Summary

Background and objective: The aim of study was to investigate the electron microscopic changes in the medulla of the spinal cord that occur with intrathecal midazolam administration. Methods: Twenty-eight albino rabbits of New Zealand type were randomized into two groups. Following anaesthesia, 16 rabbits were given 300 μg of midazolam (Group M) and 12 rabbits were given 0.3 mL of normal saline solution (Group C) intrathecally. Eight rabbits from Group M (Group M1) and 6 rabbits from Group C (Group C1) were sacrificed 24 h after the anaesthesia and 8 rabbits from Group M (Group M2) and 6 rabbits from Group C (Group C2) were sacrificed 6 days after the anaesthesia. The lumbosacral portion was removed by laminectomy and thin sections were examined microscopically. Results: Severe separation in myelin lamella of the large axons, honeycomb appearance, slight separation in myelin lamella of small to moderately large axons, degenerate vacuoles in the cytoplasm and nuclear membrane irregularity were observed in neurons of Groups M1 and M2. Myelin lamella and nuclear membranes were found to be regular, vacuoles and oedema were observed in the neurons in the Groups C1 and C2. Conclusion: Midazolam administered at single dose by the intrathecal route may have neurotoxic effects on the neurons and myelinated axons at 24 h and 6 days following administration.

Summary

Background and objective: The ease of endotracheal intubation has been recently shown to affect the incidence of laryngeal injury. There remains controversy as to whether or not a muscle relaxant is routinely required for tracheal intubation. This study examined conditions of intubation in our routine practice, which employs a relaxant-sparing approach. Methods: All adult patients scheduled for surgery with general anaesthesia were prospectively included. A muscle relaxant was used to facilitate intubation when it was required for the surgical procedure and/or otherwise regarded as necessary by the anaesthesiologist. In the remaining patients, a relaxant-free intubation was performed. Intubating conditions were evaluated in all the patients as well as the post-intubation laryngeal symptoms. Results: Between March and July 2003, 612 patients were consecutively included. A muscle relaxant was used in 32% of patients and no relaxant in the remaining patients (68%). Clinically acceptable intubating scores were observed in 98.4% overall with no significant difference between the two groups. Excellent conditions occurred more frequently in the relaxant group as compared to the relaxant-free group, 87% vs. 72%, P = 0.005. Laryngeal symptoms occurred in 184 (33%) patients with no difference between the two groups. Conclusions: Our relaxant-sparing approach did not increase the incidence of poor conditions of intubation nor laryngeal symptoms. However, excellent conditions occurred more frequently in the relaxant group. A more flexible approach to the issue of the need for neuromuscular blockade prior to intubation is proposed.

Summary

Background and objective: Epidural vein cannulation has long been recognized as a problem in parturients due to distension of epidural veins. Epidural vein engorgement is maximal when the pregnant woman is in the supine position and minimal in the lateral position. Following an initial observation of an apparently high incidence of epidural vein cannulation in the sitting position, a randomized trial was conducted to document whether such an association existed.

Methods: A total of 209 term parturients were randomized to either the sitting or lateral position (107 left lateral, 102 sitting). Epidural catheter placement was achieved using a loss of resistance to air technique with an 18-G Tuohy needle. A data sheet was completed for each patient recording patient position, patient characteristics data, stage in labour and the incidence of epidural vein cannulation. Poor labour analgesia was defined as a visual analogue scale (VAS) >40 mm on a 0–100 mm pain intensity VAS.

Results: The risk of epidural vein cannulation was significantly higher in the sitting group (16 of 102 = 15.7%) compared with the lateral position group (4 of 107 = 3.7%), P = 0.011. There was a significant association between epidural vein cannulation and poor analgesia (P = 0.006). These two variables remained independently significant on multiple regression analysis (position, P = 0.009; analgesia, P = 0.006).

Conclusions: We conclude that there is a direct correlation between the incidence of epidural vein cannulation and patient posture during epidural catheter insertion in parturients.

