The effects of remifentanil and alfentanil-based total intravenous anesthesia (TIVA) on the endocrine response to abdominal hysterectomy

STUDY OBJECTIVE: To compare the effects of remifentanil with alfentanil as a part of total intravenous anesthesia (TIVA) on plasma concentrations of cortisol, insulin, and glucose, and hemodynamic responses in patients undergoing abdominal hysterectomy. DESIGN: Randomized, double-blind study. SETTING: University hospital. PATIENTS: 24 ASA physical status I female patients scheduled for abdominal hysterectomy. INTERVENTIONS: Premedicated patients were randomly allocated to receive either remifentanil-propofol (Group R) or alfentanil-propofol (Group A). The loading dose of the study drug was administered over 60 seconds (remifentanil l microg kg(-l) or alfentanil 10 microg kg(-l)) followed by a continuous infusion (remifentanil 0.2 microg kg(-l) min(-l) or alfentanil 0.5 microg kg(-l) min(-l)). In both groups, propofol was administered until loss of consciousness and maintained with a propofol infusion rate of 100 microg kg(-l) min(-l). After induction of anesthesia, all patients were manually ventilated by mask with O2-air mixture for 20 minutes. Then rocuronium 0.6 mg kg(-l) was given for tracheal intubation. MEASUREMENTS: Mean arterial pressure (MAP) and heart rate (HR) were recorded. Plasma concentrations of cortisol, insulin, and glucose were measured during anesthesia and in the recovery room. MAIN RESULTS: In Group R, MAP and HR were lower after tracheal intubation and skin incision than in Group A (p < 0.05). Plasma cortisol concentrations decreased from baseline values at 20 minutes after induction, after tracheal intubation, and skin incision in Group R (p < 0.001). Plasma concentrations of cortisol and glucose increased from baseline values at 30 minutes after skin incision and continued to increase in both groups (p = 0.001). Plasma concentrations of cortisol, insulin, and glucose did not differ between groups at all sampling times. CONCLUSION: Remifentanil provided better hemodynamic stability than alfentanil during anesthesia and surgery. However, both remifentanil and alfentanil had similar effects on the stress endocrine response to abdominal hysterectomy.     

Assessment of depth of anesthesia and postoperative respiratory recovery after remifentanil- versus alfentanil-based total intravenous anesthesia in patients undergoing ear-nose-throat surgery

BACKGROUND: The authors investigated whether total intravenous anesthesia (TIVA) with precalculated equipotent infusion schemes for remifentanil and alfentanil would ensure appropriate analgesia and that remifentanil would result in better recovery characteristics. METHODS: Forty consenting patients (classified as American Society of Anesthesiologists physical status I-III) scheduled for microlaryngoscopy were randomized to receive, in a double-blind manner, either remifentanil (loading dose 1 microg/kg; maintenance infusion, 0.25 microg x kg(-1) x min-1) or alfentanil (loading dose, 50 microg/kg; maintenance infusion, 1 microg x kg(-1) x min-1) as the analgesic component of TIVA. They were combined with propofol (loading dose, 2 mg/kg; maintenance infusion, 100 microg x kg(-1) min(-1)). To insure an equal state of anesthesia, the opioids were titrated to maintain heart rate and mean arterial pressure within 20% of baseline, and propofol was titrated to keep the bispectral index (BIS) less than 60. Neuromuscular blockade was achieved with succinylcholine. Drug dosages and the times from cessation of anesthesia to extubation, verbal response, recovery of ventilation, and neuropsychological testing, orientation, and discharge readiness were recorded. RESULTS: Demographics, duration of surgery, and anesthesia were similar between the two groups. Both groups received similar propofol doses. There were no difference in BIS values preoperatively (mean, 96), intraoperatively (mean, 55), and postoperatively (mean, 96). Recovery of BIS and times for verbal response did not differ. At 20, 30, and 40 min after terminating the opioid infusion, the peripheral oxygen saturation and respiratory rate were significantly higher in the remifentanil group compared with the alfentanil group. CONCLUSIONS: When both the hypnotic and analgesic components of a TIVA-based anesthetic are administered in equipotent doses, remifentanil provides a more rapid respiratory recovery, even after brief surgical procedures, compared with alfentanil.     

