Background and objective Numerous drugs have been used to prevent or to treat opioid-induced pruritus in the surgical setting. Their relative efficacy is not well understood.

Methods The methods employed involved the systematic search (MEDLINE, EMBASE, Cochrane library, bibliographies, without language restriction, up to June 2000) for full reports of randomized comparisons of any intervention which is thought to be anti–pruritic (active) compared with placebo or no treatment (control) in surgical (including labour) patients receiving opioids. The number of patients who had no pruritus were analysed using relative risk and number–neededto– treat with 95% confidence interval.

Results Twenty-two trials (1477 patients) were analysed. Two trials (66 patients), both with low-dose propofol, were on treatment of established pruritus; propofol had no anti-pruritic effect compared with Intralipid. In prophylaxis trials, the average incidence of pruritus with control was 59% (range, 10% to 100%). Most mu–receptor antagonists were efficacious: intravenous naloxone 0.25–2.4 μgkg−1 h−1, relative risk 2.31 (95% confidence interval, 1.5 to 3.54), numberneeded– to–treat to prevent pruritus compared with control 3.5; oral naltrexone 9 mg, relative risk 2.80 (1.35–5.80), number-needed-to-treat 1.7; naltrexone 6mg was less effective and 3mg did not work; different intravenous and epidural nalbuphine regimens, relative risk 1.71 (1.12–2.62), number-needed-to-treat 4.2. Intravenous nalmefene 0.5 or 1mg was not antipruritic. Intravenous (but not epidural) droperidol 2.5mg was efficacious, relative risk, 1.71 (1.28–2.29), number-needed-to-treat 4.9. There was a lack of evidence for any anti–pruritic efficacy with prophylactic propofol, epidural or intrathecal epinephrine, epidural clonidine, epidural prednisone, intravenous ondansetron, or intramuscular hydroxyzine.

Conclusion Naloxone, naltrexone, nalbuphine and droperidol are efficacious in the prevention of opioidinduced pruritus; minimal effective doses remain unknown. There is a lack of valid data on the efficacy of interventions for the treatment of established pruritus.

Background and objective Late postoperative hypoxaemia after upper abdominal surgery is common even among cardiopulmonary healthy patients. Atelectasis may develop after intubation and persist into or reveal a disposition for atelectasis in the postoperative period. Positive end–expiratory pressure (PEEP) eliminates peroperative atelectasis but the effect on perioperative oxygenation is controversial. This study evaluated the effect of peroperative PEEP optimized pulmonary compliance on perioperative oxygenation and complications.

Methods Forty patients assessed by electrocardiography, spirometry, functional residual capacity and diffusion capacity were randomly assigned to receive positive end–expiratory pressure (PEEP) or zero endexpiratory pressure (ZEEP) during surgery. PaO2, SPO2 and complications in the postoperative period were evaluated without knowledge of peroperative PEEP or ZEEP application.

Results Peroperative arterial oxygenation improved for all patients receiving PEEP, mean 2.1 kPa (0.7–3.5 kPa). There was no difference in postoperative median PaO2 between the groups. The differences in the incidence of late prolonged postoperative hypoxaemia and complications were 25% (−5% to 55%) and −1% (−31% to 29%) between the ZEEP and the PEEP group, but were not statistically significant.

Background and objective The objective of this study was to determine the dose as well as the duration of exposure–dependent effects of methohexital on neutrophil [polymorphonuclear leucocyte (PMN)] free amino acid profiles and, in a parallel study, on PMN immune functions.

Methods Whole blood samples were taken from 20 volunteers and incubated with methohexital [0 (control), 3.6, 26, 130 and 260 μgmL−1] for 10, 30, 60 or 120 min. PMN amino acid profiles were documented using advanced PMN separation and highperformance liquid chromatography procedures. Superoxide anion (O2−) and hydrogen peroxide production (H2O2), and activity of released myeloperoxidase (MPO), were determined photometrically.

Results After methohexital, significant dose (≥26 μg mL−1) as well as duration of exposure–dependent (≥30 min) increases in histidine, isoleucine, leucine, valine, methionine, serine, glycine, threonine, and decreases in glutamine, glutamate, aspartate, asparagine, arginine, ornithine, citrulline, alanine and taurine were observed (P ≤0.05). Concerning PMN immune functions, methohexital significantly decreased O2−, H2O2 formation and MPO (≥26 μgmL−1, ≥30 min, P≤0.05).

