salvaged and pre-donated autologous blood had been transfused. A total of 278 patients (9.6%) received allogenic blood. Risk factors for allogenic blood transfusion were: preoperative haemoglobin concentration < 10gdL−1 (after autologous blood pre-donations) (Odds ratio: 8.7; 95% CI: 6.5–16.8; P=0.004), hip revision versus hip or knee arthroplasty (Odds ratio: 5.8; 95% CI: 3.9–8.5; P=0.0001) and inability in obtaining the number of predonations required by the Maximum Surgery Blood Order on Schedule (Odds ratio: 3.4; 95% CI: 2.7–4.1; P=0.0001). The incidence of perioperative complications, including wound infection and haematoma, as well as myocardial ischaemia, respiratory failure and thromboembolic complications, was higher in those patients requiring allogenic blood transfusion (29.8%) than that observed in patients receiving only autologous blood (6.6%) (P=0.0005); while the mean time duration from surgical procedure to patient discharge from the orthopaedic ward was shorter in those patients not receiving allogenic blood transfusion (12 days; 25–75th percentiles: 8–14 days) than in those patients who required perioperative transfusion with allogenic blood (15 days; 25–75th percentiles: 10–17 days) (P=0.0005). In conclusion, this prospective study highlighted the clinical relevance of applying an extensive and integrated autotransfusion regimen in order to reduce allogenic blood transfusion and associated complications in patients undergoing major joint replacement.

Summary

Background and objective: This study was performed to compare three supraglottic airway devices: the ProSeal laryngeal mask airway (PLMA), the laryngeal tube S (LTS) and the oesophageal–tracheal combitube (OTC) during routine surgical procedures.

Methods: Ninety American Society of Anesthesiologists (ASA) I–III patients scheduled for routine minor obstetric surgery were randomly allocated to the PLMA (n = 30), the LTS (n = 30) or the OTC (n = 30) group, respectively. The overall success rate, insertion time, cuff pressures and resulting airway leak pressures were determined as well as a subjective assessment of handling and the incidence of sore throat, dysphagia and hoarseness were performed.

Results: Insertion time until the first adequate ventilation was significantly (P < 0.0001) shorter in the PLMA (median 29 s; 25–75th percentile 25–48 s; range 10–161 s; success rate 100%) and in the LTS group (38 s; 30–44 s; 13–180 s; 100%) compared to the OTC group (75 s; 48–98 s; 35–180 s; 90%). In vivo cuff pressures and airway leak pressures increased with the inflating cuff volume in all devices and were highest in the OTC group. Postoperatively, patients in the PLMA and the LTS group complained significantly less about sore throat (P < 0.001 and 0.05) and dysphagia (P < 0.001 and 0.02) compared to the OTC group, while there was no difference regarding the incidence of hoarseness. Subjective assessment of handling was comparable with the PLMA and the LTS, but inferior with the OTC.

Conclusions: In conclusion, both PLMA and LTS proved to be suitable for routine surgical procedures and proved to be superior to the OTC which cannot be recommended for routine use.

Summary

Background and objective: Sedation is commonly required by critically ill patients and inadequate sedation may be hazardous. Traditionally, subjective scales have been used for monitoring sedation. Bispectral index has been proposed, although its utility in the intensive care unit is debated. Our aim was to evaluate the depth of sedation in intubated surgical critically ill patients by means of two sedation scales (Ramsay and Observer's Assessment of Alertness and Sedation) and bispectral index. Methods: Sedation was assessed prospectively in 50 postoperative intubated patients requiring at least 24 h of sedation (35 propofol, 15 midazolam/fentanyl), every 8 h for a 24 -h period. The bispectral index value recorded was the mean value obtained during a 10-min observation period, whenever the quality signal index was above 75% and the electromyographic signal was below 25%. Results: Most of the patients (78%) were oversedated (bispectral index < 60). The three sedation scores (global data) correlated significantly (P < 0.001). This correlation was lost in the midazolam group in which the patients were also significantly more sedated than the propofol group (P = 0.001). The correlation between the bispectral index and the scales in the midazolam group reappeared when the measurements with a Ramsay = 6 or an Observer's Assessment of Alertness and Sedation = 1 were excluded. Conclusions: Sedation should be monitored routinely in intensive care units. The Ramsay and the Observer's Assessment of Alertness and Sedation scales showed equal efficacy. Bispectral index might prove useful for discriminating between deeper levels of sedation.