Comparison of hemodynamics,recovery profile,and early postoperative pain control and costs of remifentanil versus alfentanil-based total intravenous anesthesia (TIVA)

STUDY OBJECTIVE: To compare hemodynamics, recovery profiles, early postoperative pain control and costs of total intravenous anesthesia (TIVA) with propofol and remifentanil and propofol and alfentanil. DESIGN: Randomized, double-blind study. SETTING: University hospital. PATIENTS: 40 ASA physical status I and II adult patients scheduled for lumbar discectomy. INTERVENTIONS: Patients were randomly assigned to receive either remifentanil-propofol or alfentanil-propofol. Anesthesia was induced with remifentanil 1 microg kg(-1) or alfentanil 20 microg kg(-1) with propofol 2 mg kg(-1), and maintained with infusions of propofol 150 to 100 microg kg(-1)min(-1) and either remifentanil 0.1 microg kg(-1) min(-1) or alfentanil 0.5 microg kg(-1) min(-1). MEASUREMENTS: Hemodynamic parameters (heart rate and mean arterial pressure), times to awakening, and tracheal extubation were recorded. In the postanesthesia care unit, pain level, frequency of analgesic demand, frequency of postoperative nausea and vomiting (PONV), partial oxygen saturation (SpO2), and respiratory rates were noted. Drug dosages and costs of each technique were determined. MAIN RESULTS: The mean arterial pressure significantly decreased compared to baseline values 1 minute after induction (p < 0.05) in both groups, and it significantly decreased at 5, 15, and 30 minutes perioperatively in the remifentanil group compared to the alfentanil group (p < 0.05). Time of extubation, spontaneous eye opening, and response to verbal command were similar in both groups. Visual analog scale pain scores at 30 minutes and 60 minutes were significantly lower in the alfentanil group than remifentanil group (p < 0.05). At 15, 30, and 60 minutes after terminating the operation oxygen saturation and respiratory rate were significantly higher (p < 0.05) and analgesics were required sooner in the remifentanil group than the alfentanil group (p < 0.05). The frequency of PONV was similar in both groups. The remifentanil-propofol anesthesia was found to be slightly more expensive as compared to the alfentanil based TIVA (33.41 +/- 4.53 vs. 29.97 +/- 4.1 USD) (p < 0.05). CONCLUSIONS: Both remifentanil and alfentanil provided a reasonably rapid and reliable recovery. The remifentanil-based TIVA was associated with high intraoperative cost and early postoperative pain, but it allowed a more rapid respiratory recovery.     

Remifentanil versus alfentanil in total intravenous anaesthesia for day case surgery

BACKGROUND AND OBJECTIVE: We assessed the intraoperative haemodynamic responses and recovery profiles of total intravenous anaesthesia with remifentanil and alfentanil for outpatient surgery. METHODS: Patients in Group 1 (n = 20) received alfentanil 20 microg kg(-1) followed by 2 microg kg(-1) min(-1) intravenously; patients in Group 2 (n = 20) received remifentanil 1 microg kg(-1) followed by 0.5 microg kg(-1) min(-1) intravenously. Both groups then received propofol 2 mg kg(-1) followed by 9 mg kg(-1) h(-1) intravenously. Five minutes after skin incision, infusion rates were decreased, and at the end of surgery, all infusions were discontinued. Early recovery was assessed by the Aldrete score, whereas intermediate recovery was assessed with the postanaesthetic discharge scoring system (PADS). RESULTS: Perioperative arterial pressure was similar in both groups; heart rate was lower in Group 2 (P < 0.05). The times to spontaneous and adequate respiration, response to verbal commands, extubation and times for Aldrete score > or = 9 were shorter in Group 2 patients (P < 0.05). Pain scores were higher in Group 2 patients (P < 0.05). Overall times for postanaesthetic discharge scores > or = 9 were similar. CONCLUSIONS: Early recovery of patients after day surgery is significantly shorter after total intravenous anaesthesia with remifentanil compared with that with alfentanil but postoperative pain management must be planned ahead.     

Propofol anesthesia for craniotomy: a double-blind comparison of remifentanil, alfentanil, and fentanyl

For patients undergoing craniotomy, it is desirable to have stable and easily controllable hemodynamics during intense surgical stimulation. However, rapid postoperative recovery is essential to assess neurologic function. Remifentanil, an ultra-short-acting mu-opioid receptor agonist, may be the ideal agent to confer the above characteristics. In this prospective randomized study, we compared the hemodynamic stability, recovery characteristics, and the dose of propofol required for maintaining anesthesia supplemented with an infusion of remifentanil, alfentanil, or fentanyl in 34 patients scheduled for supratentorial craniotomy. With routine monitors in place, anesthesia was induced with propofol (2-3 mg/kg), atracurium (0.5 mg/kg), and either remifentanil (1 microg/kg), alfentanil (10 microg/kg), or fentanyl (2 micro/kg). The lungs were ventilated with O2/air to mild hypocapnia. Anesthesia was maintained with infusions of propofol (50-100 microg/kg/min) and either remifentanil (0.2 microg/kg/min), alfentanil (20 microg/kg/h), or fentanyl (2 microg/kg/h). There were no significant differences among the groups in the dose of propofol maintenance required, heart rate, or mean arterial pressure. However, the time to eye opening (minutes) was significantly shorter in the remifentanil compared to the alfentanil group (6+/-3; 21+/-14; P = 0.0027) but not the fentanyl group (15+/-9). We conclude that remifentanil is an appropriate opioid to use in combination with propofol during anesthesia for supratentorial craniotomy.     