Conclusions Altogether, there is significant relevance to the pharmacological regimens which enhance the supply of methohexital in whole blood. In regards to our results, we suggest that considerable changes in PMN ‘dynamic free amino acid pool’, for example induced by methohexital, may be one of the determinants in cell nutrition adversely affecting PMN metabolism. It is partially through its effect on the PMN free amino acid pool that maleficent pharmacological stress may have an unintentional influence on PMN immune functions.

Background and objective The γ1-aminobutyric acidA receptor (GABAAR) is a target for anaesthetic agents. We investigated the interactions of sevoflurane with a recombinant GABAAR. Emphasis was on the mechanism of block, as relevant open-channel block by a volatile anaesthetic would possibly explain prolonged GABAergic postsynaptic currents.

Methods The effect of sevoflurane on GABA–induced currents through recombinant α1β1γ1 GABAAR channels was studied (patch clamp; HEK293 cells). GABA 0.01mM or 1mM was applied alone or together with sevoflurane (0.05mM to 5mM).

Results Currents elicited by GABA 0.01mM were increased by low sevoflurane concentrations to 183% and decreased by high sevoflurane concentrations (> 1mM) to 34% (P < 0.05). Ten- to 90%-rise times of the currents were reduced by sevoflurane concentration dependently. At GABA (1mM), peak currents and 10–90%-rise times decreased with increasing sevoflurane concentrations. A transient current increase was induced by discontinuation of GABA and sevoflurane. Such rebound currents indicate a reversal of an openchannel block by sevoflurane.

Conclusions Sevoflurane (a) increases the apparent affinity of GABA to the GABAAR, as suggested by the decreased current rise times. This explains the enhancement of the currents induced by low GABA concentrations (0.01mM). Additionally, sevoflurane (b) induces a picrotoxin-like open-channel block at the GABAAR. The reversal of the open-channel block elicits a delayed GABA response. These findings indicate at least two different sites of action of sevoflurane at this receptor that are both important for an enhanced GABAergic synaptic transmission.

Background and objective Situations may occur in anaesthetic practice where the use of neuromuscular blocking drugs is unsuitable or contraindicated. We investigated the use of propofol given 5 min after fentanyl to permit endotracheal intubation in children. Methods We studied the intubating conditions and cardiovascular parameters in 60 ASA I and II children. Intravenous midazolam (0.1mgkg−1) was given as premedication 5 min before the induction of anaesthesia. The children received different doses of propofol (group I, 2.5mgkg−1; group II, 3.0mgkg−1; group III, 3.5mgkg−1) preceded by fentanyl (3.0 μgkg−1) given 5 min earlier. No neuromuscular blocking agents were administered. The intubating conditionswere assessed using a four-point scoring system based on the degree of difficulty of laryngoscopy, the position of vocal cords and the intensity of coughing.

Results Tracheal intubating conditions were adequate in 20% of the patients in group I, in 75% of the patients in group II and in 80% of the patients in group III (P < 0.05 for group I vs. groups II and III). Haemodynamic changes were not significantly different between the groups.

Conclusions Propofol (3.0mgkg−1) preceded by fentanyl (3.0 μgkg−1) was adequate for the induction of anaesthesia in children and provided adequate tracheal intubating conditions without significant haemodynamic changes. This method represents a useful alternative technique for tracheal intubation when neuromuscular blocking drugs are contraindicated or should be avoided.

Background and objective Efficacy and side–effects of piritramide (pirinitramide) and morphine, given intravenously for postoperative analgesia after hysterectomy, were compared in a randomized controlled double-blind trial in 92 ASA class I–III patients.

Methods Administration was investigator–controlled during the first 90 min and subsequently via a patientcontrolled device. Visual analogue scales for pain intensity and verbal rating scales for side-effects were taken repeatedly.

