Continuous infusion of remifentanil and target-controlled infusion of propofol for patients undergoing cardiac surgery: a new approach for scheduled early extubation

Perioperative care in infective endocarditis

Patients undergoing surgery for acute infective endocarditis are among those with the highest risk. Their preoperative condition has significant impact on outcomes. There are specific issues related with the preoperative situation, intraoperative findings, and postoperative management. In this narrative review, focus is placed on the most critical aspects in the perioperative period including the management and weaning from mechanical ventilation, the management of vasoplegia, the management of the chest open, antithrombotic therapy, transfusion, coagulopathy, management of atrial fibrillation, the duration of antibiotic therapy, and pacemaker implantation.

Intraoperative Remifentanil Infusion and Postoperative Pain Outcomes After Cardiac Surgery-Results from Secondary Analysis of a Randomized, Open-Label Clinical Trial

DESIGN

Report of secondary pain outcomes from a prospective, randomized, open-label clinical trial that compared remifentanil and fentanyl on perioperative hyperglycemic response in cardiac surgery.

SETTING

Single institution, tertiary university hospital.

PARTICIPANTS

The study comprised 116 adult elective cardiac surgical patients.

INTERVENTIONS

Participants were randomly assigned to receive either intermittent fentanyl boluses (F) or continuous remifentanil infusion (R) intraoperatively.

MEASUREMENTS AND MAIN RESULTS

Postoperative pain was evaluated with pain scores every 6 hours for 48 hours. Pain threshold to mechanical stimuli was measured around the sternotomy incision at 48 and 96 hours. The development of chronic pain was assessed using the numeric rating scale at 1, 3, 6, and 12 months after discharge. The final analysis included 106 patients. Pain scores and wound hyperalgesia were not significantly different postoperatively between the groups. The incidence of chronic pain at 3 months was comparable in both groups (61% in group F v 58% in group R; p = 0.79). Pain of more-than-mild degree was seen in 13 (32%) patients in group F and 8 (19%) in group R (p = 0.25) at 3 months. Median pain scores were not significantly different between the groups at 1, 3, 6, and 12 months after discharge from the hospital.

CONCLUSIONS

The present study's findings suggested that intraoperative remifentanil infusion does not significantly worsen pain outcomes in patients undergoing elective cardiac surgery.

Bispectral Index Monitoring in Patients Undergoing Open Heart Surgery

Introduction

To obtain the optimal anesthesia depth is not easy in cardiovascular surgery patients where the haemodynamic reserve is limited, due to reasons such as not being able to give the desired dose of anesthetic agent, or the change in the pharmacokinetics of the agent in the heart-lung machine. This study was planned to assess the contribution of bispectral index (BIS) monitoring in the depth of anesthesia.

Methods

The patients were divided into 2 groups, and BIS monitoring was used for each patient. Group 1 (G1 n=35): keeping the BIS monitor screen open, the anesthesia need was set. Group 2 (G2 n=35): BIS monitor was tied to the patient and the monitor screen was closed in such a way that the anaesthesist couldn't see the BIS value. When the recording time came, the data on the monitor was recorded. The need for the anesthetic agent was set according to the parameters such as haemodynamics or follow up of pupils, instead of BIS value, by titrating the anesthetic infusion doses.

Results

BIS values were similar in both groups before the induction, BIS values in both groups showed a decrease, showing no significant statistical difference (P>0.05). One patient in each group said that he dreamt, and one patient in G2 said that he had heard a noise and felt that he was taken from one place to another.

Conclusion

The management should be done with clinical evaluation, haemodynamics and other monitorization methods and BIS monitoring findings together.

Remifentanil-acute opioid tolerance and opioid-induced hyperalgesia: a systematic review

The use of opioids may seem to be a double-edged sword; they provide straight analgesic and antihyperalgesic effects initially, but subsequently are associated with the expression of acute opioid tolerance (AOT) and opioid-induced hyperalgesia (OIH) that have been reported in experimental studies and clinical observations. It has been suggested that opioids can induce an acute tolerance and hyperalgesia in dose- and/or time-dependent manners even when used within the clinically accepted doses. Recently, remifentanil has been used for pain management in clinical anesthesia and in the intensive care units because of its rapid onset and offset. We reviewed articles analyzing AOT and/or OIH by remifentanil and focused on the following issues: (1) evidence of remifentanil inducing AOT and/or OIH and (2) importance of AOT and/or OIH in considering the reduction of remifentanil dosage or adopting preventive modulations. Twenty-four experimental and clinical studies were identified using electronic searches of MEDLINE (PubMed, Ovid, Springer, and Elsevier). However, the development of AOT and OIH by remifentanil administration remains controversial. There is no sufficient evidence to support or refute the existence of OIH in humans.

Cardioprotective Effects of Remifentanil in a Sympathetic Hyperactivity Model in Rabbits

OBJECTIVE

In this study, the antiarrhythmic and anti-ischemic effects of a 6 μg kg(-1) min(-1) infusion dose of remifentanil are investigated in a central sympathetic hyperactivity model in rabbits.

METHODS

In this study, 18 New Zealand rabbits were used. The subjects were randomly divided into three groups (n=6) and received 10 μmol L(-1) glutamate intracerebroventricularly to provide the central sympathetic hyperactivity. In group 1, 10 μmol L(-1) glutamate was used; in group 2, 1 h before L-glutamate injection, 40 mg kg(-1) N (omega)-nitro-L-arginine methyl ester was intravenously (iv) administered; and in group 3, also 1 h before L-glutamate injection, 40 mg kg(-1) N (omega)-nitro-L-arginine methyl ester was iv administered. A 6 μg kg(-1) min(-1) dose of remifentanil infusion was administered 5 min before L-glutamate injection. Heart rate, systolic arterial pressure and mean arterial pressure were measured and recorded. Within 15 min of the intracerebroventricular L-glutamate injection, premature ventricular complexes, bigeminy ventricular arrhythmia, ventricular tachycardia, ST-segment shift and T-wave inversions were recorded.

RESULTS

When incidences of heart rate, rate pressure product, premature ventricular complexes and bigeminy ventricular arrhythmia were compared between groups, significant differences were not determined. Mean arterial pressure was more significantly increased in group 2 than in the other groups (p<0.05). Ventricular tachycardia, ST-segment shift and T-wave inversions were significantly lower in group 3 than in groups 1 and 2 (p<0.05).

CONCLUSION

Remifentanil (6 μg kg(-1) min(-1) for 5 min of infusion) prevented life-threatening ventricular tachycardia and electrocardiographic signs of myocardial ischemia in a model of arrhythmia resulting from the association of central sympathetic overactivity.

