Comparison of caudal and intravenous clonidine in the prevention of agitation after sevoflurane in children

Background. In children, sevoflurane anaesthesia is associatedwith postanaesthetic agitation, which is treated mainly withopioids. We compared the effectiveness of epidural and i.v.clonidine in the prevention of this postanaesthetic agitation. Methods. Eighty children aged 3–8 yr (ASA I–II)received standardized general anaesthesia with inhaled sevofluraneand caudal epidural block with 0.175% bupivacaine 1 ml kg^–1for minor surgery. The children were assigned randomly to fourgroups: (I) clonidine 1 µg kg^–1 addedto caudal bupivacaine; (II) clonidine 3 µg kg^–1added to caudal bupivacaine; (III) clonidine 3 µg kg^–1i.v. and caudal bupivacaine; and (IV) caudal block with bupivacaine,no clonidine (control). A blinded observer assessed the behaviourof the children during the first postoperative hour. Secondaryend-points were the time to fitness for discharge from the postanaesthesiacare unit, and haemodynamic and respiratory variables. Results. The incidence of agitation was 22, 0, 5 and 39% ingroups I, II, III and IV respectively (P<0.05 for groupsII and III compared with group IV). During the first hour aftersurgery, patients in groups II and III had significantly lowerscores for agitation than group IV patients. Time to fitnessfor discharge did not differ between the four groups. Conclusions. Clonidine 3 µg kg^–1 preventedagitation after sevoflurane anaesthesia, independently of theroute of administration. The effect of clonidine appears tobe dose-dependent, as an epidural dose of 1 µg kg^–1failed to reduce it. Br J Anaesth 2002; 88: 790–6     

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     

Intrathecal morphine and clonidine for coronary artery bypass grafting

Background. After cardiac surgery adequate postoperative analgesiais necessary. We assessed analgesia using intrathecal morphineand clonidine. Methods. In a double-blind randomized study, 45 patients havingcoronary artery bypass graft surgery were allocated randomlyto receive i.v. patient-controlled analgesia (PCA) morphine(bolus, 1 mg; lock-out interval, 7 min) (control group), eitheralone or combined with intrathecal morphine 4 µg kg^–1or with both intrathecal morphine 4 µg kg^–1and clonidine 1 µg kg^–1. Intrathecal injectionswere performed before the induction of general anaesthesia.Pain was measured after surgery using a visual analogue scale(VAS). We recorded i.v. PCA morphine consumption during the24 h after operation. Results. Morphine dosage [median (25th–75th percentiles)]was less in the first 24 h in the patients who were given intrathecalmorphine + clonidine [7 (0–37) mg] than in other patients[40.5 (15–61.5) mg in the intrathecal morphine group and37 (30.5–51) mg in the i.v. morphine group]. VAS scoreswere lower after intrathecal morphine + clonidine compared withthe control group. Time to extubation was less after intrathecalmorphine + clonidine compared with the i.v. morphine group [225(195–330) vs 330 (300–360) min, P<0.05]. Conclusion. Intrathecal morphine and clonidine provide effectiveanalgesia after coronary artery bypass graft surgery and allowearlier extubation. Br J Anaesth 2003; 90: 300–3     

Pharmacokinetics of levobupivacaine 0.25% following caudal administration in children under 2 years of age

Background. Levobupivacaine, the S(–)enantiomer of racemicbupivacaine is less cardiotoxic than racemic bupivacaine andthe R(+)enantiomer dexbupivacaine, while retaining similar localanaesthetic properties and potency to racemic bupivacaine. Thepharmacokinetic profiles of the two bupivacaine enantiomersdiffers and that of racemic bupivacaine may be age dependent.We examined the pharmacokinetics of levobupivacaine after itssingle shot caudal epidural administration in children. Methods. An open-label phase 2 study was undertaken to examinethe pharmacokinetics of levobupivacaine 0.25% 2 mg kg^–1in 49 children aged less than 2 yr, after single shot caudalepidural administration. Plasma concentrations were determinedat intervals up to 60 min after caudal injection. Results. Time to peak plasma concentration (T_max) ranged between5 and 60 min (median 30 min) and was reached later in childrenaged less than 3 months (P<0.005). Peak plasma concentration(C_max) ranged between 0.41 and 2.12 µg ml^–1 (median0.80, mean (SD) 0.91 (0.40) µg ml^–1). Conclusion. After the caudal epidural administration of levobupivacaine2 mg kg^–1 in children less than 2 yr of age, C_max waswithin the accepted safe range for racemic bupivacaine. T_maxvaried and occurred later in some children, particularly thoseaged less than 3 months. Sampling in future pharmacokineticstudies in this age group should extend beyond 60 min. Br J Anaesth 2004; 92: 218–22     

