A comparison of remifentanil and fentanyl in patients undergoing carotid endarterectomy

BACKGROUND AND AIM: We investigated the haemodynamic stability and emergence characteristics of isoflurane/nitrous oxide anaesthesia supplemented with remifentanil or fentanyl in patients undergoing carotid endarterectomy. METHODS: Anaesthesia was induced with propofol (1-2 mg kg-1) and either remifentanil (0.5 microgram kg-1) or fentanyl (1 microgram kg-1), followed by an infusion of remifentanil (0.2 microgram kg-1 min-1) or fentanyl (2 micrograms kg-1 h-1). RESULTS: There were no significant differences between the groups in haemodynamic variables, postoperative pain, nausea or vomiting. After induction there was a significant decrease in mean arterial pressure for both groups (P < 0.001) and a decrease in heart rate (P = 0.001) in the remifentanil group. In both groups these haemodynamic changes continued during maintenance of anaesthesia (P < 0.05). The time to eye opening after surgery was significantly shorter with remifentanil compared with fentanyl (6.62 +/- 3.89 vs. 18.0 +/- 15.18 min, P = 0.015). CONCLUSION: Remifentanil appears to be a comparable opioid to fentanyl when supplementing isoflurane/nitrous oxide anaesthesia for carotid endarterectomy.     

老年患者长时间输注不同剂量瑞芬太尼诱发术后急性阿片耐受的研究

目的 探讨行胰十二指肠切除术老年患者术中.长时间持续输注不同剂量瑞芬太尼,能否诱发术后急性阿片耐受.方法 选择老年患者ASA Ⅰ～Ⅲ级胰十二指肠切除术患者30例,随机分为高剂量组(H组,n=15)和低剂量组(L组,n=15).H组和L组,术中分别持续输注瑞芬太尼0.3μg·kg-1·min-1和0.1μg·kg-1·min-1.术中均持续输注维库溴铵2μg·kg-1·min-1和吸人七氟醚维持麻醉.心率或平均动脉压超过或低于其基础值的20%,则将七氟醚上调或下调1%.记录术后麻醉恢复室芬太尼用量、术后24 h的芬太尼累积用量、术后芬太尼总用量(麻醉恢复室用量和术后24 h的芬太尼累积用量),用视觉模拟评分法(VAS)和PCA有效按压次数与总按压次数之比(Ⅰ/A)评价疼痛强度.对以上指标术后最初4 h.之后每4 h采集数据一次,共采集24 h.结果 与L组比较,H组术后麻醉恢复室芬太尼用量、术后24 h的芬太尼累积用量、术后芬太尼总量的需求显著升高(P<0.01);H组PCA有效按压次数与总按压次数之比明显低于L组(P<0.01);H组与L组术后芬太尼总量相差大于30%(H组较L组高出约1.6倍);两组患者VAS差异无统计学意义(P>0.05).结论 老年患者行胰十二指肠切除术时持续输注高剂量瑞芬太尼可诱发术后急性阿片耐受.     

Remifentanil-induced Postoperative Hyperalgesia and Its Prevention with Small-dose Ketamine

Background: Remifentanil-induced secondary hyperalgesia has been documented experimentally in both animals and healthy human volunteers, but never clinically. This study tested the hypotheses that increased pain sensitivity assessed by periincisional allodynia and hyperalgesia can occur after relatively large-dose intraoperative remifentanil and that small-dose ketamine prevents this hyperalgesia.

Methods: Seventy-five patients undergoing major abdominal surgery were randomly assigned to receive (1) intraoperative remifentanil at 0.05 [mu]g [middle dot]kg-1 [middle dot]min-1 (small-dose remifentanil); (2) intraoperative remifentanil at 0.40 [mu]g [middle dot]kg-1 [middle dot]min-1 (large-dose remifentanil); or (3) intraoperative remifentanil at 0.40 [mu]g [middle dot]kg-1 [middle dot]min-1 and 0.5 mg/kg ketamine just after the induction, followed by an intraoperative infusion of 5 [mu]g [middle dot] kg-1 [middle dot] min-1 until skin closure and then 2 [mu]g [middle dot]kg-1 [middle dot]min-1 for 48 h (large-dose remifentanil-ketamine). Pain scores and morphine consumption were recorded for 48 postoperative hours. Quantitative sensory tests, peak expiratory flow measures, and cognitive tests were performed at 24 and 48 h.

