Summary

Background and objective: Levobupivacaine 0.5% and racemic bupivacaine 0.5% are equally effective in spinal anaesthesia. Fentanyl has been used as an adjunct to racemic bupivacaine in spinal anaesthesia. At the time this study was designed, there was no published study on the intrathecal use of 0.5% levobupivacaine with fentanyl. Methods: This prospective, randomized, double-blind study compared the clinical efficacy, motor block and haemodynamic effects of using 2.6 mL of 0.5% levobupivacaine alone (25 patients) and 2.3 mL of 0.5% levobupivacaine with fentanyl 15 μg in 0.3 mL (25 patients) for spinal anaesthesia in urological surgery. The study solution was injected into the subarachnoid space at the L3–L4 interspace. Results: There were no significant differences between the two groups in the haemodynamic changes, and quality of sensory and motor block. Anaesthesia was adequate and patient satisfaction was good in all cases. Side-effects were minor and infrequent with both regimes. Conclusions: We conclude that 2.3 mL of 0.5% levobupivacaine with fentanyl 15 μg is as effective as 2.6 mL of 0.5% levobupivacaine alone in spinal anaesthesia for urological surgery. Further studies may be directed to find the optimal combination of levobupivacaine and opioid with maximal haemodynamic stability and least motor block.

Summary

Background and objective: Patients having spinal anaesthesia with hyperbaric bupivacaine may become sensitive to sedative drugs but no data exists about any dose-related effect of the local anaesthetic on the sedative requirement. We aimed to investigate whether hyperbaric bupivacaine dose in spinal anaesthesia has any effect on midazolam requirements. Methods: Sixty unpremedicated patients were allocated to three equal groups. Patients in Groups I and II received hyperbaric bupivacaine 0.5% 10 and 17.5 mg respectively for spinal anaesthesia and Group III was a control group without spinal anaesthesia. In Groups I and II, after the evaluation of sensory block, patients received intravenous midazolam 1 mg per 30 s until the Ramsay sedation score reached 3 (drowsy but responsive to command). In Group III, general anaesthesia was induced after sedation score had reached 3 using midazolam. The total dose of midazolam (mg kg−1) given to each patient, the level of sensory block and complications were recorded. Results: The level of sensory block was higher in Group II (T7) than Group I (T9) (P < 0.01). The doses of midazolam were 0.063 mg kg−1 in Group I, 0.065 mg kg−1 in Group II and 0.101 mg kg−1 in Group III (P < 0.001). There was no correlation between level of sensory block and dose of midazolam in Group I (r = −0.293, P = 0.21) and Group II (r = 0.204, P = 0.39). Conclusions: Different doses of hyperbaric bupivacaine for spinal anaesthesia do not affect the midazolam requirements for sedation. However, spinal anaesthesia with hyperbaric bupivacaine with a maximum spread in the middle thoracic dermatomes may be associated with sedative effects and thus a reduced need for further sedation with midazolam.

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: Stellate ganglion block has been extensively used in clinical practice for the management of painful conditions such as cephalic, facial and upper limb pains yet its mechanism of action and its analgesic efficacy are poorly understood. Method: Formalin (3% 0.2 mL) was injected into the plantar region of the right upper limb paw in rabbits and 50 min after this injection, saline or bupivacaine 2.5% 0.5 mL was administered via a chronic implantation catheter near the right stellate ganglion. Behavioural modification, changes in heart rate and plasma norepinephrine release at different time points after formalin and bupivacaine or saline injection were observed. Finally, the cervical spinal cord was harvested and immunostaining for substance P and c-Fos was performed. Results: Formalin caused stress noxious behavioural changes and a significant increase in heart rate and norepinephrine release. These changes were inhibited by bupivacaine stellate ganglion block but not by saline injection. Immunoreactants of substance P were significantly decreased by formalin injection compared with that in controls. However, with bupivacaine injection, substance P levels were restored though not reaching the levels seen in the controls. Formalin injection also caused a significant increase of c-Fos expression in cervical spinal cord. This increase was not affected by stellate ganglion block. Conclusion: Stellate ganglion block can effectively alleviate nociceptive responses induced by formalin injection. The mechanism of its action may involve reduction of substance P in the spinal cord and plasma catecholamine release caused by noxious stimuli.

