In this study, we have sought to establish whether N2O and ketamine alter the bispectral index during propofol–fentanyl anaesthesia. Fourteen surgical patients were randomly assigned to one of two groups: the N2O group (n=7) and the ketamine group (n=7). In both groups, anaesthesia was induced with propofol 1.5–2 mg kg−1 and fentanyl 2 μg kg−1 and maintained with propofol 5–7 mg kg−1 hr−1 to target the bispectral index between 40 and 50. After the bispectral index value had stabilized the propofol infusion rate was fixed. In the N2O group, the following concentrations of N2O were subsequently inhaled at 20-min intervals; 20, 40, 60 and 70%, and then N2O was terminated. In the ketamine group, ketamine (0.4 mg kg−1+1.0 mg kg−1h−1) was given. The bispectral index and 95% spectral edge frequency were recorded 20 min after each change in concentration of N2O or ketamine infusion. The bispectral index and 95% spectral edge frequency did not change significantly in the N2O group, but increased significantly from 44.1±0.7 and 16.0±0.5 to 58.6±1.4 and 19.5±0.3 (P <0.01), respectively, in the ketamine group. Additional N2O or ketamine did not decrease the bispectral index and 95% spectral edge frequency values. The depth of sedation should be assessed carefully using a bispectral index monitor when these anaesthetic agents are used together.

Summary

Background and objective: The beta-adrenergic blocker esmolol and the alpha 2-adrenergic agonist dexmedetomidine have the potential to decrease perioperative myocardial ischaemia. The pathophysiological mechanisms involved in these anti-ischaemic properties have not been thoroughly studied. We compared the effects of esmolol and dexmedetomidine on two indices of overall myocardial oxygen demand and on directly measured myocardial oxygen consumption of the left anterior coronary artery territory.

Methods: Eleven mongrel dogs were instrumented to measure aortic and left ventricular pressure, aortic and left anterior coronary artery flow and myocardial wall thickening. Variables related to myocardial oxygen metabolism were also determined. Measurements were performed during four sequential experimental conditions in each dog (Control 1: esmolol; Control 2: dexmedetomidine).

Results: Esmolol and dexmedetomidine decreased haemodynamic indices of myocardial oxygen demand to a similar extent: esmolol decreased the rate–pressure product by 16 ± 3% and the pressure–work index (PWI) by 16 ± 3%, dexmedetomidine decreased the rate–pressure product by 26 ± 3% and the PWI by 16 ± 7%. However, these similar decreases resulted from different haemodynamic effects of the two study drugs. Dexmedetomidine had a more pronounced bradycardic effect than esmolol (P = 0.01) and increased systolic aortic pressure (SAP) by 15 ± 4% while esmolol decreased SAP by 8 ± 2% (P < 0.01). dP/dtmax and regional myocardial area decrease were lower after esmolol than after dexmedetomidine. Neither drug had an effect on myocardial oxygen consumption.

Conclusions: Esmolol and dexmedetomidine decreased two haemodynamic indices of overall myocardial oxygen demand to a similar extent but neither drug decreased directly measured myocardial oxygen consumption in the territory of the left anterior descending artery.

Cocaine abuse is increasing, particularly among young people. It is no longer a drug used exclusively by higher socio-economic groups. This review highlights the dangers of both acute and chronic cocaine abuse and its lethal potential even on the first encounter. The systemic effects of cocaine are described along with the possible pathology that may present itself to the attending clinician.

This study investigated the changes in the hypnotic component of anaesthesia, estimated by the bispectral index of the electroencephalogram, during normothermic cardiopulmonary bypass. Twenty-six patients (20 men, 6 women), aged 61±11 years (Mean±SD) scheduled for cardiac surgery were premedicated with hydroxyzine and meperidine. Anaesthesia was induced and maintained with a computer-controlled continuous infusion (not adjusted for haemodilution) of sufentanil (effect site concentration 0.4–0.6 ng mL−1) and a manually adjusted continuous infusion of propofol (4.4±1.8 mg kg−1 h−1). Cardiopulmonary bypass was normothermic with moderate haemodilution. Bispectral index was measured with a referential montage before, 30 s, 1, and 3 min after cardiopulmonary bypass onset, before and after aortic cross-clamping, 30 min after cardiopulmonary bypass onset, before and after aorta cross-clamp release and before and after weaning from cardiopulmonary bypass. Bispectral index values were 48±8 before cardiopulmonary bypass onset, 50±10 before, and 48±8 after end of cardiopulmonary bypass (P=NS). No patient had increases in bispectral index values during cardiopulmonary bypass consistent with awakening. We conclude that with the anaesthetic regimen presented in this study bispectral index values do not change during normothermic cardiopulmonary bypass.

