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At least 19 recordsLinked to original sources

PubMed2001

A comparison of patient-controlled sedation using either remifentanil or remifentanil-propofol for shock wave lithotripsy.

UNLABELLED: Patient-controlled sedation (PCS) has been used for extracorporeal shock wave lithotripsy (SWL) because it allows for rapid individualized titration of anesthetics. Because of its sedating effects, the addition of propofol to remifentanil may improve patient tolerance of SWL with PCS. One hundred twenty patients were randomly assigned to receive remifentanil 10 microg or remifentanil 10 microg plus propofol 5 mg for PCS with zero-lockout interval. Nine patients in the Remifentanil group and three patients in the Remifentanil-Propofol group required additional sedatives to complete their SWL (P = 0.128). Compared with the Remifentanil group, the Remifentanil-Propofol group required less remifentanil, had a decreased incidence of postoperative nausea and vomiting, and had a better overall satisfaction level. However, they had an increased incidence of transient apnea and oxygen desaturation. The incidence of apnea was 15% in the Remifentanil group and 52% in the Remifentanil-Propofol group (P < 0.001). All patients were able to move themselves to the stretcher at the end of SWL, and median time to home discharge was <70 min in both groups. Both remifentanil and remifentanil-propofol were useful for PCS during SWL. IMPLICATIONS: The addition of propofol to remifentanil improves patient satisfaction and decreases postoperative nausea and vomiting. However, it causes more respiratory depression than remifentanil alone. When remifentanil-propofol is used with patient-controlled sedation, appropriate monitoring and a minimum 1-2 min lockout interval is required.

Adolescent↗

PubMed1997

A comparison of remifentanil and morphine sulfate for acute postoperative analgesia after total intravenous anesthesia with remifentanil and propofol.

BACKGROUND: The transition from remifentanil intraoperative anesthesia to postoperative analgesia must be planned carefully due to the short duration of action (3-10 min) of remifentanil hydrochloride, a potent, esterase-metabolized mu-opioid agonist. This study compared the efficacy and safety of transition regimens using remifentanil or morphine sulfate for immediate postoperative pain relief in patients who had surgery under general anesthesia with remifentanil/propofol. METHODS: One hundred fifty patients who had received open-label remifentanil and propofol for intraoperative anesthesia participated in this multicenter, double-blind, double-dummy study and were randomly assigned to either the remifentanil (R) group or the morphine sulfate (M) group. Twenty minutes before the anticipated end of surgery, the propofol infusion was decreased by 50%, and patients received either a placebo bolus (R group) or a bolus of 0.15 mg/kg morphine (M group). At the end of surgery, the propofol and remifentanil maintenance infusions were discontinued and the analgesic infusion was started: either 0.1 microg x kg(-1) x min(-1) remifentanil (R group) or placebo analgesic infusion (M group). During the 25 min after tracheal extubation, remifentanil titrations in increments of 0.025 microg x kg(-1) x min(-1) and placebo boluses (R group), or 2 mg intravenous morphine boluses and placebo rate increases (M group) were administered as necessary at 5-min intervals to control pain. Patients received the 0.075 mg/kg intravenous morphine bolus (R group) or placebo (M group) at 25 and 30 min after extubation, and the analgesic infusion was discontinued at 35 min. From 35 to 65 minutes after extubation, both groups received 2-6 mg open-label morphine analgesia every 5 min as needed. RESULTS: Successful analgesia, defined as no or mild pain with adequate respiration (respiratory rate [RR] > or =8 breaths/min and pulse oximetry > or = 90%), was achieved in more patients in the R group than in the M group (58% vs. 33%, respectively) at 25 min after extubation (P < 0.05). The median remifentanil rate for successful analgesia was 0.125 microg x kg(-1) x min(-1) (range, 0.05-0.23 microg x kg(-1) x min(-1)), and the median number of 2-mg morphine boluses used was 2 (range, 0-5 boluses). At 35 min after extubation, > or = 74% of patients in both groups experienced moderate to severe pain. Median recovery times from the end of surgery were similar between groups. Transient respiratory depression, apnea, or both were the most frequent adverse events (14% for the R group vs. 6% for the M group; P > 0.05). CONCLUSIONS: Remifentanil provided safe and effective postoperative analgesia when administered at a final rate of 0.05-0.23 microg x kg(-1) x min(-1) in the immediate postextubation period. Remifentanil provided more effective postoperative analgesia than did intraoperative treatment with morphine (0.15 mg/kg) followed by morphine boluses (< or = five 2-mg boluses). The effects of remifentanil dissipated rapidly after ending the infusion, and alternate analgesia was required. Further studies are underway to define transition regimens that will improve postoperative analgesia in patients receiving anesthesia with remifentanil.