Propofol protects the immature rabbit heart against ischemia and reperfusion injury: impact on functional recovery and histopathological changes

The general anesthetic propofol protects the adult heart against ischemia and reperfusion injury; however, its efficacy has not been investigated in the immature heart. This work, for the first time, investigates the cardioprotective efficacy of propofol at clinically relevant concentrations in the immature heart. Langendorff perfused rabbit hearts (7–12 days old) were exposed to 30 minutes' global normothermic ischemia followed by 40 minutes' reperfusion. Left ventricular developed pressure (LVDP) and coronary flow were monitored throughout. Lactate release into coronary effluent was measured during reperfusion. Microscopic examinations of the myocardium were monitored at the end of reperfusion. Hearts were perfused with different propofol concentrations (1, 2, 4, and 10 μg/mL) or with cyclosporine A, prior to ischemic arrest and for 20 minutes during reperfusion. Propofol at 4 and 10 μg/mL caused a significant depression in LVDP prior to ischemia. Propofol at 2 μg/mL conferred significant and maximal protection with no protection at 10 μg/mL. This protection was associated with improved recovery in coronary flow, reduced lactate release, and preservation of cardiomyocyte ultrastructure. The efficacy of propofol at 2 μg/mL was similar to the effect of cyclosporine A. In conclusion, propofol at a clinically relevant concentration is cardioprotective in the immature heart.

Factors that influence awakening in coronary artery bypass graft using propofol and remifentanil

BACKGROUND

The development of total intravenous anesthesia in coronary artery bypass graft (CABG) surgery has led to increased interest in the use of combination of propofol and remifentanil. Early extubation in post-cardiac surgery reduces the length of stay in intensive care unit and hospital and costs. The purpose of this study is to evaluate which anesthetic factors affect awakening time after anesthesia.

METHODS

We enrolled twenty patients of ASA physical status II or III, scheduled for CABG in this study. All patients received a standardized propofol/remifentanil anesthesia as an effect site target controlled infusion. We recorded times to awakening and tracheal extubation, duration of cardiopulmonary bypass (CPB) period, total time of anesthesia and operation. Also, we recorded dose of propofol, remifentanil, fentanyl and minimum body temperature during CPB. To predict the factors that affect awakening time as a dependent variable, we considered all measured parameters as independent variables, and analyzed multiple linear regressions.

RESULTS

The mean time responded to verbal command was 216.5 +/- 124.8 minutes after end of surgery. Among several parameters, minimum body temperature during CPB (P = 0.001) and total time of anesthesia (P = 0.003) were considered as significant factors that influence awakening time after CABG.

CONCLUSIONS

Minimum body temperature during CPB and the duration of anesthesia influence awakening time after CABG, significantly.

Effects of cardiopulmonary bypass on propofol pharmacokinetics and bispectral index during coronary surgery

PURPOSE

Cardiopulmonary bypass is known to alter propofol pharmacokinetics in patients undergoing cardiac surgery. However, few studies have evaluated the impact of these alterations on postoperative pharmacodynamics. This study was designed to test the hypothesis that changes in propofol pharmacokinetics increase hypnotic effects after cardiopulmonary bypass.

METHODS

Twenty patients scheduled for on-pump coronary artery bypass graft (group, n=10) or off-pump coronary artery bypass graft (group, n=10) coronary artery bypass grafts were anesthetized with sufentanil and a propofol target controlled infusion (2.0 microg/mL). Depth of hypnosis was monitored using the bispectral index. Blood samples were collected from the induction of anesthesia up to 12 hours after the end of propofol infusion, at predetermined intervals. Plasma propofol concentrations were measured using high-performance liquid chromatography, followed by a non-compartmental propofol pharmacokinetic analysis. Data were analyzed using ANOVA, considering p<0.05 as significant.

RESULTS

After cardiopulmonary bypass, despite similar plasma propofol concentrations in both groups, bispectral index values were lower in the on-pump coronary artery bypass graft group. Time to extubation after the end of propofol infusion was greater in the on-pump coronary artery bypass graft group (334 +/- 117 vs. 216 +/- 85 min, p = 0.04). Patients undergoing cardiopulmonary bypass had shorter biological (1.82 +/- 0.5 vs. 3.67 +/- 1.15 h, p < 0.01) and terminal elimination (6.27 +/- 1.29 vs. 10.5h +/- 2.18, p < 0.01) half-life values, as well as higher total plasma clearance (28.36 +/- 11.40 vs.18.29 +/- 7.67 mL/kg/min, p = 0.03), compared to patients in the off-pump coronary artery bypass graft group.

CONCLUSION

Aside from the increased sensitivity of the brain to anesthetics after cardiopulmonary bypass, changes in propofol pharmacokinetics may contribute to its central nervous system effects.

Impact of bispectral index monitoring on propofol administration in patients undergoing cardiopulmonary bypass

Propofol anaesthesia using target control infusion during cardiac surgery has become more popular recently. However, without depth of anaesthesia monitoring, the standard target concentration used may be higher than necessary to maintain adequate hypnosis during hypothermic cardiopulmonary bypass. The purpose of this study was to evaluate the effect of bispectral index monitoring on propofol administration during hypothermic cardiopulmonary bypass. After ethics committee approval and written informed consent, 20 New York Heart Association class I-III patients scheduled for elective cardiac surgery requiring hypothermic cardiopulmonary bypass were studied in this prospective randomised controlled trial. In group C, routine anaesthesia was practised, where patients received propofol at target concentration between 1.5 to 2.5 microg/ml during cardiopulmonary bypass. In group B, the target concentration was titrated to a bispectral index value of 40 to 50. Mean arterial pressure and bispectral index were recorded at various time intervals. The use of propofol, phenylephrine, sodium nitroprusside and adrenaline were recorded. The median propofol administration in group B was significantly less than that in group C (2.9 mg/kg/h compared to 6.0 mg/kg/h). The bispectral index value during bypass was significantly lower in group C than in group B, reflecting a deeper state of anaesthesia. There was no difference in the use of inotropes, vasoconstrictors or vasodilators. Bispectral index monitoring enables a 50% reduction in propofol administration at this standard dose during hypothermic cardiopulmonary bypass.

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

BACKGROUND

High-dose remifentanil (1-5 microg kg-1 min-1), commonly used for cardiac surgery, has been associated with muscle rigidity, hypotension, bradycardia, and reduced cardiac output. The aim of this study was to determine an optimal lower remifentanil dose, which should be accompanied by fewer adverse events, that still effectively suppresses haemodynamic responses to typical stressful stimuli (i.e. intubation, skin incision, and sternotomy).

METHODS

Total i.v. anaesthesia consisted of a target-controlled propofol (2 microg ml-1) and a remifentanil infusion. Forty patients were allocated to receive either a constant infusion of remifentanil at 0.1 microg kg-1 min-1 or up-titrations to 0.2, 0.3, or 0.4 microg kg-1 min-1, respectively, 5 min before each stimulus. Subsequently, changes in heart rate and mean arterial blood pressure were recorded for 8 min. Increases exceeding 20% of baseline were considered to be of clinical relevance. Patients who exhibited these alterations were termed responders.

