Comparison of the effects of sevoflurane and propofol on cooling and rewarming during deliberate mild hypothermia for neurosurgery

Background. Because the time available for cooling and rewarmingduring deliberate mild hypothermia is limited, studies of therate of the cooling and rewarming are useful. The decrease incore hypothermia caused by heat redistribution depends on theanaesthetic agent used. We therefore investigated possible differencesbetween sevoflurane and propofol on the decrease and recoveryof core temperature during deliberate mild hypothermia for neurosurgery. Methods. After institutional approval and informed consent,26 patients were assigned randomly to maintenance of anaesthesiawith propofol or sevoflurane. Patients in the propofol group(n=13) received propofol induction followed by a continuousinfusion of propofol 3–5 mg kg^–1 h^–1.Patients in the sevoflurane group (n=13) received propofol inductionfollowed by sevoflurane 1–2%. Nitrous oxide and fentanylwere also used for anaesthetic maintenance. After inductionof anaesthesia, patients were cooled and tympanic membrane temperaturewas maintained at 34.5°C. After surgery, patients were activelyrewarmed. Results. There was no difference in the rate of decrease andrecovery of core temperature between the groups. There was alsono difference in skin surface temperature gradient (forearmto fingertip), heart rate and mean arterial blood pressure betweenthe groups. Conclusions. Sevoflurane-based anaesthesia did not affect coolingand rewarming for deliberate mild hypothermia compared withpropofol-based anaesthesia. Br J Anaesth 2003; 90: 32–8     

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.     

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     

Pharmacokinetics of 0.75% ropivacaine and 0.5% bupivacaine after ilioinguinal-iliohypogastric nerve block in children

Background. Blockade of the ilioinguinal and iliohypogastricnerves is a useful procedure in paediatric patients undergoinginguinal surgery. Bupivacaine 2 mg kg^–1 has been recommendedfor this block. We compared the plasma concentrations of ropivacaineand bupivacaine following an ilioinguinal–iliohypogastricblock. Methods. Forty children scheduled for elective inguinal surgerywere randomized to receive 2 mg kg^–1 of either 0.75% ropivacaineor 0.5% bupivacaine. Surgical anaesthesia was maintained withmask inhalation of oxygen, nitrous oxide and sevoflurane. Venousblood samples were drawn at regular intervals for up to 2 hand plasma was separated. Total venous plasma concentrationswere determined by gas chromatography. Results. The groups were similar with respect to age, weightand dose of local anaesthetic. The peak plasma concentrationachieved was significantly higher in the bupivacaine group comparedwith the ropivacaine group (2.2 vs 1.2 µg ml^–1,P=0.025). The time to peak plasma concentration was significantlyshorter in the bupivacaine group (24 vs 35 min, P=0.024). Theinitial distribution half time of bupivacaine was significantlyshorter (3.6 vs 6.5 min, P=0.020) compared with that of ropivacaine. Conclusions. Bupivacaine is more rapidly absorbed from the injectionsite and leads to higher plasma concentrations than ropivacaine. Br J Anaesth 2002; 89: 438–41     

Sedation during spinal anaesthesia in infants

Background. Neuraxial anaesthesia in adults decreases the doseof i.v. or inhalational anaesthetic needed to reach a desiredlevel of sedation. Furthermore, spinal anaesthesia alone hasa sedative effect. The mechanism behind this phenomenon is presumedto be decreased afferent stimulation of the reticular activatingsystem after sympatholysis. We hypothesized that this mechanismis equally active in infants undergoing spinal anaesthesia. Methods. In total, 20 unpremedicated former preterm infantsunderwent surgery under spinal anaesthesia with hyperbaric bupivacaine0.5% 1 mg kg^–1 with epinephrine 10 µg kg^–1.No additional sedatives or anaesthetics were administered. Sedationwas evaluated using the bispectral index (BIS) score and the95% spectral edge frequency (SEF₉₅). Results. After spinal anaesthesia, mean (SD) BIS began to decreasesignificantly from baseline 97.0 (1.1) to 83.9 (14.4) after15 min (P=0.006). BIS decreased further, reaching the lowestvalues after 30 min [62.2 (14.0); P<0.00001]. Mean (SD) SEF₉₅declined from baseline 26.1 (1.8) Hz to 24.3 (3.1) after 5 min(P=0.02) and further to 9.9 (3.8) after 30 min (P<0.00001).Mean arterial pressure also decreased significantly from 66.5(4.7) mm Hg within 10 min to 56.1 (5.6) after spinal anaesthesia(P=0.0002), while heart rate remained stable. Conclusions. These results suggest that sedation after spinalanaesthesia in infants is at least as pronounced as in adults.The sedative effect of spinal anaesthesia should be kept inmind when additional sedatives are administered, especiallyin former preterm infants.     