Summary

Background and objective: To prevent neurological complications, low-flow antegrade cerebral perfusion (ACP) is used during repair of complex congenital heart defects. To overcome technical problems, continuous monitoring of cerebral blood flow and oxygenation is mandatory. The aim of the study was to evaluate the effect of different ACP flow rates on cerebral oxygen saturation obtained by near infrared spectroscopy.

Methods: Ten consecutive neonates undergoing Norwood stage I were included. In addition to near infrared spectroscopy (Invos 5100; Somanetics Corp., USA) on both hemispheres, mean arterial pressure and transcranial Doppler flow velocity were measured continuously and arterial and jugular venous oxygen saturation intermittently. Cerebral oxygen extraction ratio was calculated. Measurement points were obtained after starting bypass, during ACP with flow rates of 30, 20 and 10 mL kg−1 min−1 and immediately after ACP. ANOVA and Tukey–Kramer multiple comparison test were used for statistics.

Results: The near infrared spectroscopy signal could be obtained in all children at all measurement points, whereas transcranial Doppler failed in 1 neonate at a flow rate of 30 mL kg−1 min−1, in 3 neonates at 20 mL kg−1 min−1 and in 4 neonates at 10 mL kg−1 min−1. With the reduction of flow there was a significant decrease of cerebral oxygen saturation on both hemispheres (right: 78 ± 8 to 72 ± 9 and 66 ± 8, P < 0.001; left: 71 ± 7 to 65 ± 7 and 60 ± 7, P < 0.001), of jugular venous oxygen saturation (94 ± 6 to 89 ± 13 and 83 ± 15, P < 0.001) and a significant increase in oxygen extraction ratio (9.1 ± 8 to 14.8 ± 14 and 21 ± 16, P < 0.001) respectively, for 30, 20, 10 mL kg−1 min−1.

Conclusion: Near infrared spectroscopy reliably detects flow alterations during ACP with profound hypothermia.

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.

Background and objective It is claimed that local anaesthetics have antimicrobial properties. Our aim was to investigate the antimicrobial effects of different concentrations of ropivacaine, bupivacaine, lidocaine and prilocaine on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans.

Methods All local anaesthetic dilutions were exposed to microorganisms for 0, 30, 60, 120, 240 min at room temperature. The inoculums taken from diluted suspensions were reinoculated on blood agar and incubated for 18–24 h at 35°C and then the colonies were counted.

Results Ropivacaine did not inhibit any of the microorganisms tested. Bupivacaine reduced the viable cells of P. aeruginosa at 0.5% and 0.25% solutions. Lidocaine 5% and 2% and prilocaine 2.0% dilutions reduced the viable cells of all microorganisms tested. Prilocaine 1.0% reduced the viable cells of E. coli, S. aureus and P. aeruginosa. Lidocaine 1% reduced only the viable cells of P. aeruginosa and prilocaine 0.5% reduced only E. coli.

Conclusion Ropivacaine had no antimicrobial effect on microorganisms tested. Bupivacaine showed poor antimicrobial effectiveness. Lidocaine and prilocaine had more powerful antimicrobial effects than the other two local anaesthetics.

