Numerous in vitro studies have shown that volatile anaesthetics react with desiccated carbon dioxide (CO2) absorbents to produce carbon monoxide (CO). The effects of anaesthetic concentration, fresh gas flow rate, and the hydration of absorbent or the excretion of CO2 by patients on CO production have also been investigated. This work aims to identify the most significant one of these factors on CO concentration in a low-flow anaesthesia system, without control of the hydration of the absorbents.

A simulated clinical circle anaesthetic breathing system was used to study the CO concentration under various conditions. Desflurane was used at three different concentrations. Two CO2 flow rates and three fresh gas flow rates were used. The absorbent temperatures and hydration were measured simultaneously.

Desflurane degraded to produce CO in the breathing tube, when the CO2 absorbents were not dried beforehand. In this imitation clinical low-flow setting, fresh gas flow affected the CO production more than the CO2 did (31.7% vs. 9.5%). The actual desflurane partial pressure was not a significant factor. The CO2 flow rate explained 18.2% and 54.0% of the variation of the absorbent hydration changes (%) and temperature, respectively.

In clinical practice, the CO2 production varies among patients and is uncontrollable, but markedly affects CO production. The only controllable factor is the fresh gas flow rate if the ultimate goal is to reduce the undesirable exposure of patients to CO from the breathing tube according to this bench model without counting the oxygen consumption.

Elderly patients with heart failure undergoing urgent major surgery suffer substantial cardiac morbidity and mortality. Levosimendan, a novel calcium sensitizer, enhances myocardial contractility while simultaneously having vasodilatory and cardioprotective properties. This could be advantageous in perioperative management of heart failure patients.

Ten consecutive patients with symptomatic heart failure and left ventricular ejection fraction <35% undergoing urgent hip fracture repair were studied. Levosimendan was administered with an infusion rate of 0.1 μg kg−1 min−1 in a total dose of 12.5 mg starting a minimum of 2 h prior to surgery. Haemodynamic parameters were obtained at baseline and at 4, 8, 12, 16, 20, 24, 28, 36 and 48 h after start of levosimendan. B-type natriuretic peptide was measured on admission and after 48 h.

Patients were 86 ± 7 yr (mean ± SD) of age. Levosimendan significantly increased cardiac index from 2.4 ± 0.3 L min−1 m−2 at baseline to 3.2 ± 0.6 L min−1 m−2 after 24 h by increases in stroke volume index (baseline 27 ± 5 mL m−2, after 24 h 37 ± 10 mL m−2, P < 0.05). Systemic vascular resistance index significantly decreased from 2718 ± 841 to 1964 ± 385 dyn s cm−5 m−2 within 24 h. Haemodynamic changes exerted by levosimendan persisted up to 48 h. B-type natriuretic peptide plasma concentrations decreased from 1143 ± 792 to 935 ± 724 ng L−1 after 48 h (P = 0.006).

In patients with heart failure, preoperative start of levosimendan infusion improves intraoperative and postoperative haemodynamics. These findings suggest that levosimendan is a useful drug for preoperative optimization of cardiac function in high-risk patients undergoing major surgery.

Unlike for intensive care unit and home mechanical ventilators, no study has evaluated the user-friendliness of the recently introduced new anaesthesia workstations.

We performed a prospective study to evaluate the user-friendliness of four anaesthesia workstations, which were categorized into two groups: first-generation (Kion) and second-generation (Avance, Felix and Primus). Twenty users (12 nurse-anaesthetists and 8 anaesthesiologists) from three different anaesthesia departments at the same univeristy hospital participated in the study. The user-friendliness scale evaluated 10 criteria, including two design and monitoring criteria, four maintenance criteria and four ventilation use criteria. Each criterion was evaluated from 0 (poor) to 10 (excellent).

The mean score obtained for the first-generation workstation was lower than those obtained for the three second-generation workstations (P < 0.05). No significant differences in the overall user-friendliness score was observed for the three second-generation workstations. The first-generation workstation obtained a significantly lower score than the three second-generation workstations for the design criteria (P < 0.01). For the screen criteria, the highest score was obtained by Felix, which has the largest screen and associated characters. For the main maintenance criteria, Kion and Felix obtained the lowest scores. No significant differences between the four anaesthesia workstations were found for only three of the user-friendliness criteria (self-test, alarms and settings).