Results: Hyperalgesia to von Frey hair stimulation adjacent to the surgical wound and morphine requirements were larger (P < 0.05) and allodynia to von Frey hair stimulation was greater (P < 0.01) in the large-dose remifentanil group compared with the other two groups, which were comparable. There were no significant differences in pain, pressure pain detection threshold with an algometer, peak flow, cognitive tests, or side effects.     

Cerebral Blood Flow and CO2 Reactivity Is Similar during Remifentanil/N2 O and Fentanyl/N2 O Anesthesia

Background: Remifentanil, a rapidly metabolized [micro sign]-opioid agonist, may offer advantages for neurosurgical procedures in which prolonged anesthetic effects can delay assessment of the patient. This study compared the effects of remifentanil-nitrous oxide on cerebral blood flow (CBF) and carbon dioxide reactivity with those of fentanyl-nitrous oxide anesthesia during craniotomy.

Methods: After institutional approval and informed patient consent were obtained, 23 patients scheduled to undergo supratentorial tumor surgery were randomly assigned to remifentanil or fentanyl infusion groups in a double-blinded manner. Midazolam, thiopental, and pancuronium induction was followed by equipotent narcotic loading infusions of remifentanil (1 [micro sign]g [middle dot] kg-1 [middle dot] min-1) or fentanyl (2 [micro sign]g [middle dot] kg-1 [middle dot] min-1) for 5-10 min. Patients were ventilated with 2:1 nitrous oxide-oxygen, and opioid rates were reduced and then titrated to a stable hemodynamic effect. After dural exposure, CBF was measured by the intravenous133 xenon technique at normocapnia and hypocapnia. Reactivity of CBF to carbon dioxide was calculated as the absolute increase in CBF per millimeters of mercury increase in the partial pressure of carbon dioxide (PaCO2). Data were analyzed by repeated-measures analysis of variance, unpaired Student's t tests, or contingency analysis.

Results: In the remifentanil group (n = 10), CBF decreased from 36 +/- 11 to 27 +/- 8 ml [middle dot] 100 g-1 [middle dot] min-1 as PaCO2 decreased from 33 +/- 5 to 25 +/- 2 mmHg. In the fentanyl group (n = 8), CBF decreased from 37 +/- 11 to 25 +/- 6 ml [middle dot] 100 g-1 [middle dot] min-1 as PaCO2 decreased from 34 +/- 3 to 25 +/- 3 mmHg. Absolute carbon dioxide reactivity was preserved with both agents: 1 +/- 1.2 ml [middle dot] 100 g-1 [middle dot] min-1 [middle dot] mmHg-1 for remifentanil and 1.5 +/- 0.5 ml [middle dot] 100 g-1 [middle dot] min-1 [middle dot] mmHg-1 for fentanyl (P = 0.318).     

Acute opioid tolerance: intraoperative remifentanil increases postoperative pain and morphine requirement

BACKGROUND: Rapid development of acute opioid tolerance is well established in animals and is more likely to occur with large doses of short-acting drugs. The authors therefore tested the hypothesis that intraoperative remifentanil administration results in acute opioid tolerance that is manifested by increased postoperative pain and opioid requirement. METHODS: Fifty adult patients undergoing major abdominal surgery were randomly assigned to two anesthetic regimens: (1) desflurane was kept constant at 0.5 minimum alveolar concentrations and a remifentanil infusion was titrated to autonomic responses (remifentanil group); or (2) remifentanil at 0.1 microg. kg-1. min-1 and desflurane titrated to autonomic responses (desflurane group). All patients were given a bolus of 0.15 mg/kg morphine 40 min before the end of surgery. Morphine was initially titrated to need by postanesthesia care nurses blinded to group assignment. Subsequently, patients-who were also blinded to group assignment-controlled their own morphine administration. Pain scores and morphine consumption were recorded for 24 postoperative h. RESULTS: The mean remifentanil infusion rate was 0.3 +/- 0.2 microg. kg-1. min-1 in the remifentanil group, which was significantly greater than in the desflurane group. Intraoperative hemodynamic responses were similar in each group. Postoperative pain scores were significantly greater in the remifentanil group. These patients required morphine significantly earlier than those in the desflurane group and needed nearly twice as much morphine in the first 24 postoperative h: 59 mg (25-75% interquartile range, 43-71) versus 32 mg (25-75% interquartile range, 19-59; P < 0.01). CONCLUSIONS: Relatively large-dose intraoperative remifentanil increased postoperative pain and morphine consumption. These data suggest that remifentanil causes acute opioid tolerance and hyperalgesia.     

