Blood glucose concentration profile after 10 mg dexamethasone in non-diabetic and type 2 diabetic patients undergoing abdominal surgery

Background. Dexamethasone prevents postoperative nausea andvomiting but may increase blood glucose. We compared blood glucoseconcentrations after dexamethasone in non-diabetic and type2 diabetic patients undergoing surgery and looked for any associationwith preoperative glycosylated haemoglobin [HbA (1c)] and BMI. Methods. Sixty three patients were enrolled: 32 were non-diabetic(Group ND) and 31 type 2 diabetic (Group D) without insulintreatment. Anaesthesia was induced using i.v. anaesthetic agentsand maintained with sevoflurane. All patients received 10 mgdexamethasone at induction. Blood glucose concentrations weremeasured at induction and then every 60 min for 240 min. Datawere analysed using ANOVA. Effects of HbA (1c) and BMI wereinvestigated using linear correlation and logistic regression. Results. Blood glucose concentrations increased significantlyover time and peaked at 120 min after 10 mg dexamethasone inboth groups. The magnitude of increase was comparable betweenthe groups [mean (SD) 29 (19) and 35 (19)% of baseline in GroupD and Group ND, respectively]. Maximum concentrations were higherin Group D [8.97 (1.51) mmol litre^–1, range 6.67–12.94mmol litre^–1] than in Group ND [7.86 (1.00) mmol litre^–1,range 5.78–10.00 mmol litre^–1]. There was a significantcorrelation between the maximum concentrations and BMI (R²=0.21)or HbA (1c) (R²=0.26). Logistic regression analysis revealedthat the higher the BMI, the lower the HbA (1c) threshold associatedwith an increased probability (>0.5) of observing blood glucoselevels higher than 8.33 mmol litre^–1 during 240 min afterdexamethasone administration. Similarly, the higher the HbA(1c), the lower the BMI threshold associated with the same probability. Conclusions. After 10 mg dexamethasone, blood glucose levelsincrease in non-diabetic and type 2 diabetic patients undergoingabdominal surgery. Poorly controlled diabetes and severe obesitycan influence the development of hyperglycaemia.     

Accuracy of feedback-controlled oxygen delivery into a closed anaesthesia circuit for measurement of oxygen consumption

Background. Oxygen consumption (V^·>O₂) is rarely measuredduring anaesthesia, probably because of technical difficulties.Theoretically, oxygen delivery into a closed anaesthesia circuit(V^·>O₂-PF; PhysioFlex^TM Draeger Medical Company, Germany)should measure V^·>O₂. We aimed to measure V^·>O₂-PFin vitro and in vivo. Methods. Three sets of experiments were performed. V^·>O₂-PFwas assessed with five values of V^·>O₂ (0–300 mlmin^–1) simulated by a calibrated lung model (V^·>O₂-Model)at five values of FI_O2 (0.25–0.85). The time taken forV^·>O₂-PF to respond to changes in V^·>O₂-Modelgave a measure of dynamic performance. In six healthy anaesthetizeddogs we compared V^·>O₂-PF with V^·>O₂ measuredby the Fick method (V^·>O₂-Fick) during ventilationwith nine values of FI_O2 (0.21–1.00). V^·>O₂-PFand V^·>O₂-Fick were also compared in three dogs whenV^·>O₂ was changed pharmacologically [102 (SD 14),121 (17) and 200 (57) ml min^–1]. In patients during surgery,we measured V^·>O₂-PF and V^·>O₂-Fick simultaneouslyafter induction of anaesthesia (n=21) and during surgery (n=17)(FI_O2 0.3–0.5). Results. Compared with V^·>O₂-Model, V^·>O₂-PFvalues varied from time to time so that averaging over 10 minis recommended. Furthermore, at an FI_O2 >0.8, V^·>O₂-PFalways overestimated V^·>O₂. With FI_O2 <0.8, averagedV^·>O₂-PF corresponded to V^·>O₂-Model andadapted rapidly to changes. Averaged V^·>O₂-PF alsocorresponded to V^·>O₂-Fick in dogs at FI_O2 <0.8.V^·>O₂ measured by the two methods gave similar resultswhen V^·>O₂ was changed pharmacologically. In contrast,V^·>O₂-PF systematically overestimated V^·>O₂-Fickin patients by 52 (SD 40) ml min^–1 and this bias increasedwith smaller arteriovenous differences in oxygen content. Conclusion. V^·>O₂-PF measures V^·>O₂ adequatelywithin specific conditions. Br J Anaesth 2003; 90: 281–90     