Tracheal intubation without muscle relaxants: remifentanil or alfentanil in combination with propofol

BACKGROUND AND OBJECTIVE: In some situations, the use of muscle relaxants (neuromuscular blocking drugs) are undesirable or contraindicated. We compared intubating conditions without muscle relaxants in premedicated patients receiving either alfentanil 40 microg kg(-1) or remifentanil 2, 3 or 4 microg kg(-1) followed by propofol 2 mg kg(-1). METHODS: In a randomized, double-blind study, 80 healthy patients were assigned to one of four groups (n = 20). After intravenous atropine, alfentanil 40 microg kg(-1) or remifentanil 2, 3 or 4 microg kg(-1) were injected over 90 s followed by propofol 2 mg kg(-1). Ninety seconds after administration of the propofol, laryngoscopy and tracheal intubation were attempted. Intubating conditions were assessed as excellent, good or poor on the basis of ease of lung ventilation, jaw relaxation, laryngoscopy, position of the vocal cords, and patient response to intubation and slow inflation of the endotracheal tube cuff. RESULTS: Seven patients who received remifentanil 2 microg kg(-1) and one patient who received remifentanil 3 microg kg(-1) could not be intubated at the first attempts. Excellent intubating conditions (jaw relaxed, vocal cords open and no movement in response to tracheal intubation and cuff inflation) were observed in those who received either alfentanil 40 microg kg(-1) (45% of patients) or remifentanil in doses of 2 microg kg(-1) (20%), 3 microg kg(-1) (75%) or 4 microg kg(-1) (95%). Overall, intubating conditions were significantly better (P < 0.05), and the number of patients showing excellent conditions were significantly higher (P < 0.05) in patients who received remifentanil 4 microg kg(-1) compared with those who received alfentanil 40 microg kg(-1) or remifentanil 2 microg kg(-1). No patient needed treatment for hypotension or bradycardia. CONCLUSIONS: Remifentanil 4 microg kg(-1) and propofol 2 mg kg(-1) administered in sequence intravenously provided good or excellent conditions for tracheal intubation in all patients without the use of muscle relaxants.     

Efficacy and safety of remifentanil in coronary artery bypass graft surgery: a randomized,double-blind dose comparison study

OBJECTIVES: To compare the efficacy and safety of 3 doses of remifentanil as part of a total intravenous anesthesia technique with low-dose propofol in patients undergoing coronary artery bypass graft (CABG) surgery. DESIGN: Multicenter, multinational, double-blind, randomized, dose comparison study. SETTING: Nine hospitals in 5 countries. PARTICIPANTS: One hundred forty-one patients undergoing first-time elective CABG surgery. INTERVENTIONS: Patients were premedicated with a short-acting oral benzodiazepine up to 2 h before surgery and randomized to receive continuous infusions of remifentanil 1.0 microg/kg/min (n = 45), 1.5 microg/kg/min (n = 44), or 2.0 microg/kg/min (n = 43), in combination with propofol 3 mg/kg/h. Nine patients received remifentanil 1.0 microg/kg/min on an open-label basis. Three different induction sequences (IS) were used. In IS 1 (n = 31), induction was started with remifentanil infusion followed 5 minutes later by propofol 0.5 mg/kg bolus and infusion at 3 mg/kg/h. Further bolus doses of propofol (10 mg) were given if loss of consciousness (LOC) was not attained after 5 minutes; pancuronium, 0.04 to 0.1 mg/kg, was administered at LOC. In IS 2 (n = 68), a priming dose of pancuronium, 0.015 mg/kg, was administered just before starting remifentanil. In IS 3 (n = 42), bolus doses of propofol, 10 mg every 10 seconds, were given until LOC, followed by pancuronium, 0.04 to 0.1 mg/kg, and the remifentanil and propofol infusions were started. MEASUREMENTS AND MAIN RESULTS: There were no significant differences among the remifentanil dose groups with regard to the primary outcome measure, responses to sternotomy/sternal spread/maximal sternal spread. Responses to these stimuli were recorded in 11%, 11%, and 14% of patients in the remifentanil 1.0, 1.5, and 2.0 microg/kg/min dose groups, respectively. Similarly, there were no significant differences in the responses to other surgical stimuli. There was a high incidence of muscle rigidity when remifentanil was used to induce anesthesia. CONCLUSIONS: All 3 remifentanil dose regimens provided profound suppression of responses to surgical stimuli in the majority of patients. There was no apparent advantage in starting the remifentanil infusion rate above 1.0 microg/kg/min. Remifentanil is not suitable for use as a sole induction agent.     

