Low-dose Remifentanil Infusion Research Articles

Remifentanil for Carboprost-Induced Adverse Reactions During Cesarean Delivery Under Combined Spinal-Epidural Anesthesia

PurposeCarboprost may induce adverse reactions when used to treat postpartum hemorrhage. We aimed to explore the effects of intravenous infusion of low-dose remifentanil to prevent such reactions.MethodsWe enrolled parturient patients scheduled for elective cesarean section. Anesthesiologist administered combined spinal epidurals at the L3/4 interspace, with 0.5% hyperbaric bupivacaine subarachnoid space injections (1.5–2.5 ml). We randomly divided parturient patients, administered carboprost during surgery, into the remifentanil group (group R) and the control group (group C). Patients in group R received an intravenous target-controlled infusion of remifentanil (target effect-site concentration, 1.5 ng/ml) simultaneously with a carboprost tromethamine injection (250 µg). Patients in group C received a normal saline infusion with carboprost. We recorded and analyzed the incidence of carboprost-related adverse reactions (vomiting, nausea, chest congestion, flushing, hypertension, tachycardia, cough, and shivering), and assessed patient comfort using a numerical rating scale ([NRS], on which 0 was very uncomfortable and 10 was very comfortable).ResultsAfter applying inclusion and exclusion criteria, we conducted statistical analysis of the data from 70 women. The incidence of vomiting was significantly lower in group R than in group C (14.3 vs. 51.4%, p < 0.01); and the incidence of nausea, chest congestion, facial flushing, and hypertension were significantly lower in group R than in group C (all p < 0.01). Furthermore, the patients’ comfort scores were significantly higher in group R than in group C (8.0 ± 1.8 vs. 3.6 ± 2.1, p < 0.01).ConclusionOur results demonstrate that an intravenous low-dose remifentanil infusion can effectively prevent carboprost-related adverse reactions during cesarean delivery under combined spinal and epidural anesthesia.Clinical Trial RegistrationWe pre-registered this study at http://www.chictr.org.cn/showproj.aspx?proj=27707 (ChiCTR1800016292).

Effects of low-dose remifentanil infusion on analgesic or antiemetic requirement during brain function mapping: A retrospective cohort study.

Pain and discomfort during the awake phase in awake craniotomy should be relieved to facilitate brain mapping. Although some anaesthesiologists use low-dose (0.01-0.05µg/kg/min) remifentanil infusion to provide analgesia during this phase, its efficacy and side effects have never been evaluated. Therefore, this study primarily aimed to investigate the effects of low-dose remifentanil infusion on the need for antiemetic treatment during brain mapping and secondarily aimed to determine its effects on the need for additional analgesic treatment. This retrospective study included 218 patients who underwent awake craniotomy at our centre from 2008 to 2018. The relationship between low-dose remifentanil infusion during the awake phase and the requirement for analgesic or antiemetic treatment was examined. A multivariable competing risk regression analysis was performed to adjust for patient and operative variables. Sixty-six patients (30.3%) received low-dose (median rate: 0.01µg/kg/min) remifentanil infusion during the awake phase. Forty-nine patients (22.5%) received an antiemetic and 99 (45.4%) received additional analgesic treatment. The difference in additional analgesic treatment was not significant between patients who received low-dose remifentanil infusion and those who did not (adjusted hazard ratio: 1.13; 95% confidence interval: 0.75-1.70; P=.570); however, the use of antiemetics significantly increased in patients who received remifentanil (adjusted hazard ratio: 1.78; 95% confidence interval: 1.01-3.15; P=.047). Low-dose remifentanil infusion during the awake phase in awake craniotomy significantly increased the need for antiemetics but did not decrease the need for additional analgesic treatment.

Continuous intravenous infusion of remifentanil improves the experience of parturient undergoing repeated cesarean section under epidural anesthesia, a prospective, randomized study

