预先注射瑞芬太尼预防小儿静注罗库溴铵时的回避反应

目的:评估在儿童患者中预先注射瑞芬太尼预防静注罗库溴铵时的回避反应的效能.方法:选择40例施行全麻的择期手术患者,年龄在3-10岁,ASAⅠ-Ⅱ级,患儿随机分为两组:瑞芬组,静注瑞芬1ug/kg,(20例患儿);盐水组,静注盐水5ml(20例患儿).用5mg/kg的硫喷妥钠进行麻醉诱导,患者意识丧失并且停止呼吸后10秒,注射实验药物,注射时间超过30秒,实验药物注射后1分钟以后,1%的罗库溴铵0.6mg/kg静注,注射时间超过5秒钟.结果:总的回避反应发生率在盐水组(19人,95%)明显高于瑞芬组(5人,25%),在瑞芬组没有患者出现全身反应,而在盐水组全身反应的发生率为55%.瑞芬太尼还能防止在插管过程中平均动脉压的升高.讨论:这个实验表明了在儿童患者中预先注射1ug/kg瑞芬对减少注射罗库溴铵时的回避的发生一个安全简单的方法,并且提供了一个稳定的血液动力学环境.     

Neuromuscular effects of rocuronium in children during halothane anaesthesia

Rocuronium bromide, a nondepolarizing muscle relaxant has been shown to have a short onset and intermediate duration of action in adults and young children. We evaluated onset time, intubating conditions, as well as duration of action of rocuronium in children ages four to 12 years during nitrous oxide-halothane anaesthesia. Following a stable recording of train-of-four (TOF) impulses at the ulnar nerve, patients were given rocuronium 600 μg˙kg^?1 intravenously. We found that the time to 90% and 100% neuromuscular (N-M) block of the (TOF) was 51 ± 18 s and 66 ± 32 s respectively. Intubation was achieved at 94 ± 31 s and rated as good or excellent in all cases. Time to recovery of N-M transmission to 25%, 75% and 90% of control was 29 ± 8 min, 42 ± 14 min and 46 ± 16 min respectively. Heart rate increased ～12 BPM after drug injection, while the blood pressure remained unchanged. From our data we conclude that, as in other age groups, rocuronium has a rapid onset, intermediate duration of action in children 4–12 years of age, and appears devoid of significant side effects.     

Prolonged residual paralysis after a single intubating dose of rocuronium

It is often argued that neuromuscular monitoring is unnecessarywhen only one dose of an intermediate-acting neuromuscular blockingagent is given. This case report documents that it may takemore than 3.5 h before it is possible to antagonize a blockcaused by a normal dose of rocuronium (0.6 mg kg^–1). Possiblecauses of the extremely prolonged duration of action are discussed,as is the importance of quantitative neuromuscular monitoring.     

Recovery from propofol anaesthesia supplemented with remifentanil

We have examined the effects on recovery end-points of supplementationof a propofol-based anaesthetic with remifentanil. After inductionof anaesthesia with propofol and remifentanil 1.0 µg kg^–1,15 patients each were randomly allocated to target plasma propofolconcentrations of 2, 3, 4 or 5 µg ml^–1for maintenance of anaesthesia. Remifentanil was administeredby infusion for supplementation in doses required for maintenanceof adequate anaesthesia. All patients received 50% nitrous oxidein oxygen and ventilation was controlled. The total amount ofdrugs used and times to different recovery end-points were recorded.Cognitive function was also assessed using a Mini-Mental Statequestionnaire. The median dose of remifentanil for maintenanceof adequate anaesthesia (excluding the initial bolus dose) inthe four groups was 0.21, 0.15, 0.11 and 0.13 µg kg^–1 min^–1respectively (P=0.0026). The median times to eye opening andorientation were shortest in the 2 µg ml^–1group [6.0 and 6.5 min, 8.5 and 10.8 min, 13.4 and15.8 min, and 14.2 and 19.5 min respectively in thepropofol 2, 3, 4, and 5 µg ml^–1 groups respectively(P<0.001)]. The times to discharge from the recovery wardand the Mini-Mental State scores were not significantly different. Br J Anaesth 2001; 86: 361–5     