Effects of tirofiban on haemostatic activation in vitro

Background. Thrombin plays a critical role in normal haemostasisand pathological thrombosis. Heparin has long been a mainstaychoice of antithrombotic regimen in cardiac patients, but persistentthrombin generation seems to occur during heparin therapy. Becauseplatelets are integral to primary haemostasis and clot formation,we evaluated the use of tirofiban (Aggrastat®),a plateletinhibitor, as a therapy to improve heparin sensitivity and delaythrombin formation. Methods. Blood samples were obtained from healthy subjects (n=8)and cardiac surgical patients (n=34). Thrombin formation wasmeasured in platelet-rich plasma with a Thrombogram®-Ascentfluorescent plate reader system. Platelet inhibition by tirofibanwas evaluated with Plateletworks®, and the interaction oftirofiban and heparin (>1.5 U ml^–1) on clot formationwas evaluated with Sonoclot Analyzer® or kaolin activatedclotting times (ACTs). Results. Addition of tirofiban (70–280 ng ml^–1)progressively delayed onset of thrombin generation triggeredby adenosine diphosphate (ADP). Plateletworks showed plateletinhibition with tirofiban (>35 ng ml^–1), whereas heparinper se failed to produce platelet inhibition at 7 U ml^–1.Heparin (1.5 U ml^–1) slowed the onset and rate of fibrinformation on Sonoclot analyses, and this was further slowedafter addition of tirofiban (70 ng ml^–1) to heparin-containingblood samples. Significant increases in ACT at all heparin concentrationswere observed with the addition of tirofiban (70 ng ml^–1).The addition of antithrombin (0.2 units/ml) to heparinized bloodsamples further prolonged ACTs, but the difference was not statisticallysignificant when compared with heparin alone. Conclusion. Tirofiban delays platelet activation-mediated thrombingeneration and prolongs ACT in heparinized blood.      

Identification of polysubstance abuse in the parturient

Illicit drugs are widely used by inner city patients and theiruse by pregnant women has increased in recent years. The aimof this study was to determine the prevalence of polysubstanceabuse among parturients at our institution who received no prenatalcare (‘unbooked’) and to determine the accuracyof the Ontrak TesTcup^TM an in vitro immunodiagnostic assay.We prospectively analysed urine from 50 ‘unbooked’parturients and found that 26 (52%) tested positive for cocaine.Of these, six patients (23%) were also positive for morphine.All TesTcup^TM results were confirmed by the hospital laboratoryusing alternate chemical methods. When comparing TesTcup^TM tothe hospital laboratory, there were no false positive or negativeresults. Given the high frequency of concomitant opioid abusein cocaine-abusing parturients, anyone suspected of cocaineabuse should be tested for other illicit substances. TesTcup^TMis a clinically accurate test that allows the rapid assessmentof several drugs of abuse, which may impact on anaesthetic care. Br J Anaesth 2001; 87: 488–90     

Platelet function point-of-care tests in post-bypass cardiac surgery: are they relevant?

Background. Platelet dysfunction is an important cause of excessivebleeding after cardiac surgery. We assessed two platelet functionpoint-of-care tests: the platelet function analyser (PFA-100)and the Hemostatus^TM in patients with and without excessivebleeding after cardiac surgery with cardiopulmonary bypass. Methods. Mediastinal chest tube drainage (MCTD) was measuredfor the first 6 h in the intensive care unit (ICU). Haematologyand coagulation tests were done on arrival in the ICU, and whenexcessive bleeding occurred (MCTD >1 ml kg^–1 h^–1)or after 3 h. Results. Eighteen patients bled excessively and 27 had normalMCTD. Hemostatus measurements were prolonged in those with excessivebleeding compared with the normal group. The times for PFA-100adenosine diphosphate (ADP) and epinephrine were 91 vs 71 s(P=0.004) and 155 vs 114 s (P=0.02) in the bleeding and normalgroup s, respectively. None of the Hemostatus or PFA-100 valuescorrelated with total MCTD. Depending on the agonist used, maximumaggregation was 33–81% and 52–86% in bleeding andnormal groups, respectively. Only poor correlations were foundbetween PFA-100 epinephrine and maximum aggregation in responseto ADP (r=–0.52, P=0.03) or to collagen (r=–0.48,P=0.04). Conclusion. Patients bleeding excessively in the ICU had abnormalmeasurements in point-of-care tests without a dramatic decreasein aggregation. Except for patients with increased risk of postbypassbleeding, point-of-care tests are not useful for routine useafter cardiac surgery. Br J Anaesth 2002; 89: 715–21     