Adult↗

PubMed2003

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

UNLABELLED: 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.

Adrenergic beta-Antagonists↗

PubMed2006

Fast-track anaesthesia for laparoscopic cholecystectomy: a prospective, randomized, multicentre, blind comparison of desflurane-remifentanil or sevoflurane-remifentanil.

BACKGROUND AND OBJECTIVE: To evaluate the effects of sevoflurane and desflurane in combination with intravenous remifentanil on time for discharge from the postanaesthesia care unit and need for postanaesthesia care unit management after elective laparoscopic cholecystectomy. METHODS: 231 ASA Grade I-II patients, undergoing elective laparoscopic cholecystectomy in seven University teaching hospital, were randomly allocated to receive a desflurane-remifentanil (n = 105) or sevoflurane-remifentanil (n = 126) anaesthetic. A blinded observer recorded times for emergence and postanaesthesia care unit discharge (achievement of an Aldrete score > or =9), number of patients eligible for postanaesthesia care unit discharge when exiting the operating room and occurrence of adverse events. RESULTS: Intraoperative cardiovascular stability was similar in the two groups. Emergence, response and extubation occurred earlier after desflurane (5.4 +/- 3 min, 5.5 +/- 3 min and 7.5 +/- 4 min) than sevoflurane (6.6 +/- 3.5 min, 7.2 +/- 4 min and 9.1 +/- 4.2 min) (P = 0.0005, 0.05 and 0.003, respectively). Postanaesthesia care unit bypass was possible in 44 desflurane-remifentanil patients (41%) and 55 sevoflurane- remifenatnil patients (43%) (P = 0.69), while postanaesthesia care unit discharge occurred after 46 min (25th-75th percentiles: 18-40 min) with desflurane and 64 min (25th-75th percentiles: 20-50 min) with sevoflurane (P = 0.04). Postoperative nausea and vomiting was observed in 40 desflurane-remifentanil patients (36%) and 53 sevoflurane-remifentanil patients (42%) (P = 0.42). CONCLUSIONS: Both the desflurane-remifentanil and sevoflurane-remifentanil combinations provide a similarly adequate intraoperative cardiovascular stability. Emergence and postanaesthesia care unit discharge were faster with desflurane-remifentanil than sevoflurane-remifentanil, but this was not associated with a larger proportion of postanaesthesia care unit bypass, confirming that no clinically relevant differences are present between the two agents.

Anesthesia Recovery Period↗

PubMed2003

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.

Adult↗

PubMed1998

Remifentanil versus propofol as adjuncts to regional anesthesia. Remifentanil 3010 Study Group.

STUDY OBJECTIVE: To compare the safety and efficacy of remifentanil and propofol as adjuncts to regional anesthesia in patients undergoing orthopedic or urogenital surgery. DESIGN: Prospective, randomized study. SETTING: Multicenter university hospitals. PATIENTS: 107 ASA physical status I, II, and III adult patients who underwent orthopedic or urogenital surgery with axillary, ankle, or spinal block. INTERVENTIONS: Patients were randomized to receive either an infusion of remifentanil 0.2 microg/kg/min or propofol 100 microg/kg/min 5 minutes before nerve block placement. The infusions were decreased by 50% on block completion, increased by 50% for patient discomfort, and decreased by 50% for hypoventilation (< 8 breaths/min) or hemodynamic instability. MEASUREMENTS AND MAIN RESULTS: Pain, discomfort, anxiety, and sedation were assessed by both patient and investigator. Vital signs and adverse events were recorded. Fewer patients in the remifentanil group experienced pain during block placement (6%), and were oversedated (7%) than patients in the propofol group (23% and 26%, respectively; p < 0.05). Hypoventilation during and after block placement (21% and 25%, respectively) and nausea and vomiting during and after block placement (60% and 21%, respectively) were more common in the remifentanil group than in the propofol group (0% and 3%; 17% and 6%, respectively; p < 0.05). The incidence of hypoventilation in remifentanil-treated patients was higher in patients over 65 years of age (p < 0.05), but was transient, resolving within minutes of discontinuing the infusion. CONCLUSIONS: At the doses studied, remifentanil was more effective than propofol in minimizing pain without producing excessive sedation. Remifentanil was associated with more transient respiratory depression and short-term nausea. Our findings indicate that the initial remifentanil rate should be 0.1 microg/kg/min (50% lower than the study's initial rate) and should be further decreased an additional 50% in the elderly to minimize adverse effects.