Recovery after remifentanil and sufentanil for analgesia and sedation of mechanically ventilated patients after trauma or major surgery

We investigated the analgesic effect and the neurological recoverytime after administration of remifentanil in mechanically ventilatedpatients in an intensive care unit. Twenty patients, after traumaor major surgery with no intracranial pathology, were randomizedto receive either remifentanil/propofol (n=10) or sufentanil/propofol(n=10). A sedation score and a simplified pain score were usedto assess adequate sedation and analgesia. Medication was temporarilystopped after 24 h. Immediately before and 10 and 30 min after,the degree of sedation and pain score were evaluated. Adequateanalgesia and sedation was achieved with remifentanil 10.6 µgkg^–1 h^–1 and propofol 2.1 mg kg^–1 h^–1,or sufentanil 0.5 µg kg^–1 h^–1 and propofol1.3 mg kg^–1 h^–1. The difference in propofol dosebetween groups was significant. Ten minutes after terminatingthe medication, the degree of sedation decreased significantlyafter remifentanil and all patients could follow simple commands.During the following 20 min, all patients with remifentanilemerged from sedation and complained of considerable pain. Bycontrast, in the sufentanil group, only six (7) responded tocommands after 10 (30) min and their pain score remained essentiallyunchanged during the 30-min observation period. We concludethat, in contrast to sufentanil, remifentanil facilitates rapidemergence from analgesia and sedation, allowing a clinical neurologicalexamination within 10–30 min in mechanically ventilatedpatients with no intracranial pathology. Br J Anaesth 2001; 86: 763–8     

Prevention of withdrawal movement associated with injection of rocuronium in children: comparison of remifentanil, alfentanil and fentanyl

BACKGROUND: We compared the efficacy of remifentanil, alfentanil and fentanyl in reducing withdrawal movement associated with the injection of rocuronium in children. METHODS: In total, 164 ASA physical status I or II pediatric patients, aged 1-14 years, were randomly assigned to four treatment groups: group C received saline; group R, remifentanil 1 microg/kg; group A, alfentanil 10 micro/kg; and group F, fentanyl 2 microg/kg. Treatments were injected over 30 s, followed by thiopental 5 mg/kg. At 90 s after the start of the study drug injection, rocuronium 0.6 mg/kg was injected over 10 s. The patient's response to the injection of rocuronium was graded on a four-point scale in a double-blinded manner. RESULTS: The incidence of withdrawal movement was 89.5% in group C, 70.3% in group F, 36.3% in group A and 7.2% in group R. The incidence of generalized movement (grade 4) was 86.9% in group C, 58.5% in group F, 15.9% in group A and 2.4% in group R. CONCLUSION: Remifentanil, alfentanil and fentanyl all reduced the incidence of withdrawal movement when administered 90 s before the injection of rocuronium compared with saline. Remifentanil was the most effective, followed by alfentanil. Fentanyl was less effective but significantly different from the saline in reducing withdrawal movement in children.     

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

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

Effect of remifentanil infusion rate on stress response to the pre-bypass phase of paediatric cardiac surgery

Background. Opioids are used routinely to eliminate the stressresponse in the pre-bypass phase of paediatric cardiac surgery.Remifentanil is a unique opioid allowing a rapidly titratableeffect. No data are available regarding a suitable remifentanildose regimen for obtunding stress and cardiovascular responsesto such surgery. Methods. We recruited 49 infants and children under 5 yr oldwho were randomized to receive one of four remifentanil infusionrates (0.25, 1.0, 2.5, or 5.0 µg kg^–1 min^–1).Blood samples were obtained at induction, pre-surgery, 5 minafter opening the chest, and immediately pre-bypass. Whole bloodglucose was measured at all time points while cortisol and neuropeptideY (NPY) were measured in the first and last samples. Heart rateand arterial pressure were also recorded. Results. There was a significant increase in whole blood glucose5 min after opening the chest and pre-bypass (P=0.009, P=0.002)in patients receiving remifentanil 0.25 µg kg^–1min^–1, but not in those receiving higher doses. Increasedremifentanil dosage was associated with reduced plasma cortisolduring surgery (P<0.001). Baseline NPY showed considerablevariation and there was no association between pre-bypass NPYand remifentanil dose. There was a significantly higher heartrate at the pre-bypass stage of surgery in the remifentanil0.25 µg kg^–1 min^–1 group compared with higherdoses (P=0.0006). Four out of five neonates with complex cardiacconditions showed severe bradycardia associated with remifentanil. Conclusions. In infants and children under 5 yr, remifentanilinfusions of 1.0 µg kg^–1 min^–1 and greatercan suppress the glucose increase and tachycardia associatedwith the pre-bypass phase of cardiac surgery, while 0.25 µgkg^–1 min^–1 does not. Remifentanil should be usedwith caution in neonates with complex congenital heart disease. Br J Anaesth 2004; 92: 187–94     