A prospective, double-blind, randomized trial of caudal block using ropivacaine 0.2% with or without fentanyl 1 microg kg-1 in children

Background. It has been reported that ropivacaine produces vasoconstrictionin contrast to vasodilation produced by bupivacaine. It is possiblethat additives to ropivacaine can provide further analgesicadvantages compared with bupivacaine. We thus evaluated whetherthe addition of fentanyl to ropivacaine prolonged the durationof analgesia after a single shot caudal block. Methods. A total of 36 children undergoing surgical proceduresbelow the umbilicus were randomly allocated to one of two groups:Group F received ropivacaine 0.2%, 1 ml kg^–1 with fentanyl1 µg kg^–1 and Group S received ropivacaine 0.2%,1 ml kg^–1 with saline. The analgesic effect of the caudalblock was evaluated using the Children's Hospital of EasternOntario Pain Scale (CHEOPS) and sedation was assessed usingthe Steward score at 30 min after extubation and at 1, 2, 4,6, 12 and 24 h. The first analgesic requirement time and side-effectsin a 24 h period were also recorded. Results. There were no differences in characteristics betweenthe groups. The end-tidal concentration of sevoflurane at extubationin Group F was significantly lower than in Group S. However,there was no significant difference in time from discontinuationof the volatile anaesthetics to tracheal extubation. No statisticaldifferences were found in the CHEOPS and Steward score, andthe time to first analgesia. The incidence of postoperativevomiting was not significantly different. Conclusion. We found that the addition of fentanyl 1 µgkg^–1 to ropivacaine 0.2% for caudal analgesia providesno further analgesic advantages over ropivacaine 0.2% alone.     

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.     

High plasma ropivacaine concentrations after fascia iliaca compartment block in children

Background. The pharmacokinetic profile of local anaestheticsis influenced by the mode of administration. We sought to comparethe pharmacokinetics of two doses of ropivacaine after fasciailiaca compartment (FIC) block in children. Methods. In this prospective, double-blind study, children receivedan FIC block as a part of their anaesthetic management duringelective orthopaedic surgery on the thigh. They were randomizedto receive ropivacaine 0.7 ml kg^–1 using either a0.375% or 0.5% solution. Venous blood samples were drawn upto 6 h after injection. Plasma concentrations of ropivacainewere measured by gas–liquid chromatography. Results. Six children (10.2 (range 5–15) yr, 35.6 (SD10) kg were included. FIC block provided satisfactory peroperativepain relief. No signs of toxicity were observed, but high maximalplasma concentrations (C_max 4.33–5.6 µg ml^–1),were observed for three of four patients in the ropivacaine0.5% group. The two patients in the 0.375% group showed valueswithin the safe range (C_max 0.66 and 0.98 µg ml^–1respectively). Even though no toxic effects were observed, theseresults led us to discontinue the study. Conclusions. The administration of ropivacaine 3.5 mg kg^–1can be associated with sustained high plasma concentrationsof ropivacaine, outside the tolerable range. In view of theseresults, we recommend the use of lower ropivacaine dosage duringFIC block in children. Br J Anaesth 2004: 92: 416–18     

Haemodynamic effects of three doses of dihydroergotamine during spinal anaesthesia