Effects of intramuscular administration of lidocaine or bupivacaine on induction and maintenance doses of propofol evaluated by bispectral index

Background. Interest in combining local and general anaesthesiahas lead to studies investigating possible interactions. Ina prospective, randomized, double-blind study, we tested whetherlocal anaesthetics administered i.m. potentiate the hypnoticeffect of propofol. Methods. Sixty patients (three groups, n=20) undergoing lowerabdominal surgery with total i.v. propofol anaesthesia wereinvestigated. Patients in Group B received i.m. bupivacaine(5 mg ml^–1) 1 mg kg^–1, patients in Group Lreceived i.m. lidocaine (100 mg ml^–1) 2 mg kg^–1and patients in Group C received i.m. saline 5 ml beforeoperation. Hypnosis was measured with bispectral index (BIS). Results. The induction (BIS <45), and the maintenance dosesof propofol (BIS between 40 and 50) were significantly lessin Group B and Group L compared with the control group. Inductiondoses were 1.58 (SD 0.39), 1.56 (0.24) and 2.03 (0.33) mg kg^–1respectively; P<0.0001. Maintenance doses were 6.33 (2.06),7.08 (1.23) and 9.95 (2.02) mg kg^–1 respectively in thefirst hour; P<0.0001. Groups B and L were associated withan attenuated haemodynamic response to both induction and intubation. Conclusion. I.M. administered local anaesthetics are associatedwith a decrease in both the induction and maintenance dosesof propofol during total i.v. anaesthesia and a reduction inhaemodynamic responses. Br J Anaesth 2002; 89: 849–52     

Optimal concentration of epidural fentanyl in bupivacaine 0.1% after thoracotomy

Background. The aim of this prospective, double-blind, randomizedcontrolled trial was to investigate the analgesic and adverseeffects of three commonly used concentrations of thoracic epiduralfentanyl with bupivacaine in patients undergoing thoracotomyfor lung resection. Methods. We studied 99 patients who were randomized to receivefentanyl 2 µg ml^–1 (group 2), fentanyl 5 µgml^–1 (group 5) and fentanyl 10 µg ml^–1 (group10) in bupivacaine 0.1% via a thoracic epidural. Postoperatively,pain on coughing was assessed using a visual analogue scale(VAS) and an observer verbal rating score (OVRS) at 2, 8, 16and 24 h. At the same times, sedation, pruritus and nausea wereassessed. Results. Of 29, 28 and 32 patients who completed the study ingroups 2, 5 and 10 respectively, there was no significant differencein baseline characteristics between the three groups. The numberof patients with episodes of unsatisfactory pain, i.e. VAS scores>30 mm and OVRS >1, at each of the four assessments postoperativelywas significantly (P<0.01) higher in group 2 than in groups5 and 10. In group 10, 16 patients had sedation scores >1compared with 10 each in groups 2 and 5. In addition, 19 patientsin group 10 experienced pruritus compared with 12 each, in groups2 and 5. These differences were not significant. Nausea wasnot significantly different between the three groups. Conclusion. We conclude that thoracic epidural fentanyl 5 µgml^–1 with bupivacaine 0.1% provides the optimum balancebetween pain relief and side effects following thoracotomy. Br J Anaesth 2004: 92: 670–4     

Comparison of intrathecal isobaric bupivacaine-morphine and ropivacaine-morphine for Caesarean delivery