We performed a prospective, randomized study comparing the efficacy and safety of remifentanil, propofol or both for conscious sedation during eye surgery under retrobulbar blockade. Forty-five unpremedicated patients were assigned to receive remifentanil (group R) (n=15, mean dosage: 0.05±0.03 μg kg−1 min−1), propofol (group P) (n=15, 1.5±0.5 mg kg−1 h−1) or a combination (group RP) (n=15, R: 0.03±0.01 μg kg−1 min−1; P: 0.7±0.2 mg kg−1 h−1). Haemodynamic responses were comparable among all groups. Minimum values for respiratory rate were lower in R patients (R: 7 vs. P and RP: 10 breaths min−1). Peri-operative blood gas analysis showed differences in maximum carbon dioxide tensions (R: 51.5 vs. P: 48.3 vs. RP: 45.5 mmHg) and decrease in minimum pH values (R: −0.06 vs. P: −0.0 vs. RP: −0.01). All group P patients reported mild to intense pain during retrobulbar block, while 53% of the group R patients were free from pain. In group RP, 60% of patients experienced no pain and the remaining 40% reported mild pain only. Remifentanil, applied as the sole agent, provided superior pain relief and patient comfort when compared with propofol, but produced greater respiratory depression and postoperative nausea. The combination of remifentanil and propofol provided haemodynamic stability, adequate spontaneous respiration and pain relief, with a low risk of untoward side effects.

Summary

A variety of laboratory and clinical studies clearly indicate that exposure to anaesthetic agents can lead to a pronounced protection of the myocardium against ischaemia–reperfusion injury. Several changes in the protein structure of the myocardium that may mediate this cardioprotection have been identified. Ischaemia–reperfusion of the heart occurs in a variety of clinical situations including transplantations, coronary artery bypass grafting or vascular surgery. Ischaemia may also occur during a stressful anaesthetic induction. Early restoration of arterial blood flow and measures to improve the ischaemic tolerance of the tissue are the main therapeutic options (i.e. cardioplegia and betablockers). There exists increasing evidence that anaesthetic agents interact with the mechanisms of ischaemia–reperfusion injury and protect the myocardium by a ‘preconditioning’ and a ‘postconditioning’ mechanism. Hence, the anaesthesiologist may substantially influence the critical situation of ischaemia–reperfusion during surgery by choosing the appropriate anaesthetic agent. This review summarizes the current understanding of the mechanisms of anaesthetic-induced myocardial protection. In this context, three time windows of anaesthetic-induced cardioprotection are discussed: administration (1) during ischaemia, (2) after ischaemia–during reperfusion (postconditioning) and (3) before ischaemia (preconditioning). Possible clinical implications of these interventions will be reviewed.

Summary

Background and objective: To compare the recently introduced Microcuff® endotracheal tube with conventional tubes in respect of the cuff pressures required to prevent air leakage.

Methods: The following tubes (ID 7.0 mm) were compared: Microcuff® HVLP ICU, Mallinckrodt HiLo®, Portex Profile Soft Seal®, Rüsch Super Safety Clear® and Sheridan CF®. Fifty patients undergoing endotracheal intubation with a cuffed tube of internal diameter 7.0 mm were studied. Tracheas were intubated using one of the endotracheal tubes in random order. Cuff pressure to prevent air leakage at standardized ventilator setting (peak inspiratory pressure 20 cmH2O/PEEP 5 cmH2O/respiratory rate 15 breaths min−1) was assessed by auscultation of audible sounds at the mouth. Patients characteristics and cuff pressures from each brand were compared to the Microcuff® group using the Mann-Whitney U-test (P < 0.05 was chosen as the level of statistical significance).

Results: Patients' median age (range) was 14.2 (12.0–17.1) yr, body weight 57.5 (40.0–81.9) kg and length 164.9 (146.5–190.0) cm. No significant differences in patients' characteristics were found between groups. Mean cuff pressure (all tubes) required for air sealing was 19.1 (8–42) cmH2O. The Microcuff® tube required significantly lower sealing pressures (9.5 (8–12) cmH2O) compared to the other brands of endotracheal tube (P < 0.05, Mann-Whitney U-test).

Conclusion: The Microcuff® endotracheal tube with its ultra-thin polyurethane cuff membrane required the lowest sealing pressure to prevent air leakage. These features are potentially of interest for long-term intubated patients and for cuffed endotracheal tubes in children, allowing tracheal sealing at lower cuff pressures implying less damage to the trachea.