RESULTS

The number of responders was less with the two higher remifentanil dosages (P<0.05) while propofol target doses could either be kept at the same level or even be reduced without affecting the plane of anaesthesia. Although single phenylephrine bolus had 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 microg kg-1 min-1 in combination with a target-controlled propofol infusion in the pre-bypass period is well tolerated. It appears to mitigate potentially hazardous haemodynamic responses from stressful stimuli equally well as higher doses when compared with data from the literature.

Prise en charge anesthésique de l'œsophagectomie: avancées et perspectives

Oesophagectomy is still characterized by a high postoperative mortality and respiratory morbidity. Nevertheless, epidemiological, medical and surgical advances have improved the management of this surgical procedure. The anaesthesiologist influence is present at each level, from the preoperative evaluation to the management of postoperative complications. The preoperative period is improved by the use of assessment scores, the better knowing of respiratory risk factors and of the neoadjuvant therapy adverse effects. The main objective of the operative period is to ensure a rapid weaning procedure and stability of the respiratory and haemodynamic functions, warranting the anastomotic healing. The interest of the association between respiratory rehabilitation and thoracic epidural analgesia is highlighted in the postoperative period. The management of postoperative complications, mainly represented by respiratory failure and anastomotic leakages, requires a multidisciplinary analysis. The potential interest of non-invasive ventilation and of the modulation of postoperative inflammatory response needs further investigation.

Fast-Track Cardiac Anesthesia: Efficacy and Safety of Remifentanil Versus Sufentanil

OBJECTIVE

The purpose of this study was to compare the safety and efficacy of fast-track cardiac anesthesia with remifentanil (group R) versus sufentanil (group S).

DESIGN

Prospective, single-blinded, randomized study.

SETTING

University hospital.

PARTICIPANTS

One hundred twenty patients undergoing coronary artery bypass graft surgery and/or cardiac valve surgery.

INTERVENTIONS

After routine standardized anesthesia induction, anesthesia was maintained with isoflurane (0.4-0.8 vol%) together with either remifentanil (group R) (1 microg/kg/min) or sufentanil (group S) (1 microg/kg for induction, 0.5 microg/kg for skin incision, and then 0.02 microg/kg/min). After surgery, which included cardiopulmonary bypass in all cases, postoperative sedation was achieved in both groups with propofol until the patient was deemed ready for extubation. Additionally, patients in group R received remifentanil, 0.25 microg/kg/min.

MEASUREMENTS AND MAIN RESULTS

Recovery profile in group R patients was faster (p < 0.05), with a median time interval between end of surgery and eligibility for extubation of 295 minutes versus 375 minutes. Time from end of surgery to being eligible for discharge from intensive care unit was similar in both groups, with 22.9 hours in group R versus 26.3 hour in group S. Remifentanil provided a better protection against intraoperative stimuli at skin incision and maximal sternal spread (p < 0.05). The incidence of adverse events was comparable in both groups. Postoperative pain scores during the first hour of weaning were higher in group R (p < 0.05).

CONCLUSIONS

Remifentanil for fast-track cardiac anesthesia provided safe and stable operating conditions and facilitated earlier tracheal extubation. However, postoperative pain management should be planned carefully.

Remifentanil or sufentanil for coronary surgery

BACKGROUND AND OBJECTIVE

High-dose opioid anaesthesia contributes to decreasing metabolic and hormonal stress responses in patients undergoing cardiac surgery. However, the increase in context-sensitive half-life of opioids given as a high-dose regimen can affect postoperative respiratory recovery. In contrast, remifentanil can be given in high doses without prolonging context-sensitive half-life due to its rapid metabolism. Therefore, we performed a prospective, randomized trial to compare anaesthesia consisting of propofol/remifentanil or propofol/sufentanil with regard to postoperative respiratory function and outcome.

METHODS

Patients undergoing coronary artery bypass grafting were randomized to a propofol/remifentanil (0.5-1.0 microg kg(-1) min(-1)) or propofol/sufentanil (30-40 ng kg(-1) min(-1)) based anaesthetic. Carbon dioxide response, forced expiratory volume in one second, vital capacity, and functional residual capacity were measured 1 day prior to the operation, 1 h before extubation, 1, 24 and 72 h after extubation. In addition, the incidence of atelectasis, pulmonary infiltrates, intensive care unit and postoperative length of stay were compared. Patients and physicians were blinded to the treatment group.

RESULTS

Twenty-five patients in each treatment group completed the study. There was no difference between patients of the treatment groups regarding demographics, risk- or pain scores. In all patients, carbon dioxide response, forced expiratory volume in one second, vital capacity and functional residual capacity were decreased postoperatively compared to baseline. Patients randomized to remifentanil had less depression of carbon dioxide response, less atelectasis and shorter postoperative length of stay (12 d vs. 10 d) than after sufentanil (P < 0.05).

CONCLUSIONS

Intraoperative use of high-dose remifentanil for coronary artery bypass grafting may be associated with improved recovery of pulmonary function and shorter postoperative hospital length of stay than sufentanil.

The coronary and myocardial effects of remifentanil and sufentanil in the erythrocyte-perfused isolated rabbit heart

Remifentanil-induced hypotension may be associated with adverse ischemic myocardial events. Although these events can be easily attributed to a decrease in coronary pressure perfusion, we tested the hypothesis that remifentanil could directly affect coronary vasomotor tone. Therefore, we assessed intrinsic coronary and myocardial in vitro effects of remifentanil on a Langendorff's rabbit model and compared these effects with those provoked by similar intracoronary concentrations of sufentanil. Under general anesthesia, hearts from New Zealand rabbits were rapidly excised and mounted on an erythrocyte-perfused and isolated heart preparation. The hearts were then exposed to increasing concentrations (10-1000 nM) of either remifentanil (n = 10) or sufentanil (n = 8). Between each concentration, hearts were allowed to return to baseline status. The maximal coronary and myocardial effects of each concentration of both drugs were noted. Baseline values of coronary blood flow and myocardial performances were comparable between groups. Neither remifentanil nor sufentanil induced significant coronary and myocardial effects. These results suggest that myocardial ischemia, which may occur during remifentanil-induced hemodynamic disturbances, especially in cardiac patients, is only related to a decrease in coronary perfusion pressure provoked by peripheral hemodynamic changes.

Effects of remifentanil on the contractility of failing human heart muscle

OBJECTIVE

The purpose of this study was to determine the direct effects of remifentanil on inotropy of human myocardial tissue removed from failing explanted hearts of cardiac transplant recipients.

DESIGN

In vitro, prospective study with repeated measures.

SETTING

Research laboratory in a tertiary referral center.

INTERVENTIONS

The authors studied the effects of remifentanil on isometric myocardial contractile parameters in failing atrial and ventricular myocardial muscles. The authors also used 1 micromol/L of isoproterenol to test adrenergic responsiveness of failing myocardial tissues in the presence of supratherapeutic remifentanil concentrations.

