Ischaemia reperfusion injury is a common and important phenomenon that occurs predictably in patients undergoing such procedures as cardiopulmonary bypass, thrombolysis, surgery under tourniquet, organ transplantation or embolectomy. Oxidative stress and the resulting lipid peroxidation play a major role in reperfusion injury. Membrane and cellular dysfunction result and, subsequently, organ injury or failure may ensue. Traditional methods of quantifying ischaemia reperfusion injury, including measurement of malondialdehyde, lack specificity and sensitivity. It was reported in 1990 that isoprostanes, a series of prostaglandin-like compounds, are produced by the free radical-catalyzed peroxidation of arachidonic acid. Measurement of the isoprostane concentration in urine or plasma provides the most reliable, non-invasive method currently available to assess oxidative stress in vivo. Serial measurement of isoprostanes in biological fluids has enhanced our understanding of the mechanisms underlying ischaemia reperfusion injury itself and its role in certain diseases. Furthermore, measurement of the isoprostane concentration provides a means to assess the effects of prophylactic and therapeutic interventions. In the future, the development of rapid, simple assays for isoprostanes offers the potential to assess prognosis during and after ischaemia reperfusion events.

Background and objective: We investigated whether an increase in anaesthesia staffing to permit induction of anaesthesia before the previous case had ended (‘overlapping’) would increase overall efficiency in the operating room. Hitherto, the average duration of operating sessions was too long, thus impeding the timely commencement of physicians' ward duties.

Methods: The investigation was designed as a prospective, non-randomized, interrupted time-series analysis divided into three phases: (a) a baseline of 3.5 months, (b) a 2.5 month intervention phase, in which anaesthesia staffing was increased by one attending physician and one nurse, and (c) a further 2 months under baseline conditions. Data focussed on process management were collected from operating room staff, anaesthesia personnel and surgeons using a structured questionnaire collected daily during the entire study.

Results: Turnover time between consecutive operations decreased from 65 to 52 min per operation (95% CI: 9; 17; P = 0.0001). Operating room occupancy increased from 4:28 to 5:27 h day−1 (95% CI: 50; 68; P = 0.005). The surgeons began their work on the ward 35 min (95% CI: 30; 40) later than before the intervention and their overtime increased from 22:36 to 139:50 h.

Conclusions: The time between surgical operations decreased significantly. Increased operating room efficiency owing to overlapping induction of anaesthesia allows more intense scheduling of operations. Thus, physicians and nurses can be released to spend more time with their patients in the ward. Improving the efficiency of the operating room alone is insufficient to improve human resource management at all levels of a surgical clinic.

Background and objective: Clinical studies suggest that lidocaine may induce irreversible neurological damage after spinal application in human beings. The mechanisms underlying the possible cytotoxic action of lidocaine have only been suggested from animal studies. This study aimed to investigate if lidocaine exhibited cytotoxic action in a human model widely used for the study of neuronal apoptosis. This is important to know as it may help one to judge on possible neurotoxic risks imposed by the spinal application of lidocaine.

Methods: The concentration- and time-dependent effects of lidocaine on retinoic acid-differentiated human neuroblastoma SH-SY5Y cells were quantified by trypan blue staining, the release of lactate dehydrogenase, immunocytochemistry and flow cytometry.

Results: The local anaesthetic caused a significant increase in the number of cells staining positive for trypan blue, a significant increase of LDH release into the incubation medium, and a significant increase of 7AAD and annexin V binding. Lidocaine induced apoptosis already at 3 mm. At a concentration of 10 mmol 47% of the cells and at 30 mmol 98% of the cell population was necrotic. Both necrosis and apoptosis were time-dependent.

Conclusions: The results demonstrate that lidocaine exhibited neurotoxic effects in a human model established for the study of drug-induced neuronal apoptosis. The results were consistent with the neurotoxic clinical effects of lidocaine. These effects may be produced by more than a single mechanism.

Background and objective: Thymol is a naturally occurring phenol derivative used in anaesthetic practice as a stabilizer and preservative of halothane, usually at a concentration of 0.01%. Although analgesic effects have long been described for thymol and its structural homologue menthol, a molecular basis for these effects is still lacking. We studied the blocking effects of thymol and menthol on voltage-activated sodium currents in vitro as possible molecular target sites.

Methods: Whole cell sodium inward currents via heterologously (HEK293 cells) expressed rat neuronal (rat type IIA) and human skeletal muscle (hSkM1) sodium channels were recorded in the absence and presence of definite concentrations of either thymol or menthol.

Results: When depolarizing pulses to 0 mV were started from a holding potential of-70 mV, halfmaximum blocking concentrations (IC50) for the skeletal muscle and the neuronal sodium channel were 104 and 149 µmol for thymol and 376 and 571 µmol for menthol. The blocking potency of both compounds increased at depolarized holding potentials with the fraction of inactivated channels. The estimated dissociation constant K d for thymol and menthol from the inactivated state was 22 and 106 µmol for the neuronal and 23 and 97 µmol for the skeletal muscle sodium channel, respectively.