Adult↗

PubMed2004

Pharmacokinetics of remifentanil and its major metabolite, remifentanil acid, in ICU patients with renal impairment.

BACKGROUND: The pharmacokinetics of remifentanil, an opioid analgesic metabolized by non-specific esterases, and its principal metabolite, remifentanil acid (RA), which is excreted via the kidneys, were assessed as part of an open-label safety study in intensive care unit (ICU) patients with varying degrees of renal impairment. METHODS: Forty adult ICU patients with normal/mildly impaired renal function (creatinine clearance [CL(cr)] 62.9 (sd) 14.5 ml min(-1); n=10) or moderate/severe renal impairment (CL(cr) 14.7 (15.7) ml min(-1); n=30) were included. Remifentanil was infused for up to 72 h, at a starting rate of 6-9 microg kg(-1) h(-1) titrated to achieve a target sedation level, with additional propofol (0.5 mg kg(-1) h(-1)) if required. Intensive arterial sampling was performed for up to 72 h after infusion. Pharmacokinetic parameters obtained by simultaneous modelling of remifentanil and RA data were statistically compared between the two groups. RESULTS: Remifentanil pharmacokinetics were not significantly affected by renal status. RA clearance in the moderate/severe group was reduced to about 25% that of the normal/mild group (41 (29) vs 176 (49) ml kg(-1) h(-1), P<0.0001). Metabolic ratio, a predictor of the ratio of RA to remifentanil concentrations at steady state, was approximately eight-fold higher in the moderate/severe group relative to the normal/mild group (116 (110) vs 15 (4), P<0.0001). Maximum RA levels approached 700 ng ml(-1) in the moderate/severe group. CONCLUSIONS: Although RA accumulates in patients with moderate/severe renal impairment, pharmacokinetic modelling predicts that RA concentrations during a 9 microg kg(-1) h(-1) remifentanil infusion for up to 15 days would not exceed those reported in the present study, for which no associated prolongation of mu-opioid effects was observed.

Adolescent↗

PubMed2001

[Propofol-remifentanil versus sevoflurane-remifentanil for anesthesia for pediatric procedures in infants, children and adolescents].

INTRODUCTION: The aim of this study was to compare total intravenous anaesthesia (TIVA) using propofol and remifentanil (P/R-group) and balanced anaesthesia (BA) using sevoflurane and remifentanil (S/R-group) for paediatric surgery. PATIENTS AND METHODS: A total of 120 patients aged 6 months to 16 years scheduled for elective minor lower abdominal surgery were randomly assigned to receive either propofol (5-10 mg/kg/h) and remifentanil (0.125-1.0 microgram/kg/min) or sevoflurane (1.0-1.5 MAC) and remifentanil (0.125-1.0 microgram/kg/min). Perioperative haemodynamics as well as recovery and discharge times, PONV and side-effects were studied. The patients vigilance, comfort and pain intensity were assessed postoperatively using the objective pain discomfort scale, the Steward post-anaesthetic recovery score and a visual analogue scale. RESULTS: Postoperative recovery (9.0 vs 11.6 min) and extubation times (11.8 vs. 15.0 min) as well as the time taken until a Steward post-anaesthetic recovery score > 3/4 (15.2 vs. 21.4 min) was reached were significantly shorter in the P/R-group. However, the length of time until discharge to the ward, postoperative comfort, pain intensity and analgesic requirements as well as PONV were comparable in both groups. CONCLUSIONS: With regards to the investigated parameters, TIVA with propofol and remifentanil is equally effective as BA with sevoflurane and remifentanil in paediatric patients. However, considering the selected dosing regimen, recovery times were significantly shorter for children after TIVA.