MEASUREMENTS AND MAIN RESULTS

Muscles were studied at 37 degrees C and 1 Hz, with concentrations of remifentanil covering a wide range of therapeutic as well as supratherapeutic concentrations (ie, between 0.001 and 100 microg/mL). After the dose-response curve was obtained, the author measured the inotropic response to 1 micromol/L of isoproterenol in the presence of the cumulative dose of remifentanil. Over the wide range of concentrations, remifentanil had no significant effect on contractile function. In the presence of supratherapeutic concentration of remifentanil, isoproterenol produced a 97% +/- 58% increase in developed tension in failing atrial muscles and a 91% +/- 40% increase in failing ventricular muscles, which did not significantly differ from control muscles.

CONCLUSIONS

The authors showed that remifentanil had no significant negative inotropic effects in failing human heart muscle and that myocardial contractility remained fully responsive to beta-adrenergic stimulation at all remifentanil concentrations studied.

Modelling and multivariable control in anaesthesia using neural-fuzzy paradigms. Part I. Classification of depth of anaesthesia and development of a patient model

OBJECTIVE

The first part of this research relates to two strands: classification of depth of anaesthesia (DOA) and the modelling of patient's vital signs.

METHODS AND MATERIAL

First, a fuzzy relational classifier was developed to classify a set of wavelet-extracted features from the auditory evoked potential (AEP) into different levels of DOA. Second, a hybrid patient model using Takagi-Sugeno Kang fuzzy models was developed. This model relates the heart rate, the systolic arterial pressure and the AEP features with the effect concentrations of the anaesthetic drug propofol and the analgesic drug remifentanil. The surgical stimulus effect was incorporated into the patient model using Mamdani fuzzy models.

RESULTS

The result of this study is a comprehensive patient model which predicts the effects of the above two drugs on DOA while monitoring several vital patient's signs.

CONCLUSION

This model will form the basis for the development of a multivariable closed-loop control algorithm which administers "optimally" the above two drugs simultaneously in the operating theatre during surgery.

Postoperative Analgesia After Spinal Blockade in Infants and Children Undergoing Cardiac Surgery

The aim of this prospective, randomized, controlled clinical trial was to define the opioid analgesic requirement after a remifentanil (REMI)-based anesthetic with spinal anesthetic blockade (SAB+REMI) or without (REMI) spinal blockade for open-heart surgery in children. We enrolled 45 patients who were candidates for tracheal extubation in the operating room after cardiac surgery. Exclusion criteria included age <3 mo and >6 yr, pulmonary hypertension, congestive heart failure, contraindication to SAB, and failure to obtain informed consent. All patients had an inhaled induction with sevoflurane and maintenance of anesthesia with REMI and isoflurane (0.3% end-tidal). In addition, patients assigned to the SAB+REMI group received SAB with tetracaine (0.5-2.0 mg/kg) and morphine (7 mug/kg). After tracheal extubation in the operating room, patients received fentanyl 0.3 mug/kg IV every 10 min by patient-controlled analgesia for pain score = 4. Pain scores and fentanyl doses were recorded every hour for 24 h or until the patient was ready for discharge from the intensive care unit. Patients in the SAB+REMI group had significantly lower pain scores (P = 0.046 for the first 8 h; P =0.05 for 24 h) and received less IV fentanyl (P = 0.003 for the first 8 h; P = 0.004 for 24 h) than those in the REMI group. There were no intergroup differences in adverse effects, including hypotension, bradycardia, highest PaCO(2), lowest pH, episodes of oxygen desaturation, pruritus, and vomiting.

[Continuous infusion of remifentanil and target-controlled infusion of propofol for coronary surgery in elderly patients: comparison with continuous infusion of remifentanil and propofol]

OBJECTIVES

Comparison of the length of mechanical ventilation and postoperative complications after coronary surgery in elderly patients anaesthetised with propofol associated with either alfentanil or remifentanil.

STUDY DESIGN

Retrospective study with an historic control group.

PATIENTS

Three hundred thirty-eight consecutive patients (75-year-old or more) undergoing isolated coronary surgery. One hundred and fifty seven patients operated between January 1998 and June 2000 received alfentanil (1 microg/kg/minute) with a manually control infusion of propofol, 181 operated between July 2000 and 2002, remifentanil 0.25 microg/kg/minute with target controlled infusion of propofol (target blood concentration: 1.5 to 2 microg/ml).

METHODS

The two groups were compared for preoperative and surgical data. The length of mechanical ventilation, stay in ICU and the main postoperative complications were compared between the two groups.

RESULTS

Length of mechanical ventilation was significantly reduced in the remifentanil group (6 +/- 9 h vs. 13 +/- 63 h ; p <0.0001), 70% of the patients were extubated before the 6th postoperative hours against 53% in the alfentanil group (p =0.0023). This was not associated with a reduction of stay in ICU or postoperative complications. During surgery, an increased used of vasopressor was observed in the remifentanil group (40.2% vs 2.4% ; p <0.0001) with a postoperative elevation of blood concentration of CKMb (35.7 +/- 38.2 microg/l, vs. 27.7 +/- 31.9 microg/l, p =0.02).

CONCLUSION

Elderly patients undergoing coronary surgery were extubated earlier with remifentanil. However, this had no effect on duration of ICU stay but was associated with an increased used of vasopressor.

Fast-track coronary artery bypass grafting surgery under general anesthesia with remifentanil and spinal analgesia with morphine and clonidine

OBJECTIVE

Effective postoperative analgesia is a critical part of fast-track cardiac surgery. This study compared the postoperative analgesic effect of fast-track anesthesia with remifentanil and spinal morphine and clonidine with that of sufentanil anesthesia followed by patient-controlled administration of intravenous morphine.

DESIGN

Prospective, blinded, randomized study.

SETTING

Single private institution.

PARTICIPANTS

Forty patients selected for coronary artery bypass graft surgery allocated randomly into 2 groups.

INTERVENTIONS

General anesthesia was performed with etomidate, isoflurane, cisatracurium, and either remifentanil (0.10-0.25 microg/kg/min) or sufentanil (up to 3.5 microg/kg). In the remifentanil group, patients received spinal morphine (4 microg/kg) and clonidine (1 microg/kg) before induction. Postoperatively, patients in both groups were connected to an intravenous patient-controlled analgesia (PCA) morphine pump that delivered a 1-g bolus with a 7-minute lockout interval.

MEASUREMENTS AND MAIN RESULTS

Patients were evaluated for pain on a visual analog scale (VAS), at rest and on deep breathing, and for intravenous PCA morphine consumption during 24 hours. The intravenous PCA morphine 24-hour cumulative dose was lower in the fast-track than in the control group (15.8+/-12.6 v 32.7+/-22.3 mg, p<0.05). Before extubation, VAS scores were higher in the fast-track group, but after they were lower both at rest and during deep breathing. Extubation delay was shorter in the fast-track group (156.5+/-46.1 v 272+/-116.4 minutes, p<0.05).

CONCLUSION

The combination of anesthesia with remifentanil and spinal analgesia with morphine and clonidine produces effective analgesia after coronary artery surgery and a rapid extubation time.