Conclusions: The results suggest that antinociceptive and local anaesthetic effects of thymol and menthol might be mediated via blockade of voltage-operated sodium channels with the phenol derivative thymol being as potent as the local anaesthetic lidocaine.

Background and objective: Target-controlled infusions of anaesthetic agents have become increasingly available. They can involve the use of propofol in combination with an opioid or a benzodiazepine. The effect site concentration of propofol infusions has been advocated as a method of estimating drug distribution. We investigated the influence of co-induction with remifentanil and midazolam on effect site propofol requirements at induction of anaesthesia using target-controlled infusions.

Methods: Sixty-six consenting adult patients were randomly allocated to three treatment groups. Each group received induction of anaesthesia with a different total intravenous technique. One group was induced with target-controlled propofol alone; another received target-controlled propofol and target-controlled remifentanil (3 ng mL−1); and the last received midazolam (0.03 mg kg−1), target-controlled remifentanil (3 ng mL−1) and target-controlled propofol. Computer simulation was used to calculate effect site concentrations. We recorded propofol dose and effect site concentration at loss of verbal response.

Results: The effect site concentration (Ce50) of propofol alone was 2.19 µg mL−1. This was reduced to 1.55 µg mL−1 during co-induction with remifentanil and further reduced to 0.64 µg mL−1 with midazolam premedication (P < 0.001; ANOVA).

Conclusions: We conclude that co-induction with remifentanil alone or with midazolam can be used to reduce propofol doses at induction of anaesthesia using target-controlled infusions. We believe that using effect site concentration may prove a useful tool in routine clinical practice.

Background and objective: Cognitive dysfunction has been reported after general anaesthesia, but its assessment is time consuming and difficult to evaluate. This pilot study assessed the feasibility of using the Sustained Attention to Response Test to assess 35 ASA I-II adults (mean age 31.6 yr) undergoing day case surgery under general anaesthesia, and 25 ASA I-II adults (mean age 47.8 yr) undergoing day case surgery under local anaesthesia.

Methods: The Sustained Attention to Response Test was performed before surgery and repeated 2 h after surgery.

Results: When patients repeated the test after surgery under local anaesthesia, the number of incorrect responses increased, but reaction times decreased (P < 0.05). Following general anaesthesia, the number of incorrect responses increased (P < 0.05), but reaction times remained unchanged.

Conclusions: The Sustained Attention to Response Test is simple to administer and may be a useful tool when comparing different anaesthetic techniques and their effects on postoperative deficits in sustained attention.

Background and objective: The α2-adrenoceptor agonist clonidine has potent central antinociceptive properties. The study was designed to investigate the effects of the combined subarachnoid administration of clonidine and prilocaine on spinal block and postoperative analgesia for the transurethral resection of tumours in the urinary bladder.

Methods: The controlled, prospective, double-blind study enrolled 40 patients scheduled for elective transurethral resection of bladder tumours under spinal anaesthesia with prilocaine. Patients were randomly assigned to receive an intrathecal injection of prilocaine 75 mg alone (control group) or in combination with clonidine 75 µg. We assessed haemodynamic changes (non-invasive arterial pressure, heart rate), pulse oximetry, the upper level of block, the onset and duration of sensory and motor block, postoperative analgesia and any adverse effects.

Results: There were no statistically significant differences in demographic data, heart rate, onset time or the levels of sensory or motor block. Analgesia lasted significantly longer in the clonidine group (498.4 ± 226.9 versus 187.2 ± 103.1 min; P < 0.05). The duration of motor block was longer in the clonidine group (165.5 ± 30.6 min) than in the control group (139.7 ± 40.4 min; P < 0.05) and the duration of sensory block was also longer in the clonidine group (157.3 ± 24.5 min) than in the control group (137.2 ± 31.2 min; P < 0.05). Fewer patients in the recovery room needed metamizol (dipyrone) in the clonidine group (5%) than in the control group (50%). Arterial pressure decreased significantly in the clonidine group 75-135 min after the block.

Conclusions: The addition of clonidine 75 µg to prilocaine 75 mg for subarachnoid anaesthesia increased the duration of sensory and motor block and reduced the need for additional postoperative analgesics by providing excellent analgesia for about 8 h during recovery from transurethral resection of bladder tumours.

Background and objective: The aim of this prospective, randomized study was to compare the preparation and discharge times, the side-effects and patient satisfaction after gynaecological outpatient procedures performed using either spinal block or total intravenous anaesthesia with propofol and remifentanil.

Methods: With Ethics Committee approval and written informed consent, 40 healthy females scheduled for hysteroscopic ablation of endometrial neoplasm were randomly allocated to receive either a spinal block with bupivacaine 0.5% hyperbaric solution 10 mg (n = 20) or total intravenous anaesthesia with propofol and remifentanil (n = 20). Preparation and discharge times, as well as occurrence of untoward events and anaesthesiarelated costs, were recorded.

