Progressive changes in arterial oxygenation during one-lung anaesthesia are related to the response to compression of the non-dependent lung

Background. Arterial oxygenation can change during one-lungventilation for reasons that are not fully understood. Methods. We studied patients during anaesthesia and one-lungventilation, with an inspiratory oxygen fraction of 0.8. Arterialblood gas values were recorded every 10 s with a continuousintra-arterial sensor. The non-dependent lung was compressedseveral times during the surgical procedure, using a retractor.The change in Pa_O2 during and after compression of the non-dependentlung was measured. Results. Pa_O2 increased significantly when the non-dependentlung was compressed, and decreased when the compression wasreleased. The first compression of the non-dependent lung transientlyincreased Pa_O2, but the effect of the second compression onoxygenation was more marked and persistent. Pa_O2 increased bymore than 13 kPa at 10 min after the second compression in fourpatients (responder group). Arterial oxygenation improved markedlyin patients in this group during the surgical procedure. Conclusion. Oxygenation can improve during one-lung ventilationin some patients. This improvement is partly related to a markedincrease in Pa_O2 during compression of the non-dependent lung. Br J Anaesth 2003; 90: 21–6     

Nitric oxide and liver microcirculation during autoregulation and haemorrhagic shock in rabbit model

Background. Direct evidence of nitric oxide (NO) involvementin the regulation of hepatic microcirculation is not yet availableunder physiological conditions nor in haemorrhagic shock. Methods. A laser Doppler flowmetry was used to measure liverperfusion index and a specific NO-sensitive electrode was insertedinto liver parenchyma of anaesthetized rabbits. Hepatic autoregulationduring moderate hypovolaemia {mean arterial pressure at 50 mmHg without liver perfusion alteration; blood withdrawal 17.7(4.2) ml [mean (SD)]} or haemorrhagic shock [mean arterial pressureat 20 mm Hg associated with liver perfusion impairment and lacticacidosis; blood withdrawal 56.0 (6.8) ml] were investigatedover 60 min and were followed by a rapid infusion of the shedblood. Involvement of NO synthases was evaluated using a non-specificinhibitor, NAPNA (N-nitro-L-arginine P-nitro-anilide). Results. In the autoregulation group, a decrease [30.0 (4.0)mm Hg] of mean arterial pressure did not alter liver perfusionindex, whereas the liver NO concentration increased and reacheda plateau [125 (10)%; compared with baseline; P<0.05]. ThisNO concentration was reduced to zero by the administration ofNO synthase inhibitor. Haemorrhagic shock led to a rapid decreasein liver perfusion index [60 (7)%; compared with baseline; P<0.05]before an immediate and continuous increase in NO concentration[250 (50)%; compared with baseline; P<0.05]. Infusion ofNO inhibitor before haemorrhagic shock reduced the NO concentrationto zero and hepatic perfusion by 60 (8)% (P<0.05) of thebaseline. Mean arterial pressure increased simultaneously. Inthese animals, during haemorrhage, a continuous increase inNO concentration still occurred and liver perfusion slightlyincreased. In all groups but NAPNA+haemorrhagic shock, bloodreplacement induced recovery of baseline values. Conclusions. NO plays a physiological role in the liver microcirculationduring autoregulation. Its production is enzyme-dependent. Conversely,haemorrhagic shock induces a rapid increase in hepatic NO thatis at least partially enzyme-independent.     

Liver tissue partial pressure of oxygen and carbon dioxide during partial hepatectomy