Post-anesthesia Recovery after Infusion of Propofol with Remifentanil or Alfentanil or Fentanyl in Morbidly Obese Patients

Background: The type of opioid used during general anesthesia in the morbidly obese influences recovery and the postoperative period. In a randomized clinical trial, the postoperative recovery profile and early period after general anesthesia with remifentanil, fentanyl and alfentanil were compared in morbidly obese patients. Material and Method: 60 morbidly obese patients with BMI >35 kg/m² (mean 43.31) undergoing open Roux-en-y gastric bypass were randomly divided into 3 groups: remifentanil (R), fentanyl (F), and alfentanil (A). Dosage of opioids was based on ideal body weight (IBW): fentanyl 5 mcg/kg for intubation followed by infusion of 0.025-0.05 mcg/kg/min; alfentanil 15 mcg/kg initially, then 1.0-1.5 mcg kg/min; and remifentanil 1 mcg/kg followed by infusion of 0.25-1.5 mcg/kg/min. Anesthesia was induced with infusion of propofol and oxygen with N₂O (1:1). After anesthesia, the duration to response to verbal command, spontaneous respiration, adequate respiration, and safe extubation were recorded.The incidence of postoperative nausea and vomiting were recorded. Using verbal scale for evaluation of postoperative pain, the early postoperative analgesia requirements were assessed. Results: Demographic profiles and duration of procedure did not differ between groups. A total dose of propofol was significantly lower in Group R compared with Groups A and F (P <0.05). Duration to spontaneous respiration, adequate respiration and safe extubation were significantly shorter in Group R compared with Group F (P <0.05). Shortly after anesthesia, significantly more patients in Group R required additional dose of analgesic than in Group F (P <0.05). Postoperative nausea and vomiting (PONV) occurred significantly more often in Group R compared with Group F (P <0.05). Recovery profile of Group A was more similar to Group R, and postoperative pain and PONV evaluation more similar to Group F. Conclusion: In morbidly obese individuals, alfentanil or fentanyl and remifentanil can be safely used, but there is a higher rate of PONV and postoperative pain in the remifentanil group.     

Effects of remifentanil and alfentanil on seizure duration, stimulus amplitudes and recovery parameters during ECT

BACKGROUND AND OBJECTIVE: Propofol may decrease seizure duration in electroconvulsive therapy. Although not proven, prolonged seizures may be more efficacious. The goal of this study was to evaluate and compare effects of alfentanil and remifentanil on seizure duration, recovery parameters and degree of stimulus amplitude in patients undergoing electroconvulsive therapy. METHODS: Twenty-four ASA I-II patients enrolled in this prospective, randomized trial, each receiving a total of seven electroconvulsive therapies. Patients were randomized to receive only Propofol, group P (0.75 mg kg-1, n=8), Propofol with alfentanil, group A (10 microg kg-1 alfentanil+0.5 mg kg-1 Propofol, n=8) and Propofol with remifentanil, group R (1 microg kg-1 remifentanil +0.5 mg kg-1 propofol, n=8) via an iv route. Supplemental doses of propofol were given as required to achieve loss of consciousness. Succinylcholine 0.5 mg kg-1 iv was given to all groups for muscular paralysis. We recorded hemodynamic parameters, cortical and motor seizure durations, and recovery parameters. RESULTS: Mean motor seizure duration was found to be significantly longer in patients receiving propofol-remifentanil anesthesia (53.3+/-13.6 s) and propofol-alfentanil anesthesia (52.2+/-0.4 s) compared with propofol anesthesia (37.6+/-9.2 s) (P=0.001). Recovery parameters and stimulus amplitudes were similar in groups A and R; significantly different from group P (P=0.001). CONCLUSIONS: Adding 10 microg kg-1 alfentanil or 1 microg kg-1 remifentanil to reduced doses of propofol provided unconsciousness and increased seizure durations. For patients who need higher stimulus amplitudes for longer seizure durations, combining low-dose propofol with alfentanil or remifentanil may be good alternative regimens for ECT.     