Summary

Objective: To assess the ability of medical students to learn and retain skills of airway manipulation for insertion of the endotracheal tube, the laryngeal mask airway (Laryngeal Mask Company, Henley-on-Thames, UK) and the oesophageal–tracheal Combitube® (Kendall-Sheridan Catheter Corp., Argyle, NY, USA).

Methods: A 6-month prospective study was conducted among fifth-year medical students attending a 3-week clerkship in the Division of Anesthesiology and Critical Care Medicine in the Soroka Medical Center. All the students viewed a demonstration of insertion technique for the endotracheal tube, the laryngeal mask airway and the Combitube®, followed by formal teaching in a mannikin. At the end of the program, the insertion skills were demonstrated in the mannikin, the success rate on the first attempt was registered and the students were requested to assess (by questionnaire) their ability to execute airway manipulation (phase 1). Six months later, the students were requested to repeat the insertion technique, and a similar re-evaluation applied (phase 2).

Results: The success rate, during the first phase, at first attempts was 100% for the laryngeal mask airway and the Combitube®, compared to 57.4% for the endotracheal tube (P < 0.02), and 92.6%, 96.2% and 62.9% (P < 0.02) respectively for the second phase of the study.

Conclusion: Learning and retention skills of medical students, in a mannikin, are more accentuated with the laryngeal mask airway and the Combitube® than seen with an endotracheal tube.

Summary

Background and objective: Hydroxyethyl starch is frequently used for volume substitution during surgical procedures and for isovolaemic haemodilution. Haemodilution has also been shown to improve tissue oxygen tension in skeletal muscle. However, effects of this volume substitute on tissue oxygen tension of the liver during haemodilution remains unknown.

Methods: Fourteen foxhounds were anaesthetized with fentanyl/midazolam and mechanically ventilated with 30% oxygen. Following splenectomy animals were randomly assigned to a control group without haemodilution but fluid substitution with Ringer's lactate (Group C) or underwent isovolaemic haemodilution to a haematocrit of 25% with hydroxyethyl starch 70/0.5 (Group H). Haemodynamic parameters and oxygen transport during 100 min following isovolaemic haemodilution were measured. Liver oxygen tension was recorded using a flexible polarographic electrode tonometer, whereas in the muscle a polarographic needle probe was used.

Results: Animal characteristics and baseline haematocrit were similar in both groups. At baseline the tissue oxygen tension of liver and skeletal muscle were not different between groups. Haemodilution with hydroxyethyl starch 70/0.5 provided augmentation of mean liver tissue oxygen tension (baseline: 46 ± 13 mmHg; 20 min: 60.3 ± 12 mmHg*; 60 min: 60 ± 16 mmHg*; 100 min: 63 ± 16 mmHg*; *P < 0.05 vs. baseline), while oxygen tensions in Group C remained unchanged (baseline: 48 ± 16 mmHg; 20 min: 52 ± 19 mmHg; 60 min: 49 ± 12 mmHg; 100 min: 52 ± 16 mmHg) and no differences could be detected between groups. Oxygen tension in skeletal muscle changed as follows: Group H – baseline: 24 ± 32 mmHg; 20 min: 32 ± 3 mmHg*[dagger]; 60 min: 33 ± 7 mmHg*[dagger]; 100 min: 33 ± 11 mmHg[dagger]. Group C – baseline: 22 ± 6 mmHg; 20 min: 21 ± 3 mmHg; 60 min: 24 ± 4 mmHg; 100 min: 18 ± 4 mmHg (*P < 0.05 vs. baseline, [dagger]P < 0.05 vs. Group C).

Conclusion: In this animal model, isovolaemic haemodilution with hydroxyethyl starch 70/0.5 increased tissue oxygen tension in liver and skeletal muscle in comparison with baseline values. However, when compared between groups haemodilution only resulted in an increase of tissue oxygen tension in the muscle but not in the liver.

Summary

Background and objective: Cisatracurium is an intermediate acting, non-depolarizing neuromuscular blocking agent. Previous reports have indicated a growth-inhibitory effect of the isoforms cisatracurium and atracurium on two human cell lines in vitro. These effects were ascribed to oxidative stress elicited by acrylate esters formed during cisatracurium breakdown. Oxidative stress is a potent precipitator of apoptosis. Therefore, the aim of the present study was to investigate whether the growth-inhibitory effects of cisatracurium could be explained by initiation of apoptosis.