Implementing sevoflurane anesthesia with small doses opioid for upper abdominal surgery. Postoperative respiratory function after either remifentanil or fentanyl.

BACKGROUND: The aim of this prospective, randomized study was to compare the effects on intraoperative cardiovascular homeostasis, recovery profile and postoperative oxygen saturation after sevoflurane anesthesia with small doses of either remifentanil or fentanyl in combination with postoperative epidural analgesia. METHODS: With Ethical Committee approval and written patient consent, 30 ASA physical status I-II patients scheduled for elective upper abdominal surgery were randomly allocated to receive sevoflurane general anesthesia implemented with small doses of either remifentanil (n = 15) or fentanyl (n = 15), followed by postoperative epidural analgesia. Remifentanil group patients received a 1 mg kg-1 bolus infused during a 60 sec period followed by a 0.15 mg kg-1 min-1 infusion; while patients of Fentanyl group were given a 3 mg kg-1 initial dose followed by 50 mg boluses as requested (according to the time to peak effect of the two drugs, the initial dose was given 5 min before induction in Fentanyl group, and 1 min before induction in Remifentanil group). Postoperatively, oxygen saturation was continuously recorded and stored on a computer during the first 12 h after surgery. SpO2 decrease < 90% for more than one minute was considered as a minor respiratory complication. RESULTS: The median sevoflurane's MAC-hour was 2.7 (1.4 - 4.9) in patients receiving remifentanil infusion and 4.1 (2.2 - 5.7) in those patients receiving fentanyl during surgery (P = 0.005). However, no differences in the recovery times were observed between the two groups. Similar pain relief was reported during coughing in the two studied groups at discharge from the recovery area and during the following study period. No major respiratory complication was observed throughout the study. Oxygen therapy was required in three patients of Fentanyl group only 20% (P = 0.22); however, 11 patients in the same group (73%) showed at least one minor respiratory complication (SpO2 < 90% for more than 1 min), with a median of 1 (range 0 - 12) episode per patient, compared with no episode in Remifentanil group (P = 0.0005). CONCLUSIONS: Implementing sevoflurane anesthesia with very small remifentanil infusion provides a safe and effective hemodynamic control reducing sevoflurane consumption during the procedure, and produces less respiratory effects postoperatively as compared with intermittent bolus administration of fentanyl.     

Acute Opioid Tolerance: Intraoperative Remifentanil Increases Postoperative Pain and Morphine Requirement

Background: Rapid development of acute opioid tolerance is well established in animals and is more likely to occur with large doses of short-acting drugs. The authors therefore tested the hypothesis that intraoperative remifentanil administration results in acute opioid tolerance that is manifested by increased postoperative pain and opioid requirement.

Methods: Fifty adult patients undergoing major abdominal surgery were randomly assigned to two anesthetic regimens: (1) desflurane was kept constant at 0.5 minimum alveolar concentrations and a remifentanil infusion was titrated to autonomic responses (remifentanil group); or (2) remifentanil at 0.1 [mu]g [middle dot] kg-1 [middle dot] min-1 and desflurane titrated to autonomic responses (desflurane group). All patients were given a bolus of 0.15 mg/kg morphine 40 min before the end of surgery. Morphine was initially titrated to need by postanesthesia care nurses blinded to group assignment. Subsequently, patients-who were also blinded to group assignment-controlled their own morphine administration. Pain scores and morphine consumption were recorded for 24 postoperative h.

Results: The mean remifentanil infusion rate was 0.3 +/- 0.2 [mu]g [middle dot] kg-1 [middle dot] min-1 in the remifentanil group, which was significantly greater than in the desflurane group. Intraoperative hemodynamic responses were similar in each group. Postoperative pain scores were significantly greater in the remifentanil group. These patients required morphine significantly earlier than those in the desflurane group and needed nearly twice as much morphine in the first 24 postoperative h: 59 mg (25-75% interquartile range, 43-71) versus 32 mg (25-75% interquartile range, 19-59;P < 0.01).     

