Antiemetic and analgesic-sparing effects of diphenhydramine added to morphine intravenous patient-controlled analgesia

Background. This study was designed to examine the analgesicand dose-related antiemetic efficacy of diphenhydramine–morphinemixture for intravenous patient-controlled analgesia (PCA). Methods. Healthy women, undergoing abdominal total hysterectomywere recruited to this double-blinded randomized placebo-controlledstudy. Patients were randomly allocated to one of three groups(n=40 each). In group 1, patients received saline at inductionand morphine 1 mg ml^–1 alone for postoperative PCA. Patientsin groups 2 and 3 received diphenhydramine 30 mg i.v. at inductionand were given a 1.2:1 or a 4.8:1 ratio, respectively, of diphenhydramine–morphinemixture for postoperative PCA. Results. A total of 112 patients completed the study. The incidenceof postoperative nausea (31.6% vs 67.6%, P<0.01) and vomiting(15.8% vs 40.5%, <0.05) was significantly lower in group3 than in group 1. Furthermore, the incidence of severe nauseawas significantly lower in group 3 than in group1 (2.6% vs 24.3%,P<0.05). The rescue antiemetic requirements were also significantlyless in group 3 than in group 1 (5.3% vs 24.3%, P<0.05).However, there was no significant difference between group 2and group 1 in any of the comparisons. Pain intensity, 24-hmorphine consumption and diphenhydramine-related side-effects,such as sedation or dry mouth, did not differ among the threegroups. Conclusion. An initial bolus of diphenhydramine 30 mg at anaestheticinduction followed by postoperative PCA with a 4.8:1, but not1.2:1, diphenhydramine–morphine mixture provides an effectiveantiemetic efficacy without morphine-sparing effects.     

Double-blind randomized controlled trial of caudal versus intravenous S(+)-ketamine for supplementation of caudal analgesia in children

Background. The postoperative analgesic efficacy of S(+)-ketamineafter caudal or i.v. administration following sub-umbilicalsurgery in children was studied to investigate its principalsite of analgesic action. Methods. Sixty children undergoing caudal block during generalanaesthesia for hernia repair or orchidopexy were prospectivelyrandomized to one of three groups: the bupivicaine group receivedplain bupivacaine 0.25% 1 ml kg^–1; the caudal ketaminegroup received caudal plain bupivacaine 0.25% 1 ml kg^–1with S(+)-ketamine 0.5 mg kg^–1; the i.v. ketamine groupreceived caudal plain bupivacaine 0.25% 1 ml kg^–1 plusS(+)-ketamine 0.5 mg kg^–1 i.v.. Postoperative measurementsincluded analgesic requirements and modified objective painscore for the first 24 h. Results. The median time to first analgesia was significantlylonger in the caudal ketamine group (10 h) than in the i.v.ketamine (4.63 h) or bupivacaine (4.75 h) groups (P=0.01). Significantlyfewer doses of analgesia were required over the first postoperative24 h by subjects in the caudal ketamine group (median 1) comparedwith the i.v. ketamine (median 2) or bupivacaine (median 2.5)groups (P<0.05). There was no difference between the groupsin the incidence of postoperative nausea and vomiting or psychomotorreactions. Conclusions. We have demonstrated that the addition of caudalS(+)-ketamine to bupivacaine prolongs the duration of postoperativeanalgesia. However, the same dose of i.v. S(+)-ketamine combinedwith a plain bupivacaine caudal provides no better analgesiathan caudal bupivacaine alone, indicating that the principalanalgesic effect of caudal S(+)-ketamine results from a localneuroaxial rather than a systemic effect. Br J Anaesth 2004; 92: 344–7     

Esmolol prevents movement and attenuates the BIS response to orotracheal intubation