Results: The median (range) preparation time was 7 (7–10) min with general anaesthesia, and 11 (7–21) min with spinal block (P = 0.00005). No differences in discharge time from the postanaesthesia care unit and incidence of hypotension or bradycardia, or both, were reported between the two groups. Hospital discharge times were 156 (101–345) min after general anaesthesia and 296 (195–720) min after spinal anaesthesia (P = 0.0005). Acceptance of the anaesthesia technique was better after general (100%) than after spinal anaesthesia (75%) (P = 0.04). No differences in total costs were reported between spinal block (€155 (€117–€224)) and propofol-remifentanil general anaesthesia (€143 (€124–€203) (P = 0.125)).

Conclusions: Accurate titration of short-acting intravenous anaesthetic drugs such as propofol and remifentanil results in shorter preparation times and earlier home discharge after outpatient gynaecological procedures compared with spinal anaesthesia with hyperbaric bupivacaine 10 mg, with better patient acceptance and no increased costs.

Background and objective: Although the MAC>tetanus(minimum alveolar concentration that prevents movetetanus ment in response to electrical tetanus stimulation in 50% of patients) of isoflurane decreases during anaesthesia and surgery, it is not known whether this occurs to the same extent with other inhalational anaesthetics. We determined the MACtetanus of sevoflurane before and after surgery.

Methods: Eleven patients who underwent arthroscopy of the shoulder underwent inhalational induction of anaesthesia with sevoflurane and tracheal intubation by succinylcholine. MACtetanus was determined in each patient by testing the response to a 10 s, 50 Hz, 80 mA transcutaneous tetanic electrical stimulus to the ulnar nerve at varying concentrations of sevoflurane. The end-tidal concentration of sevoflurane was kept constant for 15 min before each stimulus and the concentration of sevoflurane varied in increments of 0.1% until a sequence of three alternate responses (move, not move, move) or (not move, move, not move) was obtained. After arthroscopy of the shoulder, individual MAC were measured as described above.

Results: The mean MACtetanus decreased from 2.22 ± 0.29% before arthroscopy to 1.82 ± 0.26% after arthroscopy (P < 0.01).

Conclusions: It is concluded that the MACtetanus of sevoflurane decreases during anaesthesia and surgery.

Background and objective: Volatile anaesthetic agents are known to influence neutrophil function. The aim was to determine the effect of chronic occupational exposure to volatile anaesthetic agents on the rate of neutrophil apoptosis among anaesthetists. To test this hypothesis, we compared the rate of neutrophil apoptosis in anaesthetists who had been chronically exposed to volatile anaesthetic agents with that in unexposed volunteers.

Methods: Venous blood (20 mL) was withdrawn from 24 ASA I-II volunteers, from which neutrophils were isolated, and maintained in culture. At 1, 12 and 24 h in culture, the percentage of neutrophil apoptosis was assessed by dual staining with annexin V-FITC and propidium iodide.

Results: At 1 h (but not at 12 and 24 h) in culture, the rate of neutrophil apoptosis was significantly less in the anaesthetists – 13.8 (12.9%) versus 34.4 (12.1%) (P = 0.001).

Conclusions: Chronic occupational exposure to volatile anaesthetic agents may inhibit neutrophil apoptosis. This may have implications for anaesthetists and similarly exposed healthcare workers in terms of the adequacy of their inflammatory response.

Background and objective: Controlled hypotension may alter organ blood flow and tissue oxygenation. The aim of the study was to investigate whether induced hypotension using sodium nitroprusside alters pancreatic function assessed by pancreatitis-associated protein concentrations in the blood.

Methods: Thirty patients undergoing elective radical prostatectomy were allocated randomly into two groups: (a) hypotension group: sodium nitroprusside was administered to lower mean arterial pressure to approximately 50 mmHg; (b) control group: no hypotension was used, mean arterial pressure was kept >70 mmHg. Pancreatitis-associated protein and lipase were measured in arterial blood samples: after induction of anaesthesia (T1), at the end of surgery (T2), 2 h (T3) and 24 h (T4) postoperatively.

Results: Pancreatitis-associated protein plasma concentrations increased significantly in patients in the hypotensive group (from 2.8 ± 1.1 to 5.5 ± 2.0 µg L−1 at T4) and pancreatitis-associated protein plasma concentrations were significantly higher in comparison with controls (5.5 ± 2.0 versus 3.5 ± 2.4 µg L−1) at T4. Lipase concentrations showed a similar course in both groups. None of the patients showed clinical signs of pancreatitis.

Conclusions: Controlled hypotension during surgery was associated with a small but significant increase in pancreatitis-associated protein compared with controls. The absence of concomitant elevation in lipase concentrations and a lack of clinical evidence of pancreatitis damage suggest that hypotension induces mild pancreatic stress.