Adequate relaxation of the masseter muscle is important during endotracheal intubation and for the patency of a patient’s airway during recovery from anaesthesia. We evaluated onset and recovery from cisatracurium-induced neuromuscular block at the masseter and adductor pollicis muscles. Thirty patients were randomly allocated to receive either 0.1 or 0.15 mg kg−1 cisatracurium. The evoked response was measured at both muscles using acceleromyography. Onset time was significantly shorter at the masseter muscle than at the adductor pollicis (0.1 mg kg−1 cisatracurium: 155±52 vs. 229±44 s; 0.15 mg kg−1 cisatracurium: 105±24 vs. 174±35 s). Following 0.1 mg kg−1 cisatracurium, recovery to a TOF-ratio of 0.7 was faster at the masseter compared to the adductor pollicis (P < 0.05). In the 0.15 mg kg−1 cisatracurium group recovery of T1 to 75% of control and to a TOF-ratio of 0.7 occurred sooner at the masseter (P < 0.05). We conclude that onset and recovery from cisatracurium neuromuscular block occurs more rapidly at the masseter than at the adductor pollicis. It appears unlikely that residual paralysis is present at the masseter once neuromuscular function at the adductor pollicis has completely recovered.

Summary

Background and objective: The study compared the analgesic efficacy and safety of two preoperatively administered cyclo-oxygenase-2 inhibitors, celecoxib and rofecoxib.

Methods: Ninety adult patients undergoing thyroid surgery were divided into three groups (each n = 30). They were given a single oral dose of placebo, celecoxib 200 mg or rofecoxib 50 mg 1 h before induction of anaesthesia. All patients received a standard anaesthetic. Intraoperative blood loss was measured. Pain scores, sedation scores, heart rate, mean arterial pressure and respiratory rate were noted at 0, 1, 2, 4, 6, 12 and 24 h postoperatively. Analgesic (meperidine) requirements and adverse effects were recorded during the first postoperative 24 h.

Results: Compared with placebo, pain scores were significantly lower with rofecoxib at all time points (P < 0.05) and were significantly lower with celecoxib (P < 0.05) during the first 4 h. Pain scores were significantly lower with rofecoxib compared with celecoxib at 6, 12 and 24 h (P < 0.05). The average cumulative 24 h meperidine dose was significantly lower with both celecoxib (54.9 ± 34.4 mg) and rofecoxib (42.8 ± 40.9 mg) compared with placebo (76.8 ± 6.2 mg) (P < 0.01 and P < 0.001, respectively). There were no differences in the intraoperative blood loss, heart rate, mean arterial pressure, respiratory rate, sedation scores and incidence of adverse effects among groups.

Conclusions: The preoperative administration of rofecoxib 50 mg and less so of celecoxib 200 mg provide a significant analgesic benefit with regard to postoperative pain relief and decrease in additional opioid requirements after thyroid surgery.

This case report describes the peri-operative management of a 48-year-old woman with three cerebral aneurysms and phaeochromocytoma. The pharmacological and anaesthetic management of such patients is complex, and needs to be managed carefully by titrating anaesthetic agents and vasoactive drugs. The primary concern is the maintenance of cerebral perfusion pressure and autoregulation throughout the procedure, although these states cannot be monitored directly. The patient survived the operation neurologically intact, and it is presumed that the course of management which was chosen helped to achieve this result.

Background and objective: To compare the application of the cuffed oropharyngeal airway and the laryngeal mask airway on anaesthetized adult patients undergoing minor outpatient surgery.

Methods: One hundred patients received intravenous fentanyl, propofol and N2O for the induction and maintenance of anaesthesia. The patients were randomly divided into two groups: a cuffed oropharyngeal airway group (n = 50) and a laryngeal mask airway group (n = 50). After insertion of the device, fibreoptic laryngoscopy was attempted and the degree of success scored. We then compared the first application success rate of both procedures while judging airway intervention requirement, fibreoptic scores, adverse airway events and haemodynamic tolerance.

Results: Both devices had an almost similar first-time placement rate (cuffed oropharyngeal airway 84% versus laryngeal mask airway 96%). The cuffed oropharyngeal airway required a higher number of airway interventions (P < 0.001). The laryngeal mask airway had a significantly better fibreoptic view compared with the cuffed oropharyngeal airway (P < 0.001). However, the number of adverse airway events was lower in the cuffed oropharyngeal airway group; there were no significant differences in adverse events and haemodynamic variables between the said two groups.

Conclusions: The results suggest that the cuffed oropharyngeal airway was an effective alternative airway in spontaneously breathing patients during short procedures.

Summary

Background and objective: Propofol is a phenol derivative (2,6 di-isopropylphenol) with a unique effect profile including activating effects on GABAA and blocking effects on voltage-operated sodium channels. If the substituents in the 2- and the 6-positions are replaced by tert-butyl groups, the resulting phenol derivative, 2,6 di-tert-butylphenol, despite being a close structural propofol analogue, completely lacks GABAA receptor effects. The aim of this in vitro study was to investigate the effects of 2,6 di-tert-butylphenol on voltage-operated neuronal sodium channels in order to determine whether and, if so, how these structural changes alter the sodium channel-blocking effect seen with propofol.

Methods: Whole-cell sodium inward currents through heterologously expressed rat type IIA sodium channels were recorded in the absence and presence of definite concentrations of 2,6 di-tert-butylphenol and propofol.