Background. Beta-adrenergic agonists enhance behavioural andelectroencephalographic arousal reactions. We explored whetheradding esmolol, a short-acting ß₁-adrenoceptor antagonist,to propofol anaesthesia modified the bispectral index (BIS)during induction of anaesthesia and orotracheal intubation. Methods. Fifty patients were randomly allocated, in a double-blindfashion, to receive esmolol 1 mg kg^–1 followed by 250µg kg^–1 min^–1 or saline (control). Esmololor saline was started 6 min after a target-controlled infusion(TCI) of propofol (effect-site concentration 4 µg ml^–1).After loss of consciousness, and before administration of vecuronium0.1 mg kg^–1, a tourniquet was applied to one arm and inflatedto 150 mm Hg greater than systolic pressure. Eleven minutesafter the TCI began, the trachea was intubated; gross movementwithin the first min after orotracheal intubation was recorded.BIS was recorded at 10-s intervals. Mean arterial pressure (MAP)and heart rate were measured non-invasively every min. Results. There were no intergroup differences in BIS, heartrate or MAP before laryngoscopy. BIS increased significantlyafter orotracheal intubation (compared with the pre-laryngoscopyvalues) in the control group only, with a maximum increase of40 (SD 18)% vs 8 (11)% in the esmolol group (P<0.01). Maximumchanges in heart rate [45 (19)% vs 23 (14)%] and MAP [62 (24)%vs 45 (23)%] with orotracheal intubation were also significantlygreater in the control group than in the esmolol group. Morepatients in the control than in the esmolol group moved afterorotracheal intubation (23 vs 12, P<0.01). Conclusion. Esmolol not only attenuated haemodynamic and somaticresponses to laryngoscopy and orotracheal intubation, but alsoprevented BIS arousal reactions in patients anaesthetized withpropofol. Br J Anaesth 2002; 89: 857–62     

Prevention of postoperative nausea and vomiting after spinal morphine for Caesarean section: comparison of cyclizine,dexamethasone and placebo

Background. Low-dose intrathecal (spinal) morphine (0.1–0.2mg) for Caesarean section delivers excellent postoperative analgesiabut is associated with significant nausea and vomiting. We comparedthe antiemetic efficacy of cyclizine, dexamethasone, and placeboin this clinical setting. Methods. Ninety-nine women undergoing elective Caesarean sectionunder spinal anaesthesia were allocated randomly, in a double-blindstudy design, to receive either cyclizine 50 mg, dexamethasone8 mg, or placebo as a single-dose infusion in saline 0.9%, 100ml on completion of surgery. Spinal anaesthesia consisted of:hyperbaric bupivacaine 0.5%, 2.0 ml; fentanyl 10 µg; andspinal morphine 0.2 mg. The primary outcome measure was theincidence of nausea. Results. The incidence of nausea was significantly less in patientsreceiving cyclizine compared with dexamethasone and placebo(33 vs 60 and 67%, respectively, P<0.05). Severity of nauseaand number of vomiting episodes were also less at 3–6h in cyclizine patients. Overall satisfaction with postoperativecare at 24 h, expressed on a 100 mm visual analogue scale, wasgreater in cyclizine [78 (28)] than either dexamethasone [58(31), P=0.03] or placebo [51 (28), P=0.008]. Conclusion. We conclude that following spinal morphine 0.2 mgand fentanyl 10 µg analgesia for Caesarean section, cyclizine50 mg i.v. reduces the incidence of nausea compared with dexamethasone8 mg i.v. or placebo. It also lessens the severity of nauseaand vomiting, and increases maternal satisfaction in the earlypostoperative period. Br J Anaesth 2003; 90: 665–70     

Propofol and halothane versus sevoflurane in paediatric day-case surgery: induction and recovery characteristics

Background. The aim of this study was to compare the inductionand recovery characteristics associated with propofol inductionand halothane maintenance with sevoflurane anaesthesia in paediatricday surgery. Methods. In total, 322 children were assigned randomly to i.v.propofol induction and halothane/nitrous oxide maintenance orsevoflurane/nitrous oxide alone. The patients’ age, sex,and type of surgery were recorded, as were the times requiredfor anaesthetic induction, maintenance, recovery and time todischarge home. Postoperative nausea and vomiting, and the incidenceof adverse events during induction and recovery were also noted. Results. No significant differences were detected in age, sex,type of surgery performed or intraoperative opioid administration.Excitatory movement was more common during induction with sevoflurane.The mean time required for induction with propofol was 3.1 mincompared with 5 min in the sevoflurane group (P<0.001). Therecovery time was shorter in the sevoflurane group comparedwith propofol/halothane (23.2 vs 26.4 min, P<0.002). Theincidence of delirium in recovery was greater in the sevofluranegroup (P<0.001). There was no difference between groups inthe time spent on the postoperative ward before discharge home.On the postoperative ward the incidence of both nausea and vomitingwas significantly higher in the sevoflurane group (P=0.034).Five children were admitted to hospital overnight, none foranaesthetic reasons. Conclusions. The increased incidence of adverse events duringinduction, postoperative nausea and vomiting and postoperativedelirium in the sevoflurane group suggests that sevofluraneis not ideal as a sole agent for paediatric day case anaesthesia. Br J Anaesth 2003; 90: 461–6     