BackgroundUnsatisfactory analgesia would occur frequently during repeated cesarean section under epidural anesthesia. The aim of this study is to observe the effects of intravenous remifentanil on maternal comfort, maternal and neonatal safety during repeated cesarean section under epidural anesthesia.MethodsA total of 80 parturients undergoing repeated cesarean section were involved in the study. The patients were randomly divided into the intravenous remifentanil- assisted epidural group (group R) and epidural group (group E), respectively (n = 40). In group R, the remifentanil was continuously intravenously infused as an adjuvant to epidural anesthesia. In group E, 0.75% ropivacaine epidural or intravenous ketamine was administered as needed. Parturient baseline characteristics, vital signs, VAS scores, and comfort scores during surgery were recorded. Adverse effects were also recorded.ResultsA total of 80 patients were enrolled in the current study and the final analyses included 39 patients in group R and 38 patients in group E. No differences in patients’ baseline characteristics were found between the two groups (p > 0.05). Compared with group E, the comfort score was significantly higher in group R (9.1 ± 1.0 vs. 7.5 ± 1.3, p < 0.001), whereas the maximum VAS score was significantly lower in group R (1.8 ± 1.2 vs. 4.1 ± 1.0, p < 0.001). Maternal and neonatal adverse effects did not differ between the two groups during surgery (p > 0.05).ConclusionsContinuous intravenous infusion of low-dose remifentanil can significantly improve the experience of parturients undergoing repeated cesarean section under epidural anesthesia, without noticeable maternal or neonatal adverse effects.Trial registrationThis study was pre-registered at http://www.chictr.org.cn/index.aspx (ChiCTR1800018423) on 17/09/2018.

Efficacy of Single-Dose Dexmedetomidine Combined with Low-Dose Remifentanil Infusion for Cough Suppression Compared to High-Dose Remifentanil Infusion: A Randomized, Controlled, Non-Inferiority Trial.

Background: Combination of dexmedetomidine and opioid may be an alternative to high-dose opioid in attenuating cough during emergence from anesthesia, while also reducing the adverse effects of high-dose opioid. We tested the hypothesis that a single-dose of dexmedetomidine combined with low-dose remifentanil infusion during emergence would not be inferior to high-dose remifentanil infusion alone in attenuating cough after thyroidectomy.Methods: One hundred sixty-nine patients undergoing thyroidectomy were enrolled and randomized in a 1:1 ratio into group DR or group R. Each patient received an infusion of dexmedetomidine (0.5 μg/kg) and low-dose remifentanil infusion of effect-site concentration (Ce) at 1 ng/mL or normal saline and high-dose remifentanil infusion of Ce at 2 ng/mL for 10 min at the end of surgery. Remifentanil was maintained until tracheal extubation. Primary endpoint was the severity of coughing, which was assessed for non-inferiority using a four-point scale at the time of extubation. For comparison of coughing incidence during emergence, coughing grade was also measured at three times: before extubation, at extubation, and after extubation. Time to awakening, hemodynamic and respiratory profile, pain, and postoperative nausea and vomiting were also evaluated for superiority.Results: The 95% confidence intervals for differences in cough grade during tracheal extubation were <0.9, indicating non-inferiority of the single dose of dexmedetomidine combined with low-dose remifentanil infusion. The incidence of coughing was similar in the two groups. Hemodynamic changes during tracheal extubation were attenuated, but emergence from anesthesia was delayed, in group DR. Use of rescue antiemetic was similar in both groups, but the incidence of vomiting was less in group DR.Conclusion: A single-dose of dexmedetomidine (0.5 μg/kg) combined with low-dose remifentanil infusion at 1 ng/mL of Ce during emergence from sevoflurane-remifentanil anesthesia was not inferior to high-dose remifentanil infusion alone at 2 ng/mL of Ce with regard to suppressing cough.

Effect of Low Dose Remifentanil on Postoperative Pain Relief and Heart Rate Variability in Post-Anaesthesia Care Unit.

Several reports have shown the negligible adverse effects of low-dose remifentanil on the autonomic nervous system. We propose that the administration of low-dose remifentanil would be beneficial without adverse respiratory and hemodynamic effects. This study aimed to examine the effects of low-dose remifentanil on postoperative pain relief and heart rate variability (HRV) after surgery. In total, 20 patients, who underwent breast cancer surgery, were analysed for HRV in the post-anaesthesia care unit (PACU). A sedative dose of remifentanil was continuously infused if patients experienced pain while in PACU. The remifentanil infusion dose was determined by achieving analgesia with no adverse effects on hemodynamics and/or respiration. Variables of low-frequency power, high-frequency power and low-frequency power/high-frequency power ratio were measured before and after the administration of remifentanil. Pain score was expressed as the numeric rating scale (NRS) from 0 to 10. The mean dosage of remifentanil administered as a continuous infusion was 0.029±0.0042 μg kg-1 min-1. After remifentanil administration, the value of the NRS decreased from 4.2±2.9 to 2.7±2.6. In addition, the value of high-frequency power increased from 35.6±14.3 to 49.4±3.0. The continuous infusion of low-dose remifentanil may reduce post-operative pain scores and trigger the relative activation of the parasympathetic nervous system in post-surgical patients. This indicates that continuous infusion of low-dose remifentanil may be a useful option for postoperative pain relief in cases where postoperative pain control proves inadequate even with the application of regional block technique.

