Background and objective: Isoflurane is a chiral, volatile anaesthetic with low metabolic rate (0.17%) that is routinely administered in its racemic form. Knowledge about the distribution of the enantiomers in human beings may give some important information about the understanding of the mechanisms of volatile anaesthetics.

Methods: Blood samples were drawn immediately after tracheal extubation and daily up to 8 days postoperatively from patients undergoing general anaesthesia with isoflurane racemate. The enantiomer enrichment of isoflurane was determined by headspace gas chromatography-mass spectrometry.

Results: At all time points, there was a statistically significant accumulation of the S(+) enantiomer in blood, especially at days 2 (52.01%) and 7 (52.1%). Separate analysis of obese patients or in a small group of patients with co-existing lung disease did not show any difference to the total population. In addition, duration of anaesthesia did not influence the enantiomer concentrations.

Conclusions: We suggest that a slower association and dissociation rate is responsible for the S(+) enrichment.

There is a risk of regurgitation if a laryngeal mask airway is used with intermittent positive pressure ventilation. The lower the pressure gradient between airway and stomach, the less will be the likelihood of stomach insufflation with gas and consequent regurgitation. A flow generator ventilator, such as the Penlon Nuffield 200 which achieves a peak pressure at the end of inspiration at any given tidal volume, is likely to produce a higher peak airway pressure than a pressure generator. Replacing the expiratory valve by a venturi gives a preferable flow pattern with an inspiratory pressure plateau. At equal tidal volumes, the venturi modification provided a 10% lower inflation pressure (standard deviation 6%, P < 0.01) and a 1.8% smaller leak (P < 0.05) past the laryngeal mask airway. The same comparison but using identical inflation pressures, gave 8% larger tidal volumes (standard deviation 5.1%, P < 0.01) and a 2% smaller leak (P < 0.01) past the laryngeal mask airway.

Intensive care patients with organ failure often suffer an acute catabolic state. Leptin is a 16-kDa hormone which is produced by mature adipocytes and correlates with human energy expenditure. We investigated whether continuous venovenous haemofiltration, which may eliminate molecules up to 20–30 kDa, is capable of removing human leptin. Leptin measurements were made in the plasma of 15 patients with sepsis before continuous venovenous haemofiltration (T0) and during the procedure at 24 h (T1), 48 h (T2), and 72 h (T3), using samples taken before and after haemofiltration. In addition, measurements were made in the ultrafiltrate at T1–T3. The plasma leptin level at T0 was 17.6 ng mL−1. The concentration at T1 was 17.5 ng mL−1 pre-filter and 26.5 ng mL−1 post-filter (T2: 14.2/23.2 ng mL−1; T3: 12.4/16.3 ng mL−1).This concentration effect after haemofiltration was also seen with albumin. The values measured at T3 tended to be lower than those recorded at T1. The mean leptin levels in the ultrafiltrate were 0.15–0.18 ng mL−1. The range of leptin levels in the ultrafiltrate was thus only 0.5–3% of that measured in plasma. We conclude that human leptin is only minimally elimininated into the ultrafiltrate by continuous venovenous haemofiltration and that plasma leptin levels may decrease during sepsis.

Forty-eight patients scheduled for elective cardiac surgery were randomly assigned to receive aprotinin in the following doses: 0.2 mg kg−1 (group A), 0.7 mg kg−1 (group B), 1 mg kg−1 (group C) and 1.4 mg kg−1 (group D). Clot formation was analysed by thromboelastography immediately after induction of anaesthesia and again 30 min after administration of aprotinin. Rate of clot formation was assessed using R (reaction time = rate of initial fibrin formation), K (clot formation time = rate of fibrin build-up and cross linking) and angle of clot formation (denoting speed at which solid clot forms). Strength of the clot was assessed by maximal amplitude of clot formation (MA)and % lysis after 30 and 60 min. Significant reduction of R and K times and increase in angle of clot formation was observed in groups A and B. This effect was not apparent in the other groups. In group D, an increase in R time was noted. These findings indicate a dose dependent effect of aprotinin on rate of clot formation with an earlier clot formation at low doses.

A 45-year-old male, with symptoms of many years standing of gastro-oesophageal reflux disease, was subjected, under general anaesthesia, to laparoscopic fundoplication.Tracheal intubation yielded no problems but great difficulties were encountered during tube insertion into the oesophagus. After surgery, aphonia developed. Laryngological examination demonstrated paralysis of the left vocal cord. Voice strength returned to the pre-operative status after 3 months, and laryngological examination confirmed normal mobility of both cords. The possible cause of the complication was damage to the left recurrent laryngeal nerve which occurred during insertion of the tube into the oesophagus. Gastro-oesophageal reflux disease causing ‘acid laryngitis’ can create conditions favouring this type of complication.

Summary

Background and objective: Spinal cord stimulation has been used successfully for many years in the management of neuropathic pain. Nociceptive pathways are closely integrated into many autonomic reflexes. The aim was to test the hypothesis that pain relief caused by spinal cord stimulation is related to changes in peripheral skin blood flow.

Methods: Twelve patients with spinal cord stimulators implanted as a treatment for neuropathic pain were entered into the study. Laser Doppler perfusion scanning was used as a direct method for selective measurement of changes in skin (peripheral) blood flow. Measurements were taken before and after the onset of spinal cord stimulation over the site of its sensory projection. The degree of pain relief due to spinal cord stimulation and the skin temperature of each patient were also recorded.

Results: Apart from one patient, spinal cord stimulation did not change skin blood flow in a statistically significant manner.

Conclusions: Pain relief due to spinal cord stimulation is not related to changes of skin blood flow.