Abdomen↗

PubMed2005

Sevoflurane-remifentanil vs isoflurane-remifentanil for the surgical correction of craniosynostosis in infants.

BACKGROUND: The aim of the present study was to compare the efficacy of isoflurane-remifentanil and sevoflurane-remifentanil combinations during neurosurgical correction craniosynostosis. METHODS: Twenty-two infants with craniosynostosis received a slow bolus of remifentanil followed by continuous infusion. The infants were randomly divided into two groups: remifentanil followed by sevoflurane (the 'sevoflurane group'), and remifentanil followed by isoflurane (the 'isoflurane group'). We monitored electrocardiogram (ECG), heart rate (HR), invasive arterial blood pressure (IABP), pulse oximetry saturation (SpO(2)), endtidal CO(2) (P(ECO(2))), inspired fraction of oxygen (FiO(2)) and endtidal volatile agent (PE volatile agent) at 12 time points, from the beginning of surgery (T0) until the cessation of drugs (T11). The volatile agent was stopped prior to skin suture and the remifentanil infusion after skin closure. Subsequently, we evaluated recovery time of spontaneous breathing and spontaneous eye opening and time of extubation at 5, 10, and 15 min after extubation, the Steward Recovery Score (SRS) was assessed. Patients were then transferred to the Pediatric Intensive Care Unit (PICU). RESULTS: During the surgical procedure the hemodynamic parameters between the two groups did not show statistically significant differences. There were also no significant differences in terms of awakening time or SRS. CONCLUSIONS: The rapid recovery of the children (confirmed by their high values of SRS) makes it possible to reliably assess the patient's neurological condition immediately after surgery.

Anesthesia Recovery Period↗

PubMed2004

[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.

Aged↗

PubMed2000

Comparison of remifentanil versus regional anaesthesia in children anaesthetised with isoflurane/nitrous oxide. International Remifentanil Paediatric Anaesthesia Study group.

We compared the efficacy and safety of a remifentanil (0.25 microg x kg(-1) x min(-1)-based balanced anaesthetic technique with a bupivacaine-based regional anaesthetic technique in an open label, multicentre study in 271 ASA physical status 1 or 2 children aged 1-12 years. Subjects requiring major intra-abdominal, urological or orthopaedic surgery were randomly allocated to receive either intravenous remifentanil (group R; n = 185) or epidural bupivacaine (group B; n = 86) with isoflurane/nitrous oxide for their anaesthesia. The majority of children in both groups (85% in group R, 78% in group B) showed no defined response to skin incision, and although the mean increase in systolic blood pressure (+11 mm Hg) was significantly greater in group R than in group B, this change did not represent a serious haemodynamic disturbance. More children in group R (31%) required interventions to treat hypotension and/or bradycardia than those in group B (12%), but these were easily managed by administration of fluids or anticholinergic drugs. Adverse events, mainly nausea and/or vomiting, occurred in 45% of group R and 42% of group B (NS). The adverse event profile of remifentanil in this study was typical of a potent mu-opioid receptor agonist. Remifentanil was as effective as epidural or caudal block in providing analgesia and suppressing physiological responses to surgical stimuli in children aged between 1 and 12 years undergoing major abdominal, urological, or orthopaedic surgery under isoflurane/nitrous oxide anaesthesia.

Analgesia, Epidural↗

PubMed2006

Sevoflurane-remifentanil versus propofol-remifentanil anesthesia at a similar bispectral level for off-pump coronary artery surgery: no evidence of reduced myocardial ischemia.