Results: When applied at concentrations ≥30 μmol, 2,6 di-tert-butylphenol completely and irreversibly blocked sodium inward currents. The blockade equilibrium time was about 2 min. A partial washout was possible only if the application was stopped before the equilibrium of the blockade was achieved.

Conclusions: 2,6 Di-tert-butylphenol exerts a high-affinity block of neuronal sodium channels. Apparently, the slight structural differences of 2,6 di-tert-butylphenol in comparison with propofol – which account for the lack of GABAA receptor effects – enhance its voltage-operated sodium channel-blocking effects. As 2,6 di-tert-butylphenol is much more potent than most sodium channel blockers in clinical use, it might be of interest in the development of local anaesthetics.

Summary

Background and objective: Perioperative hypothermia is generally regarded as undesirable, but its incidence rate in the elective procedures in our hospital and the effect of the preventative measures taken against it were unknown. An initial audit indicated that postoperative hypothermia occurred. Therefore, changes in practice were implemented to address the problem. A further audit was then undertaken to assess the impact of these measures.

Methods: The first audit recorded data from 177 patients undergoing major elective surgical procedures. Variables recorded were: ASA classification, duration of operation, use and description of preventative measures for hypothermia, blood loss, intravenous fluids, and core and peripheral temperatures on arrival and discharge from the recovery room. The subsequent audit included 158 patients undergoing major general, orthopaedic or vascular surgical procedures. Patients had core temperatures measured preoperatively, immediately upon arrival in the recovery room, and just before discharge back to the ward. Core temperatures in both audits were measured using an infrared temperature probe.

Results: The mean body temperature on arrival in the recovery room of patients in the initial audit was 35.5°C (range 32.2–37.2, SD ± 0.74), and in the subsequent audit 36.6°C (33.6–38.2, ±0.72). These differences reached significance (P < 0.0001). This was despite an average duration of surgery of 133.5 (25–330) min in the initial study compared with 154.7 (90–480) min subsequently.

Conclusions: We found that with simple but consistently implemented changes in practice, postoperative hypothermia in elective patients could largely be eradicated.

Background and objective: The common parameters of the electroencephalogram quantify a shift of its power spectrum towards lower frequencies with increasing anaesthetic drug concentrations (e.g. spectral-edge frequency 95). These ad hoc parameters are not optimized for the content of information with regard to drug effect. Using semilinear canonical correlation, different frequency ranges (bins) of the power spectrum can be weighted for sensitivity to changes of drug concentration by multiplying their power with iteratively determined coefficients, yielding a new (canonical univariate) electroencephalographic parameter.

Methods: Electroencephalographic data obtained during application of volatile anaesthetics were used: isoflurane (n = 6), desflurane (7), sevoflurane (7), desflurane during surgical stimulation (12). Volatile anaesthetic end-tidal concentrations varied between 0.5 and 1.6 minimum alveolar concentration (MAC). The canonical univariate parameter and spectral-edge frequency 95 were determined and their correlation with the volatile anaesthetic effect compartment concentration, obtained by simultaneous pharmacokinetic—pharmacodynamic modelling, were compared.

Results: The canonical univariate parameter with individually optimized coefficients, but not with mean coefficients, was superior to the spectral-edge frequency 95 as a measure of anaesthetic drug effect. No significant differences of the coefficients were found between the three volatile anaesthetics or between the data with or without surgical stimulus. The coefficients for volatile anaesthetics were similar to the coefficients for opioids, but different from coefficients for propofol and midazolam.

Conclusions: The canonical univariate parameter calculated with individually optimized coefficients, but not with mean coefficients, correlates more accurately and consistently with the effect site concentrations of volatile anaesthetics than with spectral-edge frequency 95.

Masseter muscle rigidity after suxamethonium, usually occurring in children induced with halothane,is associated with malignant hyperthermia. A case is reported in which masseter muscle rigidity occurred in an adult following vecuronium. From the limited data available, this and two similar reported cases, it appears that non-depolarizing muscle relaxants can, very rarely, cause masseter muscle rigidity in adults. This masseter muscle rigidity may complicate airway management, but is unlikely to progress to generalized rigidity and malignant hyperthermia.

Summary

Background and objectives: Teaching is an important responsibility of non-consultant hospital doctors. In Ireland, specialist registrars (SpRs) in anaesthesia are contractually obliged to teach medical students, other doctors and nurses. Both medical students and fellow non-consultant hospital doctors attribute between 30 and 40% of their knowledge gain to non-consultant hospital doctors.

Methods: We carried out a confidential telephone survey of anaesthetic SpRs in Ireland regarding their current teaching practices and the perceptions of their role as undergraduate teachers. All the SpRs currently working in clinical practice in Ireland were eligible.

Results: Fifty-five of the 79 (70%) SpRs responded to the questionnaire. Only 7 (12.7%) of the respondents said they had been well trained as a teacher. The majority of the respondents stated that they would attend a learning-to-teach course/workshop if one was available, and felt that such a course would improve their ability as a teacher. Only 8 (14.5%) agreed that adequate emphasis is placed on commitment to teaching in the assessment of SpRs, both by individual departments and by the College of Anaesthetists. Anaesthetic SpRs in Ireland spend a considerable amount of time each day teaching undergraduate medical students, the majority (68.9%) stated that they had inadequate time to prepare for teaching.

Conclusion: The majority of the respondents stated that they enjoy teaching, feel that they play an important role in undergraduate teaching but have inadequate time to prepare for teaching. An adequate emphasis is not placed on their commitment to teaching.