Background. This study was designed to evaluate the effectsof intrathecal isobaric bupivacaine 0.5% plus morphine and isobaricropivacaine 0.5% plus morphine combinations in women undergoingCaesarean deliveries. Method. Twenty-five parturients received ropivacaine 15 mg andmorphine 150 µg (RM group) and twenty-five parturientsreceived bupivacaine 15 mg and morphine 150 µg (BM group)for spinal anaesthesia. Sensory and motor block, haemodynamics,postoperative analgesia, fetal outcomes, and side-effects wereevaluated. Results. Intrathecal bupivacaine–morphine and ropivacaine–morphineprovided effective sensory anaesthesia and motor block. Timeto reach complete motor block was shorter and time to completerecovery from motor block was longer in the BM group than theRM group (P<0.05). The time to regression of two dermatomesand time for the block to recede to the S2 dermatome were similarin both groups (P>0.05). Time to first complaint of painand the mean total consumption of tenoxicam were similar inboth groups (P>0.05). APGAR scores at 1 and 5 min were similarin the two groups, as were mean umbilical blood pH values (P>0.05).Hypotension and pruritus were the most common side-effects inboth groups during the operation. Conclusion. Intrathecal isobaric ropivacaine 0.5% 15 mg plusmorphine 150 µg provides sufficient anaesthesia for Caesareandelivery. The ropivacaine–morphine combination resultedin shorter motor block, similar sensory and postoperative analgesia. Br J Anaesth 2003; 90: 659–64     

Comparison of ropivacaine 0.5% (in glucose 5%) with bupivacaine 0.5% (in glucose 8%) for spinal anaesthesia for elective surgery

Background. Hyperbaric solutions of ropivacaine have been usedsuccessfully to provide spinal anaesthesia. This study was designedto compare the clinical efficacy of hyperbaric ropivacaine withthat of the commercially available hyperbaric preparation ofbupivacaine. Methods. Forty ASA grade I–II patients undergoing lower-abdominal,perineal or lower-limb surgery under spinal anaesthesia wererecruited and randomized to receive ropivacaine 5 mg ml^–1(with glucose 50 mg ml^–1), 3 ml or bupivacaine 5 mg ml^–1(with glucose 80 mg ml^–1), 3 ml. The level and durationof sensory block, intensity and duration of motor block, andtime to mobilize and micturate were recorded. Patients wereinterviewed at 24 h and at 1 week to identify any residual problems. Results. All blocks were adequate for the proposed surgery,but there were significant differences between the two groupsin mean time to onset of sensory block at T10 (ropivacaine 5min; bupivacaine 2 min; P<0.005), median maximum extent (ropivacaineT7; bupivacaine T5; P<0.005) and mean duration of sensoryblock at T10 (ropivacaine 56.5 min; bupivacaine 118 min; P=0.001).Patients receiving ropivacaine mobilized sooner (ropivacainemean 253.5 min; bupivacaine 331 min; P=0.002) and passed urinesooner (ropivacaine mean 276 min; bupivacaine 340.5 min; P=0.01)than those receiving bupivacaine. More patients in the bupivacainegroup required treatment for hypotension (>30% decrease insystolic pressure; P=0.001). Conclusions. Ropivacaine 15 mg in glucose 50 mg ml^–1 providesreliable spinal anaesthesia of shorter duration and with lesshypotension than bupivacaine. The recovery profile for ropivacainemay be of interest given that more surgery is being performedin the day-case setting. Br J Anaesth 2003; 90: 304–8     

Analgesia with sevoflurane during labour: ii. Sevoflurane compared with Entonox for labour analgesia

Background. We determined the optimal inspired sevoflurane concentrationfor use during labour as 0.8% in our previous study. This studycompared sevoflurane at a concentration of 0.8% and Entonox^®(nitrous oxide 50%: oxygen 50%) for analgesia during labourin 32 healthy parturients. Methods. Each mother underwent two open-label, three-part sequencesin random order, Entonox-sevoflurane-Entonox or sevoflurane-Entonox-sevoflurane.In each part the agent was self-administered during 10 contractions.A 100 mm visual analogue scores for pain relief and sedationwas completed immediately after each contraction. Results. Two patients withdrew during administration of sevoflurane(because of its odour) and five during Entonox (requesting epiduralanalgesia). Of the remaining women, data were available foranalysis from 29 participants: median (IQR [range]) pain reliefscores were significantly higher for sevoflurane 67 (55–74[33–100]) mm than for Entonox 51 (40–69.5 [13–100])mm (P<0.037). Nausea and vomiting were more common in theEntonox group [relative risk 2.7 (95% CI 1.3–5.7); P=0.004].No other adverse effects were observed in the mothers or babies.There was significantly more sedation with sevoflurane thanwith Entonox {74 (66.5–81 [32.5–100]) and 51 (41–69.5[13–100]) mm, respectively; P<0.001}. Twenty-nine patientspreferred sevoflurane to Entonox and found its sedative effectshelpful. Conclusions. We conclude that self-administered sevofluraneat subanaesthetic concentration (0.8%) can provide useful painrelief during the first stage of labour, and to a greater extentthan Entonox. Although greater sedative effects were experiencedwith sevoflurane, it was preferred to Entonox.      