Reduction of pain during induction with target-controlled propofol and remifentanil

BACKGROUND: Pain on injection of propofol is unpleasant. We hypothesized that propofol infusion pain might be prevented by infusing remifentanil before starting the propofol infusion in a clinical setting where target-controlled infusions (TCI) of both drugs were used. A prospective, randomized, double-blind, placebo-controlled trial was performed to determine the effect-site concentration (Ce) of remifentanil to prevent the pain without producing complications. METHODS: A total of 128 patients undergoing general surgery were randomly allocated to receive normal saline (control) or remifentanil to a target Ce of 2 ng ml(-1) (R2), 4 ng ml(-1) (R4), or 6 ng ml(-1) (R6) administered via TCI. After the target Ce was achieved, the infusion of propofol was started. Remifentanil-related complications were assessed during the remifentanil infusion, and pain caused by propofol was evaluated using a four-point scale during the propofol infusion. RESULTS: The incidence of pain was significantly lower in Groups R4 and R6 than in the control and R2 groups (12/32 and 6/31 vs 26/31 and 25/32, respectively, P<0.001). Pain was less severe in Groups R4 and R6 than in the control and R2 groups (P<0.001). However, both incidence and severity of pain were not different between Groups R4 and R6. No significant complications were observed during the study. CONCLUSIONS: During induction of anaesthesia with TCI of propofol and remifentanil, a significant reduction in propofol infusion pain was achieved without significant complications by prior administration of remifentanil at a target Ce of 4 ng ml(-1).     

No clinical evidence of acute opioid tolerance after remifentanil-based anaesthesia

We have prospectively assessed whether remifentanil-based anaesthesiais associated with clinically relevant acute opioid tolerance,expressed as greater postoperative pain scores or morphine consumption.Sixty patients undergoing elective gynaecological, non-laparoscopic,surgery were randomly assigned to receive remifentanil (groupR, n=30) or sevoflurane (group S, n=30) based anaesthesia. Postoperativeanalgesia was provided with morphine through a patient-controlledinfusion device. Mean (SD) remifentanil infusion rate in groupR was 0.23 (0.10) µg kg^–1 min^–1 and mean inspiredfraction of sevoflurane in group S was 1.75 (0.70)%. Mean (SD)cumulative morphine consumption during the first 24 postoperativehours was similar between groups: 28.0 (14.2) mg (group R) vs28.6 (12.4) mg (group S). Pain scores, were also similar betweengroups during this period. These data do not support the developmentof acute opioid tolerance after remifentanil-based anaesthesiain this type of surgery. Br J Anaesth 2001; 87: 866–9     

Remifentanil and propofol without muscle relaxants or with different doses of rocuronium for tracheal intubation in outpatient anaesthesia