Summary

Background and objective: One of the complications of laparoscopic surgery is carbon monoxide production during electrocautery. The aim of our study was to ascertain the relationship between intraperitoneal and alveolar concentrations of carbon monoxide and systemic carboxyhaemoglobin in patients undergoing laparoscopic cholecystectomy and anaesthetized with a closed system, where the carbon monoxide excreted through the lungs is accumulated in the circuit and thus re-inhaled.

Methods: Nine consecutive patients undergoing laparoscopic cholecystectomy were studied. Patients' lungs were ventilated with a closed anaesthesia breathing system (Physioflex®). Measurements were taken after establishing pneumoperitoneum (baseline) and at 5, 15 and 30 min after starting electrocautery.

Results: Mean duration of pneumoperitoneum was 42 ± 13 min with cumulative electrocautery time of 2.4 ± 1.8 min. Intraperitoneal carbon monoxide concentrations increased significantly at 5, 15 and 30 min reaching peak values of 481 ± 151 ppm at 15 min. No significant differences were found in alveolar carbon monoxide and carboxyhaemoglobin concentrations with respect to baseline.

Conclusions: No significant increase in carboxyhaemoglobin is produced during laparoscopic surgery, even under closed-system anaesthesia without pulmonary carbon monoxide elimination. This is most likely due to a low peritoneal absorption of carbon monoxide. We conclude that in adult patients, no carbon monoxide intoxication is caused if reasonable periods of electrocautery are used and the intraperitoneal gas is regularly renewed.

Summary

Background and objective: The aim of this study was to evaluate the value of terminal complement complex (C5b-9) plasma levels as a marker for complement activation in septic shock with concomitant capillary leak syndrome. Methods: In a prospective animal study 10 fasted, anaesthetized, mechanically ventilated and multi-catheterized pigs (20.6 ± 1.3 kg) were investigated over a period of 8 h. Sepsis was induced by faecal peritonitis (1 g kg−1 body weight faeces, n = 5) and compared to controls (n = 5). The animals received 6% hydroxyethyl starch 200/0.5 to maintain a central venous pressure of 12 mmHg. To quantify capillary leak syndrome, albumin escape rate was measured using 99mTc-labelled human serum albumin. Plasma levels of terminal complement complex were measured in a double antibody immunoassay (neoepitope-specific MoAb aE11 as catching antibody). Immunohistological studies of renal specimens were performed to detect terminal complement complex deposition. Results: Albumen escape rate increased in septic animals (+52%) compared to controls (+3%, P < 0.05). Plasma levels of terminal complement complex decreased during the study period in both groups. In septic animals this finding was accompanied by a significant deposition of terminal complement complex in renal specimens (P < 0.05). Conclusion: We found an activation of the complement system proven by marked deposition of terminal complement complex in renal specimen, while its plasma levels decreased during the study period in septic and control animals. These results suggest that in septic shock with capillary leak syndrome plasma level of terminal complement complex may not be a reliable marker of complement activation.

Background and aim We evaluated the effect of the injection technique on the onset time and efficacy of interscalene brachial plexus anaesthesia.