Summary

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

Summary

Background and objective: Surgical treatment of patients presenting with subarachnoid haemorrhage secondary to a leaking cerebrovascular aneurysm involves coiling or clipping. Traditionally all patients undergoing this procedure are cross-matched routinely. With ever-increasing strains on the health budget and transfusion services in particular, as well as the real, albeit low risk of transfusion transmitted disease, we propose that a simple ‘group and save’, coupled with a reliable ‘fast-issue’ blood transfusion service should replace this outdated concept. Method: To assess this assumption, we carried out a retrospective analysis of 103 patients who underwent clipping or coiling during January to December 2001 in our Neurosurgical Unit. Results: All patients but one had been cross-matched (99%). However, only 33 patients (32%) eventually required a blood transfusion. In real terms, this meant a total of 294 units of blood that had been cross-matched routinely, in our series of 103 patients, were not used. Had these patients only been ‘group and saved’ and a system of ‘fast-issue’ been adopted, assuming that none of the patients had abnormal antibodies, the blood transfusion department would have made a saving of £4815.72 for this group of patients. Conclusion: We conclude that advances in surgical technique have made routine cross-matching of blood in cerebral aneurysm surgery unnecessary.

Summary

Background and aim: The neuromuscular effects of a bolus dose of rocuronium 0.6 mg kg−1 under propofol anaesthesia in renal failure patients are prolonged compared to healthy patients. The present study aims to describe the neuromuscular effects of 0.3 mg kg−1 rocuronium under propofol anaesthesia in patients with renal failure and to compare these effects with healthy control patients. Methods: With institutional approval and informed consent, 18 healthy patients and 18 patients with renal failure took part in this prospective open label study. The renal failure patients were undergoing either renal transplantation or insertion of a shunt. Rocuronium 0.3 mg kg−1 was given intravenously after induction of anaesthesia with propofol 1–2 mg kg−1 and fentanyl 2 μg kg−1. Propofol 6–12 mg kg−1 h−1 was used for maintenance of anaesthesia. Four acceleromyographic responses of the thumb after supramaximal stimulation of the ulnar nerve using surface electrodes at 2 Hz every 15 s were measured and recorded. The onset time, the time to recovery of the first twitch to 25% recovery and the time to a train-of-four ratio of 0.7 were all recorded. Wilcoxon rank sum testing was used to compare the pharmacodynamics and to see if medication, gender or electrolytes influenced the duration of the block. P < 0.05 was significant. Results: No statistical differences were seen in the neuromuscular blocking effects of rocuronium between the two groups but there was a significant difference (P < 0.00001) in the variability of the total duration of the block. Conclusions: Rocuronium 0.3 mg kg−1 is suitable for use in patients with renal failure when endotracheal intubation and neuromuscular block for a short period of time are needed. Tracheal intubation is facilitated within 4 min and the block can be antagonized within 20 min.

Summary

Background and objective: Emergency research (e.g. into cardiac arrest or head injury) needs to start immediately, often before the patient, or relative, can give consent. A recent European Directive will prevent or severely limit emergency research. Little is known about the public view of emergency research. Methods: Patients attending the outpatient department of a university teaching hospital were invited to complete a self-administered questionnaire. Research Ethics Committee approval was obtained and participants gave written informed consent. Results: Three hundred and five of 362 respondents (84%) thought emergency research should start in the absence of consent but should be obtained as soon as possible from the nearest relative (82%) or the patient (90%). If consent was refused 62% felt the data could still be used, as did 81% if the patient died. Despite 62% approving of public meetings to publicize emergency research only 35% would attend one. A previously recommended list of preconditions was endorsed: no other consentable group (47%); advance consent impossible (55%); unable to delay treatment (73%); consent to be obtained as soon as possible (88%); an adequately designed protocol (74%); Ethics Committee approval (71%); patient may benefit (85%); future patients may benefit (92%) and that the treatment was necessary and could not be delayed (91%). Conclusions: Emergency research must occur to improve the outcome from life-threatening illness or injury. The majority of people are aware of the importance of this research and that the normal rules of consent are not applicable. Alternative methods of recruitment need to be investigated.