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     

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     

BIS guided sedation with propofol during spinal anaesthesia: influence of anaesthetic level on sedation requirement

Background. In this prospective, clinical study we tested thehypothesis whether two different doses of spinal administeredbupivacaine and accordingly, two different levels of spinalanaesthesia can affect the dose requirement of propofol duringBIS guided sedation. Methods. Fifty women undergoing vaginal hysterectomy (high spinalgroup, HS) or transvaginal tape (TVT) procedure for urinaryincontinence (low spinal group, LS) under spinal anaesthesiawere enrolled to the study. In group HS, 17.5 mg and in groupLS, 7.5 mg of hyperbaric bupivacaine were given intrathecally.After 15 min to obtain the appropriate level of spinal anaesthesia,propofol infusion was started at a rate of 100 µg kg^–1min^–1 to reach a BIS level of less than 75 (onset time),and titrated to maintain the BIS value between 65 and 75. Propofolinfusion was stopped 45 min after placing the spinal to measurethe time to reach a BIS level of 90 (recovery time). Results. Median anaesthetic level was T3 (T1–4) in theHS group and T10 (T9-11) in the LS group. In both the HS andthe LS groups, onset time was 226 (47) vs 273 (48) s (P=0.001),recovery time was 234 (47) vs 202 (56) s (P=0.03), total doseof propofol was 2.17 (0.43) vs 3.14 (0.56) mg kg^–1 (P<0.001),respectively. Conclusion. A high spinal block obtained with hyperbaric bupivacaine17.5 mg was associated with a faster onset, delayed recoveryand lower doses of propofol sedation compared with a low spinalblock with 7.5 mg of the same drug.     

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     

Propofol 1% versus propofol 2% in children undergoing minor ENT surgery

Background. The induction characteristics of propofol 1% and2% were compared in children undergoing ENT surgery, in a prospective,randomized, double-blind study. Methods. One hundred and eight children received propofol 1%(n=55) or 2% (n=53) for induction and maintenance of anaesthesia.For induction, propofol 4 mg kg^–1 was injectedat a constant rate (1200 ml h^–1), supplementedwith alfentanil. Intubating conditions without the use of aneuromuscular blocking agent were scored. Results. Pain on injection occurred in 9% and 21% of patientsafter propofol 1% and 2%, respectively (P=0.09). Loss of consciousnesswas more rapid with propofol 2% compared with propofol 1% (47 svs 54 s; P=0.02). Spontaneous movements during inductionoccurred in 22% and 34% (P=0.18), and intubating conditionswere satisfactory in 87% and 96% (P=0.19) of children receivingpropofol 1% or 2%, respectively. There were no differences betweenthe two groups in respect of haemodynamic changes or adverseevents. Conclusions. For the end-points tested, propofol 1% and propofol2% are similar for induction of anaesthesia in children undergoingminor ENT surgery. Br J Anaesth 2003: 90: 375–7     

Dolasetron prophylaxis reduces nausea and postanaesthesia recovery time after remifentanil infusion during monitored anaesthesia care for extracorporeal shock wave lithotripsy

Background. Remifentanil is used as an analgesic for differentprocedures performed during monitored anaesthesia care. Opioid-inducednausea and vomiting can be troublesome. Methods. This prospective, randomized, double-blind study wasperformed to evaluate the efficacy of prophylaxis with dolasetronin reducing the frequency of postoperative nausea and durationof discharge time. Forty urological patients, undergoing electiveambulatory extracorporeal shock wave lithotripsy (ESWL) receivedrandomly either dolasetron 12.5 mg i.v. (Group 1) or placebo(Group 2) 10 min before a patient-adapted continuous infusionof remifentanil 0.15–0.4 µg kg^–1 min^–1was administered. Frequency and intensity (VAS 0–100 mm)of nausea, retching, and vomiting were assessed by patientsand blinded investigators during and after the procedure. Results. Patient characteristics, baseline values, durationof ESWL, and total dose of remifentanil did not differ betweengroups. The frequency (Group 1/Group 2; 20/55%; P<0.05) andmean (SD) maximal intensity [15 (9)/45 (14) mm; P<0.05] ofnausea during 24 h was significantly reduced after dolasetronand discharge times in Group 1 were less than Group 2[22 (14)/45 (28) min; P<0.05]. Br J Anaesth 2003; 90: 194–8     