Comparison of total intravenous anesthesia and sevoflurane-fentanyl anesthesia for outpatient otorhinolaryngeal surgery

STUDY OBJECTIVE: To compare the recovery characteristics of two widely used anesthetic techniques: remifentanyl-propofol and sevoflurane-fentanyl in a standardized ambulatory population.DESIGN: Randomized, single-blinded study. SETTING: University-affiliated medical center. PATIENTS: 50 ASA physical status I and II patients undergoing elective ambulatory otorhinolaryngeal surgery. INTERVENTIONS: Patients were randomized two groups to receive total intravenous anesthesia (TIVA group) with remifentanil and propofol or sevoflurane-fentanyl (SF group). TIVA patients received induction with propofol 1.5 mg/kg intravenously (IV) and remifentanil 0.5 microg/kg IV. The anesthesia was continued with a continuous infusion of propofol 100 microg/kg/min and remifentanil 0.0625-0.25 microg/kg/min. The SF group received, at induction, fentanyl 2 microg/kg followed by propofol 1.5 mg/kg IV. Maintenance was obtained with 1 to 1.5 minimum alveolar concentration of sevoflurane and bolus of fentanyl 1 microg/kg IV as needed. MEASUREMENTS AND MAIN RESULTS: Early recovery times (eye opening, response to commands, extubation, orientation, operating room stay after surgery, and Aldrete score > or =9) and patient satisfaction were similar between the two groups. Postanesthetic discharge scoring system (PADSS) > or = 9 was significantly shorter for the TIVA group (135.9 +/- 51 vs. 103 +/- 32 min) (p < 0.01) but this difference was not associated with a shorter postanesthesia care unit (PACU) length of stay. CONCLUSION: Early recovery times are comparable between total intravenous anesthesia and sevoflurane-based anesthesia. Even though patients in the TIVA group achieved home readiness criteria in a significantly shorter time, this technique does not shorten PACU length of stay, which depends instead on multiple nonmedical and administrative issues.     

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.     

A comparison of remifentanil and alfentanil for use with propofol in patients undergoing minimally invasive coronary artery bypass surgery

Most patients undergoing minimally invasive direct coronary artery bypass surgery can be awakened and tracheally extubated in the operating room. We have compared two techniques of total IV anesthesia in this patient population: 30 patients (aged 44 to 74 yr; 24 male) premedicated with temazepam were randomly assigned to receive either remifentanil-propofol or alfentanil-propofol. Anesthesia was induced with remifentanil 2 microg/kg or with alfentanil 40 microg/kg, with propofol, and maintained with remifentanil at 0.25 or 0.5 microg x kg(-1) x min(-1) or alfentanil at 0.5 or 1 microg x kg(-1) x min(-1). The stable maintenance infusion rate of propofol was adjusted for age. Times to awakening and tracheal extubation were recorded. Postoperatively, IV morphine provided by patient-controlled analgesia was used for 48 h. Times to awakening and tracheal extubation (mean +/- SD) were shorter (P < 0. 01) in patients receiving remifentanil, and interpatient variations in times to awakening and tracheal extubation smaller (awakening 25 +/- 7 vs 74 +/- 32 min, and extubation 27 +/- 7 vs 77 +/- 32 min). Analysis of variance revealed that postoperative consumption of morphine was dependent on both the intraoperative opioid and the time elapsed after surgery (P < 0.05): patient-controlled analgesia morphine use during the first 3 h after awakening was more in patients receiving remifentanil (P < 0.01). Implications: Recovery of patients undergoing Minimally Invasive Direct Coronary Artery Bypass Surgery is significantly shorter and more predictable after total IV anesthesia with remifentanil-propofol than with alfentanil-propofol, which may be important if the goal is that patients will be awakened and tracheally extubated in the operating room.     

Postoperative nausea and vomiting after total intravenous anesthesia with propofol and remifentanil or alfentanil: how important is the opioid?

