Remifentanil target-controlled infusion vs propofol target-controlled infusion for conscious sedation for awake fibreoptic intubation: a double-blinded randomized controlled trial

BACKGROUND: Awake fibreoptic intubation (AFOI) is a technique used in patients with difficult airways. This study compares the suitability of remifentanil target-controlled infusion (TCI) to propofol TCI for conscious sedation during AFOI in patients with bona fide difficult airways. METHODS: We recruited 24, ASA I-III patients, who were undergoing sedation for elective AFOI. Patients were randomized to one of the two groups, Group P (n=10) received propofol TCI and Group R (n=14) received remifentanil TCI. Primary outcome measures were conditions achieved at endoscopy, intubation, and post-intubation, which were graded using scoring systems. Other parameters measured were the endoscopy time, intubation time, and number of attempts at intubation. A postoperative interview was conducted to determine recall of events and level of patient satisfaction. RESULTS: Endoscopy scores (0-5) and intubation scores (0-5) were significantly different [Group P 3 (1-4) vs Group R 1 (0-3) P<0.0001, Group P 3 (2-4) vs Group R 1 (0-3) P<0.0001, respectively]; with much better conditions in Group R, endoscopy times and intubation times were also significantly different, being shorter in Group R (P<0.007 and P<0.023, respectively). Patient tolerance of the procedure, judged by the discomfort scores (P<0.004) and the post-intubation scores (P<0.08), was significantly better in Group R. The level of recall for events was higher in Group R. However, there were no significant differences in the patient satisfaction scores. CONCLUSIONS: Remifentanil TCI appears to provide better conditions for AFOI when compared with propofol TCI. The disadvantage of remifentanil in this setting may be a higher incidence of recall.     

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     

Low-dose remifentanil to suppress haemodynamic responses to noxious stimuli in cardiac surgery: a dose-finding study

Background: High-dose remifentanil (1–5 µg kg^–1 min^–1),commonly used for cardiac surgery, has been associated withmuscle rigidity, hypotension, bradycardia, and reduced cardiacoutput. The aim of this study was to determine an optimal lowerremifentanil dose, which should be accompanied by fewer adverseevents, that still effectively suppresses haemodynamic responsesto typical stressful stimuli (i.e. intubation, skin incision,and sternotomy). Methods: Total i.v. anaesthesia consisted of a target-controlled propofol(2 µg ml^–1) and a remifentanil infusion. Forty patientswere allocated to receive either a constant infusion of remifentanilat 0.1 µg kg^–1 min^–1 or up-titrations to 0.2,0.3, or 0.4 µg kg^–1 min^–1, respectively, 5min before each stimulus. Subsequently, changes in heart rateand mean arterial blood pressure were recorded for 8 min. Increasesexceeding 20% of baseline were considered to be of clinicalrelevance. Patients who exhibited these alterations were termedresponders. Results: The number of responders was less with the two higher remifentanildosages (P < 0.05) while propofol target doses could eitherbe kept at the same level or even be reduced without affectingthe plane of anaesthesia. Although single phenylephrine bolushad to be applied more frequently in these two groups (P <0.05), no severe haemodynamic depression was observed. Conclusions: Remifentanil at 0.3 and 0.4 µg kg^–1 min^–1in combination with a target-controlled propofol infusion inthe pre-bypass period is well tolerated. It appears to mitigatepotentially hazardous haemodynamic responses from stressfulstimuli equally well as higher doses when compared with datafrom the literature.     