Effects of intraoperative high-dose vs low-dose remifentanil for postoperative epidural analgesia after gynecological abdominal surgery: a randomized clinical trial

Study objectivesTo evaluate whether intraoperative high-dose remifentanil infusion increased local anesthetic consumption in postoperative epidural analgesia and postoperative pain scores compared with low-dose remifentanil infusion. DesignProspective, randomized controlled study. SettingOperating room, university hospital. PatientsThirty female patients scheduled for elective gynecological abdominal surgery. InterventionsAfter epidural catheter placement and induction of general anesthesia, patients were randomly assigned to 2 anesthetic regimens. In the first group (high-dose remifentanil group), sevoflurane concentration was held constant at 1.2%, and the remifentanil infusion rate was titrated to maintain systolic blood pressure within 20% of baseline. In the second group (low-dose remifentanil group), the remifentanil infusion rate was held constant at 0.1μg/(kg min), and the sevoflurane concentration was titrated to maintain systolic blood pressure within 20% of baseline. As abdominal wall closure began, 6mL of 0.2% ropivacaine was administrated via epidural catheter; a patient-controlled analgesia device was set to deliver 4mL/h of 0.2% ropivacaine with 3μg/mL of fentanyl, with 2-mL incremental doses and a 15-minute lockout time. MeasurementsLocal anesthetic consumption via postoperative epidural catheter and pain intensity with the Prince Henry pain scale were assessed for 48hours after surgery. Main resultsThe mean remifentanil infusion rate was 0.23μg/(kg min) in the high-dose remifentanil group, 2.3 times the rate used in the low-dose remifentanil group. The cumulative amount of local anesthetic used within 48hours of surgery was significant greater in the high-dose remifentanil group than in the low-dose remifentanil group (212±25mL vs. 181±35mL, respectively; P<.05), but postoperative pain scores were similar in each group. ConclusionsIntraoperative high-dose remifentanil infusion increased local anesthetic consumption in postoperative epidural analgesia relative to low-dose remifentanil.

Efficacy of a single dose of dexmedetomidine for cough suppression during anesthetic emergence: a randomized controlled trial.

Maintenance of a remifentanil infusion during anesthetic emergence has been reported to decrease the incidence of coughing and thereby help to ensure a smooth emergence. It may, however, cause respiratory depression and possibly delay emergence. The purpose of this study was to investigate the effect of a single dose of dexmedetomidine combined with a low-dose remifentanil infusion on cough suppression during emergence from general anesthesia. American Society of Anesthesiologists physical status I-II adults undergoing elective thyroidectomy under sevoflurane anesthesia were recruited and randomly allocated to receive either dexmedetomidine 0.5μg·kg(-1) iv (Group D, n=70) or saline (Group S, n=71), each combined with a low-dose remifentanil infusion ten minutes before the end of surgery. Coughing was assessed using a four-point scale. The respiratory rate (RR), heart rate (HR), and mean arterial pressure were also recorded. The incidence of coughing was lower in Group D than in Group S (64% vs 91%, respectively; mean difference 27%; 95% confidence interval [CI] 13 to 41; P<0.001). The median cough grade at extubation was also lower in Group D. Mean arterial pressure and HR were elevated in Group S during tracheal extubation but were similar to baseline values in Group D. There was no difference in RR between the two groups throughout the study. A small delay in extubation was observed in Group D (3 minutes longer than Group S; 95% CI 2 to 4; P<0.001). Compared with an infusion of low-dose remifentanil alone, the addition of a single dose (0.5μg·kg(-1)) of dexmedetomidine during emergence from sevoflurane-remifentanil anesthesia was effective in attenuating coughing and hemodynamic changes and did not exacerbate respiratory depression after thyroid surgery. This trial was registered at Clinicaltrial.gov, identifier: NCT01774305.

Dexmedetomidine does not reduce emergence agitation in adults following orthognathic surgery.