A randomised controlled trial comparing remifentanil and fentanyl for induction of anaesthesia in CABG surgery

INTRODUCTION

In a prospective randomised trial we studied haemodynamic stability during induction of anaesthesia for CABG surgery in patients receiving remifentanil-propofol or fentanyl-propofol anaesthesia.

METHODS

Fifty-four patients scheduled for elective CABG surgery were studied. Anaesthesia was induced with propofol and pancuronium. The patients were randomly assigned to two groups according to the opioid used during the induction. The remifentanil group received 0.5 microg kg(-1) min(-1) of the drug and the fentanyl group received 5 microg kg(-1). We measured blood pressure, central venous pressure and heart rate continuously for 15 min before and 30 min after orotracheal intubation. We also recorded use of rescue medication for maintaining the mean arterial pressure between 65 and 85 mmHg.

RESULTS

After induction of anaesthesia the mean arterial pressure and heart rate decreased significantly in both groups (P<0.05). After orotracheal intubation the mean arterial pressure and heart rate increased significantly in the fentanyl group but not in the remifentanil group (P<0.05). The incidence of hypertonic events necessitating the use of rescue medication was significantly higher in the fentanyl group (P<0.05).

CONCLUSIONS

Our results show more stable haemodynamics after induction of anaesthesia in CABG surgery in patients receiving remifentanil-propofol than in patients receiving fentanyl-propofol.

Comparison of bolus remifentanil versus bolus fentanyl for induction of anesthesia and tracheal intubation in patients with cardiac disease

OBJECTIVE

Large bolus-dose remifentanil may be advantageous for use during induction of anesthesia because of its short duration of effect. Currently, there are little data on the use of large bolus-dose remifentanil because of reports of severe bradycardia and hypotension. The purpose of this study is to compare the hemodynamic effects of bolus remifentanil versus fentanyl with glycopyrrolate for induction of anesthesia in patients with heart disease.

DESIGN

A randomized, double-blinded study.

SETTING

A tertiary-care academic medical center.

PARTICIPANTS

One hundred patients for coronary artery bypass or valvular surgery.

INTERVENTION

Subjects received either (1) remifentanil, 5 microg/kg, with glycopyrrolate, 0.2 mg, or (2) fentanyl, 20 microg/kg, with 0.2 mg of glycopyrrolate, and both groups also received midazolam, 70 microg/kg, for induction of anesthesia.

MEASUREMENTS AND MAIN RESULTS

Heart rate, mean arterial pressure, systemic vascular resistance, and cardiac output were similar between the 2 groups during induction of anesthesia and tracheal intubation. The incidence of adverse events such as bradycardia (remifentanil 10%, fentanyl 10%), hypotension (remifentanil 16%, fentanyl 10%), and ischemia (remifentanil 0%, fentanyl 2%) were also similar. A greater percentage of patients in the remifentanil group lost consciousness within 1 minute of opioid administration (86% v 66%, p = 0.034).

CONCLUSION

Remifentanil with glycopyrrolate is associated with rapid and predictable clinical anesthetic effect, cardiac stability, and the ability to blunt the hemodynamic responses to tracheal intubation. Bolus remifentanil may be a feasible alternative to bolus fentanyl for induction of anesthesia in patients with heart disease because of its short duration of action and its ability to blunt the hemodynamic responses to tracheal intubation.

Comparative tolerability of sedative agents in head-injured adults

Sedative agents are widely used in the management of patients with head injury. These drugs can facilitate assisted ventilation and may provide useful reductions in cerebral oxygen demand. However, they may compromise cerebral oxygen delivery via their cardiovascular effects. In addition, individual sedative agents have specific and sometimes serious adverse effects. This review focuses on the different classes of sedative agents used in head injury, with a discussion of their role in the context of clinical pathophysiology. While there is no sedative that has all the desirable characteristics for an agent in this clinical setting, careful titration of dose, combination of agents, and a clear understanding of the pathophysiology and pharmacology of these agents will allow safe sedative administration in head injury.

Similar pain scores after early and late extubation in heart surgery with cardiopulmonary bypass

OBJECTIVE

To investigate if early extubation, 2 hours after surgery, would result in more postoperative pain or in an increased use of opioid analgesics compared with late extubation, 6 hours after surgery.

DESIGN

Prospective, randomized study.

SETTING

Intensive care unit, university hospital.

PARTICIPANTS

Sixty patients undergoing cardiac surgery with cardiopulmonary bypass.

INTERVENTIONS

Patients were randomized into 2 groups: extubation at about 2 (early) or 6 (late) hours. Anesthesia was based on propofol and remifentanil. There was no epidural analgesia and no local anesthesia in the wound. A bolus of the opioid ketobemidone was administered toward the end of surgery followed by a continuous infusion.

MEASUREMENTS AND MAIN RESULTS

Pain, provoked during deep breathing or coughing, evaluated with a visual analog scale (VAS) going from 0 to 10, was measured after extubation, and at 8 and 16 hours after surgery. Unprovoked pain was measured hourly. If VAS was greater than 3, the infusion rate was increased and a bolus of ketobemidone was given. Three patients in the late group were excluded because of incomplete data. Pain did not differ between the early and late groups at any time. In all patients, 21 never scored >3, 11 scored >3 once, and 25 scored >3 more than once. Nine patients had 1 score >5. The amount of ketobemidone was similar in both groups.

CONCLUSIONS

Early extubation had no negative effect on the quality of postoperative pain control and was not followed by an increased use of analgesics.

Implications of the use of neuromuscular transmission monitoring on immediate postoperative extubation in off-pump coronary artery bypass surgery

BACKGROUND AND OBJECTIVE

When continuous infusions of neuromuscular blocking drugs are administered during lengthy interventions and no routine antagonism of their effects is applied, there is a dramatic incidence of residual curarization. We have examined whether the use of neuromuscular transmission monitoring results in differences in the incidence of postoperative residual curarization, the use of antagonist agents, and the endotracheal extubation rate and outcome after continuous infusion of rocuronium in patients undergoing off-pump coronary artery bypass surgery.

METHODS

Twenty patients were assigned to group 1 (n = 10, non-blinded neuromuscular transmission monitoring) or group 2 (n = 10, blinded neuromuscular transmission monitoring). In group 1, patients were given rocuronium at an infusion rate of 6 microg kg(-1) min(-1). The rate was manually adjusted in order to maintain T1/T0 at 10%. In group 2, a rocuronium infusion was started 30 min after induction of anaesthesia, at a rate of 6 microg kg(-1) min(-1); this rate was left unchanged during surgery. The rocuronium infusion was discontinued on completion of all vascular anastomoses; propofol was stopped at the beginning of closure of the subcutis and pirinitramide (piritramide) 15 mg was administered intravenously. Remifentanil was discontinued at the beginning of skin closure and neostigmine (50 microg kg(-1)) administered at the end of surgery when the train-of-four ratio was < 0.9 in group 1, and routinely in group 2. A 20 min test period for spontaneous ventilation was allowed once surgery had been accomplished. When the train-of-four ratio was > or = 0.9 (group 1), patients were extubated if also breathing spontaneously, fully awake and able to follow commands. When they met the clinical criteria for normal neuromuscular function after induced blockade, patients in group 2 were extubated when fully awake and able to follow commands.