Remifentanil or propofol for sedation during carotid endarterectomy under cervical plexus block

Background. During carotid endarterectomy under regional anaesthesia,patients often require medication to control haemodynamic instabilityand to provide sedation and analgesia. Propofol and remifentanilare used for this purpose. However, the benefits, side-effects,and optimal dose of these drugs in such patients are unclear. Methods. Sixty patients were included in a prospective, randomized,single blinded study. All patients received a deep cervicalplexus block with 30 ml ropivacaine 0.75% and were randomizedto receive either remifentanil 3 µg kg^–1 h^–1or propofol 1 mg kg^–1 h^–1. The infusions were startedafter performing the regional block and were stopped at theend of surgery. Arterial pressure, ECG, ventilatory rate, andPa_CO2 were measured continuously and recorded at predeterminedtimes. Twenty-four hours after surgery, patient comfort, andsatisfaction were also evaluated. Results. In three patients, the infusion of remifentanil hadto be stopped because of severe respiratory depression or bradycardia.No significant differences were found between the two groupsin haemodynamic variables or sedative effects, but there wasa significantly greater decrease in ventilatory frequency andincrease in Pa_CO2 in the remifentanil group. The patient’ssubjective impressions and pain control were excellent in bothgroups. Conclusion. As a result of the higher incidence of adverse respiratoryeffects with remifentanil and similar sedative effects, propofolis preferable for sedation during cervical plexus block in elderlypatients with comorbid disease at the dosage used. Br J Anaesth 2002; 89: 637–40     

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     

Feasibility study for the administration of remifentanil based on the difference between response entropy and state entropy

Background: Facial electromyography (FEMG) may have utility in the assessmentof nociception during surgery. The difference between stateentropy (SE) and response entropy (RE) is an indirect measureof FEMG. This study assesses an automated algorithm for remifentaniladministration that is based on maintaining an entropy difference(ED) that is less than an upper boundary condition and greaterthan a lower boundary condition. Methods: The algorithm was constructed with a development set (n = 40),and then automated and studied with a validation set (n = 20)of patients undergoing anterior cruciate ligament repair. Thepercentage of time that the ED was maintained between the twoboundary conditions was determined. Remifentanil and propofolpredicted effect-site concentrations (Ce) were determined atsurgical milestones and, after drug discontinuation, the timeto response to verbal stimulation and orientation was measured. Results: The median (25th–75th percentile) per cent of time thatthe ED was recorded between the boundary conditions was 99.3%(98.1–99.8%). Predicted propofol (µg ml^–1)and remifentanil (ng ml^–1) Ce (SD), respectively, were3.5 and 4.0 at induction, 1.9 (0.8) and 7.2 (3.7) at the endof surgery, and 1.1 (0.5) and 3.2 (2.2) at eye opening. Themedian time to eye opening and orientation was 3.8 and 6.8 min,respectively. Conclusion: This feasibility study supports the concept that remifentanilmay be delivered using an algorithm that maintains the differencebetween SE and RE between the upper and lower boundary condition.     

Target-controlled infusion of propofol and remifentanil in cardiac anaesthesia: influence of age on predicted effect-site concentrations

Background. Propofol-anaesthesia administrated via target-controlledinfusion (TCI) has been proposed for cardiac surgery. Age-relatedchanges in pharmacology explain why propofol dose requirementis reduced in elderly patients. However, the Marsh pharmacokineticmodel incorporated in the Diprifusor propofol device does nottake age into account as a covariable. In the absence of depthof anaesthesia monitoring, this limitation could cause adversecardiovascular effects resulting from propofol overdose in olderpatients. We assessed the influence of age on effect-site propofolconcentrations predicted by the Diprifusor and titrated to thebispectral index score (BIS) during cardiac anaesthesia. Methods. Forty-five patients received propofol by Diprifusorand remifentanil by software including Minto model. Propofoland remifentanil effect-site concentrations were adapted toBIS (40–60) and haemodynamic profile, respectively. Theinfluence of age on effect-site concentrations was assessedby dividing patients into two groups: young (<65 yr) andelderly (     

Propofol-alfentanil vs propofol-remifentanil for posterior spinal fusion including wake-up test