Patients undergoing orthognathic surgery are at high risk of developing emergence agitation. We hypothesised that a single-dose of dexmedetomidine would reduce emergence agitation in adults with nasotracheal intubation after orthognathic surgery. Seventy adults (20-45 years old) undergoing orthognathic surgery were randomly assigned to two groups. Patients received intravenous dexmedetomidine 1 μg/kg (dex group) or normal saline (control group) for 10 min at the end of surgery. Remifentanil was infused at 0.02 μg/kg/min during emergence in both groups. The severity of emergence agitation was assessed with the Richmond agitation-sedation scale. Cough, haemodynamic and respiratory profiles, pain, and time to eye opening were evaluated. The incidence of emergence agitation was not different between dex group and control group (38% vs. 47%, P = 0.45). However, severe cough during emergence was reduced in the dex group (P = 0.04). Tachycardia during emergence and recovery phases was attenuated in the dex group. The verbal numeric rating of pain was lower in the dex group. There were no differences in respiratory rate between the two groups. Time to eye opening was prolonged in the dex group. The addition of a single dose of dexmedetomidine (1 μg/kg) to low-dose remifentanil infusion did not attenuate emergence agitation in intubated patients after orthognathic surgery compared with low-dose remifentanil infusion alone. However, single-dose dexmedetomidine suppressed coughing, haemodynamic changes, and pain during emergence and recovery phases, without respiratory depression. Delayed awakening might be associated with this treatment.

Ultrasound-guided transversus abdominis plane/genitofemoral blocks for a patient receiving extracorporeal life support.

Extracorporeal life support may be used in patients with refractory cardiogenic shock. The femoral venoarterial route can be used for implanting cannulae in patients who are hemodynamically unstable. Here we describe the use of an ultrasound-guided transversus abdominis plane block supplemented with the femoral component of the genitofemoral nerve as the anesthesia technique for peripheral cannulation of the femoral vessels in a patient with severe acute heart failure after myocardial infarction with ST-segment elevation. The procedure was performed using 40 mL of a 50:50 mixture of 0.5% levobupivacaine and 2% lidocaine (30 mL for transversus abdominis plane and 10 mL for genitofemoral block) associated with low-dose remifentanil infusion during spontaneous breathing. A left ventricular assist device was successfully implanted 4 days later.

Randomized Double Blind Control Study Comparing the Efficacy of Intracuff Alkalinized Lidocaine to Low Dose Remifentanil Infusion in Attenuating the Endotracheal Tube Induced Emergence Phenomena

Emergence from general anesthesia is often complicated by the endotracheal tube (ETT) induced airway and circulatory reflexes which can lead to potentially dangerous complications. Considerable research has been focused on prevention of these emergence phenomena (EP). Nevertheless, the problem is still far from its final solution. Objective: To compare the efficacy of intracuff alkalinized lidocaine (ICL) vs low dose remifentanil infusion in attenuating the ETT-induced EP. Methods: 120 ASA I-III patients, aged 18-65 years, were randomly assigned to receive intracuff alkalinized lidocaine (2% lidocaine mixed 1:1 with 1.4% NaHCO 3 ) or an intravenous (IV) remifentanil infusion (0.05-0.5 mcg/ kg/min) combined with intracuff saline during desflurane-based general anesthesia. At the end of surgery, after desflurane was turned off in the assigned group, low dose remifentanil, or its equivalent placebo was decreased to one-tenth of the mean dose but not less than 0.01 mcg/kg/min and it was continued until extubation. A blinded researcher observed each patient from the time desflurane was discontinued until at least five minutes after extubation. Coughing was evaluated as either present or not, and graded on a point scale based on severity. The patients were also observed for development of any adverse events along with the vital signs during this emergence phase. Results: The incidence (44% vs 67%, p=0.02) and severity of coughing, overall, was significantly less in the lidocaine group compared to remifentanil group). The lidocaine group also had a lower incidence of significant coughing (2-3 on point scale) (25% vs 49%, p=0.009). The mean arterial pressure (MAP) in the lidocaine group was lower than the remifentanil group at extubation and 5 minutes after extubation.

Awake intubation and awake prone positioning of a morbidly obese patient for lumbar spine surgery

We describe the awake fibreoptic intubation followed by awake prone positioning of a woman weighing 180 kg with body mass index of 62 kg.m(-2) requiring emergency lumbar discectomy for cauda equina syndrome. This approach was taken to overcome difficulties in transfering an anaesthetised patient on to the operating table. Following topical anaesthesia with lidocaine and low-dose remifentanil infusion, oral intubation was performed using a split oral airway to guide the fibrescope. The patient positioned herself on the Jackson operating table, following which general anaesthesia was induced. This technique optimised protection of the patient's eyes and other pressure areas while preventing undue cardiorespiratory compromise. The patient tolerated the procedure well, and later confirmed that she would consent to undergoing the same procedure again if further surgery became necessary.