Background. Data on tissue oxygen partial pressure (Pt_O2) andcarbon dioxide partial pressure (Pt_CO2) in human liver tissueare limited. We set out to measure changes in liver Pt_O2 andPt_CO2 during changes in ventilation and a 10 min period of ischaemiain patients undergoing liver resection using a multiple sensor(Paratrend^® Diametrics Medical Ltd, High Wycombe, UK). Methods. Liver tissue oxygenation was measured in anaesthetizedpatients undergoing liver resection using a sensor insertedunder the liver capsule. Pt_O2 and Pt_CO2 were recorded with FI_O2values of 0.3 and 1.0, at end-tidal carbon dioxide partial pressuresof 3.5 and 4.5 kPa and 10 min after the onset of liver ischaemia(Pringle manoeuvre). Results. Data are expressed as median (interquartile range).Increasing the FI_O2 from 0.3 to 1.0 resulted in the Pt_O2 changingfrom 4.1 (2.6–5.4) to 4.6 (3.8–5.2) kPa, but thiswas not significant. During the 10 min period of ischaemia Pt_CO2increased significantly (P<0.05) from 6.7 (5.8–7.0)to 11.5 (9.7–15.3) kPa and Pt_O2 decreased, but not significantly,from 4.3 (3.5–12.0) to 3.3 (0.9–4.1) kPa. Conclusion. Pt_O2 and Pt_CO2 were measured directly using a Paratrend^®sensor in human liver tissue. During anaesthesia, changes inventilation and liver blood flow caused predictable changesin Pt_CO2. Br J Anaesth 2004; 92: 735–7     

Changes in apparent systemic clearance of propofol during transplantation of living related donor liver

Background. Propofol is used during living-related donor livertransplantation because its metabolism is not greatly affectedby liver failure. However, the pharmacokinetics of propofolduring liver transplantation have not been fully defined. Thepurpose of this study was to evaluate the apparent systemicclearance of propofol during the dissection, anhepatic and reperfusionphases of living-related donor liver transplantation, and toestimate the role of the small intestine and lung as extrahepaticsites for propofol disposition. Methods. Ten patients scheduled for living-related donor livertransplantation were enrolled in the study. Anaesthesia wasinduced with vecuronium 0.1 mg kg^–1 and propofol 2 mgkg^–1, and then maintained by 60% air, 0.5–1.5% isofluranein oxygen and a constant infusion of propofol at 2 mg kg^–1h^–1. Apparent systemic clearance during the dissection,anhepatic and reperfusion phases was calculated from the pseudo-steady-stateconcentration for each phase. Disposition in the small intestinewas determined by measuring arteriovenous blood concentrationin 10 liver transplantation donors. Pulmonary disposition wasdetermined by measuring the arteriovenous blood concentrationin 10 recipients during the anhepatic phase. The data are expressedas mean (SD). Results. Apparent systemic clearances in the dissection, anhepaticand reperfusion phases were 1.89 (SD 0.48) litre min^–1,1.08 (0.25) litre min^–1 and 1.53 (0.51) litre min^–1,respectively. The concentration of propofol in the portal veinwas lower than in the radial artery. The intestinal extractionratio calculated from the concentration in the radial arteryand portal vein was 0.24 (0.12). There were no significant differencesin propofol concentrations between the radial and pulmonaryarteries. Conclusion. Apparent systemic clearance was decreased by     

Effects of Pringle manoeuvre and ischaemic preconditioning on haemodynamic stability in patients undergoing elective hepatectomy: a randomized trial

Background. The Pringle manoeuvre and ischaemic preconditioningare applied to prevent blood loss and ischaemia-reperfusioninjury, respectively, during liver surgery. In this prospectiveclinical trial we report on the intraoperative haemodynamiceffects of the Pringle manoeuvre alone or in combination withischaemic preconditioning. Methods. Patients (n=68) were assigned randomly to three groups:(i) resection with the Pringle manoeuvre; (ii) with ischaemicpreconditioning before the Pringle manoeuvre for resection;(iii) without pedicle clamping. Results. Following the Pringle manoeuvre the mean arterial pressureincreased transiently, but significantly decreased after unclampingas a result of peripheral vasodilation. Ischaemic preconditioningimproved cardiovascular stability by lowering the need for catecholaminesafter liver reperfusion without affecting the blood sparingbenefits of the Pringle manoeuvre. In addition, ischaemic preconditioningprotected against reperfusion-induced tissue injury. Conclusions. Ischaemic preconditioning provides both betterintraoperative haemodynamic stability and anti-ischaemic effectsthereby allowing us to take full advantage of blood loss reductionby the Pringle manoeuvre.     