STUDY OBJECTIVE: To compare the frequency and duration of postoperative nausea and vomiting (PONV) following total intravenous anesthesia (TIVA) with propofol and either remifentanil or alfentanil in outpatients undergoing arthroscopic surgery of the extremities.DESIGN: Randomized, third-party blinded study. SETTING: University medical center. PATIENTS: 100 ASA physical status I and II patients scheduled for arthroscopic surgery of the knee or shoulder. INTERVENTIONS: The anesthesia regimen consisted of a bolus followed by continuous infusion of propofol (2 mg/kg followed by 120 microg/kg/min) and the opioid (remifentanil 0.5 microg/kg followed by 0.1 microg/kg/min or alfentanil 10 microg/kg followed by 0.25 microg/kg/min). Patients breathed 100% oxygen spontaneously through a Laryngeal Mask Airway (or an endotracheal tube when medically indicated). Opioids were titrated to maintain blood pressure and heart rate within 20% of baseline and a respiratory rate of 10 to 16 breaths/min. Propofol was titrated downward as low as possible without permitting patient movement. MEASUREMENTS: Nausea was determined by an 11-point categorical scale and was recorded before surgery and multiple time points thereafter. The times of emetic episodes were recorded. Treatment of PONV was at the discretion of the postanesthesia care unit (PACU) nurses who were blinded to the identity of the opioid used. MAIN RESULTS: Nausea scores were 0 at all time points in over 70% of the patients in each group. None of the 100 patients vomited while in the hospital, and only one patient required antiemetic therapy. CONCLUSION: When propofol-based TIVA is used for arthroscopic surgery, short-acting opioids do not significantly affect the risk of PONV.     

Remifentanil provides better analgesia than alfentanil during breast biopsy surgery under monitored anesthesia care

PURPOSE: To compare the analgesic effects of remifentanil and alfentanil during breast biopsy under monitored anesthesia care (MAC). METHODS: Sixty patients received sedation with propofol (50 microg.kg(-1).min(-1)). After receiving a loading dose of opioid (either remifentanil 0.5 microg.kg(-1), or alfentanil 2.5 microg.kg(-1)), an infusion was initiated (remifentanil 0.05 microg.kg(-1).min(-1) or alfentanil 0.25 microg.kg(-1).min(-1)), and this was supplemented with local anesthetic infiltration. The pain was evaluated with a ten-point visual analogue scale (VAS) during local anesthetic infiltration and deep tissue dissection. Inadequate analgesia, defined as VAS scores > or = 5, was treated first with boluses of opioid (remifentanil group 10 microg or alfentanil group 50 microg) and if inadequate after two treatments with additional local anesthetic. Postoperative times were recorded including the times until discharge criteria were achieved and patient's actual discharge. RESULTS: The pain scores were similar between the two groups during the initial injections of local anesthetic in the breast, however, patients in the remifentanil group had lower mean pain scores during deep tissue dissection (2.3 vs 4.3, P < 0.01). Patients in the remifentanil group required fewer rescue doses of opioid (1.9 vs 3.6, P < 0.03) and local anesthetic (5 vs 15, P < 0.006). The two study groups had comparable speed of recovery. CONCLUSION: Remifentanil was a better opioid choice than alfentanil for breast biopsy under MAC at the doses studied, but it did not increase the rapidity in which patients recovered postoperatively.     

Propofol reduces perioperative remifentanil requirements in a synergistic manner: response surface modeling of perioperative remifentanil-propofol interactions

BACKGROUND: Remifentanil is often combined with propofol for induction and maintenance of total intravenous anesthesia. The authors studied the effect of propofol on remifentanil requirements for suppression of responses to clinically relevant stimuli and evaluated this in relation to previously published data on propofol and alfentanil. METHODS: With ethics committee approval and informed consent, 30 unpremedicated female patients with American Society of Anesthesiologists physical status class I or II, aged 18-65 yr, scheduled to undergo lower abdominal surgery, were randomly assigned to receive a target-controlled infusion of propofol with constant target concentrations of 2, 4, or 6 microg/ml. The target concentration of remifentanil was changed in response to signs of inadequate anesthesia. Arterial blood samples for the determination of remifentanil and propofol concentrations were collected after blood-effect site equilibration. The presence or absence of responses to various perioperative stimuli were related to the propofol and remifentanil concentrations by response surface modeling or logistic regression, followed by regression analysis. Both additive and nonadditive interaction models were explored. RESULTS: With blood propofol concentrations increasing from 2 to 7.3 microg/ml, the C(50) of remifentanil decreased from 3.8 ng/ml to 0 ng/ml for laryngoscopy, from 4.4 ng/ml to 1.2 ng/ml for intubation, and from 6.3 ng/ml to 0.4 ng/ml for intraabdominal surgery. With blood remifentanil concentrations increasing from 0 to 7 ng/ml, the C(50) of propofol for the return to consciousness decreased from 3.5 microg/ml to 0.6 microg/ml. CONCLUSIONS: Propofol reduces remifentanil requirements for suppression of responses to laryngoscopy, intubation, and intraabdominal surgical stimulation in a synergistic manner. In addition, remifentanil decreases propofol concentrations associated with the return of consciousness in a synergistic manner.     

