Malignant hyperthermia is an autosomal-dominant inherited disorder of the skeletal muscle cell characterized by a hypermetabolic response to all commonly used inhalational anaesthetics and depolarizing muscle relaxants. The clinical syndrome includes muscle rigidity, hypercapnia, tachycardia and myoglobinuria as result of increased carbon dioxide production, oxygen consumption and muscle membrane breakdown. In human beings and animals susceptible to malignant hyperthermia, it is generally accepted that an increase in the level of myoplasmic free calcium is the cause of the syndrome. Various hypotheses have been proposed to account for the increase of intracellular calcium levels, e.g. a defect in the calcium release channel of the sarcoplasmic reticulum (ryanodine receptor), an abnormality of the excitation-contraction coupling mechanisms, or alterations in second messenger systems of skeletal muscles. This review gives an overview of the main features of this disease and recent advances in research including pathophysiology, treatment, diagnosis and genetics as well as association with other disorders.

Background and objective The recently developed transcerebral double-indicator dilution technique has proven to be a feasible monitoring alternative to measure global cerebral blood flow at the bedside. However, the short-term repeatability of transcerebral double-indicator dilution measurements has not yet been investigated. The present study was designed to investigate the accuracy in terms of reliability for repeated transcerebral double-indicator dilution measurements to assess global cerebral blood flow during a definite carbon dioxide challenge in a clinical trial.

Methods The investigation was performed in 10 patients scheduled for elective coronary artery bypass grafting. After induction of anaesthesia, repeated cerebral blood flow measurements using transcerebral double-indicator dilution were performed during target normocapnia, hypocapnia and hypercapnia. For transcerebral double-indicator dilution measurements, a bolus injection of ice-cold indocyanine green was administered into a central vein. The resulting thermal dye dilution curves were recorded simultaneously in the aorta and the jugular bulb using combined fibreoptic thermistor catheters. Cerebral blood flow was calculated from the mean transit times of the indicators through the brain. Additionally, transcranial Doppler sonography was simultaneously performed to measure transient changes in the cerebral blood flow velocity.

Results Transcerebral double-indicator dilution measurements revealed a reasonable coefficient of repeatability with 9.1, 9.7 and 20.2 mL min−1100 g−1 during normo-, hypo- and hypercapnic conditions, respectively. However, a total of 20% of the administered measurements had to be rejected for methodological reasons.

Conclusions Repeated measurements with the transcerebral double-indicator dilution method show a reasonable repeatability. With consideration to the limitations of the transcerebral double-indicator dilution technique, this new method proves to be a reliable monitoring tool to measure global cerebral blood flow at the bedside.

Background and objective Assessment of cardiac preload is of major importance in the management of critically ill patients. Echocardiographic determined left ventricular end-diastolic area and indicator dilution derived intrathoracic blood volume are used as surrogates for cardiac preload. However, no controlled comparison studies on the relationship between induced changes in end-diastolic area and intrathoracic blood volume and concomitant changes in stroke volume index are available.

Methods The effects of a change in body position on these variables were investigated in 10 anaesthetized patients.

Results Intrathoracic blood volume and end-diastolic area decreased by 18 ± 11% and 27 ± 13% respectively. Stroke volume index concomitantly decreased by 19 ± 11%. Correlation analysis revealed a close relation between stroke volume index and intrathoracic blood volume (r = 0.75) and end-diastolic area (r = 0.76).

Conclusions Within the observed range of data, intrathoracic blood volume and end-diastolic area are equivalent indices of cardiac preload.

Background and objective Little information exists on cerebrospinal fluid pressures in non-labouring pregnant women. The technique of spinal anaesthesia means that inadequate levels of sensory blockade are difficult to manage. If the block is found to be inadequate after surgery has commenced, then conversion to general anaesthesia may be the only option. It is important that any manoeuvre altering the spread of local anaesthetic is considered at the time of subarachnoid injection. This study investigates the feasibility of using a fine bore needle with an electronic transducer to measure cerebrospinal fluid pressure and whether this was affected by either of the two lateral positions. We also sought to measure whether the right or left lateral position affected subsequent block height and requirements for supplementary analgesia.

Methods Two groups of 17 women presenting for elective Caesarean section were allocated to receive spinal anaesthesia in either the right or left lateral position. Cerebrospinal fluid pressure was measured by use of a rapid response electronic transducer connected to the hub of the spinal needle. Anaesthetic levels to cold sensation were assessed at 5, 10 and 15 min after injection of hyperbaric bupivacaine. During surgery, requirements for supplementary analgesia were recorded.

