Summary

Background and objective: Although many antiemetic drugs are available for intravenous use in the hospital setting, few are available after patient discharge. Consequently, nausea and vomiting are frequent complaints from patients at home after ambulatory surgery. We tested the hypothesis that the new 8 mg ondansetron disintegrating tablets will decrease the rate of nausea and vomiting at home after laparoscopic surgery.

Methods: Ninety-six patients were studied in a randomized double-blind study. Starting the first evening after operation and continuing every 12 h for 3 days, patients received either placebo or ondansetron 8 mg disintegrating tablets orally. The patients returned a questionnaire about postoperative nausea and vomiting, other side-effects, e.g. dizziness, headache, nightmare, anxiety and pain, as well as their overall satisfaction at 24 and 72 h after completion of surgery.

Results: The rates of nausea and vomiting were similar in the two groups, both during the first 24 h (28 versus 48%, placebo and ondansetron, respectively (ns) and during the 24–72 h (21 versus 35% (ns)). The incidence rate of vomiting was 8% (placebo) versus 12% (ondansetron) during the first 24 h (ns) and 9 versus 13% respectively in the 24–72 h (ns). No difference between groups was observed in overall satisfaction, incidence of postoperative pain or other side-effects.

Conclusions: The use of ondansetron disintegrating tablets of 8 mg twice a day for 3 days did not reduce the incidence of nausea and vomiting in patients undergoing outpatient laparoscopic surgery.

Summary

Background and objective: Sevoflurane has been used for the induction and maintenance of anaesthesia during cardiac surgery owing to its favourable haemodynamic effects. It has been suggested that it offers protection against myocardial ischaemia–reperfusion injury.

Methods: We investigated the effect of sevoflurane on plasma concentrations of tumour necrosis factor-α (TNF-α) after ex vivo stimulation of whole-blood leukocytes by lipopolysaccharide from 20 patients undergoing coronary artery bypass surgery. The patients were randomized to two groups. Group 1 patients were induced and maintained with sevoflurane; those in Group 2 were anaesthetized with moderate doses of midazolam–sufentanil. Blood samples were drawn from the patients on seven occasions from before induction of anaesthesia until 24 h after skin closure.

Results: Plasma concentrations of TNF-α were lower in Group 1 than in Group 2 after cessation of cardiopulmonary bypass (median (interquartiles): 25 (21–30) versus 37 (28–79) pg mL−1; P < 0.05) and 24 h after skin closure (196 (100–355) versus 382 (233–718) pg mL−1; P < 0.05). Postoperatively, two cases of myocardial infarction were recorded, one in each group. Six patients in Group 2 needed continued inotropic support after the first morning to maintain haemodynamic stability versus one patient in Group 1 (P < 0.05). The length of stay in the intensive care unit was significantly lower in Group 1 than in Group 2 (mean ± SD: 25 ± 16 versus 54 ± 30 h; P < 0.05).

Conclusions: Sevoflurane reduces production of TNF-α more than total intravenous anaesthesia with midazolam–sufentanil during cardiac surgery. This may reduce cardiac morbidity and the length of stay in the intensive care unit.

Summary

Background and objective: In a retrospective study, we examined the suitability of a departmental clinical protocol for anaesthesia induction with target-controlled infusion of propofol developed for fibreoptic intubation in spontaneously breathing patients scheduled for outpatient oral surgery at the dental clinic of the Vienna University Hospital.

Methods: Propofol was administered using target-controlled infusion (Diprifusor®) at increasing target plasma concentrations starting at 2.5 μg mL−1. After 10 min, an intravenous dose of alfentanil (5–10 μg kg−1) was given for pain reduction. After a further 2 min, the patient was evaluated for response to auditory stimulation. If unresponsive, fibreoptic intubation was performed, otherwise the target concentration was increased by 0.2 μg mL−1 every 2 min until non-responsiveness was attained.

Results: Tracheal intubation was successful in all patients without any haemodynamic instability. However, one patient required facemask ventilation for 2 min. No patient was aware of intubation. The plasma concentration required for non-responsiveness was 2.8 ± 0.4 μg mL−1 (mean ± SD).

Conclusions: When using a target-controlled infusion of propofol, fibreoptic intubation can be performed with complete amnesia of the procedure for the patient. However, assisted ventilation of the lungs may be necessary as spontaneous ventilation may cease.

Reports about post-operative infections associated with the use of propofol prompted us to investigate the in-use contamination of lipid-formulated intravenous (i.v.) anaesthetics used for general anaesthesia or for sedation of intensive care patients in this department. The level and incidence of extrinsic contamination of propofol (‘Diprivan’) and of another intravenous anaesthetic, etomidate, formulated in lipid solution (‘Etomidat-lipuro’) was found to be low during two study periods. However, the need to observe strict aseptic precautions in handling these intravenous drugs must be emphasized.