BACKGROUND: The use of muscle relaxants in outpatient anaesthesia is controversial; some authors recommend an induction regimen including propofol and opioids without muscle relaxants. This study evaluated the requirements for rocuronium after remifentanil/propofol. METHODS: We examined in four groups of ASA I-II patients (n= 30 for each) the intubating conditions three minutes after induction of anaesthesia with remifentanil 0.5 microg kg(-1) min(-1), propofol 2 mg kg(-1) without muscle relaxants or with different doses of rocuronium (0.6 mg kg(-1), 0.45 mg kg(-1), 0.3 mg kg(-1)) applying the criteria proposed by the Copenhagen Consensus Conference. In the second part of the study the time course of neuromuscular block was determined by electromyography using train-of-four (TOF) stimulation. To this end, another 60 ASA I-II patients were randomly assigned to receive remifentanil 0.5 microg kg(-1) min(-1), propofol 2 mg kg(-1) and either rocuronium 0.6 mg kg(-1), 0.45 mg kg(-1), 0.3 mg kg(-1), or 0.3 mg kg(-1) followed by neostigmine 40 microg kg(-1) and atropine 20 microg kg(-1) at a T1 recovery of 10% (n=15 for each). RESULTS: Intubating conditions were good or excellent in 30 patients after rocuronium 0.6 mg kg(-1) and in 18 patients when rocuronium was omitted (P<0.01). After 0.45 mg kg(-1) and 0.3 mg kg(-1) rocuronium the numbers were 29 and 30 patients, respectively. Reducing rocuronium from 0.6 mg kg(-1) to 0.45 mg kg(-1) or 0.3 mg kg(-1) increased the onset time from 136 (35) s to 199 (34) s and 249 (52) s (mean (SD)), (P<0.01); the clinical duration decreased from 38 (10) min to 24 (8) min and 16 (5) min, respectively (P<0.01); and the duration to a TOF-ratio of 0.8 decreased from 60 (11) min to 45 (9) min and 34 (7) min (P<0.01). After rocuronium 0.3 mg kg(-1) this time interval further decreased to 22 (3) min when neostigmine was given at a T1 of 10% (P<0.01 compared with spontaneous recovery after rocuronium 0.3 mg kg(-1)). CONCLUSION: After remifentanil/propofol intubation conditions were poor in 40% of patients without muscle relaxants; adding reduced doses of rocuronium to this regimen improved the intubation conditions significantly. In addition, reducing the initial dose of rocuronium markedly shortened its time course of action.     

Onset and effectiveness of rocuronium for rapid onset of paralysis in patients with major burns: priming or large bolus

Background: Burn injury leads to resistance to the effects of non-depolarizingmuscle relaxants. We tested the hypothesis that a larger bolusdose is as effective as priming for rapid onset of paralysisafter burns. Methods: Ninety adults, aged 18–59 yr with 40 (2)% [mean (SE)]burn and 30 (2) days after injury, received rocuronium as apriming dose followed by bolus (0.06+0.94 mg kg^–1), orsingle bolus of either 1.0 or 1.5 mg kg^–1. Sixty-one non-burned,receiving 1.0 mg kg^–1 as a primed (0.06+0.94 mg kg^–1)or full bolus dose, served as controls. Acceleromyography measuredthe onset times. Results: Priming when compared with 1.0 mg kg^–1 bolus in burnedpatients shortened the time to first appearance of twitch depression(30 vs 45 s, P<0.05) and time to maximum twitch inhibition(135 vs 210 s, P<0.05). The onset times between priming andhigher bolus dose (1.5 mg kg^–1) were not different (30vs 30 s for first twitch depression and 135 vs 135 s for maximaldepression, respectively). The onset times in controls, however,were significantly (P<0.05) faster than burns both for primingand for full bolus (15 and 15 s, respectively, for first twitchdepression and 75 and 75 s for maximal depression). Primingcaused respiratory distress in 10% of patients in both groups.Intubating conditions in burns were significantly better with1.5 mg kg^–1 than with priming or full 1.0 mg kg^–1bolus. Conclusions: A dose of 1.5 mg kg^–1 not only produces an initial onsetof paralysis as early as 30 s, which we speculate could be areasonable onset time for relief of laryngospasm, but also hasan onset as fast as priming with superior intubating conditionsand no respiratory side-effects.     