Methods: Human umbilical vein endothelial cells were incubated with cisatracurium at concentrations of 0.96, 3.2, 9.6, 32 and 96 μmol for 24 h. DNA fragmentation was measured using the Cell Death Detection ELISA Plus assay (Roche Diagnostics, Mannheim, Germany).

Results: There was a dose dependency of cisatracurium with respect to the rate of apoptosis in human umbilical vein endothelial cells. Programmed cell death could be demonstrated at concentrations encountered in human plasma after single-bolus injections of cisatracurium. Apoptosis was attenuated by the concomitant administration of glutathione.

Conclusions: These findings strongly support the hypothesis that acrylate esters, breakdown products of cisatracurium, induce oxidative stress and, subsequently, apoptosis.

Summary

Background and objective: To evaluate orotracheal intubation conditions after 1 min.

Patients and methods: A prospective randomized study with 376 adult American Society of Anesthesiologists (ASA) Grade I–III patients. Each patient received propofol, fentanyl and either suxamethonium (1 mg kg−1) or rocuronium. The intubating dose of rocuronium (2 × ED95) was preceded 4 min earlier by saline, or a 0.1 × ED95 priming dose of rocuronium, atracurium, cis-atracurium, vecuronium or mivacurium. Intubating conditions were graded as excellent, good or poor with respect to laryngoscopy, vocal cord position and movement and reaction to intubation and/or cuff inflation.

Results: There were significant differences (P < 0.05) in laryngoscopy between suxamethonium and rocuronium primed with saline, atracurium or cis-atracurium. With respect to vocal cord position and movement during intubation, rocuronium without priming differed significantly from all other groups and for reaction to insertion of tracheal tube and/or cuff inflation. Rocuronium without priming differed significantly from all other groups except for rocuronium primed with itself. The mivacurium group showed more signs of pre-curarization than other groups (P < 0.05). There were significant differences between rocuronium alone and the other groups when final intubating conditions were compared.

Conclusions: Priming rocuronium with 0.1 × ED95 of vecuronium, rocuronium, atracurium or cis-atracurium is a safe technique and did not increase risk of pre-curarization in healthy patients.

Summary

Background and objective: Staff attitude plays a pivotal role in quality management. The objective of the present study was to further define how interdisciplinary emergency hospital staff experience their daily work and the extent to which the professional speciality and training of an individual influences his/her assessment of multiple-trauma team performance. Methods: The clinical staff involved in multiple-trauma emergency management of a university hospital was asked to answer a confidential questionnaire. Factorial analysis was used to identify 8 major dimensions from a total of 53 items. Results: The questionnaire was returned by 128 team members. All professional groups were most dissatisfied with the dimensions ‘education and training’, ‘work sequence between specialities’ and ‘communication between specialities’. Assessment of the quality of in-hospital emergency-trauma management differed significantly between professional specialities (ANOVA, F = 5.2; P = 0.028); surgeons gave the highest ratings for all but one dimension. Having taken an Advanced Trauma Life Support (ATLS®) course influenced significantly the total rating of multiple-trauma treatments of anaesthetists and surgeons (F = 5.5; P = 0.024). Conclusions: The perceptions of interdisciplinary trauma team members without the completion of an ATLS® training course were that they did not communicate enough with each other and that there were differences between their expectations and reality. The differences and the communication deficits were overcome in team members who had passed an ATLS® course.