Emetic effects of morphine and piritramide

Background. Successful management of postoperative pain requiresthat adequate analgesia is achieved without excessive adverseeffects. Opioid-induced nausea and vomiting is known to impairpatients’ satisfaction, but there are no studies providingsufficient power to test the hypothesis that the incidence ofopioid-induced nausea and vomiting differs between µ-opioidreceptor agonists. Thus, we tested the hypothesis that the incidenceof vomiting and nausea differs between morphine and piritramide. Methods. In a prospective, randomized, double-blind fashion,we administered either morphine (n=250) or piritramide (n=250)by patient-controlled analgesia (PCA) for postoperative painrelief. We used a bolus dose of 1.5 mg with a lockout time of10 min. Incidence and intensity (numerical rating scale) ofpostoperative nausea, vomiting, pain, patient satisfaction (score0–10), side-effects (score 0–3) and drug consumptionwere measured. Results. Mean drug consumption did not differ between the piritramideand morphine groups (30.8 (SD 22.4) mg day^–1 vs 28.4 (21.8)mg day^–1) during the first postoperative day and therewere no significant differences in the overall incidence ofnausea (30% vs 27%) and vomiting (19% vs 15%). Intensity ofnausea correlated inversely (P=0.01) with morphine consumptionbut not with piritramide consumption. Pain scores both at rest(2.2 (1.9) vs 2.6 (2)) and during movement (4.4 (2.2) vs 4.9(2.3)) were slightly but significantly less with morphine. Conclusions. Opioid-induced emesis was observed in about one-thirdof the patients using morphine and piritramide for PCA and theincidence of vomiting was one-half of that. Potential differencesin the incidence of vomiting during PCA therapy between theseµ-opioid receptor agonists can be excluded. Br J Anaesth 2003; 91: 218–23     

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     

Early recovery after remifentanil-pronounced compared with propofol-pronounced total intravenous anaesthesia for short painful procedures

Background. We compared recovery from high-dose propofol/low-doseremifentanil (‘propofol-pronounced’) compared withhigh-dose remifentanil/low-dose propofol (‘remifentanil-pronounced’)anaesthesia. Methods. Adult patients having panendoscopy, microlaryngoscopy,or tonsillectomy were randomly assigned to receive either propofol-pronounced(propofol 100 µg kg^–1 min^–1; remifentanil0.15 µg kg^–1 min^–1) or remifentanil-pronounced(propofol 50 µg kg^–1 min^–1; remifentanil 0.45µg kg^–1 min^–1) anaesthesia. In both groups,the procedure was started with remifentanil 0.4 µg kg^–1,propofol 2 mg kg^–1, and mivacurium 0.2 mg kg^–1.Cardiovascular measurements and EEG bispectral index (BIS) wererecorded. To maintain comparable anaesthetic depth, additionalpropofol (0.5 mg kg^–1) was given if BIS values were greaterthan 55 and remifentanil (0.4 µg kg^–1) if heartrate or arterial pressure was greater than 110% of pre-anaestheticvalues. Results. Patient and surgical characteristics, cardiovascularmeasurements, and BIS values were similar in both groups. Therewere no differences in recovery times between the groups (timeto extubation: 12.7 (4.5) vs 12.0 (3.6) min, readiness for transferto the recovery ward: 14.4 (4.4) vs. 13.7 (3.6) min, mean (SD)). Conclusions. In patients having short painful surgery, lesspropofol does not give faster recovery as long as the same anaestheticlevel (as indicated by BIS and clinical signs) is maintainedby more remifentanil. However, recovery times were less variablefollowing remifentanil-pronounced anaesthesia suggesting a morepredictable recovery. Br J Anaesth 2003; 91: 580–2     

Dexamethasone is a cost-effective alternative to ondansetron in preventing PONV after paediatric strabismus repair