Prevention of pain on injection of propofol: a comparison of remifentanil with alfentanil in children

AIM: Propofol has a high incidence of pain on injection, particularly when a vein on the back of hand is used. Administration of lidocaine, either before or mixed with propofol remains the most widely used method to attenuate this pain. The use of opioids such as alfentanil and fentanyl has been found to decrease pain induced by propofol injection. The purpose of this study was to evaluate the effects of different doses of remifentanil and alfentanil in minimizing the pain caused by propofol. METHODS: In this randomized, double-blind, placebo-controlled study, healthy premedicated children between the age group of 5-12 years admitted for adenotonsillectomy were randomly allocated to one of 6 treatment groups. Group I: remifentanil 0.25 microg kg(-1); Group II: remifentanil 0.50 microg kg(-1); Group III: alfentanil 15 microg kg(-1); Group IV: alfentanil 20 microg kg(-1) 60 s prior to propofol mixed with 1 mL of 0.9% normal saline; Group V: lidocaine 1 mL of 1% (10 mg) added to 100 mg of propofol and Group VI: normal saline. During the injection of propofol (3 mg kg(-1)) pain perception was assessed with a four-point behavioural scale: none, mild, moderate, or severe. RESULTS: There were 52 subjects in Group I, 51 in Group II, 49 in Group III, 52 in Group IV, 52 in Group V and 52 in Group VI; 63.46% of patients in Group I, 39.21% in Group II, 38.77% in Group III, 36.53% in Group IV, 38.46% in Group V and 84.61% in Group VI experienced pain. Statistically, Groups II, III, IV and V were significantly better than placebo in the reduction of propofol pain (P<0.0001). Groups II, III and IV significantly reduced the pain in comparison with Group I (P<0.001). CONCLUSION: Pretreatment with intravenous remifentanil 0.5 microg kg(-1), alfentanil 15 microg kg(-1) and 20 microg kg(-1) were equally effective in reducing pain associated with propofol injection in children between the age group of 5-12 years.     

Postoperative analgesia after preincisional administration of remifentanil

AIM: The aim of this study was to assess postoperative analgesia after preincisional and postincisional administration of remifentanil. METHODS: Randomized trial, 24 hours. Setting: University hospital, hospitalized care. Patients: 48 adult patients scheduled for lumbar vertebral surgery. Interventions: in group R5, patients received an infusion of 0.2 microg kg(-1) min(-1) remifentanil over 5 minutes, followed by a break of 15 minutes before anesthesia was started. Anesthesia was induced by infusion of 0.25 microg kg(-1) min(-1) remifentanil and a bolus of 1.5 microg kg(-1) propofol, followed by a continuous infusion of 2 to 3 microg kg(-1) h-1 propofol and 0.25 microg kg(-1) min(-1) remifentanil until end of anesthesia. In group R20, patients received 0.05 microg kg(-1) min(-1) remifentanil over 20 minutes before the induction of anesthesia. In group RL, anesthesia was induced and maintained with propofol. After surgery began, a remifentanil infusion of 0.5 microg kg(-1) min(-1) was given for 50 minutes, then reduced to 0.25 microg kg(-1) min(-1). The total remifentanil doses were similar in the 3 groups. Measures: patients used patient-controlled analgesia (piritramide) for postoperative pain management. They recorded pain on a numeric rating scale every half hour. Statistics: Kruskal-Wallis test, pairwise Mann-Withney U-test, orthogonal polynomials (pain scores). RESULTS: Patients given postincisional remifentanil (RL) had the slowest decrease in postoperative pain scores (p<0.01) and the highest cumulative piritramide consumption (p<0.08). CONCLUSION: The preincisional administration of remifentanil followed by a continuous infusion of 0.25 microg kg(-1) min(-1) appears to reduce pain scores and piritramid consumption when compared with a postincisional regimen.     