Summary

Background and objective: We studied the effect of different recumbent positions (supine, left and right lateral decubitus), on arterial oxygenation in 42 valvular heart disease patients planned for cardiac surgery. All patients had cardiomegaly (cardiothoracic ratio ≥0.5) in their chest X-rays. Their left ventricular end-diastolic diameter was also noted from the preoperative echocardiogram. Methods: Arterial blood gas analysis was performed in supine, left and right lateral positions after keeping the patient in a given position for 15 min. During this period all patients received 35% oxygen supplementation. Results: Arterial oxygen tension and haemoglobin saturation were significantly higher in the right lateral position (PaO2 = 120.6 ± 29.5 mmHg, SaO2 = 98.1 ± 1.4%) than in supine (PaO2 = 111.0 ± 30.6 mmHg, SaO2 = 97.6 ± 2.2%) and left lateral positions (PaO2 = 109.7 ± 32.0 mmHg, SaO2 = 97.6 ± 1.7%; mean ± SD; P < 0.01). There was no significant difference in arterial oxygenation between left lateral and supine positions (P > 0.05). The change in PaO2 and SaO2 with change of posture from left to right was significantly related to left ventricular end-diastolic diameter (r = 0.50 and r = 0.63, respectively; Pearson correlation). Repeated measures of analysis of variance with left ventricular end-diastolic diameter as a covariate showed a significant change in arterial PaO2 with posture (P = 0.011). Conclusion: Right lateral posture improves arterial oxygenation in the valvular heart disease patient with an enlarged left ventricle. In the preoperative period, these patients may benefit from a right lateral posture when lying in bed.

Summary

Background: Ketamine has been claimed to prevent acute opioid tolerance and hyperalgesia following acute exposure to opioids and its use has been proposed to decrease postoperative morphine consumption.

Methods: We conducted a randomized, double-blind, controlled study to evaluate the effect of intravenous (i.v.) ketamine on postoperative pain for 48 h after major ear, nose and throat (ENT) surgery. Thirty-one patients received i.v. ketamine 0.15 mg kg−1 before induction and 2 μg kg−1 min−1 during anaesthesia, and 31 patients were administered placebo in a similar manner. Anaesthesia was standardized with remifentanil and propofol, but without nitrous oxide. Standardized postoperative analgesia included paracetamol, methylprednisolone and morphine administered via a patient controlled analgesia (PCA) device.

Results: Intra-operative remifentanil consumption was not different between the ketamine group (0.25 ± 0.07 μg kg−1 min−1) and the control group (0.22 ± 0.07 μg kg−1 min−1). In the postoperative period, both groups experienced an identical pain course evolution. Cumulative morphine consumption was not significantly different between groups: at 24 h it was 33.3 ± 14.9 with ketamine and 31.9 ± 15.3 mg in controls, at 48 h it was 40.4 ± 20.6 mg with ketamine and 42.5 ± 25.9 mg in controls.

Conclusion: Low-dose ketamine added to a remifentanil-based propofol anaesthesia did not reduce morphine consumption after major ENT surgery.

Summary

Background and objective: Patients undergoing total abdominal hysterectomy under general anaesthesia have a high risk of developing postoperative nausea and vomiting (PONV). The aim of this study was to evaluate the incidence of PONV in patients undergoing total abdominal hysterectomy under spinal anaesthesia with intravenous patient-controlled analgesia (PCA) using morphine and to compare its incidence with and without antiemetic prophylaxis. Methods: Thirty-four patients undergoing total abdominal hysterectomy under spinal anaesthesia with i.v. PCA morphine postoperatively were divided into two groups. The first (n = 17) received ondansetron prophylaxis near the end of surgery while the second (n = 17) received no prophylaxis. Morphine consumption, emetic episodes (on a 3-point scale), patient satisfaction (visual analogue score), sedation and pruritus were evaluated 2, 4, 6, 9, 12, 18 and 24 h postoperatively. Results: Patient characteristics, postoperative morphine consumption (43.3 ± 7.6 vs. 40.3 ± 12.3 mg) and peristaltic recovery time (16.9 ± 5 vs. 18.4 ± 5.2 h) were similar in both groups. Overall nausea and vomiting were significantly lower in the ondansetron prophylaxis group than in the group without prophylaxis (52.9% vs. 88.2%, P < 0.05). Though nausea alone was higher in the prophylaxis group (41.2% vs. 29.4%), nausea with vomiting was significantly lower in the prophylaxis group (11.8% vs. 58.8%, P < 0.01). Patients' satisfaction scores were higher in the ondansetron group at all times and the difference was significant (P < 0.05) 4 h postoperatively. Conclusions: The incidence of PONV in patients undergoing total abdominal hysterectomy under spinal anaesthesia with i.v. PCA morphine is very high (88.2%). Antiemetic prophylaxis with ondansetron is highly recommended in this patients group resulting in a lower incidence of nausea and vomiting, and significantly improves patient' satisfaction and life quality in the early postoperative period.