Ultrasonography for ilioinguinal/iliohypogastric nerve blocks in children

Background. The ilioinguinal/iliohypogastric nerve block isa popular regional anaesthetic technique for children undergoinginguinal surgery. The success rate is only 70–80% andcomplications may occur. A prospective randomized double-blindedstudy was designed to compare the use of ultrasonography withthe conventional ilioinguinal/iliohypogastric nerve block technique. Methods. One hundred children (age range, 1 month–8 years)scheduled for inguinal hernia repair, orchidopexy or hydrocelerepair were included in the study. Following induction of generalanaesthesia, the children received an ilioinguinal/iliohypogastricblock performed either under ultrasound guidance using levobupivacaine0.25% until both nerves were surrounded by the local anaestheticor by the conventional ‘fascial click’ method usinglevobupivacaine 0.25% (0.3 ml kg^–1). Additional intra-and postoperative analgesic requirements were recorded. Results. Ultrasonographic visualization of the ilioinguinal/iliohypogastricnerves was possible in all cases. The amount of local anaestheticused in the ultrasound group was significantly lower than inthe ‘fascial click’ group (0.19 (SD 0.05) ml kg^–1vs 0.3 ml kg^–1, P<0.0001). During the intraoperativeperiod 4% of the children in the ultrasound group received additionalanalgesics compared with 26% in the fascial click group (P=0.004).Only three children (6%) in the ultrasound-guided group neededpostoperative rectal acetaminophen compared with 20 children(40%) in the fascial click group (P<0.0001). Conclusions. Ultrasound-guided ilioinguinal/iliohypogastricnerve blocks can be achieved with significantly smaller volumesof local anaesthetics. The intra- and postoperative requirementsfor additional analgesia are significantly lower than with theconventional method.      

Pharmacokinetics of remifentanil and its major metabolite, remifentanil acid, in ICU patients with renal impairment

Background. The pharmacokinetics of remifentanil, an opioidanalgesic metabolized by non-specific esterases, and its principalmetabolite, remifentanil acid (RA), which is excreted via thekidneys, were assessed as part of an open-label safety studyin intensive care unit (ICU) patients with varying degrees ofrenal impairment. Methods. Forty adult ICU patients with normal/mildly impairedrenal function (creatinine clearance [CL_cr] 62.9 (SD) 14.5 mlmin^–1; n=10) or moderate/severe renal impairment (CL_cr14.7 (15.7) ml min^–1; n=30) were included. Remifentanilwas infused for up to 72 h, at a starting rate of 6–9µg kg^–1 h^–1 titrated to achieve a target sedationlevel, with additional propofol (0.5 mg kg^–1 h^–1)if required. Intensive arterial sampling was performed for upto 72 h after infusion. Pharmacokinetic parameters obtainedby simultaneous modelling of remifentanil and RA data were statisticallycompared between the two groups. Results. Remifentanil pharmacokinetics were not significantlyaffected by renal status. RA clearance in the moderate/severegroup was reduced to about 25% that of the normal/mild group(41 (29) vs 176 (49) ml kg^–1 h^–1, P<0.0001).Metabolic ratio, a predictor of the ratio of RA to remifentanilconcentrations at steady state, was approximately eight-foldhigher in the moderate/severe group relative to the normal/mildgroup (116 (110) vs 15 (4), P<0.0001). Maximum RA levelsapproached 700 ng ml^–1 in the moderate/severe group. Conclusions. Although RA accumulates in patients with moderate/severerenal impairment, pharmacokinetic modelling predicts that RAconcentrations during a 9 µg kg^–1 h^–1 remifentanilinfusion for up to 15 days would not exceed those reported inthe present study, for which no associated prolongation of µ-opioideffects was observed. Br J Anaesth 2004; 92: 493–503     

Cerebrospinal fluid and blood propofol concentration during total intravenous anaesthesia for neurosurgery