Results Median visual analogue scores for pain intensity on a 100-mm scale 4, 8 and 24 h after surgery were 10, 8.5 and 5mm in the piritramide group and 18, 10 and 8.5mm in the morphine group. These differences are neither statistically nor clinically significant. Median values for nausea on a verbal rating scale from 0 to 3 were zero for both groups at all times with similar ranges. There was no difference in number of episodes of vomiting and retching and usage of antiemetics. The mean amount of piritramide used for initial titration was 15.2 mg; the respective amount of morphine was 15.4 mg.

Conclusions In this setting the two agents are equally effective and show a similar profile of sideeffects.

Background and objective Few and conflicting data are available regarding the changes of plasma potassium concentration during acute respiratory acidosis in human beings. This study compares the acute changes in plasma potassium concentration in acutely hypercapnic patients and in non–hypercapnic patients during general anaesthesia.

Methods Thirty-three patients undergoing interventional rigid bronchoscopy were studied. Ventilation of the lungs was randomly conducted using either spontaneous–assisted ventilation or intermittent negative–pressure ventilation. All patients received the same anaesthetic protocol. Arterial blood gases and osmolality, and plasma concentrations of glucose, sodium, potassium and chloride were measured.

Results Intraoperatively, PaCO2 was higher during spontaneous-assisted ventilation than during intermittent negative-pressure ventilation (9±1.8 vs. 5.4±1.2 kPa, P < 0.001) and the pH was also lower during spontaneous-assisted ventilation than during intermittent negative-pressure ventilation (7.24±0.07 vs. 7.4 ±0.08, P < 0.001). Plasma potassium concentration remained similar in both groups (3.8± 0.2mmolL−1 with spontaneous–assisted ventilation vs. 3.7± 0.4mmol L−1 with intermittent negativepressure ventilation).

Conclusion Acute respiratory acidosis does not affect plasma potassium concentration.

Background and objective Pressure-controlled inverse ratio ventilation was compared with controlled mechanical ventilation in patients after cardiac surgery.

Methods Ten patients were ventilated after sternal closure using a Siemens Servo 900C ventilator to a target end–tidal PCO2 of 4.0 kPa. They were randomized to receive controlled mechanical ventilation or pressure–controlled inverse ratio ventilation. CO2-based data were recorded on a laptop personal computer, which together with arterial PCO2 permitted measurement of the respiratory dead space. Once measurements were complete the ventilator was switched to the other mode and new measurements taken. Results PaCO2 and VCO2 were virtually the same in both modes. Peak airway pressure (17.2±2.7 vs. 20.8±2.5 cmH2O, P < 0.01) and minute ventilation (4.9±1.1 vs. 5.3±1.1 cmH2O, P < 0.01) were less during pressure–controlled inverse ratio ventilation. Physiological dead space fraction (0.39±0.06 vs. 0.51±0.05, P <0.001), airway dead space (56±15 vs. 81±15 mL, P <0.001) and alveolar dead space fraction (0.25±0.07 vs. 0.31±0.09, P<0.01) were all less during pressure–controlled inverse ratio ventilation. There were no differences in heart rate or mean arterial pressure.

Conclusions The prolonged inspiratory period and pressure–controlled flowpattern of pressure–controlled inverse ratio ventilation reduce the alveolar and airway dead spaces, and give lower peak airway pressures, compared with conventional ventilation, in cardiac surgical patients.

A 51-year-old man presented with a right upper lobe adenocarcinoma with carinal extension. He underwent a right sleeve pneumonectomy, which involved a carinal resection with anastomosis between the trachea and left main bronchus. This report describes the successful use of jet ventilation, administered via the lumen of the bronchial blocker of a Univent tube. During 15 min of carinal resection, oxygenation of his left lung was maintained with the bronchial blocker bridging the airway discontinuity.

A 41-year-old multigravida presented at 32 weeks of gestation with polyhydramnios and an anencephalic fetus. Abnormal bleeding as a result of disseminated intravascular coagulation complicated an emergency Caesarean section for severe abdominal pain thought to be due to uterine rupture. Massive transfusion with blood products was necessary and the abdomen packed to control bleeding. The patient was transferred to the intensive care unit where she made a slow but complete recovery. Amniotic fluid embolism with atypical presentation of isolated coagulopathy is the likely diagnosis in this case. The case serves to demonstrate that amniotic fluid embolism may present with symptoms and signs other than the classical pattern of dyspnoea, cyanosis and hypotension.