Probable allergic reaction to cyclosporin and early formation of thrombi on a pulmonary artery catheter: two unusual complications during bilateral lung transplantation

We describe a patient who had two rare complications (a probableallergic reaction to cyclosporin and the early formation ofa right atrial thrombus) during bilateral sequential singlelung transplantation performed under the one anaesthetic. Thethrombus, discovered at the end of the procedure, was then removedunder cardiopulmonary bypass. Peroperative transoesophagealechocardiography was useful in providing critical diagnosticand therapeutic information. Br J Anaesth 2002; 89: 930–3     

Effect of intrathecal tramadol administration on postoperative pain after transurethral resection of prostate

Background. Tramadol administered epidurally has been demonstratedto decrease postoperative analgesic requirements. However, itseffect on postoperative analgesia after intrathecal administrationhas not yet been studied. In this double-blind, placebo-controlledstudy, the effect of intrathecal tramadol administration onpain control after transurethral resection of the prostate (TURP)was studied. Methods. Sixty-four patients undergoing TURP were randomizedto receive bupivacaine 0.5% 3 ml intrathecally premixed witheither tramadol 25 mg or saline 0.5 ml. After operation, morphine5 mg i.m. every 3 h was administered as needed for analgesia.Postoperative morphine requirements, visual analogue scale forpain at rest (VAS) and sedation scores, times to first analgesicand hospital lengths of stay were recorded by a blinded observer. Results. There were no differences between the groups with regardto postoperative morphine requirements (mean (SD): 10.6 (7.9)vs 9.1 (5.5) mg, P=0.38), VAS (1.6 (1.2) vs 1.2 (0.8), P=0.18)and sedation scores (1.2 (0.3) vs 1.2 (0.2), P=0.89). Timesto first analgesic (6.3 (6.3) vs 7.6 (6.2) h, P=0.42) and lengthof hospital stay (4.7 (2.8) vs 4.4 (2.2) days, P=0.66) weresimilar in the two groups. Conclusion. Intrathecal tramadol was not different from salinein its effect on postoperative morphine requirements after TURP. Br J Anaesth 2003; 91: 536–40     

Detection of cerebral hypoperfusion with bispectral index during paediatric cardiac surgery

Background. The bispectral index (BIS) may indicate changesin cerebral activity when the cerebral circulation is affectedby acute hypotension. Methods. We measured BIS and cerebral haemoglobin saturation(Sr_O2) by near-infrared spectroscopy in 10 children undergoingcardiac surgery. Results. We noted 14 episodes of simultaneous decreases in Sr_O2and BIS during acute hypotension in five children. An acutedecrease in BIS, which coincided with a decrease in Sr_O2 suggestinga reduction in cerebral blood flow, was associated with acuteslowing of the raw EEG waveforms. Conclusions. Our findings suggest that an acute decrease inBIS during acute hypotension indicates cerebral hypoperfusion,and that cerebral hypoperfusion caused by hypotension may occurfrequently during paediatric cardiac surgery. Br J Anaesth 2003; 90: 694–8     

Efficacy of intravenous magnesium in neuropathic pain

Background. Postherpetic neuralgia is a complication of acuteherpes zoster characterized by severe pain and paraesthesiain the skin area affected by the initial infection. There isevidence that the N-methyl-D-aspartate receptor is involvedin the development of hypersensitivity states and it is knownthat magnesium blocks the N-methyl-D-aspartate receptor. Method. A double-blind, placebo-controlled, cross-over studywas conducted in which magnesium sulphate was administered asan i.v. infusion. Spontaneous pain was recorded and qualitativesensory testing with cotton wool was performed in seven patientswith postherpetic neuralgia before and after the i.v. administrationof either magnesium sulphate 30 mg kg^–1 or saline. Results. During the administration, pain scores were significantlylower for magnesium compared with placebo at 20 and 30 min (P=0.016)but not at 10 min. I.V. magnesium sulphate was safe, well-toleratedand effective in patients with postherpetic neuralgia. Conclusion. The present study supports the concept that theN-methyl-D-aspartate receptor is involved in the control ofpostherpetic neuralgia. Br J Anaesth 2002; 89: 711–14     