Methods With Ethical Committee approval and written consent, 30 patients undergoing elective shoulder acromioplasty or capsuloplasty were randomly allocated to receive interscalene brachial plexus block with 20 mL of ropivacaine 0.75% by using either a single injection (Single group, n = 15) or multiple injection (Multiple group, n = 15). Nerve blocks were placed with the aid of a nerve stimulator using short bevelled, Teflon® coated needles. The stimulation frequency was set at 2 Hz and the intensity of stimulating current, initially set at 1 mA, was gradually decreased to ≤0.5 mA after each muscular twitch was observed. In the Single group, the anaesthetic solution was slowly injected after the first muscular twitch had been observed. In the Multiple group, 6mL were injected at shoulder abduction, 6mL were njected at arm flexion, and 6ml_ at the extension of the arm.

Results Placing the block required 5min (4–8 min) in the Multiple group and 3 min (1–10 min) in the Single group (P=0.001); however, total preoperative time (from skin disinfection to complete loss of pinprick sensation from C4 to C7 with inability to elevate the limb from the operating table) was shorter in the Multiple group (15 min; range 10–28 min) than in the Single group (23 min; range 14–60 min) (P=0.03). Additional intravenous fentanyl supplementation was required in two patients of the Multiple group (13%) and eight patients of the Single group (53%) (P=0.05).

Conclusion We conclude that using a multiple injection technique shortened the preparation time and improved the quality of interscalene brachial plexus anaesthesia performed with small volumes of ropivacaine 0.75%.

Summary

Background and objective: Adverse effects associated with difficult airway management can be catastrophic and include death, brain injury and myocardial injury. Closed-malpractice claims have shown prolonged and persistent attempts at endotracheal intubation to be the most common situation leading to disastrous respiratory events. To date, there has been no evaluation of the types of difficult airway equipment currently available in Irish departments of emergency medicine. The objective of this survey was to identify the difficult airway equipment available in Irish departments of emergency medicine.

Methods: Departments of emergency medicine in the Republic of Ireland with at least one dedicated Emergency Medicine consultant were surveyed via telephone.

Results: All of the departments contacted held at least one alternative device on site for both ventilation and intubation. The most common alternative ventilation device was the laryngeal mask airway (89%). The most common alternative intubating device was the surgical airway device (100%).

Conclusions: Irish departments of emergency medicine compare well with those in the UK and USA, when surveyed concerning difficult airway equipment. However, we believe that this situation could be further improved by training inexperienced healthcare providers in the use of the laryngeal mask airway and intubating laryngeal mask airway, by placing greater emphasis on the ready availability of capnography and by the increased use of portable difficult airway storage units.

Summary

Background and objective: The degradation of the cytoskeletal protein microtubule-associated protein 2 (MAP2), by calpain has been known to occur following traumatic brain injury. We examined the therapeutic potential of calpain inhibitor 2, compared with that of moderate hypothermia in traumatic brain injury produced by weight drop in rats.

Methods: An inhibitor treated group (n = 8) received calpain inhibitor 2 intravenously (i.v.) for 5 min before and for 6 h after injury (total 2 μmol); a hypothermic (HT) group (n = 8) was maintained at 30°C (temporalis muscle temperature) for 45 min prior to and 60 min after injury; an untreated (UT) group (n = 8) received an infusion of inactive vehicle. Eight rats (sham group) underwent surgery without brain injury. Histopathological (haematoxylin and eosin staining) and MAP2 (immunohistchemistry and western blotting) evaluations were performed at 6 h after injury.

Results: Ipsilateral cortical damage was marked in the injured groups. In the hippocampus, marked pyramidal neuronal damage was observed in the UT and calpain inhibitor treated (CI) groups, while these neurons were better preserved in the HT group. The hippocampal MAP2 levels in the UT, CI and HT groups were significantly decreased to 13 ± 9%, 28 ± 33% and 62 ± 25% of the sham control, respectively. MAP2 concentration in the HT group was significantly higher than in UT and CI groups (P < 0.05).

Conclusion: The results suggest that moderate hypothermia, but not calpain inhibitor 2 with the tested regime, attenuates cytoskeletal damage in the ipsilateral hippocampus at 6 h after traumatic brain injury.