RESULTS

In group 1, the rate of rocuronium infusion required to keep T1/T0 at 10% was 5 +/- 1.9 microg kg(-1) min(-1); this was not significantly different from the fixed rate in group 2 (P = 0.15). One patient in group 2 was excluded. Eight out of 10 and eight out of nine patients in groups 1 and 2, respectively, reached the extubation criteria. Three out of eight, and five out of eight, patients from groups 1 and 2, respectively, were extubated in the operating room. At that time of endotracheal extubation, all three patients from group 1, but only four of the five patients from group 2 had a train-of-four ratio > or = 0.9. In group 2, one patient was reintubated in the intensive care unit. The incidence of pharmacological reversal was high in group 1.

CONCLUSIONS

Although we found no additional benefit of using neuromuscular transmission monitoring, it seems an absolute necessity for safety reasons. Pharmacological antagonism was mandatory. However, in our opinion, it is not wise routinely to perform immediate postoperative extubation in off-pump coronary artery bypass surgery.

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

BACKGROUND

Propofol-anaesthesia administrated via target-controlled infusion (TCI) has been proposed for cardiac surgery. Age-related changes in pharmacology explain why propofol dose requirement is reduced in elderly patients. However, the Marsh pharmacokinetic model incorporated in the Diprifusor propofol device does not take age into account as a covariable. In the absence of depth of anaesthesia monitoring, this limitation could cause adverse cardiovascular effects resulting from propofol overdose in older patients. We assessed the influence of age on effect-site propofol concentrations predicted by the Diprifusor and titrated to the bispectral index score (BIS) during cardiac anaesthesia.

METHODS

Forty-five patients received propofol by Diprifusor and remifentanil by software including Minto model. Propofol and remifentanil effect-site concentrations were adapted to BIS (40-60) and haemodynamic profile, respectively. The influence of age on effect-site concentrations was assessed by dividing patients into two groups: young (<65 yr) and elderly (> or =65 yr).

RESULTS

For a similar depth of anaesthesia, effect-site propofol concentrations were significantly lower in elderly patients at the different stages of cardiac surgery. The mean dose of propofol required to perform tracheal intubation was significantly lower in elderly patients. However, the overall doses of propofol were comparable in both groups. Neither effect-site remifentanil concentrations nor overall doses of remifentanil were significantly different between the two groups.

CONCLUSIONS

In cardiac anaesthesia, target concentrations of propofol must be reduced in elderly patients. Although this probably contributes to improving intraoperative haemodynamic stability, the absence of decrease in overall dose requirement of propofol suggests that this adjustment is relatively moderate.

Comparison of three remifentanil dose-finding regimens for coronary artery surgery

OBJECTIVES

To identify the remifentanil dosing regimen providing safe and optimal anesthetic conditions during coronary artery bypass graft surgery and to evaluate postoperative recovery characteristics.

DESIGN

Open-label, randomized, parallel group.

SETTING

Three centers in the United States.

PARTICIPANTS

Seventy-two patients with left ventricular stroke volumes >or=50 mL.

INTERVENTIONS

Patients were randomized to remifentanil doses of 1 microg/kg/min (group 1, n = 23); 2 microg/kg/min (group 2, n = 24), or 3 microg/kg/min (group 3, n = 25). Somatic, sympathetic, and hemodynamic responses indicating inadequate anesthesia were treated with bolus doses of remifentanil, 1 to 2 microg/kg, and infusion rate increases, and, if necessary, isoflurane 0.5% to 1.0% was added as a rescue anesthetic. In the intensive care unit, the remifentanil infusion was reset to 1 microg/kg/min, with midazolam administered for supplemental sedation and morphine for analgesia.

MEASUREMENTS AND MAIN RESULTS

The durations of anesthesia, surgery, and cardiopulmonary bypass were similar for the 3 study groups. In addition, dose of lorazepam premedication, time to loss of consciousness, preoperative left ventricular ejection fraction, age, weight, and sex were similar for the 3 study groups. Remifentanil alone (infusion and boluses) prevented and controlled all responses to stimulation in 44% of group 3, 37% of group 2 and 9% of group 1 patients intraoperatively. Isoflurane (0.5%-1% inspired) rescue was successful in the remaining patients in each group. Hypotension indicating discontinuation of isoflurane and reductions of remifentanil infusion rates occurred in 64% to 75% of all patients. The optimal range of remifentanil infusion was 2 to 4 microg/kg/min with isoflurane to supplement the opioid. Fifty-one patients (71%) met the criteria for extubation within 6 hours postoperatively; because of surgical practice differences, only 30 patients (59%) were actually extubated.

CONCLUSIONS

After lorazepam premedication, remifentanil infusion (2-4 microg/kg/min) supplemented intermittently with low inspired concentrations of isoflurane provided an effective anesthetic regimen for coronary artery bypass graft surgery. Early extubation times were feasible after remifentanil continuous infusions (1-5 microg/kg/min) used as the primary anesthetic component intraoperatively and for analgesia (<or=1 microg/kg/min) in the immediate postoperative setting.

Target-controlled infusion for remifentanil in vascular patients improves hemodynamics and decreases remifentanil requirement

Remifentanil is a potent ultra-short-acting opioid, which permits rapid emergence. However, remifentanil is expensive and may have detrimental effects on hemodynamics in case of overdose. Target-controlled infusion (TCI) permits adapting infusion to pharmacokinetic models. In this prospective randomized study, we compared intra- and postoperative hemodynamics, remifentanil requirement during anesthesia, and postoperative morphine requirement in patients scheduled for carotid surgery, and receiving either continuous IV weight-adjusted infusion of remifentanil (RIVA) or TCI for remifentanil (TCIR). Forty-six patients were enrolled in this study: all were anesthetized by using TCI for propofol. Twenty-three received RIVA (0.5 micro g. kg(-1) x min(-1)) for the induction of anesthesia and endotracheal intubation, with the infusion rate decreased to 0.25 micro g x kg(-1) x min(-1) after intubation, then adapted by step of 0.05 micro g x kg(-1) x min(-1) according to hemodynamics. Twenty-three patients received TCIR (Minto model, Rugloop), with an effect-site concentration at 4 ng/mL during induction, then adapted by step of 1 ng/mL according to hemodynamics. All patients received atracurium and a 50% mixture of N(2)O/O(2). Hemodynamic variables were recorded each minute. The number and duration of hemodynamic events were collected, and total doses of anesthetics (remifentanil and propofol) and vasoactive drugs were noted in both groups of patients. Data were analyzed by using unpaired t-tests. RIVA was significantly associated with more frequent episodes of intraoperative hypotension (16 versus 6, P < 0.001) and more frequent episodes of postoperative hypertension and/or tachycardia requiring more frequent administration of beta-adrenergic blockers (16 vs 10, P < 0.04) in comparison with TCIR. The need for morphine titration was not significantly different between groups. TCIR led to a significantly smaller requirement of remifentanil (700 +/- 290 versus 1390 +/- 555 micro g, P < 0.001) without difference in propofol requirement. This prospective randomized study demonstrated that, during carotid endarterectomy, in comparison with patients receiving remifentanil using continuous RIVA, TCI results in less hypotensive episodes during the induction of anesthesia, in fewer episodes of tachycardia and/or hypertension and a smaller beta-adrenergic blocker requirement during recovery, and a decrease in remifentanil requirement. Recommendations to prefer TCI for remifentanil administration during carotid endarterectomy may be justified.