Adjunctive analgesia with intravenous propacetamol does not reduce morphine-related adverse effects

Background. Propacetamol is widely used in the management ofpostoperative pain. It decreases morphine requirements but itseffect on the incidence of morphine-related adverse effectsremains unknown. Methods. Patients (550) were randomly assigned to receive propacetamolor a placebo over the first 24 h after operation in a blindedstudy. Intravenous morphine titration was performed, after whichmorphine was administered s.c. every 4 h according to theirpain score. Pain was assessed using a visual analogue scale(VAS). The primary end-point was the incidence of morphine-relatedadverse effects. The main secondary end-points were morphinerequirements and VAS score. Results. After morphine titration, the VAS score and the numberof patients with pain relief did not differ between groups.Morphine requirements were decreased in the propacetamol group(21 vs 14.5 mg, P<0.001) but the incidence of morphine-relatedadverse effects did not differ between groups (42 vs 46%, notsignificant). In patients with moderate pain (n=395), morphinerequirements decreased by 37% (P<0.001) and the percentageof patients requiring no morphine was greater (21 vs 8%, P=0.002)in the propacetamol group. In patients with severe pain (n=155),morphine requirements decreased by 18% (P=0.04) in the propacetamolgroup and the number of patients who did not require morphine(3 vs 8%) did not differ significantly. Conclusions. Although propacetamol induced a small morphine-sparingeffect, it did not change the incidence of morphine-relatedadverse effects in the postoperative period. Moreover, no benefitcould be demonstrated in patients with severe postoperativepain. Br J Anaesth 2003; 90: 314–19     

Endotoxaemia during left ventricular assist device insertion: relationship between risk factors and outcome

Background. Endotoxaemia, caused by splanchnic ischaemia duringsurgery, is believed to trigger systemic inflammation and causepostoperative organ dysfunction. A relationship between theplasma concentration of endotoxin during surgery and known riskfactors for postoperative morbidity and mortality (e.g. age,abnormal gastric tonometric variables) and adverse outcome aftersurgery has not been demonstrated. Methods. In a prospective study, the plasma concentration ofendotoxin was measured in 12 patients undergoing implantationof a left ventricular assist device. Automated air gastric tonometrywas performed in all patients. The relationship between plasmaendotoxin concentration, risk factors, and postoperative outcomewas explored. Results. Carbon dioxide gap increased from 0.7 (0.3) to 3.6(1.6) kPa at the end of surgery. Endotoxin was detected in oneof 12 patients at baseline and in nine of 12 patients at theend of surgery (P=0.003). A high plasma concentration of endotoxinat the end of surgery was associated with a higher carbon dioxidegap (r=0.59, P<0.05), and a higher postoperative multipleorgan dysfunction score (r=0.7, P=0.01). Conclusions. The finding of an association between high intraoperativeplasma concentrations of endotoxin, abnormal gastric tonometricvariables and adverse outcome supports the view that endotoxaemiais caused by gut hypoperfusion during surgery and is associatedwith postoperative organ dysfunction. Br J Anaesth 2004; 92: 131–3     

Patient well-being after general anaesthesia: a prospective, randomized, controlled multi-centre trial comparing intravenous and inhalation anaesthesia