Low-Dose Remifentanil Infusion during Ventilator Weaning and Tracheal Extubation in Postoperative Intensive Care Unit Patients Sedated with Propofol-Remifentanil: A Randomised Clinical Trial

Discontinuation of sedatives for ventilator weaning and extubation can be associated with hyperdynamic responses, including hypertension and tachycardia. We examined the effects of a maintained low dose of remifentanil infusion on cardiovascular responses and coughing during extubation in postoperative intensive care unit patients sedated with propofol-remifentanil. Fifty patients who required mechanical ventilation after major abdominal surgery were randomised into remifentanil group (n=25) or control group (n=25). Sedation during mechanical ventilation was maintained with remifentanil and propofol via a target-controlled infusion system. These drugs were titrated to the target sedation range, bispectral index values of 60 to 75 and Richmond Agitation Sedation Scale values of -3 to -2. When weaning was initiated, propofol was stopped in both groups. In the control group, remifentanil infusion was also stopped; in the remifentanil group, remifentanil infusion was maintained until extubation at a target effect site concentration of 1.0 ng/ml. Extubation was performed if the patient's respiratory, haemodynamic states were stable and if the patient was able to follow commands. Heart rate, mean arterial pressure and cough severity were evaluated. The mean arterial pressure, heart rate and cough severity did not differ between the two groups during extubation. The time from stopping of propofol infusion to extubation was significantly longer in the remifentanil group compared to that in the control group (P=0.020). Maintaining a low-dose remifentanil infusion during ventilator weaning, delayed tracheal extubation without any differences in haemodynamic changes or coughing in postoperative intensive care unit patients.

Ketamine, propofol and low dose remifentanil versus propofol and remifentanil for ERCP outside the operating room: Is ketamine not only a “rescue drug”?

SummaryBackgroundEndoscopic retrograde cholangiopancreatography ERCP is a painful and long procedure requiring transient deep analgesia and conscious sedation. An ideal anaesthetic that guarantees a rapid and smooth induction, good quality of maintenance, lack of adverse effects and rapid recovery is still lacking.This study aimed to compare safety and efficacy of a continuous infusion of low dose remifentanil plus ketamine combined with propofol in comparison to the standard regimen dose of remifentanil plus propofol continuous infusion during ERCP.Material/Methods322 ASAI-III patients, 18–85 years old and scheduled for planned ERCP were randomized. Exclusion criteria were a predictable difficult airway, drug allergy, and ASA IV–V patients.We evaluated Propofol 1 mg/kg/h plus Remifentanil 0.25 μg/kg/min (GR) vs. Propofol 1 mg/kg/h plus Ketamine 5 μg/kg/min and Remifentanil 0.1 μg/kg/min (GK).Main outcome measures were respiratory depression, nausea/vomiting, quality of intraoperative conditions, and discharge time. P≤0.05 was statistically significant (95% CI).ResultsRespiratory depression was observed in 25 patients in the GR group compared to 9 patients in the GK group (p=0.0035). ERCP was interrupted in 9 cases of GR vs. no cases in GK; patients ventilated without any complication. Mean discharge time was 20±5 min in GK and 35±6 min in GR (p=0.0078) and transfer to the ward delayed because of nausea and vomiting in 30 patients in GR vs. 5 patients in GK (p=0.0024). Quality of intraoperative conditions was rated highly satisfactory in 92% of GK vs. 67% of GR (p=0.028).ConclusionsThe drug combination used in GK confers clinical advantages because it avoids deep sedation, maintains adequate analgesia with conscious sedation, and achieves lower incidence of postprocedural nausea and vomiting with shorter discharge times.