Summary

Background and objectives: To analyse the prevalence of positive prick-tests to all medicaments normally checked in allergy units when a patient is suspected of being allergic to anaesthetics. To establish the degree of agreement between the antecedents of a previous history of an allergic reaction to a medicament and the positive result, or not, to the specific prick-test for the said medicament. Methods: This was a prospective study, during 2003 and 2004, which analysed 473 patients referred by their doctors to allergy units to make retrospective diagnoses of an allergy to a drug. The prick-test was done using the undiluted drug. All patients were tested for 41 drugs. These include antibiotics, trimethoprim–sulphamethoxazole, non-steroidal anti-inflammatory drugs (NSAIDs) and perioperative drugs (PD): neuromuscular blocking drugs, latex, iodine, local anaesthetics, hypnotics, opioids and coadjuvants. Cohen's Kappa Index was used to determine the degree of agreement. Results: 71.5% of patients studied presented a positive prick-test. The largest number of positive cases was found in antibiotics (56.4%), followed by PD (15.6%), NSAIDs (14.4%) and trimethoprim–sulphamethoxazole (12.7%). Among PD, the highest prevalence of positive prick-tests was found for neuromuscular blocking drugs (5.3%). Agreement between the substance suspected of causing the allergic reaction and the positive prick-test was excellent for penicillin (Kappa = 0.74) and other antibiotics (Kappa = 0.721) and good for NSAIDs (Kappa = 0.47) and iodine (Kappa = 0.54). Conclusions: The prevalence of patients with positive prick-tests to PD occurred in 15.6% in this prospective cohort. Neuromuscular blocking drugs were found to have the highest prevalence of positive prick-tests. There is positive agreement when the substance responsible for the allergic reaction is suspected, otherwise agreement is low.

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.

The effectiveness of a balanced analgesia with buprenorphine ketoprofen-propacetamol for pain control during extracorporeal shock wave lithotripsy (ESWL) was evaluated in order to reduce the requirements for general anaesthesia. Two hundred and ninety-one consecutive patients were included in a randomized, placebo-controlled, double-blind study. Patients in each group received midazolam 5 mg pre-operatively as premedication. The subjects then received either placebo (group 1), buprenorphine 0.3 mg (group 2) or the combination buprenorphine 0.3 mg plus ketoprofen 100 mg and propacetamol 2 g (group 3) intravenously (i.v.) at a constant rate. The treatment was started 45 min prior to ESWL. Pain was assessed using a three-point verbal scale: (0)no pain; (1) moderate pain; and (2) intense pain needing general anaesthesia. The patients assessed their pain intensity on a 0–100 mm visual analogue scale. Only 69% of group 1 patients received ESWL with midazolam premedication. Buprenorphine provided good analgesia in 87% of group 2 patients, while the combination buprenorphine-ketoprofen-propacetamol was effective in 99% of group 3 patients (P<0.05). The incidence of nausea and vomiting was similar in the buprenorphine groups. No respiratory depression was reported. In conclusion, the buprenorphine-ketoprofen-propacetamol combination provided effective analgesia, allowing ESWL to be performed without the need for general anaesthesia.

One of the greatest but also most unfortunate ironies in life is how modern medicine owes some of its existence to the deadly cancer of war. For those whose image of armed conflict is one of disease, death and destruction, this will no doubt be a surprise. However, these very conditions have allowed military surgeons and physicians unparalleled opportunities to experiment and develop using large and dependent populations of potential patients. The catalyzing effect of war has seen the ambulance, the hospital, plastic surgery, preventative medicine and penicillin as just a few products whose history is linked to war. This paper examines whether anaesthesia, and in particular British anaesthesia, can be added to this list when focussing on the First World War (1914–1918). The anaesthesia that was being practiced at the outbreak of the First World War had not drastically altered from that of the mid-nineteenth century. Old anaesthetics given via basic facemasks could be performed by many doctors; specialists were rare. This situation, however, altered during the First World War. This is because the vast number of wounded in the war demanded the introduction of casualty clearing stations to help triage and treat the wounded quickly and efficiently. The workload of these ‘mini hospitals’ created specialist anaesthetist posts within the military. Once in place, the anaesthetists were able to help develop the relatively new concepts of blood transfusion and resuscitation. These were recognized to be vital against shock, something that had previously not been well researched or understood. While at the casualty clearing stations, Geoffrey Marshall readdressed this by studying the effects of different anaesthetic agents in varying amounts of shock. This work led to the popularity of nitrous oxide, ether and oxygen, which in turn stimulated interest in anaesthesia machines. Finally, the treating of facial wounds in casualties at the Queen’s Hospital for facial and jaw injuries at Sidcup, highlighted the possibility of endotracheal intubation, a technique that had a drastic effect on the administration of anaesthetics. Although there were no new wonder anaesthetics, something which would not occur until the neuromuscular blocking drugs of the 1940s, many of these concepts moved into civilian anaesthesia and enabled British anaesthesia to be at the forefront of anaesthesia development for much of the twentieth century.