Background. The aim of this study was to assess postoperativepatient well-being after total i.v. anaesthesia compared withinhalation anaesthesia by means of validated psychometric tests. Methods. With ethics committee approval, 305 patients undergoingminor elective gynaecologic or orthopaedic interventions wereassigned randomly to total i.v. anaesthesia using propofol orinhalation anaesthesia using sevoflurane. The primary outcomemeasurement was the actual mental state 90 min and 24 h afteranaesthesia assessed by a blinded observer using the AdjectiveMood Scale (AMS) and the State-Trait-Anxiety Inventory (STAI).Incidence of postoperative nausea and vomiting (PONV) and postoperativepain level were determined by Visual Analogue Scale (VAS) 90min and 24 h after anaesthesia (secondary outcome measurements).Patient satisfaction was evaluated using a VAS 24 h after anaesthesia. Results. The AMS and STAI scores were significantly better 90min after total i.v. anaesthesia compared with inhalation anaesthesia(P=0.02, P=0.05, respectively), but equal 24 h after both anaesthetictechniques (P=0.90, P=0.78, respectively); patient satisfactionwas comparable (P=0.26). Postoperative pain was comparable inboth groups 90 min and 24 h after anaesthesia (P=0.11, P=0.12,respectively). The incidence of postoperative nausea was reducedafter total i.v. compared with inhalation anaesthesia at 90min (7 vs 35%, P<0.001), and 24 h (33 vs 52%, P=0.001). Conclusion. Total i.v. anaesthesia improves early postoperativepatient well-being and reduces the incidence of PONV. Br J Anaesth 2003; 91: 631–7     

Comparison of isoflurane and propofol-fentanyl anaesthesia in a swine model of asphyxia

Background. There have been few studies comparing the responseto asphyxia and the effectiveness of typical cardiopulmonaryresuscitation (CPR) using exogenous epinephrine administrationand manual closed-chest compression between total intravenousanaesthesia (TIVA) and inhalational anaesthesia. Methods. Twenty pigs were randomly assigned to two study groupsanaesthetized using either 2% end-tidal isoflurane (n=10) orpropofol (12 mg kg^–1 h^–1)–fentanyl (50 µgkg^–1) (n=10). Asphyxia was induced by clamping the trachealtube until the mean arterial pressure (MAP) decreased to 40%of the baseline value (40% MAP time). The tracheal tube wasdeclamped at that point, and CPR was performed. Haemodynamicparameters and blood samples were obtained before the inductionof asphyxia, at 1-min intervals during asphyxia, and 1, 2, 3,5, 10, 30 and 60 min after asphyxia. Results. TIVA maintained the MAP against hypoxia–hypercapniastress significantly longer than isoflurane anaesthesia (mean(SD) 40% MAP time 498 (95) and 378 (104) s respectively). Inall animals in the isoflurane group, spontaneous circulationreturned within 1 min of the start of CPR. In six of the TIVAanimals, spontaneous circulation returned for 220 (121) s; spontaneouscirculation did not return within 5 min in the remaining fouranimals. Conclusions. Although TIVA is less prone than isoflurane anaesthesiato primary cardiovascular depression leading to asphyxia, TIVAis associated with reduced effectiveness of CPR in which resuscitationbecause of asphyxic haemodynamic depression occurs. Br J Anaesth 2003; 91: 871–7     

Effects of magnesium sulphate on cerebral haemodynamics in healthy volunteers: a transcranial Doppler study

Background. Magnesium is increasingly being considered as aneuroprotective agent. We aimed to study its effects on middlecerebral artery blood flow velocity (V_mca), cerebral autoregulationand cerebral vascular reactivity to carbon dioxide (CRCO₂) inhealthy volunteers. Methods. Fifteen healthy volunteers were recruited. Using transcranialDoppler ultrasonography, V_mca was recorded continuously. Thestrength of autoregulation was assessed by the transient hyperaemicresponse test, and the CRCO₂ was measured by assessing changesin V_mca to the induced changes in end-tidal carbon dioxide.I.V. infusion of magnesium sulphate was then started (loadingdose of 16 mmol followed by an infusion at the rate of 2.7 mmolh^–1) for 45 min. The cerebral haemodynamic variables weremeasured again near the end of the infusion of magnesium sulphate. Results. Total serum magnesium levels were doubled by the infusionregimen. However, there were no significant changes in V_mca,strength of autoregulation, or CRCO₂. Five of the volunteersreported marked nausea and two developed significant hypotensionduring the loading dose. Conclusions. Infusion of magnesium sulphate, in a dose thatdoubles its concentration in plasma, does not affect V_mca, strengthof autoregulation or CRCO₂ in healthy volunteers. However, itcan be associated with nausea and hypotension. Br J Anaesth 2003; 91: 273–5     

Does bispectral analysis of the electroencephalogram add anything but complexity?