Anaesthesia machines have benefited from considerable advances in design and technology. This novel user-friendliness scale revealed that the most recent workstations were more appreciated by users than the first-generation of anaesthesia workstations. This user-friendliness scale may help the anaesthetic staff to ‘consensually’ choose the future workstation for their anaesthesia department.

The influence of the combined application of cisplatin and sevoflurane on a variety of cell types of healthy mice or mice bearing Ehrlich ascites tumour has been investigated in an in vivo study.

The alkaline comet assay method was carried out on peripheral blood leucocytes, brain, liver, kidney and tumour cells of healthy mice or mice bearing Ehrlich ascites tumour. Groups of mice were treated intraperitoneally with cisplatin, exposed to sevoflurane or by combined treatment of sevoflurane after treatment with cisplatin for 3 consecutive days.

The in vivo exposure to sevoflurane induced genotoxicity to all assayed cells. A strong synergistic genotoxic effect to peripheral blood leucocytes, liver and kidney cells was found in mice receiving both cisplatin and sevoflurane. In contrast, a decrease of the comet tail lengths of brain cells in the combined treatments was found as compared to cisplatin alone in both healthy (P < 0.001) and Ehrlich ascites tumour-bearing mice (P < 0.05), respectively. In addition, Ehrlich ascites tumour cells of mice treated with combined treatments showed a decrease in tail lengths (P < 0.001). These findings indicate an antagonistic effect of combined treatments.

Treatment of mice with cisplatin and sevoflurane induced genotoxic effect in peripheral blood leucocytes, liver, kidney, brain and Ehrlich ascites tumour cells; synergistic effect of combined treatments was expressed in all cells but brain and Ehrlich ascites tumour cells.

The generation of shunt criteria by somatosensory evoked potentials is controversial. This study was designed to validate somatosensory evoked potentials’ tracings and their derived shunt criteria compared with clinical-neurological examination.

We prospectively studied the somatosensory evoked potentials’ tracing in 102 patients who underwent carotid endarterectomy under cervical plexus blockade, comparing different somatosensory evoked potentials’ derived thresholds of impaired cerebral blood flow with the neurological examination.

The 50% reduction of the primary cortical response to median nerve stimulation as threshold of critical cerebral blood flow showed a sensitivity of 87% and a specificity of 66%. In case of total collapse of primary cortical response, we observed a sensitivity of 85% and a specificity of 89%. Concerning the prolongation of central conduction time between the spinal response at N13 and the cortical response at N20/P25 as critical threshold of impaired cerebral blood flow, the sensitivity was 87% and specificity 40%. The need-to-shunt index with its threshold at >0.5 showed a sensitivity of 85% and a specificity of 88%.

Compared to other studies, we have shown a much lower sensitivity and specificity of somatosensory evoked potentials in detecting critical cerebral perfusion; thus its use remains controversial and has to be assessed in further investigations.

This study was carried out to clarify the effect of the combination of acute hypervolaemic haemodilution and hypotensive anaesthesia induced with sevoflurane on human middle cerebral artery flow velocity using transcranial Doppler ultrasonography.

Thirty patients who were maintained with N2O–O2–sevoflurane anaesthesia undergoing hip surgery were randomly divided into two groups (no controlled hypotension group, Group A, and controlled hypotension group, Group B). Haemodilution was produced by acute preoperative infusion of 1000 mL of hydroxyethylstarch without removing blood in both groups. Mean arterial pressure was maintained at approximately 95 mmHg in Group A and at 55 mmHg for 80 min by increasing the inspired concentration of sevoflurane in Group B. Middle cerebral artery flow velocity was measured before haemodilution, after haemodilution, 80 min after starting hypotension, and 60 min after recovery from hypotension.