Background. Wake-up test can be used during posterior spinalfusion (PSF) to ensure that spinal function remains intact.This study aims at assessing the characteristics of the wake-uptest during propofol–alfentanil (PA) vs propofol–remifentanil(PR) infusions for PSF surgery. Methods. Sixty patients with scoliosis and candidates for PSFsurgery were randomly allocated in either alfentanil (PA) orremifentanil (PR) group. After an i.v. bolus of alfentanil 30µg kg^–1 in the PA group or remifentanil 1 µgkg^–1 in the PR group, anaesthesia was induced with thiopentaland atracurium. During maintenance, opioid infusion consistedof alfentanil 1 µg kg^–1 min^–1 or remifentanil0.2 µg kg^–1 min^–1, in the PA group and thePR group, respectively. All patients received propofol 50 µgkg^–1 min^–1. Atracurium was given to maintain therequired surgical relaxation. At the surgeon's request, allinfusions were discontinued. Patients were asked to move theirhands and feet. Time from anaesthetic discontinuation to spontaneousventilation (T₁), and from then until movement of the handsand feet (T₂), and its quality were recorded. Results. The average T₁ and T₂ were significantly shorter inthe PR group [3.6 (2.5) and 4.1 (2) min] than the PA group [6.1(4) and 7.5 (4.5) min]. Quality of wake-up test, however, didnot show significant difference between the two groups studied. Conclusion. Wake-up test can be conducted faster with remifentanilcompared with alfentanil infusion during PSF surgery.     

Accuracy of the 'Paedfusor' in children undergoing cardiac surgery or catheterization

Background. A prototype paediatric propofol target-controlledinfusion (TCI) system, the ‘Paedfusor’ has beendeveloped. This system incorporates a paediatric pharmacokineticdata set and algorithm specific for children in a Graseby 3500anaesthesia syringe driver. In this study we have evaluatedthe accuracy of the Paedfusor TCI system in children who underwenteither cardiac surgery or cardiac catheterization procedures. Methods. Twenty-nine children aged 1–15 yr were investigated.General anaesthesia was provided using propofol administeredby the Paedfusor system. Accuracy of the system was evaluatedby obtaining up to 9 arterial samples for measurement of propofolconcentration both during anaesthesia and in the recovery period.Measured arterial propofol concentrations were then comparedwith values calculated by the Paedfusor. Results. The predictive indices of median performance error(MDPE), and median absolute performance error (MDAPE) of thePaedfusor system were found to be 4.1% and 9.7%, respectivelyand the median value for wobble was 8.3%. These values are muchbetter than those found with the adult ‘Diprifusor’system. Conclusion. The Paedfusor performance was found to be withinthe accepted limits for use as a TCI system. Br J Anaesth 2003; 91; 507–13     

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     

Predictive performance of computer-controlled infusion of remifentanil during propofol/remifentanil anaesthesia

Background. The predictive performance of the available pharmacokineticparameter sets for remifentanil, when used for target-controlledinfusion (TCI) during total i.v. anaesthesia, has not been determinedin a clinical setting. We studied the predictive performanceof five parameter sets of remifentanil when used for TCI ofremifentanil during propofol anaesthesia in surgical patients. Methods. Remifentanil concentration–time data that hadbeen collected during a previous pharmacodynamic interactionstudy in 30 female patients (ASA physical status I, aged 20–65 yr)who received a TCI of remifentanil and propofol during lowerabdominal surgery were used in this evaluation. The remifentanilconcentrations predicted by the five parameter sets were calculatedon the basis of the TCI device record of the infusion rate–timeprofile that had actually been administered to each individual.The individual and pooled bias [median performance error (MDPE)],inaccuracy [median absolute performance error (MDAPE)], divergenceand wobble of the remifentanil TCI device were determined fromthe pooled and intrasubject performance errors. Results. A total of 444 remifentanil blood samples were analysed.Blood propofol and remifentanil concentrations ranged from 0.5to 11 µg ml^–1 and 0.1 to 19.6 ng ml^–1respectively. Pooled MDPE and MDAPE of the remifentanil TCIdevice were –15 and 20% for the parameter set of Mintoand colleagues (Anesthesiology 1997; 86: 10–23), 1 and21%, –6 and 21%, and –6 and 19% for the three parametersets described by Egan and colleagues (Anesthesiology 1996;84: 821–33, Anesthesiology 1993; 79: 881–92, Anesthesiology1998; 89: 562–73), and –24 and 30% for the parameterset described by Drover and Lemmens (Anesthesiology 1998; 89:869–77). Conclusions. Remifentanil can be administered by TCI with acceptablebias and inaccuracy. The three pharmacokinetic parameter setsdescribed by Egan and colleagues resulted in the least biasand best accuracy. Br J Anaesth 2003; 90: 132–41     