We performed a randomized study comparing the haemodynamic effectsof three doses of the vasopressor dihydroergotamine (DHE) (5,10 and 15 µg kg^–1) in 30 ASA 1 and 2 patients,aged 53–87 yr, undergoing spinal anaesthesia. Non-invasivesystolic arterial pressure (SAP), heart rate and central venouspressure (CVP) were recorded continuously for 25 min. Intravenousfluids were withheld during this period. All three doses ofDHE reversed the lowering effects of spinal anaesthesia on SAPand CVP (P<0.0001), and these effects were smooth in onsetand sustained. Whereas the lowest (5 µg kg^–1)dose restored SAP and CVP to near prespinal values, the higher(10 and 15 µg kg^–1) doses resulted inabove-baseline increases in SAP of 7% and in CVP of 2.7 cm H₂O(P<0.05). The haemodynamic profile of DHE makes it a usefulagent for managing hypotension during spinal anaesthesia. Adose of 5–10 µg kg^–1 is recommended. Br J Anaesth 2001; 87: 499–501     

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     

Activation of electrocorticographic activity with remifentanil and alfentanil during neurosurgical excision of epileptogenic focus

Background. Opioids are known to stimulate surface electroencephalographicactivity in patients with temporal lobe epilepsy. The objectiveof the current study was to compare the electrocorticographicactivation effects of the newer short-acting opioid remifentanilwith those of alfentanil during epilepsy surgery under generalanaesthesia. Methods. Thirteen patients undergoing temporal lobe epilepsysurgery under general anaesthesia received alfentanil 30 µg kg^–1and remifentanil 1 µg kg^–1 as i.v. bolusesin sequence. The design was a randomized double-blind cross-overstudy. After opening the dura, electrocorticogram (ECoG) electrodecontact strips were placed over the temporal and supratemporalneocortex and depth electrodes were inserted in the amygdalaand hippocampus. Alfentanil 30 µg kg^–1or remifentanil 1 µg kg^–1 were administeredrandomly in a blinded fashion. The ECoG was recorded continuouslybefore and after the injection of each drug. The interictalepileptiform activity (spikes and sharp waves) above baselinewas analysed. Results. Both drugs increased epileptiform activity especiallythat recorded from depth electrodes in the temporal limbic structures.No epileptiform activity was recorded from the electrodes overlyingthe supratemporal neocortex before or after drug administration.The more potent activator was alfentanil, which caused an increasein activation from baseline of 99.8% compared with 67.4% forremifentanil. In addition, alfentanil activated the epileptiformactivity in 3 patients in which remifentanil had no effect.There were no changes in heart rate after the opioid boluses.Both remifentanil and alfentanil caused significant reductionsin blood pressure at 3 and 5 min after administration. Conclusion. We conclude that at the doses used in this study,alfentanil is the better opioid for intraoperative activationof the ECoG in neurosurgical patients undergoing resection ofa temporal lobe epileptic focus. This pharmacological activationof epileptiform activity assists in localizing and confirmingthe site of surgical excision. Neither alfentanil nor remifentanilactivated epileptiform activity in non-epileptic brain tissue. Br J Anaesth 2003; 91: 651–5     

The effect of addition of intrathecal clonidine to hyperbaric bupivacaine on postoperative pain and morphine requirements after Caesarean section: a randomized controlled trial

Background. Intrathecal clonidine prolongs spinal anaesthesia.We investigated the effect of the addition of clonidine (75µg) to hyperbaric bupivacaine on postoperative morphineconsumption after Caesarean section in a randomized controlleddouble-blind trial. Methods. A group of 106 women received spinal anaesthesia usingeither bupivacaine 0.5% (2.2 ml) heavy with 0.5 ml normal saline0.9% (B) or bupivacaine 0.5% (2.2 ml) heavy with clonidine (75µg) in 0.5 ml normal saline 0.9% (BC). The primary outcomewas the total morphine consumption in the first 24 h after surgery.Secondary outcomes were the duration of postoperative analgesia,postoperative pain scores, the need for alfentanil during surgery,block regression, clonidine side-effects and morphine side-effects. Results. Total morphine consumption was similar in both studygroups. The mean time to the first analgesic request in theBC group was 129 (SD 13.8) min, compared with 55 (14.2) minin the B group [mean difference (95% CI) –75 (–106to –44) min]. In the BC group 22 (42%) patients had acomplete motor block 1 h after surgery compared with 4 (8%)patients in the B group [RR (95% CI) 0.18 (0.07–0.49)].Side-effects of intrathecal clonidine were not detected. Conclusions. The addition of clonidine (75 µg) to hyperbaricbupivacaine prolongs spinal anaesthesia after Caesarean sectionand improves early analgesia, but does not reduce the postoperativemorphine consumption during the first 24 h. No clinically relevantmaternal or neonatal side-effects were detected.     