Effects of sevoflurane and propofol on left ventricular diastolic function in patients with pre-existing diastolic dysfunction

Background. The effects of anaesthetics on left ventricular(LV) diastolic function in patients with pre-existing diastolicdysfunction are not well known. We hypothesized that propofolbut not sevoflurane will worsen the pre-existing LV diastolicdysfunction. Methods. Of 24 randomized patients, 23 fulfilled the predefinedechocardiographic criterion for diastolic dysfunction. Theyreceived general anaesthesia with sevoflurane 1 MAC (n=12) orpropofol 4 µg ml^–1 (n=11). Echocardiographic examinationswere performed at baseline and in anaesthetized patients underspontaneous breathing and under positive pressure ventilation.Analysis focused on peak early diastolic velocity of the mitralannulus (E_a). Results. During spontaneous breathing, E_a was higher in thesevoflurane than in the propofol group [mean (95% CI) 7.0 (5.9–8.1)vs 5.5 (4.7–6.3) cm s^–1; P<0.05], reflectingan increase of E_a from baseline only in the sevoflurane group(P<0.01). Haemodynamic findings were similar in both groups,but the end-tidal carbon dioxide content was more elevated inthe propofol group (P<0.01). During positive pressure ventilation,E_a was similarly low in the sevoflurane and propofol groups[5.3 (4.2–6.3) and 4.4 (3.6–5.2) cm s^–1, respectively]. Conclusions. During spontaneous breathing, early diastolic functionimproved in the sevoflurane but not in the propofol group. However,during positive pressure ventilation and balanced anaesthesia,there was no evidence of different effects caused by the twoanaesthetics.     

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     

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.     

Multi-level approach to anaesthetic effects produced by sevoflurane or propofol in humans: 2. BIS and tetanic stimulus-induced withdrawal reflex

Background: General anaesthesia could be assessed at two sites: corticalstructures and the spinal cord. However, the practicalitiesof measurement at these two sites differ substantially. Methods: We simultaneously analysed effects of sevoflurane (Group S;n = 16) or propofol (Group P; n = 17) on bispectral index (BIS)and the tetanic stimulus-induced withdrawal reflex (TIWR). TIWRwas quantified by the area under the curve of the electromyogramof the biceps femoris muscle after electrical stimulation ofthe sural nerve. After loss of consciousness, TIWR was evokedonce per minute. The anaesthetic was increased until TIWR disappeared.After discontinuation of the anaesthetic and reappearance ofTIWR, the amount of anaesthetic was increased again. Using asigmoid E_max model and a first-order rate constant k_e0, we characterizedthe dose–response relationships for BIS and TIWR. Results: Concentration-dependent depression of TIWR was reasonably wellmodelled for sevoflurane, but poorly for propofol. TIWR wascompletely suppressed by sevoflurane, but not propofol. Sevofluranereduced TIWR to 5 mV ms (very weak movement) at 1.68 vol% end-expiredconcentration [ minimum alveolar concentration (MAC value)].The k_e0s for TIWR were smaller than those for BIS: 0.25 (0.16–0.39)vs 0.41 (0.33–0.51) min^–1 for Group S; 0.25 (0.22–0.30)vs 0.34 (0.29–0.40) min^–1 for Group P [geometricmean (95% CI)]. Conclusions: High concentrations of sevoflurane depress TIWR more than propofol.With propofol, we frequently observed a paradoxical behaviourof muscles of the lower leg. TIWR lags behind BIS, indicatingdifferent effect sites for two intended anaesthetic effects:unresponsiveness to noxious stimulation and unconsciousness.     