Effect of propofol on twitch diaphragmatic pressure evoked by cervical magnetic stimulation in patients

Background: Several studies have demonstrated the inhibitory effect of propofolon diaphragmatic contractility in laboratory animals, but therehave been few studies in humans. We have investigated the effectof a single bolus injection of propofol on twitch diaphragmaticpressure (TwPdi) evoked by cervical supramaximal magnetic stimulation,and its impact on diaphragmatic contractility. Methods: In 16 patients scheduled for elective operation, TwPdi was evokedbilaterally at the cervical phrenic nerves with supramaximalmagnetic stimulations using a 140 mm diameter magnetic coil.Changes of TwPdi were monitored dynamically before and duringgeneral anaesthesia induced by single bolus of propofol 2 mgkg ^–1. During the study, all patients breathed 100% oxygenby a face mask, maintaining Sp_O2 99% and PE'_CO2 4.6–5.2kPa. Results: TwPdi declined after administration of propofol with gradualrecovery. Compared with baseline [20.6 (6.0) cm H₂O], TwPdidecreased by 23.3% (P<0.001) to [15.8 (6.4) cm H₂O]. Whenthe patients regained awareness, TwPdi returned to [19.1 (6.1)cm H₂O], close to baseline (P=0.063). The time from startingthe propofol infusion to the lowest TwPdi was [240 (86) s].Total time course of stimulation lasted [363 (89) s]. Conclusions: A single bolus propofol depressed TwPdi evoked by cervical magneticstimulation, demonstrating inhibitory effects of propofol ondiaphragmatic contractility in patients during general anaesthesia.     

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.     

Comparative efficacy and safety of remifentanil and fentanyl in 'fast track' coronary artery bypass graft surgery: a randomized, double-blind study

This multi-centre, parallel group, randomized, double-blindstudy compared the efficacy and safety of high-dose remifentaniladministered by continuous infusion with an intermittent bolusfentanyl regimen, when given in combination with propofol forgeneral anaesthesia in 321 patients undergoing elective coronaryartery bypass graft surgery. A significantly lower proportionof the patients who received remifentanil had responses to maximalsternal spread (the primary efficacy endpoint) compared withthose who received fentanyl (11% vs 52%; P<0.001). More patientswho received remifentanil responded to tracheal intubation comparedwith those who received fentanyl (24% vs 9%; P<0.001). However,fewer patients who received remifentanil responded to sternalskin incision (11% vs 36%; P<0.001) and sternotomy (14% vs60%; P <0.001). Median time to extubation was longer in thesubjects who received remifentanil than for those who receivedfentanyl (5.1 vs 4.2 h; P=0.006). There were no statisticallysignificant differences between the two groups in the timesfor transfer from intensive care unit or hospital dischargebut time to extubation was significantly longer in the remifentanilgroup. Overall, the incidence of adverse events was similarbut greater in the remifentanil group with respect to shivering(P<0.049) and hypertension (P<0.001). Significantly moredrug-related adverse events were reported in the remifentanilgroup (P=0.016) There were no drug-related adverse cardiac outcomesand no deaths from cardiac causes before hospital dischargein either treatment group. Br J Anaesth 2001; 87: 718–26     

Optimization of desflurane administration in morbidly obese patients: a comparison with sevoflurane using an 'inhalation bolus' technique