This study evaluated the antiemetic efficacy, cost-effectivenessand clinical utility of prophylactic ondansetron and dexamethasonecompared with placebo in the prevention of postoperative nauseaand vomiting (PONV) in 135 children (2–15 yr, ASA I–II)undergoing strabismus repair. After induction with halothaneand nitrous oxide in oxygen or i.v. thiopental, the childrenreceived i.v. dexamethasone 1 mg kg^–1 to a maximumof 25 mg, ondansetron 100 µg kg^–1to a maximum of 4 mg or placebo (n=45). Episodes of PONVwere recorded for the first 24 h after the operation. Trueoutcome measures (parental satisfaction score, duration of stayin the postanaesthesia care unit and fast tracking time), therapeuticoutcome measures (number needed to prevent (NNTP) PONV) andthe cost to benefit a child with each drug were analysed. Theincidence and severity of PONV in the first 24 h were significantlyless in the dexamethasone and ondansetron groups than in theplacebo group (P<0.05). The incidence (P=0.04) and severity(P=0.03) of PONV at the 6–24 h epoch were significantlyless in the dexamethasone group than in the ondansetron group.Recovery time (P=0.07), fast tracking time (P=0.6), parentalsatisfaction scores (P=0.08) and NNTP PONV were comparable (NNTP=2)in both the ondansetron and the dexamethasone group. The costto benefit a child with dexamethasone was approximately 22 timesless than that of ondansetron. Br J Anaesth 2001; 86: 84–9     

Bispectral index changes following etomidate induction of general anaesthesia and orotracheal intubation

Background. Etomidate-associated hypnosis has only been studiedusing standard clinical criteria and raw EEG variables. We conducteda BIS-based investigation of etomidate induction of generalanaesthesia. Methods. Thirty hydroxyzine-premedicated ASA I patients wererandomly allocated to receive etomidate 0.2, 0.3, or 0.4 mgkg^–1 intravenously over 30 s. The BIS was continuouslyrecorded. A tourniquet was placed on a lower limb to recordpurposeful movements and myoclonia. Tracheal intubation wasfacilitated using rocuronium 0.6 mg kg^–1 when the BISvalue was 50. The times to disappearance of the eyelash reflex,to a decrease in the BIS to 50, and to tracheal intubation werecompared. The BIS values 30 s following tracheal intubation,and mean arterial pressure (MAP) and heart rate (HR) at alltime points were also recorded. Results. The BIS value decreased to 50 for tracheal intubationwith no purposeful movement in all but one patient in the 0.2mg kg^–1 group. There was no difference between the etomidategroups (0.2, 0.3, and 0.4 mg kg^–1) in regards to timeto loss of the eyelash reflex (103 (67), 65 (34), 116 (86) s,P=0.2), or to a decrease in BIS to 50 (135 (81), 82 (36), 150(84) s, P=0.1). Also, the BIS value 30 s after intubation (41(10), 37 (4), 37 (4), P=0.4), and plasma etomidate concentrations(161 [29–998], 308 [111–730], 310 [90–869]ng ml^–1, P=0.2) did not differ between groups. The timeto loss of the eyelash reflex was 12–140 s shorter thanthe time to a decrease in BIS to 50 in three patients in eachgroup who received etomidate 0.2 and 0.4 mg kg^–1, andin four patients who received 0.3 mg kg^–1. No awarenesswas recorded. MAP and HR increases following tracheal intubationwere comparable between groups. Conclusions. Etomidate induction doses do not predict the timefor BIS to decrease to 50 as this variable varies markedly followingthree etomidate dose regimen. Br J Anaesth 2003; 91: 341–6     

Comparison of hyperbaric and plain ropivacaine 15 mg in spinal anaesthesia for lower limb surgery

Background. Previously, plain ropivacaine 15 mg given intrathecallyhas been shown to be feasible for ambulatory surgery of lower-extremities.Hypothetically, hyperbaric solution could improve and shortenthe block. Methods. This prospective, randomized, double-blind study included56 patients undergoing surgery of lower extremities. They receivedintrathecally either 1.5 ml of ropivacaine 10 mg ml^–1and 0.5 ml of glucose 300 mg ml^–1 (HYP) or 2 ml of ropivacaine7.5 mg ml^–1 (PL). Results. All patients in Group HYP achieved T₁₀ dermatome analgesiabut only 64% (18/28) of Group PL. T₁₀ analgesia was reachedin 5 min (median, range 5–20 min) in the HYP group vs10 min (5–45 min) in the PL group (P=0.022), and fullmotor block in 10 min (5–45 min) vs 20 min (5–60min) (P=0.003), respectively. Group HYP had a longer durationof analgesia at T₁₀; 83 min (5–145 min) vs 33 min (0–140min) (P=0.004). Duration of sensory block from injection ofthe anesthetic to complete recovery was shorter in Group HYPthan in Group PL, 210 min (120–270 min) vs 270 min (210–360min) (P<0.001), as was duration of motor block, 120 min (5–150min) vs 210 min (120–330 min) (P<0.001). Patients ofGroup HYP attained discharge criteria earlier than those ofGroup PL (P=0.009). Conclusion. In comparison with the plain solution, 15 mg ofintrathecal hyperbaric ropivacaine produced a faster onset,greater success rate of analgesia at the level of T₁₀ dermatome,and faster recovery of the block.     