Background. The aim of this paper is to compare the propofolconcentration in blood and cerebrospinal fluid (CSF) in patientsscheduled for different neurosurgical procedures and anaesthetizedusing propofol as part of a total intravenous anaesthesia technique. Methods. Thirty-nine patients (ASA I–III) scheduled forelective intracranial procedures, were studied. Propofol wasinfused initially at 12 mg kg^–1 h^–1 and thenreduced in steps to 9 and 6 mg kg^–1 h^–1. Duringanaesthesia, bolus doses of fentanyl and cis-atracurium wereadministered as necessary. After tracheal intubation the lungswere ventilated to achieve normocapnia with an oxygen-air mixture(FI_O2=0.33). Arterial blood and CSF samples for propofol examinationwere obtained simultaneously directly after intracranial drainageinsertion and measured using high-performance liquid chromatography.The patients were divided into two groups depending on the typeof neurosurgery. The Aneurysm group consisted of 13 patientswho were surgically treated for ruptured intracranial aneurysm.The Tumour group was composed of 26 patients who were undergoingelective posterior fossa extra-axial tumour removal. Results. Blood propofol concentrations in both groups did notdiffer significantly (P>0.05). The propofol concentrationin CSF was 86.62 (SD 37.99) ng ml^–1 in the Aneurysm groupand 50.81 (26.10) ng ml^–1 in the Tumour group (P<0.005). Conclusions. Intracranial pathology may influence CSF propofolconcentration. However, the observed discrepancies may alsoresult from quantitative differences in CSF composition andfrom restricted diffusion of the drug in the CSF. Br J Anaesth 2003; 90: 84–6     

Desflurane affords greater protection than halothane against focal cerebral ischaemia in the rat

Background. We studied the potential neuroprotective effectsof halothane and desflurane, compared with the awake state,on infarct size following 2 h of intraluminal middle cerebralartery occlusion (MCAo) and 22 h of reperfusion. Methods. Male Sprague–Dawley rats were anaesthetized withdesflurane or halothane, intubated, and mechanically ventilated.Mean arterial pressure (MAP), blood gases, and pH were controlled.Body temperature was maintained at 37.5–38°C. Animalswere assigned to one of four groups according to the anaesthetictype (halothane or desflurane) and the duration of anaesthesia:‘short-duration’, during the preparation only; ‘long-duration’,during both preparation and ischaemia. Twenty-four hours afterMCAo, infarcts were visualized by staining with 2,3,5-triphenyltetrazoliumchloride. Two additional groups of rats were subjected to thesame protocol as that of long-duration halothane and long-durationdesflurane with additional pericranial temperature measurementsmade. Results. Physiological parameters were comparable between thegroups but MAP was higher (P<0.0001) in the short-durationgroups. In the short-duration groups, cerebral infarct volumeswere not significantly different between anaesthetics (short-durationhalothane: 288 (61) mm³, mean (SD); short-duration desflurane:269 (71) mm³, P>0.56). Compared with the awake state (short-durationgroups), halothane and desflurane significantly reduced infarctvolumes (long-duration halothane: 199 (54) mm³, P<0.0047vs short-duration halothane; long-duration desflurane: 121 (55)mm³, P<0.0001 vs short-duration desflurane). The mean infarctvolume in the long-duration desflurane group was significantlylower than that in the long-duration halothane group (P<0.0053).Pericranial temperatures were similar in the desflurane andhalothane long-duration groups (P>0.17). Conclusions. In rats, desflurane-induced neuroprotection againstfocal cerebral ischaemia was greater than that conferred byhalothane. Br J Anaesth 2003; 91: 390–6     

Effect of obesity and site of surgery on perioperative lung volumes

Background. Although obese patients are thought to be susceptibleto postoperative pulmonary complications, there are only limiteddata on the relationship between obesity and lung volumes aftersurgery. We studied how surgery and obesity affect lung volumesmeasured by spirometry. Methods. We prospectively studied 161 patients having eitherbreast surgery (Group A, n=80) or lower abdominal laparotomy(Group B, n=81). Premedication and general anaesthesia werestandardized. Spirometry was measured with the patient supine,in a 30° head-up position. We measured vital capacity (VC),forced vital capacity, peak expiratory flow and forced expiratoryvolume in 1 s at preoperative assessment (baseline), after premedication(before induction of anaesthesia) and 10–20 min, 1 h and3 h after extubation. Results. Baseline spirometric values were all within the normalrange. All perioperative values decreased significantly withincreasing body mass index (BMI). The greatest reduction ofmean VC (expressed as percentage of baseline values) occurredafter extubation, and was more marked after laparotomy thanafter breast surgery (23 (SD 14)% vs 20 (14)%). Consideringpatients according to BMI (<25, 25–30, >30), VCdecreased after surgery by 12 (7)%, 24 (8)% and 40 (10)%, respectively.VC recovered more rapidly in Group A. Conclusion. Postoperative reduction in spirometric volumes wasrelated to BMI. Obesity had more effect on VC than the siteof surgery. Br J Anaesth 2004; 92: 202–7     