Background and objective: Myocardial ischaemia and infarction are major complications immediately after coronary artery bypass grafting. They may be due to incomplete surgical revascularization, perioperative anaesthetic management or vasospasm of arterial grafts, e.g. the internal mammary artery. Infusions of nifedipine or milrinone have been advocated to prevent spasm of the mammary artery. The study compared the incidence of myocardial ischaemia after continuous infusion of either nifedipine (0.2 µg kg−1 min−1) or milrinone (0.375 µg kg−1 min−1) in patients with compromised left ventricular function scheduled for elective coronary artery bypass graft.

Methods: After Institutional Review Board approval, this double-blinded randomized clinical study enrolled 30 adult patients with compromised left ventricular function (ejection fraction <0.4) scheduled for elective coronary artery bypass grafting after written informed consent had been obtained. Ischaemia was detected by Holter electrocardiographic monitoring. The incidence of myocardial cell death was monitored by serial determinations of the creatine kinase-MB (CK-MB) and troponin-I.

Results: New ST elevation ≥0.2 mV or new ST depression ≤0.1 mV occurred in five of 15 patients in the milrinone group (33.3%) and in 13 of 15 patients (86.6%) in the nifedipine group (P < 0.05). There were increases in CK-MB and troponin-I in both groups. Twenty-four hours postoperatively, CK-MB (P = 0.003) and troponin-I (P = 0.001) were significantly higher in the nifedipine group.

Conclusions: Perioperative continuous infusion of milrinone, compared with nifedipine, results in a significantly lower incidence of myocardial ischaemia and myocardial cell damage after elective coronary artery bypass grafting.

Summary

Background and objective: The implication of intrathecal lidocaine in neurological toxicity has made intrathecal bupivacaine the commonly used drug for local anaesthesia in ambulatory surgery. However, in high doses intrathecal bupivacaine may produce a high level of sensory and motor block, and arterial hypotension; discharge from hospital may be delayed. Intrathecal opioids added to low-dose local anaesthetics produce a synergistic effect without increasing the sympathetic block or delaying discharge. The aim of our study was to identify the minimum effective dose of intrathecal fentanyl that in combination with low-dose intrathecal bupivacaine would provide adequate surgical conditions without prolonging recovery.

Methods: A prospective, single, blind, randomized study was conducted in 45 adult males scheduled for minor urological procedures using intrathecal anaesthesia on a day care basis. Patients were randomly assigned to one of three groups (n = 15 each). They received bupivacaine 0.17% 5 mg – with either fentanyl 7.5 μg (fenta-7.5), 10 μg (fenta-10) or 12.5 μg (fenta-12.5) intrathecally in a total volume of 3 mL. The quality of anaesthesia, haemodynamic stability, time to two-segment and S2 regression, time to micturition, and time to discharge were assessed.

Results: The time to two-segment regression and S2 regression with fenta-12.5 was significantly longer than with fenta-7.5 and fenta-10 (P < 0.01). Fenta-7.5 had a significantly higher number of failed blocks (four patients) compared with fenta-12.5 (P < 0.05). The time out of bed, time to micturition and time to discharge were significantly longer with fenta-10 and fenta-12.5 compared with fenta-7.5, and also with fenta-12.5 compared with fenta-10 (P < 0.01). Haemodynamic stability did not differ for all the drug combinations.

Conclusions: Fentanyl 12.5 μg added to low-dose bupivacaine (5 mg) intrathecally provides better surgical anaesthesia and increased reliability of block than intrathecal fentanyl 7.5 or 10 μg. Haemodynamic stability was the same for all dose combinations used.

Patients expected to need at least three units of blood for their elective cardiovascular or orthopaedic surgery, were allocated randomly to receive intravenous (i.v.) Epoetin alfa 600 IU kg−1 (n = 27), 300 IU kg−1 (n = 30) or placebo (n = 23), on days 1, 4 and 7. Provided haemoglobin ≥ 11 g dL−1, one unit of blood was collected on days 1, 4, 7, 11 and 14. Iron supplementation was given throughout the study. Surgery was scheduled between days 18 and 21. Significantly more patients treated with Epoetin alfa (100% for 600 IU kg −1 ; 97% for 300 IU kg−1) were able to donate ≥ 4 units of blood compared with placebo (78%) (P = 0.011 and P = 0.032). No significant differences were seen in total patient exposure to homologous blood (7.4%, 3.3% and 17.4%, respectively). Mean red cell volume donated (P = 0.005 for 600 IU kg−1 ; P = 0.158 for 300 IU kg−1 both vs. placebo) and production (P < 0.001 and P = 0.012, respectively) were dose related. Twenty-four patients became iron deficient. No differences in the incidence of adverse events were seen between the groups.

The increasing use of ambulatory surgery requires methods of anaesthesia that allow patients to be discharged soon after the operation is completed. Spinal anaesthesia is usually simple and quick, and the incidence of post-spinal headache has been reduced by using non-cutting small-gauge needles. Limiting the spread of spinal anaesthesia, as long as it still provides analgesia for surgery, should reduce the haemodynamic effects and speed recovery. Restricted spinal anaesthesia, intended to be unilateral using 0.18% hypobaric bupivacaine via a 25G or 27G Whitacre unidirectional needle, was compared with epidural anaesthesia (using a mixture of lignocaine and prilocaine) in 64 matched-pair patients undergoing ambulatory arthroscopy. Motor blockade, assessed for the specific myotomes L2 to S1, was significantly more unilateral in the spinal group. Two patients in the spinal group and nine patients in the epidural group were treated for hypotension (P < 0.05). One patient in the spinal group developed a post-spinal headache. One patient in the epidural group rated the anaesthesia poor.