Middle cerebral artery flow velocity significantly increased in both groups after haemodilution; by 28%, in Group A, P < 0.05 vs. before haemodilution and by 30% vs. before haemodilution in Group B, P < 0.05). During controlled hypotension, it decreased towards the pre-haemodilution value (P < 0.05 vs. after haemodilution).

Sevoflurane-induced hypotension to a mean arterial pressure of 55 mmHg would reduce middle cerebral artery flow that had been increased by acute hypervolaemic haemodilution, such as haematocrit value of 26%, whereas it could preserve the flow in pre-haemodilution condition during normocapnia.

We retrospectively reviewed the first 25 planned cases of awake craniotomies using the ‘asleep–awake’ technique, an alternative to the often-used ‘asleep–awake–asleep’ technique.

The patients were anaesthetized using propofol/remifentanil anaesthesia, a laryngeal mask and controlled ventilation according to a protocol defined before the start of this series of patients. The patients were awakened before the brain mapping and were kept awake throughout the rest of the procedure allowing for additional mapping and modification of the resection of the tumour if symptoms should develop. A small dose of remifentanil was infused during this period if necessary.

Twenty-three patients were mapped as planned. One patient was not awakened due to protrusion of the brain during the awakening phase. Another patient was intubated preoperatively as it was impossible to obtain a tight laryngeal mask. All of the 23 patients were awake as from when the mapping session began and throughout the rest of the operation. In five cases the resection of the tumour was modified as symptoms emerged. These symptoms all subsided in due course. No case of hypoxia was recorded. In no case the respiratory rate was below 10 breaths min−1 in the awake period. Complications were comparable to other studies. The patients in the present study were all satisfied with the method.

Different methods of anaesthesia have been described, but no method has been shown to be superior. The presented method seems to be a rational and useful technique allowing for modification of tumour resection, if symptoms should develop. The method was well tolerated by the patients.

To evaluate the use of remifentanil–propofol administered as target-controlled infusion during awake fibreoptic intubation for anticipated difficult tracheal intubation in acromegalic patients.

In all, 20 consecutive acromegalic patients underwent elective endonasal endoscopic transsphenoidal pituitary surgery. After premedication with midazolam 0.03 mg kg−1, initially a target-controlled infusion of remifentanil 1.0 ng mL−1 and propofol 1.5 μg mL−1 was started. The fibreoptic intubation was performed by the same physician experienced with the fibreoptic technique. During the fibreoptic procedure the target concentrations of remifentanil and propofol ranged between 1.0 and 5.0 ng mL−1, and between 1.5 and 3.5 μg mL−1, respectively. Changes in heart rate and mean arterial pressure were recorded during airway manipulation, during tracheal intubation, and at 1 and 3 min after. On the first postoperative day, patient recall and level of discomfort during fibreoptic intubation were evaluated.

Endotracheal intubation was efficaciously and quickly secured in all patients. A significant increase in mean arterial pressure and heart rate was recorded only during tracheal intubation (P < 0.05). Oxygenation was sufficient and no bradypnea or apnoea was recorded. All patients later described their anaesthetic experience as satisfactory. During fibreoptic intubation, remifentanil (ng mL−1) and propofol (μg mL−1) mean effect-site concentrations were 3.2 ± 0.3 and 2.0 ± 1.0, respectively.

Remifentanil and propofol target-controlled infusion provided satisfactory conscious sedation allowing for successful oral fibreoptic intubation in acromegalic patients with no recall.

There have been many studies to find the optimum anaesthetics to provide excellent conditions for laryngeal mask insertion. We compared the effects of dexmedetomidine administered before propofol, on laryngeal mask insertion with fentanyl combined with propofol.

In all, 52 patients, ASA I–II, scheduled to have minor urological procedures were randomized into two groups. Group F received 1 μg kg−1 fentanyl (in 10 mL normal saline) and Group D received 1 μg kg−1 dexmedetomidine (in 10 mL normal saline). We used 1.5 mg kg−1 propofol for induction and 50% N2O and 1.5% sevoflurane in oxygen for maintenance. We observed jaw mobility (1: fully relaxed; 2: mild resistance; 3: tight but opens; 4: closed), coughing or movement (1: none; 2: one or two coughs; 3: three or more coughs; 4: bucking/movement) and other events such as spontaneous ventilation, breath holding, expiratory stridor and lacrimation. In each category, scores <2 were acceptable for laryngeal mask insertion.