Tramadol does not modify the Bispectral Index during anaesthesia with sevoflurane and remifentanil

Background. The aim of this study was to investigate the effectsof tramadol administered with ketorolac on the Bispectral Index(BIS) during anaesthesia with sevoflurane and remifentanil. Methods. Forty-six adult patients, ASA I–III, scheduledfor elective minor surgical procedures were studied. Patientswere premedicated with remifentanil infusion 0.4 µg kg^–1min^–1 and anaesthesia was induced 4–5 min laterwith propofol 1.5 mg kg^–1 and maintained with air–oxygen( 0.4), remifentanil 0.1–0.15 µg kg^–1 min^–1 and sevoflurane, adjusted to keep theBIS between 40 and 50. After 20 min of stable anaesthesia, thesubjects were allocated randomly to receive i.v. tramadol 1.5mg kg^–1 and i.v. ketorolac 0.3 mg kg^–1 (tramadolgroup) or saline (control group). BIS values, mean arterialpressure, heart rate and end-tidal carbon dioxide were recordedevery 5 min for 20 min. Results. Mean BIS values after tramadol administration werenot significantly different from those recorded in patientsreceiving saline throughout the period of observation. Therewere no patients who presented explicit recall of events underanaesthesia. No significant changes in mean arterial pressure,heart rate and end-tidal carbon dioxide were noted after tramadolinjection. Conclusion. Tramadol, given with ketorolac to prevent postoperativepain, during anaesthesia maintained with sevoflurane and remifentanilat BIS between 40 and 50, does not modify the BIS value.     

Target controlled infusion of rocuronium: analysis of effect data to select a pharmacokinetic model

Background. We aimed to evaluate whether area under the curve(AUC) analysis of pharmacodynamic data can be used to comparepharmacokinetic models taken from the literature, during a targetcontrolled infusion (TCI) of rocuronium. Methods. Seventy-two patients scheduled for orthopaedic surgeryreceived a TCI of rocuronium (Stanpump) based on one of fourpharmacokinetic models: those described by Szenohradszky, Alvarez-Gomez,Wierda, and Cooper. The resulting theoretical plasma concentrationversus time curve was calculated for all patients based on allfour pharmacokinetic models. Predicted effect versus time curveswere calculated following the pharmacokinetic–pharmacodynamiclink model (Sheiner and colleagues). Neuromuscular block wasevaluated acceleromyographically. The difference between thearea under the observed effect (AUC_OE) and predicted effect(AUC_PE) versus time curves was used for comparison. Results. AUC_PE differed significantly from AUC_OE in the Szenohradszkyand Alvarez-Gomez models, both with the reference link-pharmacodynamicdata and with altered link-pharmacodynamic variables. AUC_PEand AUC_OE were comparable for the Wierda and Cooper models.The mean AUC_OE was 25.1 (SD 11.9)% blockxh. AUC_PE–AUC_OEwas significantly larger in the Szenohradszky model when comparedwith all other pharmacokinetic models. This difference remainedwhen link or pharmacodynamic variables were modified. The smallestAUC_PE–AUC_OE difference was found with the Wierda model. Conclusion. It was possible to use AUC analysis for identificationof the pharmacokinetic model that best predicted the pharmacodynamiccharacteristics of our patients. Br J Anaesth 2003; 90: 183–8     

Prevention of rocuronium-induced withdrawal movement in children: a comparison of remifentanil with alfentanil

BACKGROUND: This study was designed to compare the efficacy of remifentanil and alfentanil without the venous occlusion technique in preventing the withdrawal response associated with rocuronium injection in children. METHODS: One hundred and twenty children aged between 3 and 10 years were randomly allocated into one of four groups to receive either i.v. remifentanil 0.5 microg.kg(-1) (remi 0.5 group), remifentanil 1 microg.kg(-1) (remi 1.0 group), alfentanil 15 microg.kg(-1) (alfentanil group) or saline 5 ml (saline group). Anesthesia was induced with 2.5% thiopental sodium 5 mg.kg(-1) and the test drug was injected over 30 s. One minute later, 1% rocuronium 0.6 mg.kg(-1) was injected over 5 s and the response was recorded. Mean arterial pressure (MAP) and heart rate (HR) were recorded on arrival in the operating room, before and 1 min after tracheal intubation. RESULTS: The incidence of withdrawal movement in the saline group (93%) was significantly higher than that in the remi 0.5, remi 1.0, and alfentanil groups (53%, 17%, and 20%, respectively) (P < 0.05). The incidence in the remi 1.0 and alfentanil groups was significantly less than that in the remi 0.5 group (P < 0.05). After intubation, MAP and HR were significantly higher in the saline group than that in remi 1.0 and alfentanil groups. CONCLUSIONS: Both remifentanil 1 microg.kg(-1) and alfentanil 15 microg.kg(-1) can be used to prevent rocuronium-associated withdrawal movement in children because they are equally effective and attenuate the increase in MAP and HR after intubation.     