OBJECTIVE: Sevoflurane could decrease myocardial ischemic injury in patients undergoing off-pump coronary artery bypass surgery. This study was designed to compare postoperative troponin I (cTnI) concentrations after sevoflurane-remifentanil versus propofol-remifentanil anesthesia. DESIGN: Prospective, randomized single-blind clinical study. SETTING: University hospital. PARTICIPANTS: Eighteen patients. INTERVENTIONS: General anesthesia was conducted with sevoflurane-remifentanil (n = 9) or propofol-remifentanil (n = 9). Administration of sevoflurane and propofol was adjusted to maintain the bispectral index (BIS) between 40 and 60. MEASUREMENTS AND MAIN RESULTS: Groups were comparable regarding the patients' characteristics. The objective of BIS was maintained in both groups except during the period of coronary artery grafts (p < 0.001) when the BIS number in the propofol group fell below 40 and was significantly lower than in the sevoflurane group. Intraoperative hemodynamic variables were similar between groups. No patient required cardiopulmonary bypass. Need for inotropic and vasoactive support during the first graft was not necessary in the propofol group and occurred in 4 patients in the sevoflurane group (not significant). During the second graft, 2 patients in the propofol group and 3 in the sevoflurane group needed hemodynamic support. Postoperative hemodynamic variables were comparable between groups. Areas under the curve of postoperative increases in cTnI were 27.0 +/- 38.6 and 17.4 +/- 14.6 ng/mL/hour in the sevoflurane and propofol groups, respectively (not significant). CONCLUSION: This study does not support cardioprotective effects of sevoflurane. The particularly short total cumulative duration of ischemia and the relatively low administered end-tidal sevoflurane concentrations may explain this result.

Anesthesia, General↗

PubMed1998

An open, randomized comparison of alfentanil, remifentanil and alfentanil followed by remifentanil in anaesthesia for craniotomy.

We studied 52 adults undergoing elective craniotomy, allocated randomly to one of three opioid treatments: alfentanil 50 micrograms kg-1 followed by 0.833 microgram kg-1 min-1 until dural closure (group Alf.); alfentanil 50 micrograms kg-1 followed by 0.833 microgram kg-1 min-1 for 2 h, then remifentanil 0.25 microgram kg-1 min-1 (group Alf.-Remi.); or remifentanil 1 microgram kg-1 followed by 0.5 microgram kg-1 min-1 reducing to 0.25 microgram kg-1 min-1 after craniotomy (group Remi.). Anaesthesia was maintained with infusion of propofol and 66% nitrous oxide in oxygen. Infusions of propofol and remifentanil were stopped at head bandaging. Group Remi. had the least intraoperative haemodynamic responses and group Alf. the most (P < 0.05). Times to tracheal extubation and obey commands were similar in all groups. In all patients in group Alf.-Remi. and group Remi., the trachea was extubated 27 min from the end of anaesthesia; three patients in group Alf. were slower to recover. Use of analgesia in the recovery room and time to transfer to the neurosurgical unit were similar in the three groups.

Adult↗

PubMed2000

Postoperative pain management and recovery after remifentanil-based anaesthesia with isoflurane or propofol for major abdominal surgery. Remifentanil Study Group.

We have assessed if recovery times after morphine or fentanyl, given before terminating remifentanil anaesthesia with isoflurane or propofol, are compromised. We studied patients undergoing elective, major abdominal surgery, allocated randomly to receive remifentanil and isoflurane (n = 277) or remifentanil and propofol (n = 274) anaesthesia. Twenty-five minutes before the end of surgery, patients received fentanyl 0.15 mg or morphine 15 mg in a randomized, double-blind manner followed by a second dose (fentanyl 0.05 mg, morphine 7 mg) for moderate or severe pain in recovery. Recovery was rapid and at an Aldrete score > or = 9 (median 12-15 min), 42-51% of patients reported none or mild pain. However, 26-35% of patients reported severe pain and > 90% required a second dose of opioid within 21-27 min after anaesthesia.

Abdomen↗

PubMed2006

Bronchial mucus transport velocity in patients receiving propofol and remifentanil versus sevoflurane and remifentanil anesthesia.