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     

Effect of clonidine pre-medication on propofol requirements during lower extremity vascular surgery: a randomized controlled trial

Background. Pre-medication with clonidine reduces the requirementfor volatile agents during general anaesthesia. This may alsobe true for anaesthesia with propofol, but the amount of dosereduction has not been measured. Because clonidine also affectscardiac output and thus regional blood flow it could alter thepharmacokinetics of propofol. This randomized, double-blindplacebo-controlled trial aimed to study the effect of clonidinepre-medication on dose requirement for propofol during lowerextremity vascular surgery using the bispectral index (BIS)as a measure of anaesthetic depth. Methods. After oral pre-medication with either clonidine 3 µgkg^–1 or placebo, 39 subjects had lower limb vascular surgeryusing propofol infusion for anaesthesia. Anaesthetic depth wasadjusted to a BIS of 45. Predicted plasma propofol concentrationswere noted every 30 min from a target-controlled propofol infusionpump and arterial samples were taken at the same time for propofolmeasurements. Results. Patients in both groups were anaesthetized to similardepths of anaesthesia as indicated by BIS readings (P=0.44).The groups had comparable mean (95% CI) arterial concentrationsof propofol, 4.8 (3.5–6.1) µg ml^–1 in thepatients given clonidine, and 4.6 (3.4–5.7) µg ml^–1in the patients given placebo (P=0.81). However, the averageplasma concentration predicted by the target-controlled infusionwas less in the clonidine group [3.2 (2.9–3.5)] than inthe group given placebo [3.6 (3.3–3.9)] µg ml^–1(P<0.05). Conclusions. Pre-medication with clonidine reduces the requirementfor propofol, which is a pharmacokinetic effect and not a pharmacodynamiccentral sedative effect.     

Double-blind comparison of ropivacaine 7.5 mg ml(-1) with bupivacaine 5 mg ml(-1) for sciatic nerve block

Two groups of 12 patients had a sciatic nerve block performedwith 20 ml of either ropivacaine 7.5 mg ml^–1 or bupivacaine5 mg ml^–1. There was no statistically significant differencein the mean time to onset of complete anaesthesia of the footor to first request for post-operative analgesia. The qualityof the block was the same in each group. Although there wasno statistically significant difference in the mean time topeak plasma concentrations the mean peak concentration of ropivacainewas significantly higher than that of bupivacaine. There wereno signs of systemic local anaesthetic toxicity in any patientin either group. Br J Anaesth 2001; 86: 674–7     

Unconscious learning during surgery with propofol anaesthesia

Background. Learning during anaesthesia has been demonstrated,but little is known about the circumstances under which it mayoccur. This study investigated the hypothesis that learningduring anaesthesia occurs during, but not before, surgical stimulation. Methods. Words were played through headphones to 64 day-surgerypatients during propofol anaesthesia. Fourteen words were playedrepeatedly (15 times) for 1 min each either before (n=32) orduring (n=32) surgical stimulation. The depth of anaesthesiawas estimated using the bispectral index^TM (BIS^TM). Heart rate,ventilatory frequency, mean arterial pressure, end-tidal carbondioxide concentration, and infusion rate of propofol were recordedat 1 min intervals during word presentation. On recovery, memorywas assessed using an auditory word stem completion test andword recognition test. Results. The mean BIS^TM, arterial pressure, end-tidal carbondioxide and heart rate during word presentation did not differbetween the groups. The infusion rate of propofol and the ventilatoryfrequency were significantly greater in the during-surgicalstimulation group. There was no evidence for explicit recallor recognition, nor of awareness during anaesthesia (medianmean-BIS^TM=38 in the before-surgical stimulation group and 42in the during-surgical stimulation group). Only patients whowere played words during surgical stimulation showed significantimplicit memory on recovery (mean score=0.08, P<0.02) However,their scores were not significantly higher than those of thebefore-surgical stimulation group (mean score=0.01). Conclusions. Learning during anaesthesia seems more likely tooccur during rather than before surgical stimulation at comparableanaesthetic depth. We hypothesize that surgical stimulationfacilitates learning during anaesthesia, independently of itseffects on anaesthetic depth. Br J Anaesth 2004; 92: 171–7     