Comparison of rocuronium and suxamethonium for rapid tracheal intubation in children

BACKGROUND: The purpose of our study was to determine whether a smaller dose of rocuronium than previously reported could provide similar intubating conditions to suxamethonium during rapid-sequence induction of anaesthesia in children. METHODS: One hundred and twenty ASA I, unpremedicated children, aged 1-10 years, who were undergoing elective surgery, were randomized into three groups to receive rocuronium 0.6 mg.kg-1, rocuronium 0.9 mg.kg-1 or suxamethonium 1.5 mg.kg-1. The study was double-blinded, anaesthesia and timing of injection was standardized to alfentanil 10 microg.kg-1, thiopentone 5 mg.kg-1 and the study drug. Intubation was attempted at 30 s after injection of neuromuscular relaxant and intubating conditions graded as excellent, good, poor or impossible. RESULTS: All 120 children were successfully intubated within 60 s without need for a second attempt after administration of neuromuscular relaxant. Differences between suxamethonium and rocuronium 0.6 mg.kg-1 and between the two doses of rocuronium were statistically significant (P=0.016 and 0.007, respectively). CONCLUSIONS: Rocuronium 0.9 mg.kg-1 provides similar intubating conditions to suxamethonium 1.5 mg.kg-1 during modified rapid-sequence induction using alfentanil and thiopentone in children (P=0.671). Rocuronium 0.6 mg.kg-1 was inadequate.     

Estimation of the plasma effect-site equilibration rate constant (ke0) of rocuronium by the time of maximum effect: a comparison with non-parametric and parametric approaches

BACKGROUND: The first order plasma-effect-site equilibration rate constant (k(e0)) links the pharmacokinetics (PK) and pharmacodynamics (PD) of a given drug. For the calculation of the k(e0), one method uses a single point of the response curve corresponding to the time to peak effect of a drug (t(peak)); however, it has not been validated. This study compares the k(e0) calculated with the method of t(peak) and the k(e0) calculated with traditional non-parametric and parametric methods. METHODS: Fifteen adult patients receiving total intravenous anaesthesia (TIVA) were studied. All patients were monitored with an NMT Monitor 221 (GE Healthcare, Helsinki, Finland) to obtain the evoked compound EMG of the adductor pollicis to a train-of-four stimuli at 10 s intervals. During TIVA, rocuronium 0.15 mg kg(-1) was given i.v. as a bolus, and the neuromuscular response was recorded until recovery from block. Using the t(peak) and the complete response curve, k(e0) of rocuronium was calculated with the three methods using the predicted plasma concentrations of rocuronium from a PK model. Values of k(e0) are median (range). RESULTS: The k(e0)s obtained were 0.19 min(-1) (0.09-0.72) with the 't(peak)' method, 0.20 min(-1) (0.14-0.44) with the non-parametric method, and 0.19 min(-1) (0.11-0.38) [typical value (range)] with the parametric method (NS). CONCLUSIONS: If the t(peak) can be adequately estimated from the data, the 't(peak) method' is a valid alternative to traditional methods to calculate the k(e0).     

Comparison of different quantitative sensory testing methods during remifentanil infusion in volunteers

Background. The aim of this study was to compare thermal andcurrent sensory testing stimuli with respect to opioid responsiveness. Methods. Eighteen healthy volunteers were randomized in a placebo-controlled,double-blind crossover study to receive an infusion of remifentanil0.08 µg kg^–1 min^–1 or saline for 40 min. Testprocedures included determination of pain perception thresholds(PPT) and pain tolerance thresholds (PTT) to heat, cold, andcurrent at 5, 250 and 2000 Hz, at baseline and at the end ofthe infusion. Results. Both current at 5 Hz (PPT 3.69 (SD 2.48) mA vs 2.01(1.52) mA; PTT 6.42 (2.79) mA vs 3.63 (2.31) mA; P<0.001)and 250 Hz (PPT 4.31 (2.42) mA vs 2.89 (1.57) mA; PTT 7.08 (2.68)mA vs 4.81 (2.42) mA; P<0.001) and heat (PPT 47.4 (2.7)°Cvs 45.2 (3)°C; PTT 51.1 (1.8)°C vs 49.7 (1.8)°C;P<0.05) detected a significant analgesic effect of remifentanilcompared with placebo. No analgesic effect was shown on coldor current at 2000 Hz. The magnitude of responsiveness of currentstimuli at 5 Hz and 250 Hz was superior to heat stimuli. Conclusion. Both current (5 and 250 Hz) and heat sensory testingdetected a significant analgesic effect of a remifentanil infusioncompared with saline. There was more response to current testing. Br J Anaesth 2003; 91: 203–8     