妇科腹腔镜手术患者右美托咪啶或瑞芬太尼复合七氟醚麻醉效果的比较

目的 比较妇科腹腔镜手术患者使用右美托咪啶复合七氟醚与瑞芬太尼复合七氟醚麻醉的效果.方法 择期拟行妇科腹腔镜手术患者40例,年龄18～64岁,BMI 18～30 kg/m2,ASA分级Ⅰ或Ⅱ级.采用随机数字表法,将患者随机均分为2组(n=20):右美托咪啶复合麻醉组(D组)和瑞芬太尼复合麻醉组(R组).D组和R组麻醉诱导前5 min时静脉输注右美托咪啶0.05μg·kg·min-1或瑞芬太尼0.1μg·kg-1·min-1,10 min后输注速率为右美托咪啶0.3μg·kg-1·h-1,瑞芬太尼0.15μg·kg-1·min-1.麻醉诱导:静脉注射异丙酚1.5～2.0 mg/kg、顺阿曲库铵0.15 mg/kg和芬太尼2 μg/kg,气管插管后行机械通气,维持PET CO2 35～40 mm Hg.麻醉维持:吸人3%七氟醚,并调节其吸入浓度维持Narcotrend指数40～50,气腹开始时静脉注射芬太尼1 μg/kg,按需静脉注射顺阿曲库铵.分别于给药前、气管插管后5 min、气腹10 min和气管拔管后5 min时,抽取颈外静脉血样,测定血清皮质醇、去甲肾上腺素和肾上腺素的浓度,并行血气分析,记录pH值、乳酸和葡萄糖的浓度.记录呼吸恢复时间、睁眼时间、气管拔管时间和定向力恢复时间.记录围术期不良反应的发生情况和术后2 h内镇痛药的使用情况.结果 与R组比较,D组气腹10 min时血清去甲肾上腺素和肾上腺素的浓度降低,呼吸恢复时间缩短,睁眼时间延长,气管拔管期间心动过速、术后寒战和恶心呕吐的发生率降低,术后芬太尼的使用率降低(P＜0.05).结论 妇科腹腔镜手术患者右美托咪啶复合七氟醚麻醉的效果优于瑞芬太尼复合七氟醚.

Abstract：

Objective To compare the efficacy of dexmedetomidine versus remifentanil in combination with sevoflurane for gynecological laparoscopy. Methods Forty ASA Ⅰ or Ⅱ patients aged 18-64 yr with body mass index of 18-30 kg/m2 undergoing gynecological laparoscopy were randomly assigned to one of two groups ( n =20 each): dexmedetomidine group (group D) and remifentanil group (group R). Starting from 5 min before induction of anesthesia, dexmedetomidine was infused at 0.05 μg · kg - 1 · min- 1 in group D and remifentanil at 0.1 μg· kg- 1· min-1 in group R for 10 min, then dexmedetomidine infusion rate was increased to 0. 3 μg· kg-1 · h-1 and remifentanil infusion rate was increased to 0.15 μg· kg-1 · min-1 . Anesthesia was induced with propofol 1.5-2.0 mg/kg and fentanyl 2 μg/kg. Tracheal intubation was facilitated with cis-atracurium 0.15 mg/kg. Anesthesia was maintained with sevoflurane and fentanyl 1 μg/kg and intermittent iv boluses of cis-atracurium. Narcotrend index was maintained at 40-50. Blood sample was taken from external jugular vein for blood gas analysis and determination of serum concentrations of corticosteroid, norepinephrine and epinephrine before administration, at 5 min after intubation, at 10 min of aeroperitoneum and at 5 min after extubation. The pH value and concentrations of lactic acid and glucose were recorded. The time for recovery of spontaneous breathing, eye-opening time, extubation time, orientation time and perioperative side-effects were recorded. Numeric rating scale was used to assess the intensity of pain during 2 h after operation. The analgesics used were also recorded. Results The serum concentrations of norepinephrine and epinephrine were significanfly lower at 10 min of aeroperitoneum, the time for recovery of spontaneous breathing was shorter, eye-opening time longer and the incidence of shivering and nausea and vomiting lower, the percentage of patients requiring rescue opioids lower in group D than in group R ( P ＜ 0.05). Conclusion The efficacy of dexmedetomidine combined with sevoflurane anesthesia is better than remifentanil combined with sevoflurane anesthesia for gynecological laparoscopy.     