Epidural analgesia with 0.15% ropivacaine plus sufentanil 0.5 microgram ml-1 versus 0.10% bupivacaine plus sufentanil 0.5 microgram ml-1: a double-blind comparison during labour

Background. Ropivacaine has been claimed to produce less motorblock than bupivacaine during epidural analgesia. However, thisadvantage has not been clearly confirmed in obstetric studiesusing low analgesic concentrations in a ratio close to thatsuggested to be equianalgesic. Methods. This double-blind, randomized, prospective study wasperformed in 140 parturients who requested epidural analgesia.After a lumbar epidural catheter had been placed, patients receivedeither 0.10% bupivacaine plus sufentanil 0.5 µg ml^–1or 0.15% ropivacaine plus sufentanil 0.5 µg ml^–1followed by a continuous infusion. Additional boluses were usedfor inadequate levels of analgesia. Visual analogue pain scores,motor block, level of sensory block, supplementary boluses andmain characteristics of labour were recorded. Results. No differences were observed between the two groupsfor pain scores, total volume of anaesthetic solution used [59(23) and 57 (24) ml in the bupivacaine and ropivacaine groupsrespectively], duration of labour, mode of delivery, side-effectsor satisfaction score. The incidence of motor block was notstatistically different between the groups (54 and 69% in thebupivacaine and ropivacaine groups respectively, P=0.07). However,when motor block occurred, survival analysis showed that itoccurred sooner in the course of labour with ropivacaine comparedwith bupivacaine (log rank test, P=0.012). Conclusion. Combined with sufentanil 0.5 µg ml^–1,0.10% bupivacaine and 0.15% ropivacaine produce effective andequivalent analgesia during labour, with similar incidencesof motor block. Br J Anaesth 2002; 88: 809–13     

Sedative, analgesic and cognitive effects of clonidine infusions in humans

This placebo-controlled, randomized study evaluated, on separatedays, the dose–response relationship for 1 h infusionsof clonidine 1, 2 and 4 µg kg^–1 h^–1,in eight healthy volunteers aged 22–30 yr. Responseend-points included sedation (bispectral index, visual analoguescale and observer assessment of sedation), analgesia to a coldpressor test, memory (recall of word lists), cognitive function(digit symbol substitution test (DSST)), respiratory function(respiratory rate, end-tidal carbon dioxide, oxygen saturation)and haemodynamic stability (heart rate and mean arterial pressure).Clonidine infusions resulted in significant and progressivesedation, but all subjects were easily awoken to perform testsand evaluations. Statistically significant analgesia, memoryimpairment and reduced performance on the DSST occurred during4 µg kg^–1 h^–1 infusions (resultingin a plasma concentration of 2 ng ml^–1. There were nostatistically significant changes in cardiorespiratory variablesthroughout the study. Br J Anaesth 2001; 86: 5–11     