Results There was no significant difference in cerebrospinal fluid pressure between the two positions. While there was a trend towards more rapid analgesia in the right lateral group, this did not reach statistical significance. Two blocks performed in the left lateral group were inadequate for surgery but this was not statistically significant. Overall, 39% of women required supplementary analgesia during surgery. The incidence was not significantly different between the two groups.

Conclusion Adoption of either the right or left lateral position for placement of spinal anaesthesia results in no difference in cerebrospinal fluid pressure or quality of block. The technique described gives a reliable and reproducible method of cerebrospinal fluid pressure measurement.

Background and objective The effects of sepsis on gut mucosal blood flow have not been fully clarified. We designed an experiment to explicitly describe the effects of sepsis on gut mucosal blood flow in rats using an advanced intravital microscopy technique.

Methods This work was performed as a prospective, controlled laboratory experiment. Twenty-four hours after sham laparotomy or laparotomy and caecal ligation and perforation to create sepsis, rats were anaesthetized and their lungs mechanically ventilated (n = 7 per group). Intravital videomicroscopy was performed on 6–12 villi of ileum mucosa. Video recordings were analysed off-line using computerized image analysis.

Results Intercapillary area size (inversely related to capillary density) was increased in sepsis as compared with the control group (941 ± 92 vs. 669 ± 79 μm2, P < 0.05). In the central villus arteriole, blood flow was similar between groups (control: 3.5 ± 0.4 nL min−1; caecal ligation and perforation group: 3.6 ± 0.5 nL min−1). There were no relevant changes in arteriolar red cell velocity and diameter.

Conclusions In the gut mucosa of rats, sepsis resulting from caecal ligation and perforation depressed the perfused capillary density without affecting blood flow in the central villus arteriole. Mucosal hypoperfusion at the level of the capillary networks may occur in the presence of precapillary shunting in the villus microcirculation.

Background and objective Hypothermia may alter the disposition of opioids. Because opioids are commonly used as analgesics in the postoperative period, it is of clinical interest to clarify whether perioperatively developed hypothermia affects postoperative opioid requirements.

Methods Fifty-nine patients undergoing subtotal hysterectomy were prospectively randomized and either treated intraoperatively with forced air warming, or served as controls covered with conventional blankets without active warming. Both groups received postoperative patient-controlled analgesia with the opioid ketobemidone. Total analgesic requirements, demands, analgesic requirements over 6-h intervals and pain scores were measured for 48 h. Core temperature at the tympanic membrane and ambient room temperature were measured during the perioperative period.

Results There were no postoperative differences in analgesic requirements or pain intensity between normothermic and hypothermic patients. Patients treated with warm air had an up to 1°C higher core temperature from 0.5 h after anaesthesia induction until almost 2 h postoperatively. The actively warmed patients also had a lower intraoperative blood loss than the hypothermic patients (186 ± 27 mL vs. 308 ± 47 mL; P < 0.05).

Conclusion In a clinical setting, opioid requirements do not seem to be affected by mild postoperative hypothermia after lower abdominal surgery.

Background and objective It is claimed that local anaesthetics have antimicrobial properties. Our aim was to investigate the antimicrobial effects of different concentrations of ropivacaine, bupivacaine, lidocaine and prilocaine on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans.

Methods All local anaesthetic dilutions were exposed to microorganisms for 0, 30, 60, 120, 240 min at room temperature. The inoculums taken from diluted suspensions were reinoculated on blood agar and incubated for 18–24 h at 35°C and then the colonies were counted.

Results Ropivacaine did not inhibit any of the microorganisms tested. Bupivacaine reduced the viable cells of P. aeruginosa at 0.5% and 0.25% solutions. Lidocaine 5% and 2% and prilocaine 2.0% dilutions reduced the viable cells of all microorganisms tested. Prilocaine 1.0% reduced the viable cells of E. coli, S. aureus and P. aeruginosa. Lidocaine 1% reduced only the viable cells of P. aeruginosa and prilocaine 0.5% reduced only E. coli.

Conclusion Ropivacaine had no antimicrobial effect on microorganisms tested. Bupivacaine showed poor antimicrobial effectiveness. Lidocaine and prilocaine had more powerful antimicrobial effects than the other two local anaesthetics.