General anesthesia with propofol and fentanyl for adult cardiac surgery

We employed propofol anesthesia with a restricted dose of fentanyl in adult cardiac surgery with the aim of early tracheal extubation and evaluated its effects on the intraoperative factors and postoperative recovery compared with those of a previous benzodiazepine-fentanyl regimen. During surgery, control group patients (n = 17) received intermittent bolus of benzodiazepines and fentanyl without restriction, whereas propofol group patients (n = 17) received continuous administration of propofol and the restricted dose of fentanyl (20 micrograms.kg-1). There were no significant differences in the times to eye opening (average 2.4 hr vs 1.6 hr, respectively, P = 0.30) and tracheal extubation (average 5.4 hr vs 4.0 hr, P = 0.25) between the groups. Both groups had similar postanesthetic circulatory status: cardiac index (average 3.6 l.min-1.m-2 vs 3.4 l.min-1.m-2, P = 0.46). The propofol group patients required smaller doses of vasodilators during cardiopulmonary bypass (average PGE1: 0.096 microgram.kg-1.min-1 vs 0.047 microgram.kg-1.min-1, P = 0.046, NTG: 0.69 microgram.kg-1.min-1 vs 0.31 microgram.kg-1.min-1, P = 0.009). It is suggested that propofol-based anesthesia could replace the previous regimen with no adverse hemodynamic effects and might have a potential to provide faster recovery and improve peripheral circulatory status in adult cardiac surgery.     

Remifentanil vs. fentanyl during interventional rigid bronchoscopy under general anaesthesia and spontaneous assisted ventilation.

The treatment of tracheo-bronchial diseases with rigid bronchoscopy requires general anaesthesia without tracheal intubation. Spontaneous assisted ventilation is a safe modality of ventilation. In this study the use of remifentanil and fentanyl is compared during rigid bronchoscopy with spontaneous assisted ventilation. Ninety high-risk patients received fentanyl or remifentanil with propofol for general anaesthesia. During the maintenance fentanyl was delivered at 6.1 +/- 4.6 micrograms kg-1 h-1 and remifentanil at 0.15 +/- 0.07 microgram kg-1 min-1. The same degree of intra-operative respiratory acidosis with similar good operating conditions resulted in both groups. Patients treated with remifentanil recovered more quickly compared with those in the fentanyl group (3.8 +/- 2 vs. 10.4 +/- 9.2 min, P < 0.001). In conclusion, the use of remifentanil during rigid bronchoscopy under general anaesthesia with spontaneous assisted ventilation is safe and assures good operating conditions. Moreover, remifentanil permits a more rapid recovery than fentanyl. The dose of remifentanil is higher than previously described for spontaneously breathing patients.     

Metabolism of remifentanil during liver transplantation

We have investigated the pharmacokinetics of remifentanil and its less potent metabolite, GR90291, in six adult patients undergoing orthotopic liver transplantation (OLT). A single bolus infusion of remifentanil 10 micrograms kg-1 min-1 was given at the beginning of the dissection and anhepatic phases of OLT. Remifentanil and GR90291 concentrations were measured in subsequent serial arterial and mixed venous blood samples. Mean arterial clearance of remifentanil was significantly greater (P = 0.02) in the dissection phase (79.54 ml min-1 kg-1) than in the anhepatic phase (39.57 ml min-1 kg-1). Steady state volumes of distribution were not significantly different. Clearance of remifentanil during the anhepatic phase was similar to that of healthy adult patients. Mean maximum concentration (Cpmax) of GR90291 was lower in the dissection phase than in the anhepatic phase (P = 0.026). There was no significant pulmonary metabolism of remifentanil.      

Remifentanil reduces auditory and somatosensory evoked responses during isoflurane anaesthesia in a dose-dependent manner

We studied 60 patients during stable isoflurane anaesthesia (0.4 MAC) after premedication with temazepam. Patients were allocated randomly to one of three dose regimens of remifentanil: 1 microgram kg-1 i.v. over 1 min and an infusion of 0.2 microgram kg-1 min-1 (low dose); 2.5 micrograms kg-1 and 0.5 microgram kg-1 min-1 (medium dose); and 5 micrograms kg-1 and 1 microgram kg-1 min-1 (high dose). The auditory (AER) and median nerve somatosensory (SER) responses were elicited throughout, and recorded before and after tracheal intubation, and surgical incision, together with systolic and diastolic arterial pressure and heart rate. Venous blood concentrations of remifentanil were measured at the above times. After administration of remifentanil, Pa and Nb amplitudes of the AER increased at the low dose, remained constant at the medium dose and decreased at the high dose. This dose- related effect was linear and significant (P = 0.012, P = 0.05). Pa amplitude correlated inversely with remifentanil blood concentrations before and after intubation and incision (P = 0.002, P < 0.001, P < 0.001 and P < 0.001). In the SER, P15-N20 amplitudes decreased after administration of remifentanil (P < 0.001), whereas P25-N35 and N35-P45 amplitudes increased at all dose concentrations (P < 0.001 and P < 0.001). After intubation, P15-N20 and N35-P45 amplitudes increased at the low dose, did not change at the medium dose and decreased at the high dose (P = 0.001, P = 0.027). After remifentanil, systolic and diastolic arterial pressure and heart rate decreased in a linearly dose- related manner (P = 0.033, P < 0.001, P < 0.001). At all doses the three variables increased after intubation (P = 0.001, P < 0.001, P < 0.01), and systolic and diastolic arterial pressure increased after incision (P = 0.027, P = 0.039).      