Volatile anesthetics reduce ciliary beat frequency in vitro. It has been reported that impaired bronchial mucus transport velocity (BTV) is associated with significantly increased pulmonary complications. In this study, we sought to determine in vivo differences in BTV, comparing patients having total IV anesthesia (TIVA) with propofol and remifentanil to anesthesia with sevoflurane and remifentanil. Twenty-two patients scheduled for elective general surgery were randomized to one of two groups: TIVA (propofol/remifentanil) or SEVO (sevoflurane/remifentanil). Thirty minutes after tracheal intubation, BTV was assessed by fiberoptic observation of the movement of methylene blue dye applied to the dorsal surface of the right main bronchus. BTV was significantly reduced in the SEVO group compared with the TIVA group (mean, 1.5 +/- 0.7 [0-2.3] versus 4.8 +/- 2.1 [2.3-8.8] mm/min; P < 0.0001). Anesthesia with sevoflurane may lead to significantly impaired bronchociliary clearance in comparison to TIVA. This could have implications for perioperative pulmonary complications, in particular in patients at risk for pulmonary complications.

Adolescent↗

PubMed1997

Remifentanil versus remifentanil/midazolam for ambulatory surgery during monitored anesthesia care.

BACKGROUND: This study was designed to define the appropriate dose of remifentanil hydrochloride alone or combined with midazolam to provide satisfactory comfort and maintain adequate respiration for a monitored anesthesia care setting. METHODS: One hundred fifty-nine patients scheduled for outpatient surgery participated in this multicenter, double-blind study. Patients were randomly assigned to one of two groups: remifentanil, 1 microgram/kg, given over 30 s followed by a continuous infusion of 0.1 microgram.kg-1.min-1 (remifentanil), remifentanil, 0.5 microgram/kg, given over 30 s followed by a continuous infusion of 0.05 microgram.kg-1.min-1 (remifentanil+midazolam). Five minutes after the start of the infusion, patients received a loading dose of saline placebo (remifentanil) or midazolam, 1 mg, (remifentanil+midazolam). If patients were not oversedated, a second dose of placebo or midazolam, 1 mg, was given. Remifentanil was titrated (in increments of 50% from the initial rate) to limit patient discomfort or pain intraoperatively, and the infusion was terminated at the completion of skin closure. RESULTS: At the time of the local anesthetic, most patients in the remifentanil and remifentanil+midazolam groups experienced no pain (66% and 60%, respectively) and no discomfort (66% and 65%, respectively). The final mean (+/-SD) remifentanil infusion rates were 0.12 +/- 0.05 microgram.kg-1.min-1 (remifentanil) and 0.07 +/- 0.03 microgram.kg-1.min-1 (remifentanil+midazolam). Fewer patients in the remifentanil+midazolam group experienced nauses compared with the remifentanil group (16% vs. 36%, respectively; P < 0.05). Four patients (5%) in the remifentanil group and two patients (2%) in the remifentanil+midazolam group experienced brief periods of oxygen desaturation (SpO2 < 90%) and hypoventilation (< 8 breaths/ min). CONCLUSIONS: Remifentanil alone or combined with midazolam provided adequate analgesia and maintained adequate respiration at the doses reported. The low dose of remifentanil combined with 2 mg midazolam, compared with remifentanil alone, resulted in fewer side effects, slightly greater sedation, and less anxiety.

Adult↗

PubMed1993

Pharmacokinetics of remifentanil (GI87084B) and its major metabolite (GI90291) in patients undergoing elective inpatient surgery.

BACKGROUND: Remifentanil is a highly potent opioid with a rapid onset and a short duration of action due to its rapid hydrolysis by esterases in blood and tissues. The major metabolite of remifentanil, GI90291, is much less potent than remifentanil. METHODS: The pharmacokinetics of remifentanil and its major metabolite, GI90291, were determined in 24 patients undergoing elective inpatient surgery. Remifentanil was administered as a 1-min infusion (2, 5, 15, and 30 micrograms/kg) after the induction of anesthesia and tracheal intubation. Serial arterial blood samples were collected over 6 h and assayed for remifentanil and GI90291. RESULTS: The pharmacokinetics of remifentanil were described using a three-compartment model. Total clearance (250-300 l/h) of remifentanil was independent of dose and was approximately three to four times greater than the normal hepatic blood flow. Volume of distribution at steady state (25-40 l) also was independent of dose. The terminal half-life of remifentanil ranged from 10 to 21 min. Covariate analysis of remifentanil clearance and patient demographics showed that patient body weight, age, and gender did not influence total clearance. This suggests that remifentanil may not need to be dosed according to body weight in adult patients. A simulation was conducted to determine the time required for a 50% reduction in effect site concentration after an infusion designed to maintain a constant effect site concentration. The time required for a 50% reduction in the effect site concentration of remifentanil (3.65 min) was considerably less than that for sufentanil (33.9 min), alfentanil (58.5 min), and fentanyl (262 min). The pharmacokinetics of the major metabolite, GI90291, were independent of the dose of remifentanil. The mean terminal half-life of GI90291 ranged from 88 to 137 min. CONCLUSIONS: The pharmacokinetics of remifentanil are consistent with its rapid elimination by blood and tissue esterases; its major metabolite is eliminated more slowly but is not likely to make any significant contribution to the total effect because of its much lower potency. The rapid onset and short duration of action of remifentanil make it well suited for titration of dose (infusion rate) to the desired degree of effect.