IMPLICATIONS

Remifentanil for intraoperative analgesia in carotid artery surgery is associated with a better stability in perioperative hemodynamics when administered in target-controlled infusion compared with continuous weight-adjusted infusion. This may be related to a smaller requirement of this drug when using target-controlled infusion, as well as a smooth mode of administration.

A combination of intrathecal morphine and remifentanil anesthesia for fast-track cardiac anesthesia and surgery

OBJECTIVE

To determine if the combined remifentanil and intrathecal morphine (RITM) anesthetic technique facilitates early extubation in patients undergoing coronary artery bypass graft (CABG) surgery.

DESIGN

Prospective, randomized, controlled clinical trial.

SETTING

Referral center for cardiothoracic surgery at a university hospital.

PARTICIPANTS

Patients (n = 24) undergoing first-time elective CABG surgery.

INTERVENTIONS

Two groups represented RITM (n = 12) and fentanyl-based (controls, n = 12) anesthesia. Premedication was standardized to temazepam, 0.4 mg/kg, and anesthesia was induced with etomidate, 0.3 mg/kg, in both groups. The RITM group received remifentanil, 1 microg/kg bolus followed by 0.25 to 1 microg/kg/min infusion, and intrathecal morphine, 2 mg. The control group received fentanyl, 12 microg/kg in 3 divided doses. Anesthesia was maintained with isoflurane and pancuronium in both groups. After completion of surgery, the remifentanil infusion was stopped. Complete reversal of muscle relaxation was ensured with a nerve stimulator, and a propofol infusion, 0.5 to 3 mg/kg/h, was started in both groups. All patients were transferred to the intensive care unit (ICU) to receive standardized postoperative care. Intensivists and ICU nurses were blinded to the group assignment. Propofol infusion was stopped, and the tracheal extubation was accomplished when extubation criteria were fulfilled.

MEASUREMENTS AND MAIN RESULTS

Both groups were similar with respect to demographic data and surgical characteristics. Extubation times were 156 +/- 82 minutes and 258 +/- 91 minutes in the RITM and control groups (p = 0.012). Patients in the RITM group exhibited lower visual analog scale pain scores during the first 2 hours after extubation (p < 0.04). Morphine requirements during the 24 hours after extubation were 2.5 +/- 3 mg in the RITM group and 16 +/- 11 mg in the control group (p = 0.0018). Sedation scores were lower in the RITM group during the first 3 hours after extubation (p < 0.03). Pulmonary function tests as assessed by spirometry were better in the RITM group at 6 and 12 hours after extubation (p < 0.04). There were no significant differences in PaO(2) and PaCO(2) after extubation between the 2 groups. None of the patients had episodes of apnea during the immediate 24-hour postextubation period. Two patients from the RITM group required reintubation on the second and sixth postoperative days. There were no differences in ICU and hospital length of stay between the 2 groups.

CONCLUSION

Implementation of the RITM technique provided earlier tracheal extubation, decreased level of sedation, excellent analgesia, and improved spirometry in the early postoperative period. The impact of RITM on ICU and hospital length of stay and potential cost benefits require further evaluation.

Remifentanil-clonidine-propofol versus sufentanil-propofol anesthesia for coronary artery bypass surgery

OBJECTIVE

To compare a remifentanil-clonidine-propofol regimen with conventional sufentanil-propofol anesthesia.

DESIGN

Randomized, nonblinded trial.

SETTING

A single university hospital.

PARTICIPANTS

Male patients scheduled for coronary artery bypass graft (CABG) surgery.

INTERVENTIONS

In the control group, anesthesia was induced with 0.5 microg/kg of sufentanil and 0.2 to 0.3 mg/kg of etomidate after preoxygenation. Propofol (50 to 100 microg/kg/min) and sufentanil (0.5 to 1.0 microg/kg/h) were started after endotracheal intubation. Sufentanil was stopped after aortic decannulation. In the remifentanil-clonidine group, anesthesia was started with remifentanil (0.15 to 0.3 microg/kg/min), followed by etomidate (0.2 to 0.3 mg/kg). Propofol was started at 50 to 100 microg/kg/min, and after endotracheal intubation, clonidine infusion was started (6 to 20 microg/h). Patients received piritramide (0.15 mg/kg) and metamizole (20 mg/kg) for transitional analgesia. In both groups, propofol infusion was reduced to 30 to 60 microg/kg/min at skin closure and stopped when assisted spontaneous breathing led to adequate gas exchange.

MEASUREMENTS AND MAIN RESULTS

The main outcomes were recovery times; somatic variables; plasma catecholamine levels; and self-recorded pain, nausea, and vomiting. Patients in the remifentanil-clonidine group were extubated earlier and had lower plasma epinephrine and norepinephrine levels. After transitional analgesia, the remifentanil-clonidine patients had similar postoperative analgesic use and self-reported pain and side-effect scores.

CONCLUSION

Compared with a sufentanil-propofol regimen, an anesthetic regimen for CABG surgery that combines remifentanil, clonidine, and propofol provides similar hemodynamics. The remifentanil-clonidine regimen reduces catecholamine levels and hastens recovery from anesthesia.

Remifentanil, fentanyl, and cardiac surgery: a double-blinded, randomized, controlled trial of costs and outcomes

Remifentanil may be beneficial in patients undergoing coronary artery bypass graft surgery, by promoting hemodynamic stability, reducing drug requirements, and attenuating the neurohumoral "stress response." We enrolled 77 cardiac surgical patients in a double-blinded, randomized trial and randomly allocated them to one of three groups: remifentanil infusion at 0.83 micro g. kg(-1). min(-1) (Group R); fentanyl bolus, small dose, at 12 micro g/kg (Group FLD); and fentanyl bolus, moderate dose, at 24 micro g/kg (Group FMD). We found a significant difference in the median time to tracheal extubation: Group FLD, 6.5 h; Group R, 7.3 h; and Group FMD, 9.7 h (P = 0.025). Group R patients had similar times to those of Groups FLD (P = 0.14) and FMD (P = 0.30). Group FLD patients had a longer length of hospital stay (P = 0.030). Patients in Group R had a significantly infrequent rate of hypertension but a frequent rate of hypotension (P < 0.01). The urinary cortisol excretion was larger in Group FLD patients (P < 0.0005), and urine flow was smaller (P < 0.0005). Remifentanil was associated with a propofol dose reduction (P = 0.0005) and a concomitant higher bispectral index (P = 0.032). Three Group FLD patients, but none in groups FMD and R, had postoperative myocardial infarctions (P = 0.032). Remifentanil has larger drug acquisition costs but does not increase the total hospital costs associated with cardiac surgery.