Summary

Background and objective: The use of remifentanil requires other analgesics for postoperative pain relief compared to fentanyl in patients undergoing craniotomy. This could possibly reduce the postoperative advantages of this short-acting opioid.

Methods: We compared remifentanil and fentanyl-based anaesthesia in a randomized observer and patient blinded trial on patients, undergoing an elective craniotomy. Twenty patients received anaesthesia using remifentanil with a small dose of piritramide (0.1 mg kg−1) after closure of the dura mater. Twenty patients underwent a fentanyl-based protocol. In both groups, anaesthesia was induced with thiopental and rocuronium, and maintained with 0.6–1 minimum alveolar concentration (MAC) isoflurane in a nitrous oxide/oxygen mixture 2 : 1 and rocuronium. Patients received 1 g of paracetamol rectally postoperatively. A visual analogue scale (VAS) for pain, the Glasgow Coma Score, a modified Aldrete Score, arterial carbon dioxide tension (PaCO2) and piritramide consumption were evaluated every half an hour postoperatively.

Results: No significant differences were found for pain, Aldrete or Glasgow Coma scores or for PaCO2 between the groups when controlled for age, although the pain and Glasgow Coma Scores were consistently higher and PaCO2 lower in the remifentanil group. Furthermore, 13 out of 20 patients in the remifentanil group requested extra piritramide as opposed to 7 out of 20 in the fentanyl group (P = 0.11).

Conclusions: Despite the intraoperative use of piritramide in the remifentanil group, patients experienced more pain postoperatively. A significant influence of age on pain intensity was found. The use of remifentanil with a small dose of piritramide of 0.1 mg kg−1 has no evident advantage over the use of fentanyl considering the postoperative conditions after craniotomy.

Rocuronium administration may cause tachycardia and an increase in cardiac index. Pancuronium, another steroidal non-depolarizing muscle relaxant, augments release of, and blocks re-uptake of catecholamines at adrenergic nerve endings. This study compared the haemodynamic effects of, and changes in catecholamine concentrations following administration of vecuronium (0.12 mg kg−1) or rocuronium (0.9 mg kg−1) to elderly patients. Thirty patients, 65 years or older, not receiving β-blockers, were studied. During thiopentone, fentanyl, nitrous oxide anaesthesia, either rocuronium (0.9 mg kg−1) or vecuronium (0.12 mg kg−1) was administered, according to random allocation. In all 30 patients, blood pressure and heart rate were measured before induction of anaesthesia, immediately and 1 min after induction, 1 and 2 min after muscle relaxant administration, and immediately, 1 and 2 min after tracheal intubation. In the latter 20 patients, samples for plasma catecholamine estimation were obtained prior to, and 1 min after muscle relaxant administration and 1 min after tracheal intubation. Blood pressure and heart rate were similar in the two groups throughout the study. Plasma noradrenaline concentrations were similar in the vecuronium and rocuronium groups prior to muscle relaxant administration (589(SD240) and 444(SD213) pg mL−1, respectively), 1 min after muscle relaxant administration (602(SD220) and 520(SD392) pg mL−1, respectively) and 1 min after tracheal intubation (597(SD351) and 440(SD181) pg mL, respectively). There was no significant change in either plasma noradrenaline or adrenaline concentrations in either group following muscle relaxant administration or tracheal intubation. The use of rocuronium (0.9 mg kg−1) in elderly patients does not result in a clinically significant change in heart rate, blood pressure or plasma catecholamine concentration.