Background. The concept of an ‘inhalation bolus’can be used to optimize inhaled drug administration. We investigatedthe depth of anaesthesia, haemodynamic stability, and recoverytime in morbidly obese patients resulting from bispectral index^TM(BIS^TM)-guided sevoflurane or desflurane administration andBIS-triggered inhalation boluses of sevoflurane or desfluranecombined with titration of remifentanil. Methods. Fifty morbidly obese patients undergoing laparoscopicgastroplasty received either BIS-guided sevoflurane or desfluraneanaesthesia in combination with a remifentanil target-controlledinfusion. Intraoperative haemodynamic stability and BIS controlwere measured. Immediate recovery was recorded. Results. Intraoperatively, the BIS was between 40 and 60 fora greater percentage of time in the sevoflurane (78 (13)% ofcase time) than in the desflurane patients (64 (14)% of casetime), owing to too profound anaesthesia in the desflurane patientsat the start of the procedure. However, fewer episodes of hypotensionwere found in the desflurane group, without the occurrence ofmore hypertensive episodes. During immediate recovery, eye opening,extubation, airway maintenance, and orientation occurred soonerin the desflurane group. Conclusions. Immediate recovery was significantly faster inthe desflurane group. Overall hypnotic controllability measuredby BIS was less accurate with desflurane. Overall haemodynamiccontrollability was better when using desflurane. Fewer episodesof hypotension were found in the desflurane group. The use ofthe inhalation bolus was found to be appropriate in both groupswithout causing severe haemodynamic side effects. Minimal BISvalues were significantly lower after a desflurane bolus. Br J Anaesth 2003; 91: 638–50     

Predictive performance of 'Servin's formula' during BIS-guided propofol-remifentanil target-controlled infusion in morbidly obese patients

Background. The aim of this study was to assess the predictiveperformance of ‘Servin's formula’ for bispectralindex (BIS)-guided propofol-remifentanil target-controlled infusion(TCI) in morbidly obese patients. Methods. Twenty patients (ASA physical status II–III,age 32–64 yr) undergoing bilio-intestinal bypass surgery,were recruited. Anaesthesia was induced by using a TCI of propofolwith an initial target plasma concentration of 6 µg ml^–1,then adapted to maintain stable BIS values ranging between 40and 50. A TCI of remifentanil was added to achieve pain controland haemodynamic stability. For propofol, weight was correctedas suggested by Servin and colleagues. With ideal body weight(IBW) corrected according to formula suggested by Lemmens andcolleagues. For remifentanil, weight was corrected accordingto IBW. Arterial blood samples for the determination of bloodpropofol concentrations were collected at different surgicaltimes. The predictive performance of propofol TCI was evaluatedby examining performance accuracy. Results. Median prediction error and median absolute predictionerror were –32.6% (range –53.4%; –2.5%) and33.1% (10.8%; 53.4%), respectively. Wobble median value was5.9% (2.5%; 25.2%) while divergence median value was –1.5%h^–1 (–7.7; 33.8% h^–1). Conclusion. Significant bias between predicted and measuredplasma propofol concentrations was found while the low wobblevalues suggest that propofol TCI system is able to maintainstable drug concentrations over time. As already suggested before,a computer simulation confirmed that the TCI system performancecould be significantly improved when total body weight is used.     

Influence of peroperative opioid on postoperative pain after major abdominal surgery: sufentanil TCI versus remifentanil TCI. A randomized, controlled study

Background. Sufentanil and remifentanil are characterized bytwo different pharmacokinetic profiles. The aim of this studywas to compare the effects of sufentanil and remifentanil administeredusing target-controlled infusion (TCI) on recovery and postoperativeanalgesia after major abdominal surgery. Methods. Thirty adult patients scheduled for open colorectalsurgery were included in a prospective, randomized study. SufentanilTCI (sufentanil group) or remifentanil TCI (remifentanil group)was administered during surgery. In the remifentanil group,30 min before the anticipated end of surgery, morphine 0.15mg kg^–1 was administered i.v. In the sufentanil group,an effect-site concentration of 0.25 ng ml^–1 wastargeted at extubation. In both groups, postoperative pain wascontrolled by titration of i.v. morphine and then patient-controlledanalgesia with morphine. Results. The extubation time was similar in the two groups (mean(SD) 13 (6) and 14 (6) min in the sufentanil and remifentanilgroups respectively). Visual analogue scale scores were significantlygreater during the first 2 h after tracheal extubation in theremifentanil group than in the sufentanil group. The time tofirst analgesic request in the postanaesthesia care unit wassignificantly longer in the sufentanil group than in the remifentanilgroup (55 (64) (range 2–240) vs 11 (7) (1–29) min;P<0.001). The cumulative morphine dose for titration wassignificantly greater in the remifentanil group (P<0.01).The cumulative morphine dose used during titration and patient-controlledanalgesia was significantly greater in the remifentanil group4, 12 and 24 h after extubation (P<0.05). Conclusion. TCI sufentanil (0.25 ng ml^–1 effect-siteconcentration at extubation) is more effective than the intraoperativecombination of remifentanil TCI infusion with morphine bolus(0.15 mg kg^–1) for postoperative pain relief aftermajor abdominal surgery and does not compromise extubation andrecovery. Br J Anaesth 2003; 91: 842–9     