Occipital nerve block is usually considered to be a very simple and safe regional anaesthetic technique. We describe a case of sudden unconsciousness during a lesser occipital nerve block in a patient with an occipital bone defect. A 63-year-old man complained of headache, which was localized to the right occipital region. A right lesser occipital nerve block with a local anaesthetic was performed for treatment. During the lesser occipital nerve block, the patient suddenly became disturbed and lost consciousness. Two hours after the incident, the patient was fully awake without neurological sequelae. He had previously undergone a microvascular decompression for right trigeminal neuralgia. The patient had a bone defect following craniotomy. We believed that the loss of consciousness during lesser nerve block may be due to a subarachnoid injection. Occipital nerve block is relatively contraindicated in the presence of a bone defect.

A 17-nation survey was undertaken with the aim of studying the availability of acute pain services (APS) and the use of newer analgesic techniques, such as epidural and patient-controlled analgesia (PCA). A questionnaire was mailed to selected anaesthesiologists in 105 European hospitals from 17 countries. Depending on the population, between five and ten representative hospitals from each country were selected by a country coordinator. A total of 101 (96.2%) completed questionnaires were returned. A majority of respondents were dissatisfied with pain management on surgical wards. Pain management was better in post-anaesthesia care units (PACUs); however, 27% of participating hospitals did not have PACUs. There were no organized APS in 64% of hospitals, although anaesthesiologists from chronic pain centres were available for consultation. In the hospitals that had APS, the responsible person for the APS was either: (1) a junior anaesthesiologist (senior anaesthesiologist available for consultation); or (2) a specially trained nurse (supervised by consultant anaesthesiologists). Many anaesthesiologists were unable to introduce techniques such as PCA on wards because of the high equipment costs. Although 40% of hospitals used a visual analogue scale (VAS) or other methods for assessment of pain intensity, routine pain assessment and documenting on a vital sign chart was rarely practised. There was a great variation in routines for opioid prescription and documentation procedures. Nursing regulations regarding injection of drugs into epidural and intrathecal catheters also varied considerably between countries. This survey of 105 hospitals from 17 European countries showed that over 50% of anaesthesiologists were dissatisfied with post-operative pain management on surgical wards. Only 34% of hospitals had an organized APS, and very few hospitals used quality assurance measures such as frequent pain assessment and documentation. There is a need to establish organized APS in most hospitals and also a need for clearer definition of the role of anaesthesiologists in such APS.

Summary

Background and objective: This study was designed to evaluate early postoperative cognitive recovery after total intravenous anaesthesia with remifentanil–propofol or sufentanil–propofol in patients undergoing craniotomy for supratentorial expanding lesions. Methods: Sixty patients were consecutively enrolled, and randomly assigned to one of two study groups: remifentanil–propofol or sufentanil–propofol anaesthesia. To evaluate cognitive function the Short Orientation Memory Concentration Test (SOMCT) and Rancho Los Amigos Scale (RLAS) were administered to all patients in a double-blind procedure before surgery at 15, 45 min and 3 h after extubation. Results: Mean extubation time was similar in the two groups (13 ± 5 min vs. 19 ± 6 min). A significantly larger number of patients in the remifentanil–propofol group than in the sufentanil–propofol group required antihypertensive medication postoperatively to maintain mean arterial pressure within 20% of baseline (18/30 vs. 4/29; P = 0.0004). Intergroup analysis showed no differences in baseline SOMCT scores (28 ± 1 vs. 28 ± 1) whereas mean SOMCT scores at 15, 45 min and 3 h after extubation were significantly higher in the remifentanil–propofol group (30 patients) than in the sufentanil–propofol group (29 patients) (22 ± 3 vs. 16 ± 3; P < 0.0001 and 27 ± 1 vs. 22 ± 3; P < 0.0001; 28 ± 1 vs. 26 ± 2; P = 0.0126). Conclusions: In conclusion, propofol–remifentanil and propofol–sufentanil are both suitable for fast-track neuroanaesthesia and provide similar intraoperative haemodynamics, awakening and extubation times. Despite a higher risk of treatable postoperative hypertension propofol–remifentanil allows earlier cognitive recovery.