Background. Analysis of the bispectrum of EEG waveforms is acomponent of the proprietary BIS index—a commonly usedcommercial monitor of depth of anaesthesia. Does the use ofthe bispectrum give more information about depth of anaesthesiathan the power spectrum? Methods. We collected and analysed EEG waveforms during inductionof general anaesthesia in 39 patients, comparing the changesin bispectral parameter (SynchFastSlow), with an analogous powerspectrum-based parameter (PowerFastSlow). Both compare the logarithmicratio of high frequency components (40–47 Hz) with thetotal (1–47 Hz). Because the changes in bispectrum areaffected by signal amplitude, we also calculated a third parameter(SFSbicoh) from the bicoherence, which is an amplitude-independentstatistic. Results. The SynchFastSlow and PowerFastSlow were correlated(r=0.84) and neither was superior in predicting the awake oranaesthetized state (area under receiver operating characteristiccurves = 0.85 vs 0.93). There was no change in the SFSbicohover the induction period, and it did not correlate with SynchFastSlow(r=0.07). Conclusions. We could not show that bispectral analysis gavemore information than power spectral-based analysis. Most ofthe changes in the bispectral values result from decreases inthe relative high frequency content of the EEG caused by anaesthesia. Br J Anaesth 2004; 92: 8–13     

Cerebral ischaemia during cardiac surgery in children detected by combined monitoring of BIS and near-infrared spectroscopy

Background. Children frequently suffer transient cerebral ischaemiaduring cardiac surgery. We measured cerebral ischaemia in childrenduring cardiac surgery by combining two methods of monitoring. Methods. We studied 65 children aged between 5 months and 17yr having surgery to correct non-cyanotic heart disease usinghypothermic cardiopulmonary bypass (CPB). During surgery, wemeasured the Bispectral Index (BIS) and regional cerebral haemoglobinoxygen saturation (Sr_O2) with near-infrared spectroscopy (NIRS).Cerebral ischaemia was diagnosed if both Sr_O2 and BIS decreasedabruptly when acute hypotension occurred. In each patient, therelationship between Sr_O2 and arterial blood pressure (AP) wasindicated by a plot of mean Sr_O2 against simultaneous mean AP. Results. We noted 72 episodes of cerebral ischaemia in 38 patients.Sixty-three ischaemic events were during CPB. Cerebral ischaemiawas less frequent in older patients. Cerebral ischaemia wasmore common and more frequent in children under 4 yr old. Haematocritduring CPB was lower and Sr_O2 was more dependent on AP in childrenunder 4 yr. Conclusions. Children less than 4 yr of age are more likelyto have cerebral ischaemia caused by hypotension during cardiacsurgery. Ineffective cerebral autoregulation and haemodilutionduring CPB may be responsible. Br J Anaesth 2004: 92: 662–9     

Stereoselective in vitro degradation pattern of mivacurium in human plasma

Background. Mivacurium is a mixture of three isomers, two ofwhich are rapidly broken down in vivo by plasma cholinesterases.This study investigates the stereospecificity of mivacuriumin vitro degradation to determine if it accounts for its invivo behaviour. Methods. The in vitro rate of degradation of each isomer ofmivacurium and the in vitro rate of formation of their primary(monoesters and alcohols) and secondary (alcohols) metaboliteswere examined using human plasma from six healthy volunteers.The in vitro rate of degradation of the monoester metaboliteswas also assessed. All these determinations were made usinga stereospecific high-performance liquid chromatography assay. Results. The in vitro rate of disappearance of the two activeisomers of mivacurium was very rapid, with mean values for thetrans trans and cis trans isomers of 0.803 and 0.921 min^–1respectively. These values are twofold faster than publishedin vivo data. The in vitro rate of disappearance was much slowerfor the cis cis isomer, with a mean value of 0.0106 min^–1.The cis trans isomer was converted exclusively to cis monoesterand trans alcohol, while only metabolites in the trans and cisconfiguration were found for the trans trans and cis cis isomersrespectively. Mean in vitro rates of disappearance for the transand cis monoester were 0.00750 and 0.000633 min^–1respectively. Conclusions. The in vitro rates of hydrolysis of the activeisomers of mivacurium confirm that plasma cholinesterases playa major role in their in vivo degradation, but that in vivoelimination is slowed by extravascular distribution. Mivacuriumhydrolysis is stereoselective, the ester group in the transconfiguration being more accessible to enzymatic attack. Thisstereoselective pattern, along with the relatively slow breakdownof the cis cis isomer, sheds light on the in vivo dispositionof the cis alcohol metabolite. Br J Anaesth 2002; 89: 832–8     