Mid-latency auditory evoked response during propofol and alfentanil anaesthesia

Background. Propofol has been shown to affect the mid-latencyauditory evoked response (MLAER) in a dose-dependant manner.Few studies have investigated the addition of alfentanil. Myogenicresponses, such as the post-auricular responses (PAR), can confoundthe MLAER but there has been little investigation as to whichelectrode site reduces this interference. Methods. We studied the MLAER in 27 women. They received aninfusion of alfentanil 15 µg kg^–1 h^–1, followedby either a high or low infusion regimen of propofol (finalinfusion rates 6 and 3 mg kg^–1 h^–1). We comparedthe results with those of our study using propofol alone. Wecollected the data from two electrode sites: vertex–inionand vertex–mastoid. We evaluated the occurrence of thePAR and the shape of the MLAER at each electrode site. Results. The infusion rate of propofol associated with lossof the eyelash response in 50% of subjects was 3.3 mg kg^–1h^–1. This was significantly lower than using propofolalone (5.8 mg kg^–1 h^–1). Nb latency was the bestMLAER discriminator of unconsciousness (sensitivity 94%, specificity88%), with a threshold of 46 ms (propofol alone was 53 ms).The addition of alfentanil did not alter the relationship betweenpropofol infusion rate and MLAER. The vertex–inion electrodesite gave the best protection against PAR in awake subjects(P=0.0003), and after 30 min of propofol infusion (P=0.06).The magnitude of the MLAER obtained from the vertex–mastoidelectrodes was larger than from the other site, although theincrease was not consistent throughout the waveform (brain stem100%, Nb 14%). Conclusions. Addition of alfentanil lowers the propofol infusionrate required to produce unconsciousness and the Nb latencythat predicts it. The better of the two sites to reduce theincidence of PAR is the vertex–inion electrode site. Br J Anaesth 2004; 92: 25–32     

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     

Comparison of propofol/remifentanil and sevoflurane/remifentanil for maintenance of anaesthesia for elective intracranial surgery

Background. Propofol and sevoflurane are suitable agents formaintenance of anaesthesia during neurosurgical procedures.We have prospectively compared these agents in combination withthe short-acting opioid, remifentanil. Methods. Fifty unpremedicated patients undergoing elective craniotomyreceived remifentanil 1 µg kg^–1 followed by an infusioncommencing at 0.5 µg kg^–1 min^–1 reducing to0.25 µg kg^–1 min^–1 after craniotomy. Anaesthesiawas induced with propofol, and maintained with either a target-controlledinfusion of propofol, minimum target 2 µg ml^–1 orsevoflurane, initial concentration 2%_ET. Episodes of mean arterialpressure (MAP) more than 100 mm Hg or less than 60 mm Hg formore than 1 min were defined as hypertensive or hypotensiveevents, respectively. A surgical assessment of operating conditionsand times to spontaneous respiration, extubation, obey commandsand eye opening were recorded. Drug acquisition costs were calculated. Results. Twenty-four and twenty-six patients were assigned topropofol (Group P) and sevoflurane anaesthesia (Group S), respectively.The number of hypertensive events was comparable, whilst morehypotensive events were observed in Group S than in Group P(P=0.053, chi-squared test). As rescue therapy, more labetolol[45 (33) vs 76 (58) mg, P=0.073] and ephedrine [4.80 (2.21)vs 9.78 (5.59) mg, P=0.020] were used in Group S. Between groupdifferences in recovery times were small and clinically unimportant.The combined hourly acquisition costs of hypnotic, analgesic,and vasoactive drugs appeared to be lower in patients maintainedwith sevoflurane than with propofol. Conclusion. Propofol/remifentanil and sevoflurane/remifentanilboth provided satisfactory anaesthesia for intracranial surgery.