Measurement of motor evoked potentials following repetitive magnetic motor cortex stimulation during isoflurane or propofol anaesthesia

Background. Isoflurane and propofol reduce the recordabilityof compound muscle action potentials (CMAP) following singletranscranial magnetic stimulation of the motor cortex (sTCMS).Repetition of the magnetic stimulus (repetitive transcranialmagnetic stimulation, rTCMS) might allow the inhibition causedby anaesthesia with isoflurane or propofol to be overcome. Methods. We applied rTCMS (four stimuli; inter-stimulus intervalsof 3, 4, 5 ms (333, 250, 200 Hz), output 2.5 Tesla) in 27 patientsand recorded CMAP from the hypothenar and anterior tibial muscle.Anaesthesia was maintained with fentanyl 0.5–1 µgkg^–1 h^–1 and either isoflurane 1.2% (10 patients)or propofol 5 mg kg^–1 h^–1 with nitrous oxide 60%in oxygen (17 patients). Results. No CMAP were detected during isoflurane anaesthesia.During propofol anaesthesia 333 Hz, four-pulse magnetic stimulationevoked CMAP in the hypothenar muscle in 75%, and in the anteriortibial muscle in 65% of the patients. Less response was obtainedwith 250 and 200 Hz stimulation. Conclusions. In most patients, rTCMS can overcome suppressionof CMAP during propofol/nitrous oxide anaesthesia, but not duringisoflurane anaesthesia. A train of four magnetic stimuli ata frequency of 333 Hz is most effective in evoking potentialsfrom the upper and lower limb muscles. The authors concludethat rTCMS can be used for evaluation of the descending motorpathways during anaesthesia. Br J Anaesth 2003; 91: 487–92     

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     

Antagonism of neuromuscular blockade but not muscle relaxation affects depth of anaesthesia

Background. Conflicting effects of neuromuscular blocking drugsand anticholinesterases on depth of anaesthesia have been reported.Therefore we evaluated the effect of atracurium and neostigmineon bispectral index (BIS) and middle-latency auditory evokedpotentials (AAI). Methods. We studied 40 patients (ASA I–II) aged 18–69yr. General anaesthesia consisted of propofol and remifentanilby target-controlled infusion and neuromuscular function wasmonitored by electromyography. When BIS reached stable values,patients were randomly assigned to one of two groups. Group1 received atracurium 0.4 mg kg^–1 and, 5 min later, thesame volume of NaCl 0.9%; group 2 received saline first andthen atracurium. When the first twitch of a train of four reached10% of control intensity, patients were again randomized: onegroup (N) received neostigmine 0.04 mg kg^–1 and glycopyrrolate0.01 mg kg^–1, and the control group (G) received onlyglycopyrrolate. Results. Injection of atracurium or NaCl 0.9% had no effecton BIS or AAI. After neostigmine–glycopyrrolate, BIS andAAI increased significantly (mean maximal change of BIS 7.1[SD 7.5], P<0.001; mean maximal change of AAI 9.7 [10.5],P<0.001). When glycopyrrolate was injected alone BIS andAAI also increased (mean maximal change of BIS 2.2 [3.4], P=0.008;mean maximal change of AAI 3.5 [5.7], P=0.012), but this increasewas significantly less than in group N (P=0.012 for BIS; P=0.027for AAI). Conclusion. These data suggest that neostigmine alters the stateof propofol–remifentanil anaesthesia and may enhance recovery.     