Tetanic stimulus of ulnar nerve as a predictor of heart rate response to skin incision in propofol remifentanil anaesthesia

Background: To study adequate antinociception during general anaesthesia,tetanic stimulus of 5–10 s duration has been used previouslyas a standardized nociceptive stimulus. However, such stimulihave been found to correlate poorly with intraoperative nociception.We hypothesized that an electrical tetanic stimulus of the ulnarnerve, lasting 30 s, would provide a reliable experimental painmodel. Methods: Thirty-three patients, undergoing open abdominal surgery, werestudied. Propofol and remifentanil were used for anaesthesia.Patients were randomized to receive remifentanil at three target-controlledinfusion levels (1, 3, or 5 ng ml^–1) during short (5 s,Tet5) and a long-lasting (30 s, Tet30) tetanic (50 mA, 50 Hz)stimulus and skin incision. RR intervals (RRI) were obtainedfrom the ECG and the mean RRI before each stimulus (Tet5, Tet30,incision) was compared with that after the stimulus. Results: At remifentanil level 1 ng ml^–1, the RRI responses totetanic stimuli and skin incision were prominent but with higherconcentrations (3 and 5 mg ml^–1), responses were verysmall. Tet30 (r²=0.780) was the best predictor of the RRI responseto skin incision when compared with Tet5 (r²=0.611), remifentanillevel (r²=0.340), or propofol level (r²=0.036). Conclusions: Long-lasting tetanic stimulus of ulnar nerve may provide a betterexperimental pain model for surgical pain during general anaesthesiathan shorter stimuli, which have been applied in earlier studies.     

Rectal acetaminophen does not reduce morphine consumption after major surgery in young infants

BACKGROUND: The safety and value of acetaminophen (paracetamol) in additionto continuous morphine infusion has never been studied in newbornsand young infants. We investigated the addition of acetaminophento evaluate whether it decreased morphine consumption in thisage group after major thoracic (non-cardiac) or abdominal surgery. METHODS: A randomized controlled trial was performed in 71 patients giveneither acetaminophen 90–100 mg kg^–1 day^–1orplacebo rectally, in addition to a morphine loading dose of100 µg kg^–1 and 5–10 µg kg^–1h^–1 continuous infusion. Analgesic efficacy was assessedusing Visual Analogue Scale (VAS) and COMFORT scores. Extramorphine was administered if VAS was 4. RESULTS: We analysed data of 54 patients, of whom 29 received acetaminophenand 25 received placebo. Median (25–75th percentile) agewas 0 (0–2) months. Additional morphine bolus requirementsand increases in continuous morphine infusion were similar inboth groups (P = 0.366 and P = 0.06, respectively). There wasno significant difference in total morphine consumption, respectively,7.91 (6.59–14.02) and 7.19 (5.45–12.06) µg kg^–1 h^–1for the acetaminophen and placebo group (P = 0.60). COMFORT[median (25–75th percentile) acetaminophen 10 (9–12)and placebo 11 (9–13)] and VAS [median (25–75thpercentile) acetaminophen 0.0 (0.0–0.2) and placebo 0.0(0.0–0.3)] scores did not differ between acetaminophenand placebo group (P = 0.06 and P = 0.73, respectively). CONCLUSIONS: Acetaminophen, as an adjuvant to continuous morphine infusion,does not have an additional analgesic effect and should notbe considered as standard of care in young infants, 0–2months of age, after major thoracic (non-cardiac) or abdominalsurgery.