Comparison of Adenosine and Remifentanil Infusions as Adjuvants to Desflurane Anesthesia

Background: Because adenosine has been alleged to produce both anesthetic and analgesic sparing effects, a randomized, double-blinded study was designed to compare the perioperative effects of adenosine and remifentanil when administered as intravenous adjuvants during general anesthesia for major gynecologic procedures.

Methods: Thirty-two women were assigned randomly to one of two drug treatment groups. After premedication with 0.04 mg/kg intravenous midazolam, anesthesia was induced with 2 [micro sign]g/kg intravenous fentanyl, 1.5 mg/kg intravenous propofol, and 0.6 mg/kg intravenous rocuronium, and maintained with desflurane, 2%, and nitrous oxide, 65%, in oxygen. Before skin incision, an infusion of either remifentanil (0.02 [micro sign]g [middle dot] kg-1 [middle dot] min-1) or adenosine (25 [micro sign]g [middle dot] kg-1 [middle dot] min-1) was started and subsequently titrated to maintain systolic blood pressure, heart rate, or both within 10-15% of the preincision values.

Results: Adenosine and remifentanil infusions were effective anesthetic adjuvants during lower abdominal surgery. Use of adenosine (mean +/- SEM, 166 +/- 17 [micro sign]g [middle dot] kg-1 [middle dot] min-1) was associated with a significantly greater decrease in systolic blood pressure and higher heart rate values compared with remifentanil (mean +/- SEM, 0.2 +/- 0.03 [micro sign]g [middle dot] kg-1 [middle dot] min-1). Total postoperative opioid analgesic use was 45% and 27% lower in the adenosine group at 0-2 h and 2-24 h after surgery, respectively.     

Remifentanil, propofol or both for conscious sedation during eye surgery under regional anaesthesia

We performed a prospective, randomized study comparing the efficacy and safety of remifentanil, propofol or both for conscious sedation during eye surgery under retrobulbar blockade. Forty-five unpremedicated patients were assigned to receive remifentanil (group R) (n = 15, mean dosage: 0.05 +/- 0.03 microgram kg-1 min-1), propofol (group P) (n = 15, 1.5 +/- 0.5 mg kg-1 h-1) or a combination (group RP) (n = 15, R: 0.03 +/- 0.01 microgram kg-1 min-1; P: 0.7 +/- 0.2 mg kg-1 h-1). Haemodynamic responses were comparable among all groups. Minimum values for respiratory rate were lower in R patients (R: 7 vs. P and RP: 10 breaths min-1). Perioperative blood gas analysis showed differences in maximum carbon dioxide tensions (R: 51.5 vs. P: 48.3 vs. RP: 45.5 mmHg) and decrease in minimum pH values (R: -0.06 vs. P: -0.0 vs. RP: -0.01). All group P patients reported mild to intense pain during retrobulbar block, while 53% of the group R patients were free from pain. In group RP, 60% of patients experienced no pain and the remaining 40% reported mild pain only. Remifentanil, applied as the sole agent, provided superior pain relief and patient comfort when compared with propofol, but produced greater respiratory depression and postoperative nausea. The combination of remifentanil and propofol provided haemodynamic stability, adequate spontaneous respiration and pain relief, with a low risk of untoward side effects.     

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.      

Clinical comparison of either small doses of fentanyl or remifentanil for blunting cardiovascular changes induced by tracheal intubation