Summary

Background and objectives: A recent survey in the British Medical Journal reported the attitudes of orthopaedic surgeons towards the intraoperative death of a patient. Several replies to this article were from anaesthetists, who pointed out that other staff might be affected by ‘death on the table’. We designed a questionnaire survey to assess the attitudes of anaesthetists, concerning intraoperative death. Methods: Three hundred anonymized questionnaires were distributed to 12 anaesthetic departments throughout England. Results: Two hundred and fifty-one replies were received (84% response rate); 92% of respondents had experienced an intraoperative death, the majority of deaths being expected (60%) and non-preventable (77%), occurring mainly during emergency surgery (80%), particularly involving vascular surgery (41% of cases); 87% had administered another general anaesthetic in the following 24 h, most without their professional ability being compromised (77%). Conclusions: This survey shows that anaesthetists are highly likely to experience intraoperative death, the consequences of which can be extremely stressful. Although the majority of anaesthetists (71%) agreed that it was reasonable for medical staff not to take part in operations for 24 h after an intraoperative death, fewer (25%) thought the proposal practicable. Nevertheless, all departments should provide for the discontinuation of further operations, if the circumstances require it. Consideration should be given by all departments of anaesthesia towards the prevention of intraoperative death, and the management of its aftermath, including the provision of support for psychologically traumatized staff.

Summary

Background and objective: An anti-inflammatory effect of α2-adrenoreceptor agonists has been suggested. Phospholipase A2 is a key enzyme in the production of precursors of inflammatory lipid mediators. The aim of the present study was to investigate the effect of clonidine on phospholipase A2 activity in an established in vitro model. Methods: Human being platelet membranes containing active phospholipase A2 were exposed to buffer control or to three increasing concentrations of clonidine. Phospholipase A2 was measured by a radioisotope technique. Results: A massive increase in phospholipase A2 activity was measured after clonidine exposure leading to final values of 92.5 ± 3.1 pmol mg protein−1 min−1 (4.5-fold higher than control values; P ≤ 0.01 vs. control). After clonidine exposure the maximal reaction velocity increased, while the Michaelis–Menten constant did not change. The Lineweaver–Burk representation suggested an interaction of clonidine with the phospholipase A2–substrate complex as well as the phospholipase A2 molecule. Conclusion: We conclude that the putative anti-inflammatory effect of clonidine was not caused by inhibition of phospholipase A2.

Summary

Background and objective: The tunnelling phase of ventriculoperitoneal shunt insertion is the most painful part but patients are often given inadequate opioid analgesic for fear of post operative delayed recovery and/or respiratory depression. This may result in an increase in intracranial pressure. Methods: Twenty adults scheduled to undergo ventriculoperitoneal shunt insertion were administered standard anaesthesia. Monitoring included heart rate, electrocardiogram, end-tidal carbon dioxide, invasive blood pressure, and oxygen saturation. Intracranial pressure was monitored by placing the ventricular end of shunt catheter in the dilated lateral ventricle. Five minutes before tunnelling, fentanyl 1 μg kg−1 was administered. Mean arterial pressure, heart rate and intracranial pressure were recorded during tunnelling and subsequently at 1-min interval for 5 min. Data were analysed using t-test and repeated measured test. Results: Tunnelling caused significant increase in mean arterial pressure (from 81.4 ± 11.0 to 110.9 ± 15.3 mmHg, P < 0.05), intracranial pressure (from 21.4 ± 8.1 to 29.2 ± 12.5 mmHg, P < 0.05) and heart rate (from 74.4 ± 13.8 to 94.1 ± 17.8 beats min−1, P < 0.05). Whereas, the increase in haemodynamic parameters persisted for 3 min post-tunnelling, elevated intracranial pressure lasted for 2 min. Conclusion: Tunnelling significantly increases intracranial pressure and blood pressure despite prior fentanyl administration. This may be deleterious in the presence of intracranial pathology.