Sedation caused by clonidine in patients with spinal cord injury

Background. In patients with spinal cord injury, cephalad spreadof intrathecal (i.t.) medication could be delayed. Methods. We used bispectral index and an observer scale to assesssedation after two different doses of i.t. clonidine in patientswith or without spinal cord injury. Twelve patients with neurologicaldeficit caused by trauma (Spinal Cord Injury, SCI) were comparedwith patients without neurological disease. They received 10mg of i.t. bupivacaine with clonidine, with either 50 µg(low dose, n=6) or 150 µg (high dose, n=6) at L₂–L₃.A further 12 patients, six with spinal trauma lesion and sixhealthy, received i.t. bupivacaine and 150 µg of i.m.clonidine. Results. Sedation and a decrease in BIS occurred only in patientsreceiving 150 µg of clonidine. Onset of sedation and thedecrease in BIS was delayed in most spinal cord injured patientswhatever the route of administration (P<0.001). Durationof sedation was not different between the groups. Delayed sedationand decrease of BIS after i.t. clonidine in patients with spinalcord injury are similar than those observed after i.m. clonidine. Conclusion. A systemic effect is likely to be the main reasonfor sedation. Br J Anaesth 2003; 90: 742–5     

Fentanyl versus sufentanil: plasma concentrations during continuous epidural postoperative infusion in children

No pharmacokinetic data are available with respect to the plasmaconcentrations and fentanyl or sufentanil during epidural administrationin children. This double-blind randomized study included 12children (5–12 yr). Patients in group F were givenan epidural loading dose of fentanyl 1.5 µg kg^–1and in group S sufentanil 0.6 µg kg^–1.Both groups then received a continuous epidural infusion ofbupivacaine 5 mg kg^–1 day^–1 witheither fentanyl 5 µg kg^–1 day^–1or sufentanil 2 µg kg^–1 day^–1.An epidural PCA system was also given to the children (bolus:bupivacaine 0.2 mg kg^–1 and fentanyl 0.2 µg kg^–1or sufentanil 0.08 µg kg^–1). Maximal medianconcentrations of plasma (0.117–0.247 ng ml^–1for fentanyl and 0.027–0.074 ng ml^–1 forsufentanil) were reached approximately 30 and 20 min respectivelyafter the loading doses. These values were similar to thosemeasured after 48 h. Br J Anaesth 2000; 85: 615–7 ^* Corresponding author: Service d’Anesthésie et deRéanimation Chirurgicale, Hôtel-Dieu, F-44093 Nantescedex 01, France     

Analgesic efficacy of tramadol 2 mg kg(-1) for paediatric day-case adenoidectomy

We studied the analgesic efficacy of tramadol 2 mg kg^–1for post-operative analgesia after day-case adenoidectomy inchildren aged 1–3 yr. Eighty children were allocatedrandomly to receive tramadol 2 mg kg^–1 i.v.or placebo immediately after induction of anaesthesia. Anaesthesiawas induced with alfentanil 10 µg kg^–1and propofol 4 mg kg^–1 followed by mivacurium0.2 mg kg^–1 for tracheal intubation. Anaesthesiawas continued with sevoflurane in nitrous oxide and oxygen.All children were given ibuprofen rectally at approximately10 mg kg^–1 before the start of surgery. Post-operativepain and recovery assessments were performed by a nurse blindedto the analgesic treatment using the Aldrete recovery score,the pain/discomfort scale and measurement of recovery times.Rescue medication (pethidine in increments of 5 mg i.v.)was administered according to the pain scores. A post-operativequestionnaire was used to evaluate the need for analgesia athome up to 24 h after operation. Rescue analgesic at homewas rectal or oral ibuprofen 125 mg. Children in the tramadolgroup required fewer pethidine doses than those in the placebogroup (P=0.014). Forty-five per cent of children receiving tramadoldid not require post-operative analgesia at all compared with15% of children receiving placebo (P=0.003). Recovery timesand the incidence of adverse effects were similar in the twogroups in the recovery room and at home. The requirement forrectal ibuprofen at home did not differ between groups. Br J Anaesth 2001; 86: 572–5     

Orally administered clonidine significantly reduces pain during injection of propofol