BACKGROUND: To compare in a prospective, randomized study the effects on cardiovascular changes after tracheal intubation produced by small doses of either remifentanil or fentanyl. METHODS: With Ethical Committee approval, after intravenous midazolam premedication (0.05 mg.kg-1), 30 normotensive, ASA physical status I-II patients, without cardiovascular or respiratory diseases, and with a Mallampati score < 2, were randomly allocated to receive an intravenous bolus of either 3 micrograms.kg-1 fentanyl (n = 15) or 1 microgram.kg-1 remifentanil (n = 15) infused over 60 sec and followed by a 0.15 microgram.kg-1.min-1 continuous intravenous infusion. General anesthesia was then induced with propofol (2 mg.kg-1), followed by atracurium besilate (0.5 mg.kg-1) to facilitate tracheal intubation. Following intubation, the lungs were ventilated mechanically using a 60% nitrous oxide in oxygen mixture with a 1% inspired fraction of sevoflurane. Arterial blood pressure and heart rate were recorded before anesthesia induction (baseline), one minute after induction of anesthesia, immediately after tracheal intubation and every minute for the first five minutes after intubation. RESULTS: Systolic arterial blood pressure values were significantly higher in the Fentanyl than in the Remifentanil group patients from 2 to 5 min after tracheal intubation (p < 0.01), while no differences were observed between the two groups in either diastolic arterial blood pressure or heart rate values. Four patients in the Remifentanil group (26%) but only one patient in the Fentanyl group (7%) showed systolic blood pressure values < 90 mmHg during the study period (p = not significant); however, the observed decreases in systolic arterial blood pressure values were transient and did not require treatment for any subject. CONCLUSION: We conclude that in healthy normotensive patients, the control of cardiovascular responses to tracheal intubation obtained with a 1 microgram.kg-1 loading dose of remifentanil is more effective than that provided by a 3 micrograms.kg-1 bolus of fentanyl, with the advantage of no risks for postoperative respiratory depression.     

射频消融辅助上气道手术患者瑞芬太尼、异丙酚联合局部麻醉的效果

目的 评价射频消融辅助上气道手术(CAUP)患者瑞芬太尼、异丙酚联合局部麻醉的效果.方法 拟在局麻下行CAUP手术的中、重度阻塞性睡眠呼吸暂停低通气综合征患者80例,年龄25～60岁,体重指数≤35 kg/m2,ASA Ⅰ或Ⅱ级,随机分为4组(n=20):生理盐水组(S组)、异丙酚组(P组)、瑞芬太尼组(R组)和异丙酚复合瑞芬太尼组(PR组).1%丁卡因咽部表面麻醉后,S组静脉输注生理盐水0.15 ml·kg-1·h-1,P组静脉输注异丙酚25μg·kg-1·min-1,R组静脉输注瑞芬太尼O.05μg·kg·min-1,PR组静脉输注异丙酚25μg·ks-1·min-1和瑞芬太尼0.05μg·kg-1·min-1.10 min后用含1:200 000肾上腺素的利多卡因行术野局部浸润麻醉.术中每5分钟采用Ramsay评分评价镇静程度;采用主诉疼痛分级(VRS)评价疼痛程度.S组VRS分级为Ⅲ级时为麻醉失败,其余3组VRS分级为Ⅲ级时,增加输注速率或静脉注射异丙酚10 mg或瑞芬太尼20μg;如出现Ramsay评分>3分或呼吸抑制(RR<8次/min或SpO2<95%),则为麻醉失败.于射频消融前和射频消融5 min时记录BP和HR.记录气道阻塞和呼吸暂停等不良反应的发生情况.结果 R组、PR组麻醉成功率(分别为90%、100%)高于s组和P组(分别为40%、65%)(P<0.05).与S组比较,射频消融5 min时P组SP、DP和HR差异无统计学意义(P>0.05),R组和PR组SP、DP和HR降低(P<0.05).4组不良反应发生率比较差异无统计学意义(P>O.05).结论 瑞芬太尼和异丙酚复合瑞芬太尼联合局部麻醉可安全、有效地用于患者射频消融辅助上气道手术.     

Hepatic oxygen supply-uptake relationship and metabolism during anesthesia in miniature pigs

The study evaluated the effects of different anesthetics on the hepatic oxygen supply-demand relationship and hepatic lactate uptake (HLu). Miniature pigs (n = 33), weighing 20-31 kg, were divided into five groups and accordingly anesthetized with halothane, isoflurane, enflurane (0.9%, 1.5%, and 2.2% end-expired concentrations, respectively), fentanyl (100 micrograms/kg iv bolus followed by a continuous infusion of 50 micrograms.kg-1.h-1), or sodium pentobarbital (30 mg/kg iv bolus followed by a continuous infusion at a rate of 1-2 mg.kg-1.h-1). The surgical preparation allowed the authors to induce a stepwise decrease in hepatic blood supply without congestion in the preportal tissues. Prior to induced hepatic hypoperfusion, the values of hepatic oxygen delivery (HDO2) were the greatest in the isoflurane and fentanyl groups and the smallest in the halothane group, while the values of hepatic oxygen uptake (HVO2) were the smallest in the halothane group without differences among the other four groups. During stepwise decrease in hepatic blood and oxygen supply, HLu started to decrease at higher values of hepatic oxygen delivery in the fentanyl group (HDO2 = 10 mlO2.min-1.100 g-1) than in all others (HDO2 = 6-7 mlO2.min-1.100 g-1). At values of HDO2 equal to 2-3 mlO2.min-1.100 g-1, the values of HLu became negative, signifying that the liver began to release rather than to metabolize lactate. There was a linear relationship between the values of HDO2 and hepatic venous oxygen tension or saturation (r = 0.96; P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Remifentanil and fentanyl during anaesthesia for major abdominal and gynaecological surgery. An open, comparative study of safety and efficacy.