More patients developed apnoea and their apnoea times were longer in Group F than Group D (P < 0.001). Respiratory rates increased in Group D (P < 0.001). Adverse events during laryngeal mask insertion were similar. The reductions in systolic and mean blood pressures were greater in Group F (systolic: P < 0.05, mean: P < 0.01). Emergence times were shorter in Group F than in Group D (P < 0.001).

Dexmedetomidine, when used before propofol induction provides successful laryngeal mask insertion comparable to fentanyl, while preserving respiratory functions more than fentanyl.

It has been reported that the left molar approach of laryngoscopy can make difficult intubation easier. The aim of this study was to investigate whether left molar approach to laryngoscopy provided a better laryngeal view in cases of unexpected difficult intubation.

Following the approval of local Ethics Committee and written informed consent from the patients, out of 1386 patients who underwent general anaesthesia for surgery, 20 patients who could be ventilated by face mask but could not be intubated with conventional midline approach on the first attempt were included in the study. Those 20 patients, who had Grade III-IV laryngeal views on laryngoscopy by conventional midline approach, were subjected to left molar laryngoscopy, and their laryngeal views were evaluated. The external laryngeal compression was routinely used to improve the laryngeal view. When endotracheal intubation failed by left molar laryngoscopy, we performed the conventional midline approach again. All data were recorded.

Of the 20 patients studied, 18 had a Grade III laryngeal view and two had a Grade IV laryngeal view. Eighteen of them had a better laryngeal view with left molar laryngoscopy. Eleven of the 20 patients underwent successful intubation with the left molar laryngoscopy, which provided a significantly better laryngeal view and success rate of tracheal intubation than did the conventional midline approach (P < 0.01 and P < 0.01, respectively).

Left molar laryngoscopy can make unexpected difficult intubation easier and should be attempted in cases of difficult intubation.

For more than 50 yr, uncuffed tracheal tubes have been the gold standard for intubation in children under the age of 8 yr. However, recently there has been interest in the use of cuffed tubes in paediatric practice. This survey aimed to benchmark UK practice with regard to tracheal intubation within specialist paediatric centres, exploring current cuffed tracheal tube use in children.

A questionnaire was e-mailed to the paediatric intensive care unit and anaesthetic department clinical leads in all UK specialist paediatric hospitals with a paediatric intensive care unit (n = 30). Information was requested on the use of tracheal tubes across all paediatric age groups, as well as the reasons for non-use and the incidence of complications attributed to cuffed tubes.

A total of 20 paediatric intensive care unit and 15 anaesthetic questionnaires were returned, equating to a response rate of 67% and 50%, respectively. Only 5% of the paediatric intensive care unit and 7% of the anaesthetic respondents routinely use a cuffed tube in children under the age of 8 yr. The commonest reason cited in both groups for non-cuff use was that there is minimal benefit to be gained over using an uncuffed tracheal tube. The most frequent specific indication for use of a cuffed tube was a reduced lung compliance (60% respondents both groups). In all, 45% of the paediatric intensive care unit respondents and 100% of the anaesthetists reported that they did not routinely monitor the intracuff pressure when using a cuffed tube. The incidence of observed complications attributed to the use of cuffed tubes was far higher amongst paediatric intensive care unit consultants (65% vs. 7% anaesthetists); however, the majority in both groups stated that such complications were no more common than when using an uncuffed tube (60% paediatric intensive care unit and 53% anaesthetists).

Cuffed tracheal tubes are rarely routinely used in children, particularly in the under 8 yr age group, in specialist paediatric centres in the UK. When used, it is predominantly for a specific indication, and the monitoring of intracuff pressure is not routine. Current expert consensus is that complications are equally as common when using a cuffed as an uncuffed tube.