Determination of the pharmacodynamic interaction of propofol and remifentanil during esophagogastroduodenoscopy in children

BACKGROUND: Propofol is commonly used to anesthetize children undergoing esophagogastroduodenoscopy. Opioids are often used in combination with propofol to provide total intravenous anesthesia. Because both propofol and remifentanil are associated with rapid onset and offset, the combination of these two drugs may be particularly useful for procedures of short duration, including esophagogastroduodenoscopy. The authors previously demonstrated that the median effective concentration (C50) of propofol during esophagogastroduodenoscopy in children is 3.55 microg/ml. The purpose of this study was to describe the pharmacodynamic interaction of remifentanil and propofol when used in combination for esophagogastroduodenoscopy in pediatric patients. METHODS: The authors studied 32 children aged between 3 and 10 yr who were scheduled to undergo esophagogastroduodenoscopy. Propofol was administered via a target-controlled infusion system using the STANPUMP software based on a pediatric pharmacokinetic model. Remifentanil was administered as a constant rate infusion of 25, 50, and 100 ng.kg(-1).min(-1) to each of three study groups, respectively. A sigmoid Emax model was developed to describe the interaction of remifentanil and propofol. RESULTS: There was a positive interaction between remifentanil and propofol when used in combination. The concentration of propofol alone associated with 50% probability of no response was 3.7 microg/ml (SE, 0.4 microg/ml), and this was decreased to 2.8 microg/ml (SE, 0.1 microg/ml) when used in combination with remifentanil. CONCLUSION: A remifentanil infusion of 25 ng.kg(-1).min(-1) reduces the concentration of propofol required for adequate anesthesia for esophagogastroduodenoscopy from 3.7 to 2.8 microg/ml. Increasing the remifentanil infusion yields minimal additional decrease in propofol concentration and may increase the risk of side effects.     

丙泊酚复合瑞芬太尼靶控输注在腹腔镜胆囊切除术中的应用

目的:观察丙泊酚复合瑞芬太尼靶控输注全凭静脉麻醉对腹腔镜胆囊切除术血流动力学及术后苏醒时间的影响。方法:50例择期行腹腔镜胆囊切除术的患者均采用丙泊酚复合瑞芬太尼靶控输注全凭静脉麻醉。设定诱导时静注咪达唑仑2mg,先血浆靶控输注瑞芬太尼4ng/ml,1min后血浆靶控输注丙泊酚3μg/ml或3.5μg/ml,患者意识消失后静注维库溴铵0.1mg/kg,3min后气管内插管,插管后丙泊酚靶浓度调至2μg/ml,术中维持根据需要调整丙泊酚靶浓度,以0.2μg/ml递增或递减,瑞芬太尼维持不变。记录诱导前、诱导后2min、插管即刻、插管后5min、气腹时、气腹后5min的收缩压(systolic bloodpressure,SBP)、舒张压(diastolic blood pressure,DBP)、心率(heart rate,HR)及术后呼吸恢复时间、呼之睁眼时间。结果:诱导后2min的SBP、DBP、HR与诱导前差异均有统计学意义(P0.05),气腹时SBP、DBP、HR有所升高,但差异无统计学意义,其他时点经适当调整丙泊酚靶浓度处理后逐渐平稳,术后呼吸恢复时间为(6.5±2.2)min,呼之睁眼时间(8.9±3.1)min。结论:丙泊酚复合瑞芬太尼靶控输注用于腹腔镜胆囊切除术安全,术中血流动力学平稳,术后苏醒快。     

Total intravenous anesthesia with remifentanil, propofol and cisatracurium in end-stage renal failure

PURPOSE: To compare recovery parameters of total intravenous anesthesia (TIVA) with remifentanil and propofol, hemodynamic responses to perioperative events, and pharmacodynamic parameters of cisatracurium in 22 end-stage renal failure and 22 normal renal function patients. METHODS: Anesthesia was induced with 2-3 mg x kg(-1) propofol and 1 microg x kg(-1) remifentanil and maintained with 75 microg x kg(-1) x min(-1) propofol and propofol initial infusion of 0.2 microg x kg(-1) x min(-1) propofol. Arterial pressure and heart rate were maintained by remifentanil infusion rate adjustments. The first twitch (T1) was maintained at 25% by an infusion of cisatracurium. RESULTS: There was no difference in the time to maintenance of adequate respiration, date of birth recollection, first analgesic administration, between the renal failure (4.8+/-2.5, 7.8+/-3.2, 12.3+/-5.3 min respectively) and the control group (5.2+/-2.8, 8.1+/-3.1, 12.7+/-5.5 min): nor were there any differences in the time to 25% T1 recovery, T1 recovery from 25% to 75%, or cisatracurium infusion rate between the renal failure group (32.1 +/-10.8 min, 18.2+/-5.5 min, 0.89+/-0.29 microg x kg(-1) min(-1) respectively) and the control group (35.9 (7.9 min, 18.4+/-3.8 min, 0.95+/-0.22 microg x kg(-1) x min(-1)). CONCLUSION: End-stage renal failure does not prolong recovery from TIVA with remifentanil and propofol, or the recovery from cisatracurium neuromuscular block.