Summary

Background and objective: To test the hypothesis that gabexate mesilate, a protease inihibitor, hastens recovery from neuromuscular blockade, we examined the effect of gabexate mesilate on the recovery of vecuronium-induced neuromuscular blockade in anaesthetized patients in a double-blind, randomized fashion.

Methods: Thirty adult patients were divided into two groups of 15. In the gabexate mesilate group, immediately after administration of vecuronium 0.1 mg kg−1, a continuous infusion of gabexate mesilate was started at a speed of 1.5 mg kg−1 h−1. In the control group, normal saline was administered instead of gabexate mesilate. Times to the return of T1, T2, T3 or T4 (first, second, third and fourth response of train-of-four (TOF)), times to the recovery of T1/control to 0.25 (T25) or 0.5 (T50), recovery of T1/control or TOF ratio (T4/T1) were compared between the two groups.

Results: Times to the returns of T1, T2, T3 and T4 in the gabexate mesilate group were significantly shorter than in the control group (19.4 ± 6.8 vs. 25.7 ± 7.2 min for T1; mean ± SD, P = 0.020). Times to T25 and T50 were significantly shorter in the gabexate mesilate group than in the control group (34.0 ± 9.9 vs. 51.3 ± 10.2 min for T25, P < 0.001). T1/control and TOF ratio in the gabexate mesilate group were significantly higher than in the control group 40–80 min and 40–120 min after administration of vecuronium, respectively (P < 0.05).

Conclusion: Gabexate mesilate hastens recovery from neuromuscular block in anaesthetized patients receiving vecuronium.

Summary

Background and objective: The timing of interscalene block in relation to general anaesthesia remains a controversial subject. We believe that the results of our study demonstrate that this block may be performed safely on anaesthetized patients, providing that certain conditions are met.

Methods: Five hundred and forty-eight cases of arthroscopic shoulder surgery were analysed retrospectively in order to identify the results of interscalene block performed after induction of general anaesthesia, but before the start of surgery. Patients were kept in hospital for 24 h and assessed before being discharged from the hospital and again in the period from 4 to 8 weeks after surgery. Duration of the block, quality of postoperative pain relief and neurological complications were recorded.

Results: Our study failed to reveal any permanent or long-term neurological complications attributable to interscalene block performed after induction of general anaesthesia.

Conclusion: It is our opinion that the primary factor for safe interscalene block is modification of the anaesthetic technique rather than the timing of regional block in relation to induction of general anaesthesia.

Summary

Background and objectives: Increasing numbers of patients taking herbal medicine products are presenting for anaesthesia and surgery. Anaesthetists need to consider the perioperative implications of herbal medicines and should, therefore, have some knowledge of this subject. Methods: A postal questionnaire survey was sent to a random 5% of practising members of the Association of Anaesthetists of Great Britain and Ireland residing in the UK, to identify attitudes, practice and knowledge regarding herbal medicines. Results: From 341 questionnaires there were 221 replies, a 65% response rate. Ninety per cent stated that they seldom or never asked patients about herbal medicine usage, yet 65% felt that there could be potentially harmful effects of herbal medicines in the perioperative period. There was a very poor level of knowledge with respect to the current management of 10 well-known herbal medicines. However, 75% agreed that information about perioperative usage of herbal medicines is important, and 77% felt that herbal medicines should be in the undergraduate medical curriculum. Reading was the usual source of herbal medicine product information. Most (82%) felt their knowledge of herbal medicine products and the implications in patient care were inadequate. Conclusions: This sample of anaesthetists require education on herbal medicines. Suggestions for remedial action are given.