Changes in cortical electrical activity during induction of anaesthesia with thiopental/fentanyl and tracheal intubation: a quantitative electroencephalographic analysis

Background. There are regional differences in the effects ofanaesthetics agents and perioperative stimuli on the EEG. Westudied the topography of the EEG during induction of anaesthesiaand intubation in patients receiving thiopental and fentanylto document regional electrical brain activity. Methods. EEG was recorded in 25 patients in the awake state,after pre-medication, during induction, at loss of consciousnessand after intubation. Eight bipolar recordings were made andthe relative power of the frequency bands delta, theta, alpha,and beta were used (after z-score transformation for age) tomeasure changes in regional EEG activity. Results. Noxious stimulation during tracheal intubation partiallyreversed the slowing of the EEG caused by anaesthesia. Duringinduction of anaesthesia alpha activity was most reduced intemporal and occipital regions. The most prominent EEG changesafter intubation were an increase in alpha and a decrease indelta power (P<0.001). The largest changes were in the frontaland temporal leads for alpha and in the frontal and centralleads for delta. Heart rate and arterial pressure remained constantduring intubation. Conclusions. Changes in alpha and delta power were identifiedas the most sensitive EEG measures of regional changes in electricalbrain activity during anaesthesia and noxious stimulation. Br J Anaesth 2004; 92: 33–8     

Propofol requirement for insertion of cuffed oropharyngeal airway versus laryngeal mask airway with and without fentanyl: a dose-finding study

Background. The cuffed oropharyngeal airway (COPA) is a modifiedGuedel-type oral airway with a cuff at its distal end. The objectivesof this prospective, randomized study were to compare the COPAand the laryngeal mask airway (LMA     

Predictive performance of the Domino, Hijazi, and Clements models during low-dose target-controlled ketamine infusions in healthy volunteers

Background: Healthy volunteers received low-dose target-controlled infusions(TCI) of ketamine controlled by the Domino model while cognitivefunction tests and functional neuroimaging were performed. Theaim of the current study was to assess the predictive performanceof the Domino model during these studies, and compare it withthat of three other ketamine models. Methods: Fifty-eight volunteers received ketamine administered by a TCIdevice on one or more occasions at target concentrations ofeither 50, 100, or 200 ng ml^–1. At each target concentration,two or three venous blood samples were withdrawn during infusion,with a further sample after the infusion ended. Ketamine assayswere performed by gas chromatography. The plasma concentrationtime courses predicted by the Hijazi, Clements 125, and Clements250 models were calculated retrospectively, and the predictiveperformance of each of the models was assessed using Varvelmethodology. Results: For the Domino model, bias, inaccuracy, wobble, and divergencewere – 2.7%, 33.9%, 24.2%, and 0.1463 % h^–1, respectively.There was a systematic increase in performance error over time.The Clements 250 model performed best by all criteria, whereasthe Hijazi model performed least well by all criteria exceptfor bias. Conclusions: Performance of the Domino model during control of low-dose ketamineinfusions was sub-optimal. The Clements 250 model may be a bettermodel for controlling low-dose TCI ketamine administration