IMPLICATIONS

Remifentanil did not significantly reduce the duration of tracheal intubation after cardiac surgery. Remifentanil, when compared with fentanyl (total doses of approximately 15 and 28 micro g/kg), blunts the hypertensive responses associated with cardiac surgery but is associated with more hypotension; when compared with fentanyl 15 micro g/kg, remifentanil reduces cortisol excretion. Larger-dose opioids (remifentanil 0.85 micro g. kg(-1). min(-1) or fentanyl 28 micro g/kg) were associated with a decreased rate of myocardial infarction after cardiac surgery.

Bispectral index in patients with target-controlled or manually-controlled infusion of propofol

In this prospective, randomized study we compared bispectral index (BIS), hemodynamics, time to extubation, and the costs of target-controlled infusion (TCI) and manually-controlled infusion (MCI) of propofol. Forty patients undergoing first-time implantation of a cardioverter-defibrillator were included. Anesthesia was performed with remifentanil (0.2-0.3 micro g. kg(-1). min(-1)) and propofol. Propofol was used as TCI (plasma target concentration, 2.5-3.5 micro g/mL; n = 20) or MCI (3.0-4.0 mg. kg(-1). h(-1); n = 20). BIS, heart rate, and arterial blood pressure were measured at six data points: T1, before anesthesia; T2, after intubation; T3, after skin incision; T4, after first defibrillation; T5, after third defibrillation; and T6, after extubation. There were no significant hemodynamic differences between the two groups. BIS was significantly lower at T3 and T4 in the TCI group than in the MCI group. The mean dose of propofol was larger in TCI patients (5.8 +/- 1.4 mg. kg(-1). h(-1)) than in the MCI patients (3.7 +/- 0.6 mg. kg(-1). h(-1)) (P < 0.05), whereas doses of remifentanil did not differ. Time to extubation did not differ between the two groups (TCI, 13.7 +/- 5.3 min; MCI, 12.3 +/- 3.5 min). One patient in the MCI group had signs of intraoperative awareness without explicit memory after first defibrillation (BIS before shock, 49; after shock, 83). Costs were significantly less in the MCI group (34.83 US dollars) than in the TCI group (39.73 US dollars). BIS failed to predict the adequacy of anesthesia for the next painful stimulus.

IMPLICATIONS

In this prospective, randomized study, bispectral index (BIS), hemodynamics, time to extubation, and costs of target-controlled infusion (TCI) and manually-controlled infusion of propofol were compared. TCI increased the amount of propofol used. BIS failed to predict the adequacy of anesthesia for the next painful stimulus.

Target-controlled infusion or manually controlled infusion of propofol in high-risk patients with severely reduced left ventricular function

OBJECTIVE

To compare hemodynamics, time to extubation, and costs of target-controlled infusion (TCI) with manually controlled infusion (MCI) of propofol in high-risk cardiac surgery patients.

DESIGN

Prospective, randomized.

SETTING

Major community university-affiliated hospital.

PARTICIPANTS

Twenty patients undergoing first-time implantation of a cardioverter-defibrillator with severely reduced left ventricular function (left ventricular ejection fraction <30%).

INTERVENTIONS

Anesthesia was performed using remifentanil, 0.2 to 0.3 microg/kg/min, and propofol. Propofol was used as TCI (plasma target concentration, 2 to 3 microg x mL; n = 10) or MCI (2.5 to 3.5 mg/kg/hr; n = 10).

MEASUREMENTS AND MAIN RESULTS

Hemodynamics were measured at 6 data points: T1, before anesthesia; T2, after intubation; T3, after skin incision; T4, after first defibrillation; T5, after third defibrillation; and T6, after extubation. There were no significant hemodynamic differences between the 2 groups. Dobutamine was required to maintain cardiac index >2 L/min/m(2) in significantly more patients of the TCI group than of the MCI group. Mean dose of propofol was higher in the TCI patients (6.0 +/- 1.0 mg/kg/hr) than in the MCI patients (3.0 +/- 0.4 mg/kg/hr) (p < 0.05), whereas doses of remifentanil did not differ. Time to extubation was significantly shorter in the MCI (11.9 +/- 2.4 min) versus the TCI group (15.6 +/- 6.8 min). Costs were significantly lower in MCI patients (34.73 dollars) than in TCI patients (44.76 dollars).

CONCLUSIONS

In patients with severely reduced left ventricular function, TCI and MCI of propofol in combination with remifentanil showed similar hemodynamics. TCI patients needed inotropic support more often than MCI-treated patients. Although extubation time was longer in TCI patients and costs were higher, both anesthesia techniques can be recommended for early extubation after implantation of a cardioverter-defibrillator.

A randomized double-blinded multicenter comparison of remifentanil versus fentanyl when combined with isoflurane/propofol for early extubation in coronary artery bypass graft surgery

We compared a fentanyl/isoflurane/propofol regimen with a remifentanil/isoflurane/propofol regimen for fast-track cardiac anesthesia in a prospective, randomized, double-blinded study on patients undergoing elective coronary artery bypass graft surgery. Anesthesia was induced with a 1-min infusion of 0.5 mg/kg propofol followed by 10-mg boluses of propofol every 30 s until loss of consciousness. After 0.2 mg/kg cisatracurium, a blinded continuous infusion of remifentanil at 1 microg. kg(-1). min(-1) or the equivalent volume rate of normal saline was then started. In addition, a blinded bolus syringe of 1 microg/kg remifentanil or 10 microg/kg fentanyl, respectively, was given over 3 min. Blinded remifentanil, 1 microg. kg(-1). min(-1) (or the equivalent volume rate of normal saline), together with 0.5% isoflurane, were used to maintain anesthesia. Significantly more patients (P < 0.01) in the fentanyl regimen experienced hypertension during skin incision and maximum sternal spread compared with patients in the remifentanil regimen. There were no differences between the groups in time until extubation, discharge from the surgical intensive care unit, ST segment and other electrocardiogram changes, catecholamine levels, or cardiac enzymes. The remifentanil-based anesthetic (consisting of a bolus followed by a continuous infusion) resulted in significantly less response to surgical stimulation and less need for anesthetic interventions compared with the fentanyl regimen (consisting of an initial bolus, and followed by subsequent boluses only to treat hemodynamic responses) with both drug regimens allowing early extubation.

IMPLICATIONS

Both fentanyl and the newer opioid remifentanil, when each is combined with isoflurane and propofol, allowed for fast-track cardiac anesthesia. The remifentanil regimen used in this study resulted in significantly less hemodynamic response to surgical stimulation.