Summary

Objective: This retrospective study aims to describe the airway management and benefits of nasotracheal intubation over tracheostomy in 260 patients with oral cancer undergoing surgery. Methods and Results: The medical records of 260 patients undergoing surgery for oral cancer were reviewed for airway management during the perioperative period. Eighteen patients had previous surgery for oral cancer and were scheduled for flap reconstruction, recurrence or other complications. In 28 cases neck movement was restricted and decreased mouth opening was found in 50% of all patients because of a large growth or fixation of tissues of head and neck, oral cavity, pharynx or larynx by tumour, or radiation fibrosis. In 53 patients intubation was undertaken under spontaneous ventilation. In 20 cases the trachea was extubated in the immediate postoperative period. In 220 cases patients were extubated next morning in the intensive care unit. In none of the cases was elective tracheostomy under local anaesthesia performed before surgery for the maintenance of the airway for anaesthesia. Elective tracheostomies were done in 17 cases. Three patients remained intubated for 24–48 h because of a high suspicion of airway obstruction following extubation due to a large pectoralis major flap. These three patients received a tracheostomy because of increased oropharyngeal and laryngeal oedema. In three cases emergency tracheostomies were performed due to upper airway obstruction after extubation and in one case prolonged elective ventilation was required due to severe chest infection. Conclusion: Oral cancer patients have a potentially difficult airway but, if managed properly during perioperative period, morbidity and mortality can be reduced or avoided. Oral cancer patients can be managed safely without the routine use of a tracheostomy. Nasotracheal intubation is a safe alternative to tracheostomy in oral cancer patients except in some selected patients.

Summary

Background and objective: Prospective longitudinal studies now indicate that cognitive dysfunction following coronary artery bypass surgery (CABG) is both common and persistent. This dysfunction is due in part to the inflammatory response and cerebral ischaemia–reperfusion, with nitric oxide (NO) as an important mediator of both. We hypothesized that a clinically significant association exists between plasma concentrations of nitrate/nitrite (NO3−/NO2−) and cognitive dysfunction after CABG.

Methods: Cognitive assessment was performed on 36 adult patients the day before CABG, on the fourth postoperative day and 3 months postoperatively. Patient spouses (n = 10) were also studied.

Results: A new cognitive deficit was present in 22/36 (62%) 4 days postoperatively and in 16/35 (49%) of patients, 3 months postoperatively. Patients who had cognitive dysfunction 3 months postoperatively were more likely to have cognitive dysfunction and increased plasma NO3−/NO2− concentrations compared to the non-deficit group preoperatively (22.6 (9.2) vs. 27.6 (8.4)) (P = 0.002). Plasma NOx (NO3− plus NO2−) concentrations were greater in patients with cognitive dysfunction 3 months postoperatively, 2 h (24.2 (6.3) vs. 19.1 (5.2)) (P = 0.002), and 12 h postoperatively (24.8 (7.6) vs. 18.8 (5.6)) (P = 0.001). There was, however, a time course similarity in NOx elevations for both deficit and non-deficit groups.

Conclusions: Perioperative plasma NOx concentrations do not serve as an effective biomarker of cognitive deficit after CABG.

Summary

Background and objective: Since the introduction of the laryngeal mask into clinical practice, various additional supraglottic ventilatory devices have been developed. Although it has been demonstrated that the laryngeal tube is an effective airway device during positive pressure ventilation no clinical study has been performed thus far regarding its use in patients with predicted ventilation and intubation difficulties. Methods: The aim of this study was to prospectively evaluate the use of the laryngeal tube for temporary oxygenation and ventilation in adult patients with supraglottic airway tumours scheduled to undergo a pharyngeal–laryngeal oesophagoscopy and bronchoscopy under general anaesthesia. In addition to our standard airway management with face mask ventilation and rigid bronchoscopy, all patients were temporarily ventilated with an laryngeal tube. Also, in patients requiring laryngeal biopsies, endotracheal intubation was performed with a 6.0 mm microlaryngeal tracheal tube. Minute ventilation volumes, tidal volumes, ventilation pressures, end-expiratory CO2 concentration, oxygen saturation and arterial blood gas samples were measured. Results: From 54 enrolled patients only patients with relevant tumour masses were evaluated (n = 23). Mask ventilation was performed without difficulty in 15 of 23 patients. Mechanical ventilation with the laryngeal tube was possible in 22 of 23 patients with an audible leak present in three. Conventional endotracheal intubation was successfully performed in 19 of 23 patients. During face mask ventilation, minute volume, tidal volume, ventilation pressure, end-tidal CO2, oxygen saturation and arterial PO2 were significantly lower and PCO2 significantly higher (P < 0.05, paired t-test). No statistically significant differences were noted between the laryngeal tube and the microlaryngeal tracheal tube. Conclusions: The possibility of difficult ventilation and intubation must always be considered in patients with supraglottic airway tumours. In these cases, the laryngeal tube can be considered for routine airway management and may be useful in the ‘cannot-intubate’ situation although difficulties should be anticipated in patients with previous irradiation, specifically of the throat area.