Assessment of preoperative fluid depletion using bioimpedance analysis

Background. Fluid depletion during the perioperative periodis associated with poorer outcome. Non-invasive measurementof total body water by bioimpedance may enable preoperativefluid depletion and its influence on perioperative outcome tobe assessed. Methods. Weight and foot bioimpedance were recorded under standardizedconditions in patients undergoing bowel preparation (n=43) orday surgery (n=44). Fifteen volunteers also followed standardnil-by-mouth instructions on two separate occasions to assessthe variabilities of weight and bioimpedance over time. Results. Body weight fell by 1.27 kg (95% CI 1.03–1.50kg; P<0.0001) and foot bioimpedance increased by 51 ohm afterbowel preparation (95% CI 36–66; P<0.0001). Weightchange after the nil-by-mouth period in day-surgery patients(mean –0.22 kg, 95% CI –0.05 to –0.47 kg;P=0.07) correlated (r=–0.46; P=0.005) with an increasein bioimpedance (16 ohms, 95% CI 5–27 ohms; P=0.01). Nodifference between two separate bioimpedance measurements wasseen in the volunteer group. Conclusions. Further work is warranted to determine if bioimpedancechanges may serve as a useful indicator of perioperative fluiddepletion. Br J Anaesth 2004; 92: 134–6     

Posture used by anaesthetists during laryngoscopy

Background. There is little advice on the posture to be usedwhen intubating the trachea. Does the stance used depend onexperience? Methods. Twenty-six subjects with varying experience of intubationwere photographed during laryngoscopy of an intubation trainingmannequin. Posture was measured from the photographs and thedata were analysed with the Mann–Whitney U-test. Results. The less experienced group had shallower lines of sight,levered more, and stood with their face closer to the mannequin(P=0.037, 0.018 and 0.06 respectively). Conclusions. Novice anaesthetists should be given explicit instructionson correct trolley height and should be taught to intubate witha straight back. Br J Anaesth 2002; 89: 772–4     

Double lumen tube location predicts tube malposition and hypoxaemia during one lung ventilation

Background. Poor positioning of an endobronchial double lumentube (DLT) could affect oxygenation during one lung ventilation(OLV). We set out to relate DLT position to hypoxaemia and DLTmisplacement during OLV. Methods. We recruited 152 ASA physical status I–II patientsabout to have elective thoracic surgery. The trachea was intubatedwith a left-sided DLT. Tube position was assessed by fibre-opticscope and correction was made after patient positioning andduring OLV. If Pa_O2 was less than 10.7 kPa, the DLT positionwas checked and then PEEP, continuous positive airway pressure(CPAP), oxygen insufflation, or two lung ventilation (TLV) weretried. Results. The DLT was found to be misplaced in 49 patients (32%)after patient positioning, and in 38 patients (25%) during OLV.PEEP to the dependent lung, CPAP or apneic oxygen insufflationto the non-dependent lung, or brief periods of TLV, were appliedin 46 patients (30%). Patients who had DLT malposition afterplacing the patient in the lateral position had a greater incidenceof DLT malposition during OLV (59 vs 9%) and also required eachintervention more frequently (57 vs 10%). Patients with DLTmalposition during OLV also required interventions more often(84 vs 12%). Conclusions. Patients who have DLT malposition after placingthe patient in the lateral position had more DLT malpositionduring OLV and hypoxaemia during OLV. Br J Anaesth 2004; 92: 195–201