Adolescent↗

PubMed1998

[Characterization of dose profile of remifentanil with computer simulation: comparative study with fentanyl and alfentanyl].

OBJECTIVES: To estimate the optimum dosing regimen and delivery system for remifentanil, a new opioid, using computer simulations based on information from pharmacokinetic and pharmacodynamic models available for fentanyl, alfentanil and remifentanil, as well as from clinical trials of fentanyl and alfentanil. PATIENTS AND METHODS: We estimated the site concentration ranges likely to be needed to blunt response to anesthetic or surgical stimuli and to recover from spontaneous ventilation. Dosing guidelines for remifentanil, fentanyl and alfentanil were estimated for three methods of administration (bolus, bolus + variable continuous infusion or constant continuous infusion). To that end, the time course of opioid concentration was simulated for hypothetical balanced anesthesia lasting 60 min. We then studied the number of boluses, the number of infusion rate steps, time taken to reach the terapeutic threshold, and time from turning off the infusion until reaching a concentration compatible with spontaneous ventilation. RESULTS: The estimated "effect site" concentration ranges for remifentanil were 6 to 10 ng.ml-1 during intubation; 4 to 6 ng.ml-1 during cutaneous incision; 4 to 7 ng.ml-1 for maintenance; and less than 2.5 ng.ml-1 for recovery of spontaneous ventilation. Simulated bolus administration indicated that 21 boluses of remifentanil, 4 boluses of fentanyl and 7 boluses of alfentanil were needed during one hour. The therapeutic threshold was reached within the first minute with remifentanil, within 2 minutes with fentanyl and within 1 min with alfentanil. Time until recovery of spontaneous ventilation was 7 min with remifentanil, 22 min with fentanyl and 14 min with alfentanil. In the simulation of bolus plus variable infusion, the initial bolus of remifentanil was 100 micrograms, the infusion rate for induction and maintenance was 25 micrograms.min-1 and the maintenance rate was 15 micrograms.min-1. The initial bolus of fentanyl was 300 micrograms, the infusion rate for induction and maintenance was 5 micrograms.min-1. The initial bolus of alfentanil was 2,000 micrograms, the infusion rate for induction was 200 micrograms.min-1 and the maintenance rates were 75 and 25 micrograms.min-1. The therapeutic threshold was reached in 1 min with remifentanil, in 2 min with fentanyl and within 1 min with alfentanil. Spontaneous ventilation was recovered 4 min after turning off the infusion of remifentanil, 4 min afterwards with fentanyl and 6 min afterwards with alfentanil. The simulated constant infusion rate for remifentanil of 15 micrograms.min1 (8 micrograms.min-1 for fentanyl and 75 micrograms.min-1 for alfentanil) allowed the therapeutic threshold to be reached in 10 min with remifentanil, in 22 min with fentanyl and in 17 min with alfentanil. Recovery of spontaneous ventilation occurred 5 min after closure of the infusion pump with remifentanil (24 min with fentanyl and 17 min with alfentanil). CONCLUSIONS: Information from pharmacokinetic and pharmacodynamic models allows us to establish the effect site concentration ranges for remifentanil and determine the ideal administration technique for this drug. The simulation also allows us to compare the properties of remifentanil to those of other common opioids such as fentanyl and alfentanil. The results are fairly consistent with clinical evidence, demonstrating the power of pharmacokinetic and pharmacodynamic models for rationally establishing opioid dosing guidelines.

Adult↗