Parecoxib sodium has opioid-sparing effects in patients undergoing total knee arthroplasty under spinal anaesthesia

Background. This multicentre, double-blind, placebo-controlledstudy compared the opioid-sparing effectiveness and clinicalsafety of parecoxib sodium over 48 h, in 195 postoperativepatients after routine total knee replacement surgery. Methods. Elective total primary knee arthroplasty was performedunder spinal anaesthesia, with a single dose of spinal bupivacaine10–20 mg, and intraoperative sedation with midazolam0.5–1.0 mg i.v., or propofol <6 mg kg^–1h^–1. Patients were randomized to receive either parecoxibsodium 20 mg twice daily (bd) i.v. (n=65), parecoxib sodium40 mg bd i.v. (n=67), or placebo (n=63) at the completionof surgery, and after 12, 24, and 36 h. Morphine (1–2 mg)was taken by patient-controlled analgesia or by bolus dosesafter 30 min. Results. Patients receiving parecoxib sodium 20 mg bd and40 mg bd consumed 15.6% and 27.8% less morphine at 24 hthan patients taking placebo (both P<0.05). Both doses ofparecoxib sodium administered with morphine provided significantlygreater pain relief than morphine alone from 6 h (P<0.05).A global evaluation of study medication demonstrated a greaterlevel of satisfaction among patients taking parecoxib sodiumthan those taking placebo. Parecoxib sodium administered incombination with morphine was well tolerated. However, a reductionin opioid-type side-effects was not demonstrated in the parecoxibsodium groups. Conclusion. Parecoxib sodium provides opioid-sparing analgesiceffects in postoperative patients. Br J Anaesth 2003; 90: 166–72     

Effect of sevoflurane/nitrous oxide versus propofol anaesthesia on somatosensory evoked potential monitoring of the spinal cord during surgery to correct scoliosis

Background. Use of intraoperative somatosensory evoked potential(SSEP) monitoring is helpful in spinal corrective surgery butmay be affected by anaesthetic drugs. An anaesthetic techniquethat has less effect on SSEP or allows faster recovery is anadvantage. We compared the effects on SSEP and the clinicalrecovery profiles of sevoflurane/nitrous oxide and propofolanaesthesia during surgery to correct scoliosis. Methods. Twenty adolescent patients were randomized into twogroups of 10. One group received sevoflurane–nitrous oxideanaesthesia and the other received propofol i.v. anaesthesia.An alfentanil infusion was used for analgesia in both groups. Results. Changes in anaesthetic concentration produced littleeffect on the latency of SSEP, but the effect on the variabilityof SSEP amplitude was significant (P<0.05). Sevoflurane produceda faster decrease in SSEP and a faster recovery than propofol(P<0.05). On emergence, patients who received sevofluranetended to have shorter recovery times to eye opening (mean 5.1vs 20.6 min, P=0.09) and toe movement (mean 7.9 vs 15.7 min,P=0.22). Those who had received sevoflurane were significantlymore lucid and cooperative in recovery. Conclusions. Sevoflurane produces a faster decrease and recoveryof SSEP amplitude as well as a better conscious state on emergencethan propofol. Br J Anaesth 2002; 88: 502–7     

Efficacy of prophylactic ketamine in preventing postoperative shivering

Background. Treatment with ketamine and pethidine is effectivein postoperative shivering. The aim of this study was to comparethe efficacy of low-dose prophylactic ketamine with that ofpethidine or placebo in preventing postoperative shivering. Methods. A prospective randomized double-blind study involved90 ASA I and II patients undergoing general anaesthesia. Patientswere randomly allocated to receive normal saline (Group S, n=30),pethidine 20 mg (Group P, n=30) or ketamine 0.5 mg kg^–1(Group K, n=30) intravenously 20 min before completion of surgery.The anaesthesia was induced with propofol 2 mg kg^–1, fentanyl1 µg kg^–1 and vecuronium 0.1 mg kg^–1. It wasmaintained with sevoflurane 2–4% and nitrous oxide 60%in oxygen. Tympanic temperature was measured immediately afterinduction of anaesthesia, 30 min after induction and beforeadministration of the study drug. An investigator, blinded tothe treatment group, graded postoperative shivering using afour-point scale and postoperative pain using a visual analoguescale (VAS) ranging between 0 and 10. Results. The three groups did not differ significantly regardingpatient characteristics. The number of patients shivering onarrival in the recovery room, and at 10 and 20 min after operationwere significantly less in Groups P and K than in Group S. Thetime to first analgesic requirement in Group S was shorter thanin either Group K or Group P (P<0.005). There was no differencebetween the three groups regarding VAS pain scores. Conclusion. Prophylactic low-dose ketamine was found to be effectivein preventing postoperative shivering.     

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