We examined the analgesic effects of orally administered clonidineon pain induced by injection of propofol (Diprivan; 2,6-diisopropylphenol). Female patients (n=81) were randomly allocated to oneof two groups: oral clonidine (5.5 µg kg^–1)followed by i.v. propofol and a control group given placebofollowed by i.v. propofol. The median pain score in the groupreceiving clonidine, using a four-point scale (0=no pain, 1=minimalpain, 2=moderate pain, 3=severe pain) was 1 (0–2), significantlylower than in the control group [2 (1–3), median (25–75percentiles), P<0.001]. Br J Anaesth 2001; 86: 874–6     

Spinal anaesthesia for Caesarean section with bupivacaine 5 mg ml(-1) in glucose 8 or 80 mg ml(-1)

The standard spinal preparation of bupivacaine contains a highconcentration of glucose (80 mg ml^–1). However,the addition of only a small amount of glucose (8 mg ml^–1)to plain solutions of bupivacaine results in a solution which,although no more than marginally hyperbaric, produces a morepredictable block when used for spinal anaesthesia in non-pregnantpatients. However, bupivacaine 5 mg ml^–1 inglucose 8 mg ml^–1 has a density [1.00164 (SD0.00008) at 37°C] which is relatively greater than thatof the cerebrospinal fluid (CSF) of the pregnant patient atterm (1.0003 at 37°C) because CSF density decreases duringpregnancy. Therefore, a double-blind, randomized, controlledstudy was carried out to compare intrathecal bupivacaine (glucose8 mg ml^–1) with bupivacaine (glucose 80 mg ml^–1)in 40 pregnant patients at term. Although there was no differencebetween groups in onset of sensory block, dose of ephedrineor patient satisfaction, patients receiving bupivacaine (5 mg ml^–1)with glucose (8 mg ml^–1) had persistently highersensory blocks between 60 and 120 min after intrathecalinjection, suggesting that the spread of spinal solutions inthe pregnant patient at term is not dependent on density. Br J Anaesth 2001; 86: 805–7     

Differential effects of thiopental on methacholine- and serotonin-induced bronchoconstriction in dogs

Background. Thiopental sometimes causes bronchospasm duringinduction of anaesthesia. In addition, we have reported previouslythat thiopental produced transient bronchospasm, which was blockedby atropine pretreatment, and worsened histamine-induced bronchoconstrictionin dogs. Previous in vitro reports suggest that synthesis ofcontractile cyclooxygenase products, such as thromboxane A₂,may be involved in the mechanism of bronchospasm. However, thein vivo spastic effects have not been defined comprehensively. Methods. Twenty-seven mongrel dogs were anaesthetized with pentobarbital.Bronchoconstriction was elicited with methacholine (0.5 µg kg^–1+5.0µg kg^–1 min^–1; Mch group, n=7) orserotonin (10 µg kg^–1+1 mg kg^–1 h^–1;5HT group, n=20), and assessed as percentage changes in bronchialcross-sectional area (BCA, basal=100%) using a bronchoscope.In the 5HT group, dogs were subdivided into four groups of fiveeach: S-5HT, I-5HT, 5HT-S and 5HT-A. In the S-5HT and I-5HTgroups, 30 min before serotonin infusion dogs were given salineand indomethacin respectively at 5 mg kg^–1 i.v. Inall groups, 30 min after bronchoconstrictor infusion started,dogs were given thiopental at doses between 0 (saline) and 20mg kg^–1. In the 5HT-S and 5HT-A groups, dogs weregiven saline or atropine 0.2 mg kg^–1 i.v. 5 min afterthiopental 20 mg kg^–1. Results. Methacholine and serotonin reduced BCA by about 50and 40% respectively. Thiopental 20 mg kg^–1 increasedand decreased BCA by about 20 and 10% in the Mch and 5HT groupsrespectively. Indomethacin and atropine did not attenuate thepotentiation of serotonin bronchoconstriction produced by thiopental. Conclusion. The present study indicates that thiopental mayattenuate or worsen bronchoconstriction induced by muscarinicor serotonin receptor stimulation, respectively. The synthesisof contractile cyclooxygenase products and cholinergic stimulationmay not be involved in the contractile effect of thiopentalon serotonin bronchoconstriction. Br J Anaesth 2003; 91: 379–84