Evaluation of effects of magnesium sulphate in reducing intraoperative anaesthetic requirements

Background. The present randomized, placebo-controlled, double-blindstudy was designed to assess the effect of peroperatively administeredi.v. magnesium sulphate on anaesthetic and analgesic requirementsduring total i.v. anaesthesia. Methods. Eighty-one patients (36 women, 45 men) undergoing electivespinal surgery were included in one of two parallel groups.The magnesium group received magnesium sulphate 30 mg kg^–1as a bolus before induction of anaesthesia and 10 mg kg^–1h^–1 by continuous i.v. infusion during the operation period.The same volume of isotonic solution was administered to thecontrol group. Anaesthesia was maintained with propofol (administeredaccording to the bispectral index) and remifentanil (adjustedaccording to heart rate and arterial blood pressure) infusions. Results. A significant reduction in hourly propofol consumptionwas observed with magnesium administration. For example, themean infusion rate of propofol in the second hour of the operationwas 7.09 mg kg^–1 h^–1 in the controlgroup vs 4.35 mg kg^–1 h^–1 in themagnesium group (P<0.001). The magnesium group required significantlyless remifentanil (P<0.001) and vecuronium (P<0.001).No side-effects were observed with magnesium administration. Conclusion. The administration of magnesium led to a significantreduction in the requirements for anaesthetic drugs during totali.v. anaesthesia with propofol, remifentanil and vecuronium. Br J Anaesth 2002; 89: 594–8     

Weal and flare responses to intradermal rocuronium and cisatracurium in humans{dagger}

Thirty volunteers underwent intradermal skin testing with increasingconcentrations of rocuronium and cisatracurium to evaluate wealand flare responses, and whether either agent would cause mastcell degranulation and sensitization upon re-exposure. We foundthat intradermal injection of rocuronium and cisatracurium atconcentrations >10^–4 M resulted in positive weal (>8 mm)responses, and positive flare responses at >10^–4 and>10^–5 M respectively. Only cisatracurium caused mildto moderate mast cell degranulation, and neither drug causedsignificant in vitro histamine release from whole blood collectedfrom study subjects 4 weeks after skin testing. Skin testingwith rocuronium and cisatracurium should be performed at concentrations<10^–4 and <10^–5 M respectively to avoid false-positiveresponses. The ability of these agents to produce positive wealand flare responses at relatively low concentrations may explainthe high incidence of potential reactions reported. Br J Anaesth 2000; 85: 844–9     

Efficacy of three doses of tramadol with bupivacaine for caudal analgesia in paediatric inguinal herniotomy

Background. This study was designed to evaluate the analgesicefficacy of three doses of tramadol, administered caudally withbupivacaine, in providing postoperative pain relief in children. Methods. Eighty children, aged between 2 and 8 yr, undergoinginguinal herniotomy were randomly allocated to receive bupivacaine0.25% 0.75 ml kg^–1 (Group B; n=20), bupivacaine 0.25%0.75 ml kg^–1 with tramadol 1 mg kg^–1 (Group BT1;n=20), bupivacaine 0.25% 0.75 ml kg^–1 with tramadol 1.5mg kg^–1 (Group BT1.5; n=20), or bupivacaine 0.25% 0.75ml kg^–1 with tramadol 2 mg kg^–1 (Group BT2; n=20)by the caudal route immediately after induction of general anaesthesia.Heart rate, arterial pressure and oxygen saturation were monitored.Postoperative pain was assessed at regular intervals for 24h using All India Institute of Medical Sciences pain score.Analgesia was supplemented whenever pain score was 4. Durationof analgesia and requirement for additional analgesics was noted. Results. Duration of analgesia was longer in Group BT2 [(mean(SD) 12 (0.9) h] compared with Group B [4 (1) h], Group BT1[8 (0.9) h], or Group BT1.5 [11 (1) h]; all P<0.001. Totalconsumption of rescue analgesic was significantly lower in groupBT2 compared with other groups (P<0.001). There were no significantchanges in heart rate, arterial pressure and oxygen saturationbetween groups. Adverse effects were not observed. Conclusions. Caudal tramadol 2 mg kg^–1, combined withbupivacaine 0.25% 0.75 ml kg^–1, provided longer durationof postoperative analgesia and reduced requirement for rescueanalgesic compared with tramadol 1 mg kg^–1 or 1.5 mg kg^–1in children undergoing inguinal herniotomy.     