Summary

Background and objective: The expression of P-selectin on the surface of platelets and platelet–leucocyte conjugate formation are considered to be an indicator of platelet activation in thrombotic and inflammatory disease. Midazolam is a widely used sedative and anaesthetic induction agent. It may inhibit platelet aggregation and suppress interleukin-6 and -8 response in human leucocytes, but any effect on the adhesion of activated platelets to leucocytes remains obscure. We have examined the influence of midazolam on adenosine diphosphate (ADP)-induced platelet surface P-selectin expression and platelet–leucocyte aggregation in whole blood.

Methods: Human whole blood was stimulated with 2 × 10−5M ADP in the presence of midazolam (3 × 10−4 to 3 × 10−6M). Samples were stained with a fluorochrome-conjugated CD62P and CD41a antibody for detecting human platelet P-selectin antigens. The leucocyte subpopulations were separately gated and platelet–leucocyte aggregates were defined as cells found positive for CD45 and CD62P. All samples were analysed and were electronically separated into specific cell types (platelets, neutrophils, monocytes and lymphocytes) according to their typical forward/side scattering by flow cytometry.

Results: Midazolam significantly inhibited ADP-induced platelet P-selectin expression and attenuated platelet–leucocyte aggregation (mainly in neutrophils and monocytes) in a dose-dependent manner with a maximum inhibitory effect at 3 × 10−4M (P < 0.01).

Conclusions: This study demonstrated that midazolam decreases the ADP-induced expression of platelet surface P-selectin and platelet–leucocyte aggregation.

Background and objective: Myocardial ischaemic preconditioning is characterized by a reduction in the rate of glycolysis. Brief myocardial ischaemia also reduces the glycogen content of the heart. The first objective was to determine whether augmenting glucose oxidation by activation of the pyruvate dehydrogenase complex would prevent the infarct limitation of ischaemic preconditioning. The second part of the study evaluates whether glycogen depletion before ischaemia mimics the infarct-limiting effect of ischaemic preconditioning.

Methods: Dichloroacetate (300 + 150 mg kg−1), an activator of the pyruvate dehydrogenase complex, was administered intravenously in the anaesthetized open-chest rabbit. All animals underwent 45 min of regional ischaemia and 3 h of reperfusion. Ischaemic preconditiong was elicited by 5 min of coronary occlusion. Control rabbits, those with ischaemic preconditioning with no dichloroacetate, received a saline vehicle. An isolated perfused rabbit heart model was employed to test the second hypothesis. Hearts were depleted of glycogen by perfusing them with a substrate-free buffer. Infarction was assessed by triphenyl tetrazolium chloride and area at risk determined with fluorescent particles.

Results: (a) Pyruvate dehydrogenase complex activation experiments. Treatment with dichloroacetate alone did not alter infarct size (58 ± 7% control vs. 60 ± 5% dichloroacetate). Addition of dichloroacetate did not attenuate the infarct-limiting effect of ischaemic preconditioning as evidenced by a similar reduction in infarct size in the ischaemic preconditioning group (22 ± 5%) and in the ischaemic preconditioning + dichloroacetate group (27 ± 7%). (b) Glycogen depletion experiments. Compared with control hearts with a normal glycogen content (4.84 ± 0.15 mg g−1 wet weight), glycogen depleted and ischaemic preconditioning hearts had reduced glycogen content before ischaemia (2.15 ± 0.26, 1.62 ± 0.17 mg g−1 wet weight, respectively; P < 0.01). Glycogen depletion did not reduce infarct size: 25.0 ± 4.5% cf. 27.9 ± 3.4% in the control group. However, ischaemic preconditioning resulted in a significant reduction of infarct size (11.5 ± 2.3% vs. 27.9 ± 3.4% control; P < 0.01).

Conclusions: Augmentation of oxidative glycolysis by dichloroacetate in in situ rabbit hearts does not alter the effect of ischaemic preconditioning, and glycogen depletion in the isolated rabbit heart does not influence infarct size after subsequent coronary occlusion.