BACKGROUND: and objective This open, multicentre study compared the efficacy and safety of remifentanil with fentanyl during balanced anaesthesia with 0.8% isoflurane (end-tidal concentration) for major abdominal and gynaecological surgery, and the efficacy and safety of remifentanil for pain management in the immediate postoperative period. METHODS: Two-hundred and eighty-six patients were randomized to receive remifentanil 1 microg kg(-1) followed by 0.2 microg kg(-1) min-1 (n=98), remifentanil 2 microg kg(-1) followed by 0.4 microg kg(-1) min(-1) (n=91) or fentanyl 3 microg kg(-1) (n=97) at induction. Thereafter, the study opioids and isoflurane were titrated to effect during the operation. RESULTS: Compared with fentanyl, remifentanil 2 microg kg(-1) followed by 0.4 microg kg(-1) min(-1) reduced the incidence of response to tracheal intubation (30% vs. 13%, P < 0.01), skin incision (33% vs. 4%, P < 0.001) and skin closure (11% vs. 3%, P < 0.05), respectively. Patients receiving remifentanil 1 microg kg(-1) followed by 0.2 microg kg(-1) min(-1) had fewer responses to skin incision than the fentanyl group (12% vs. 33%, P < 0.001), but the incidences of response to tracheal intubation and skin closure were similar. Significantly fewer patients in both remifentanil groups had > or = 1 responses to surgical stress intraoperatively compared with fentanyl (68% and 48% vs. 87%, P < 0.003). The mean isoflurane concentrations required were less in both remifentanil groups compared with the fentanyl group (0.1%, P=0.05). In remifentanil-treated patients, continuation of the infusion at 0.1 microg kg(-1) min(-1) with titration increments of +/- 0.025 microg kg(-1) min(-1) was effective for the management of immediate postoperative pain prior to transfer to morphine analgesia. However, a high proportion of patients experienced at least moderate pain whilst the titration took place. CONCLUSIONS: Anaesthesia combining isoflurane with a continuous infusion of remifentanil was significantly more effective than fentanyl at blunting responses to surgical stimuli. Significantly fewer patients responded to tracheal intubation with remifentanil at 0.4 microg kg(-1) min(-1), supporting the use of a higher initial infusion rate before intubation. Both remifentanil and fentanyl were well-tolerated, with reported adverse events typical of mu-opioid agonists.     

瑞芬太尼对肝硬化大鼠肝脏缺血再灌注损伤的影响

目的 探讨瑞芬太尼对肝硬化大鼠肝脏缺血再灌注损伤的影响.方法 成年健康雄性SD大鼠30只,体重260～300 g,采用随机数字表法,将其随机分为3组(n=10):肝硬化组(C组)、肝硬化+肝缺血再灌注组(I/R组)和瑞芬太尼组(R组).C组、I/R组和R组采用四因素综合法制备大鼠肝硬化模型,I/R组和R组在肝硬化模型制备成功后1周制备大鼠70％肝脏缺血再灌注模型,R组于缺血前10 min开始静脉输注瑞芬太尼1μg·kg-1·min-至再灌注结束.于再灌注4h时取静脉血样和肝组织,测定血清ALT和AST活性、肝细胞Bcl-2和Bax表达及肝细胞凋亡情况,计算细胞凋亡指数,光镜下观察肝组织病理学结果.结果 与C组比较,I/R组血清ALT和AST的活性升高,肝细胞Bcl-2表达下调,Bax表达上调,细胞凋亡指数升高(P＜0.05);与I/R组比较,R组血清ALT和AST的活性降低,肝细胞Bcl-2表达上调,Bax表达下调,细胞凋亡指数降低(P＜0.05).R组肝组织病理学损伤轻于I/R组.结论 瑞芬太尼可减轻肝硬化大鼠肝脏缺血再灌注损伤,其机制与平衡肝细胞Bcl-2与Bax表达而抑制肝细胞凋亡有关.