Effects of three different L-type Ca2+ entry blockers on airway constriction induced by muscarinic receptor stimulation

Background. The crucial role of L-type Ca²⁺ channels in airwaysmooth muscle contraction suggests that these channels couldbe an important therapeutic target. There are three separatedrug binding sites on this channel: those for dihydropyridines,benzothiazepines and phenyl alkylamines. In this study, we examinedthe effects of the dihydropyridines nifedipine and nicardipine,the benzothiazepine diltiazem, and the phenylalkylamine verapamilon airway constriction. Methods. Tension of guinea-pig tracheal strips was measuredisometrically in vitro with a force displacement transducer.Strips were precontracted with carbachol 10^–7 M with orwithout 4-aminopyridine 10^–3 M, a voltage-sensitive K⁺channel blocker. Then, nifedipine 10^–8–10^–4M, diltiazem 10^–8–3x10^–4 M or verapamil 10^–8–3x10^–4M was added cumulatively to the organ bath (n=6 each). The bronchialcross-sectional area of pentobarbital-anaesthetized dogs wasassessed using a bronchoscopy method. Bronchoconstriction waselicited with methacholine 0.5 µg kg^–1 plus 5 µgkg^–1 min^–1, and then nicardipine 0–1000 µgkg^–1, diltiazem 0–3000 µg kg^–1 or verapamil0–3000 µg kg^–1 were given i.v. (n=7 each). Results. In the in vitro experiments, nifedipine and diltiazemfully reversed carbachol-mediated tracheal contraction withlogIC₅₀ values of 4.76 (SEM 0.22) (mean 17.5 µM) and 4.60(0.33) (mean 24.8 µM), respectively. Although verapamil10^–6–10^–4 M reversed the contraction by 87.2%,strip tension re-increased by 18.1% following maximal relaxationwith verapamil 3x10^–4 M. This re-increase was almost fullyabolished by pretreatment with 4-aminopyridine. In the in vivoexperiments, nicardipine and diltiazem dose-dependently reversedmethacholine-induced bronchoconstriction, with logID₅₀ valuesof 3.22 (0.05) (mean 0.60 mg kg^–1) and 1.85 (0.32) (mean14.0 mg kg^–1), respectively. Verapamil worsened methacholine-inducedbronchoconstriction. Conclusions. Although supraclinical doses of dihydropyridinesand benzothiazepines can produce airway relaxant effects, theseagents are unlikely to be used in the treatment of bronchoconstriction.In addition, verapamil may aggravate airway constriction. Br J Anaesth 2003; 90: 671–5     

Sevoflurane and propofol decrease intraocular pressure equally during non-ophthalmic surgery and recovery

Background. To provide good control of intraocular pressure(IOP) during anaesthesia and surgery, we conducted a study comparingthe effects on IOP during maintenance and recovery of sevofluranevs propofol anaesthesia in 33 patients (ASA I–II) undergoingelective non- ophthalmic surgery. Methods. Anaesthesia was induced with propofol 2 mg kg^–1,fentanyl 2 µg kg^–1 and vecuronium 0.1 mg kg^–1.Patients were allocated randomly to receive either propofol4–8 mg kg^–1 h^–1 (group P; n=16)or 1.5–2.5 vol% sevoflurane (group S; n=17) for maintenanceof anaesthesia. Fentanyl 2–4 µg kg^–1was added if necessary. The lungs were ventilated with 50% airin oxygen. Blood pressure, heart rate, oxygen saturation andend-tidal carbon dioxide were measured before and throughoutanaesthesia and in the recovery room. IOP was determined withapplanation tonometry (Perkins) by one ophthalmologist blindedto the anaesthetic technique. Results. There was a significant decrease in IOP after inductionand during maintenance of anaesthesia in both groups. No significantdifferences in IOP between the two groups was found. Conclusion. Sevoflurane maintains the IOP at an equally reducedlevel compared with propofol. Br J Anaesth 2002; 89: 764–6