Ninety patients undergoing scheduled upper limb orthopaedic surgery were studied to determine the optimal anaesthetic dose using the ‘orthogonal two-needle technique’. The patients were randomly assigned to one of three groups to receive one of three different volumes (20, 30 and 40mL) (n = 30) of anaesthetic solution (a mixture of equal parts of 0.5% bupivacaine with adrenaline 1:200 000 and 2% lignocaine). A significant correlation was found between the volume injected and the anaesthetic spread for all tested areas. A better analgesic spread to all the major branches of the plexus was obtained when increased volumes of anaesthetic solution were injected. The comparisons between the 20 mL group and the other two groups are significant in all the tested areas, as well as the comparisons between 30 and 40 mL groups in the areas innervated by radial and musculo-cutaneous nerves. Only the area innervated by the axillary nerve showed a weaker volume-analgesia relation, confirming the elusiveness of this area to anaesthesia in the axillary approaches. The improved results observed using greater amounts of anaesthetic solution might result from a higher intrasheath pressure with disruption of sheath septa, or from a greater availability of drug for all the terminal branches of brachial plexus, or both.

Summary

Background and objective: Differences in sensitivity to anaesthetic drugs may exist among human races. Allelic variants for drug metabolizing isoenzymes and other pharmacokinetic/pharmacodynamic differences may account for a variable response to anaesthetic drugs. This study was designed to investigate comparatively the anaesthetic requirements and the recovery trends of three different ethnic groups: Caucasians, African blacks and Brazilians.

Methods: The anaesthetic depth and recovery of groups of 45 patients undergoing total intravenous anaesthesia with propofol and fentanyl were compared. The bispectral index and clinical parameters were used to assess the depth of anaesthesia. The bispectral index, the response to verbal stimuli and the eye opening time were used to assess recovery.

Results: After stopping propofol, the bispectral index values of Caucasians returned to the baseline in about 10.8 ± 4 min, that of Kenyan African blacks in 18 ± 7 min and that of Brazilians in a highly variable time ranging from 5 to 25 min, (14.9 ± 9.9). The time from discontinuation of propofol and fentanyl infusion to eye opening was 18.8 ± 7.1 min in African blacks (P < 0.01) and 13.5 ± 8.8 min in Brazilians (P > 0.05) vs. 11.6 ± 4.5 min in Caucasians. Time to respond to verbal commands was 16.8 ± 8 min in African blacks (P < 0.01) and 12.8 ± 8.1 min in Brazilians (P > 0.05) vs. 9.9 ± 4.5 min in Caucasians.

Conclusions: The recovery of Kenyan African blacks from anaesthesia with propofol and fentanyl is much slower, in comparison with Caucasians. The recovery time of Brazilians is much more variable, in comparison with Caucasians.

Summary

Background and objective: To evaluate the effects of pneumoperitoneum and the reverse Trendelenburg position on respiratory mechanics and blood-gases in morbid obese patients with chronic obstructive pulmonary disease and hypertension.

Methods: Sixteen morbid obese patients with chronic obstructive pulmonary disease and hypertension were studied. Mean arterial pressure, heart rate, respiratory resistance, dynamic respiratory compliance and peak inspiratory pressures were measured at four time points: 5 min after induction of anaesthesia (T1), 5 min after insufflation of the peritoneum (T2), 5 min after adoption of a 20° reverse Trendelenburg position (T3), and 5 min after deflation of the peritoneum (T4). Arterial blood-gas status was measured at the same measuring points.

Results: Respiratory compliance was 40 ± 12, 28 ± 8, 32 ± 8 and 37 ± 11 mL cmH2O−1 in T1, T2, T3 and T4, respectively. The changes were significant at T2, T3 and T4. Airway resistance and peak inspiratory pressures showed comparable changes throughout the study with that of respiratory compliance. Haemodynamic measurements showed no clinically significant changes in this study.

Conclusions: In morbid obese patients with chronic obstructive pulmonary disease and hypertension, a 20° reverse Trendelenburg position improved respiratory mechanics and oxygenation without any apparent adverse effects on haemodynamics during laparoscopic gastric banding surgery.

Summary

Background and objective: Trazodone hydrochloride is used in the treatment of neuropathic pain. However, the analgesic effects of trazodone on neuropathic pain are controversial. The study was undertaken to determine the analgesic effect of trazodone on a chronic constriction injury model.

Methods: We tested the effect of trazodone on thermal hyperalgesia due to a chronic constriction injury of the sciatic nerve in rats and examined the effects of lesions in the descending and ascending serotonergic system induced by 5,7-dihydroxytriptamine (5,7-DHT).

Results: The analgesic effects of trazodone showed a clear dose dependency. Furthermore, the analgesic effect of trazodone was observed in rats injected with 5,7-DHT into the dorsal raphe nucleus and medial raphe nucleus.

Conclusions: The results suggest that a mainly serotonergic descending pain control pathway mediates the analgesic effects of trazodone.