Summary

Background and objective: The aim of this prospective, randomized, double-blind study was to determine the effects of adding nitrous oxide on sevoflurane requirement for blunting sympathetic responses after surgical incision combined with two different target-controlled concentrations of remifentanil (1 and 3 ng mL−1) in female.

Methods: 102 female patients, aged 20–50 yr, ASA I, undergoing general anaesthesia for elective abdominal surgery were enrolled and randomly allocated to receive sevoflurane anaesthesia alone (Group A, n = 53), or with the addition of 60% nitrous oxide (Group N, n = 49). Patients of both groups were further assigned to receive a target-controlled remifentanil infusion with an effect-site concentration of either 1 ng mL−1 (Group N1, n = 27; Group A1, n = 30), or 3 ng mL−1 (Group N3, n = 22; Group A3, n = 23). Sympathetic responses to surgical incision were determined after a 20-min period of stable end-tidal sevoflurane and target-controlled remifentanil concentrations. Predetermined end-tidal sevoflurane concentrations and minimum alveolar concentration (MAC) for each group were determined using an up-and-down sequential allocation technique.

Results: The MAC of sevoflurane was 3.96% (95% confidence interval, CI95: 3.69–4.23%) in Group A1 and 1.2% (CI95: 0.9–1.3%) in Group N1 (P < 0.01), while in Groups A3 and N3 the MAC of sevoflurane was 0.36% (CI95: 0.24–0.47%) and 0.18% (CI95: 0.1–0.3%), respectively (P < 0.05).

Conclusion: Adding 60% nitrous oxide reduces the MAC of sevoflurane by 70% when using a remifentanil concentration of 1 ng mL−1 and 50% when using a remifentanil concentration of 3 ng mL−1.

Summary

Background and objective: In our algorithm for management of the anticipated difficult airway the induction agent (etomidate) is administered after the tip of the fibreoptic is placed in the trachea but before the tube is advanced over it. In a previous investigation we demonstrated the safety of this method. Due to its popularity as an induction agent, some would like to replace etomidate with propofol. However, because rapid recovery of spontaneous breathing is crucial with this technique, substitution might not be advisable. We compared the speed of recovery of spontaneous breathing after fibreoptic intubation between etomidate and propofol. Methods: In this prospective, randomized, double-blind study we used either 0.2 mg kg−1 etomidate or 2 mg kg−1 propofol for induction. Our technique of nasotracheal fibreoptic intubation consists of using fentanyl, cocaine instillation into the lower nasal canals, cricothyroid injection of lidocaine, performing bronchoscopy, administration of etomidate and advancing the tube after loss of consciousness. We measured time to loss of consciousness, time to recovery of spontaneous breathing, lowest bispectral index value and time to lowest value. Results: Time to loss of consciousness did not differ. The time to recovery of spontaneous breathing differed significantly: the median time (interquartile range [range]) for etomidate was 81 s (62–102 [0–166]), and for propofol 146 s (95–260 [65–315]); P = 0.001. The lowest bispectral index values were not different. The time of the lowest bispectral index values differed significantly: for etomidate 58 s (51–68 [38–100]), and for propofol 90 s (52–125 [38–172]); P = 0.015. Conclusion: For nasotracheal fibreoptic intubation, where the tube is advanced after induction of anaesthesia, we still recommend etomidate because spontaneous breathing recovers faster than with propofol.

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.