Remifentanil for percutaneous intravenous central catheter placement in preterm infant: a randomized controlled trial

There is limited evidence on the analgesic efficacy of opioids during percutaneous intravenous central catheter (PICC) insertion in preterm infants. To assess the analgesic and procedural efficacy of low-dose remifentanil infusion during PICC in preterm infants. Fifty-four neonates [mean gestational age (+/-sd) 28 +/- 2 weeks; birth weight 1126 +/- 337 g] were randomly assigned to remifentanil infusion at 0.03 mcg.kg(-1).min(-1) (R) or placebo (C) in addition to 0.3 ml of 12% sucrose per os and non-nutritive sucking. Validated pain scales [Neonatal Infants Pain Scale (NIPS) and Premature Infants Pain Profile (PIPP)] administered at the baseline T0, skin preparation T1, needle insertion T2, and recovery T3, revealed differences in mean NIPS scores (C 5.3 +/- 1.3 vs R 4.2 +/- 1.4 at T1 and C 5.0 +/- 1.3 vs R 3.4 +/- 1.3 at T2) and PIPP scores (C 9.3 +/- 1.6 vs R 7.1 +/- 1.5 at T1 and C 8.6 +/- 1.7 vs R 6.1 +/- 1.4 at T2); P < 0.05. Cardiovascular and respiratory response, and body movements during PICC suggested better pain and distress control with remifentanil (P < 0.05), but the time to complete the maneuver and the number of attempts needed remained the same in the two groups. Low-dose remifentanil has a measurable, synergic analgesic effect in combination with 12% sucrose and non-nutritive sucking, but does not make PICC easier or quicker.

Cannot ventilate, difficult to intubate

Reply EDITOR: The intention of reporting this case was to warn anaesthetists of the potential difficulties with airway management where the orbital floor has been removed, and therefore stimulate debate. We are pleased that Drs Chethan and Rassam and also Dr Massimiliano and colleagues have entered this debate. The patient did not initially have a prosthesis, simply a large dressing over the exenterated area. Concerning the preoperative evaluation, clearly in this case the ideal assessment would have been to carefully insert a fibreoptic scope under local anaesthesia into the orbital defect. It would then have been clear that the defect leads directly to the larynx and therefore that positive pressure ventilation via a facemask would not have been possible. Unfortunately this was not a practical option on the ophthalmic ward and, because of lack of accurate surgical information and a recent general anaesthetic in another hospital apparently without incident, was not considered. Limitation of mouth opening is a concern for the anaesthetist; however, it is not our practice to conduct an awake intubation unless the limitation is extreme. We would normally plan to use a McCoy laryngoscope with a bougie or consider the use of the Bullard laryngoscope, which can be used down to a mouth opening of 6 mm [1]. Awake fibreoptic intubation would be available but held in reserve. It is often the case, and it was so for this gentleman, that such patients return for further surgery. As it happens, between submission of the letter and publication, further general anaesthesia was required on two occasions. As Chethan and Rassam suggested, we placed an intubating laryngeal mask (size 5), and ventilated through the mask following the induction of anaesthesia. Although placement and ventilation was straightforward, successful intubation through the intubating laryngeal mask airway (ILMA) proved impossible both without and with fibreoptic assistance. This was abandoned and nasotracheal fibreoptic intubation was again successful. In retrospect, the difficulty with the ILMA probably related to the patient's airway anatomy, in that he is tall with a long neck. Thus the ILMA, although adequately positioned for ventilation, was not positioned optimally for successful endotracheal intubation. Using the Aintree catheter with the classic LMA would almost certainly have failed for the same reason. A subsequent successful general anaesthetic was achieved with an awake fibreoptic intubation with the aid of a low-dose remifentanil infusion. Total intravenous anaesthesia with infusions of propofol and remifentanil was used for maintenance of anaesthesia in each case. The major advantage of this technique was that further doses of muscle relaxants were not required, thus ensuring complete recovery from neuromuscular blockade after several hours of surgery, and once both anaesthetic agents had worn off, the patient was fully co-operative for controlled extubation without the risk of residual anaesthesia or paralysis.

Can remifentanil be a better choice than propofol for colonoscopy during monitored anesthesia care?

This prospective, randomized trial was designed to test the hypothesis that continuous infusion of low-dose remifentanil can provide effective analgesia, sedation, amnesia, patient comfort and stable recovery profile without respiratory depression when compared with propofol infusion during colonoscopy. One hundred patients were randomly assigned to receive either remifentanil (group R, 0.5 microg/kg followed by 0.05 microg/kg/min, n = 50) or propofol (group P, 0.5 mg/kg followed by 50 microg/kg/min, n = 50). Supplemental doses of remifentanil 12.5 microg in group R and propofol 10 mg in group P were given to treat complaints of moderate to severe pain and discomfort. Hemodynamic and respiratory data, pain, discomfort and sedation scores, patient and gastroenterologist satisfaction and recovery profiles were recorded. The duration of colonoscopy was longer in group P. The mean arterial pressure, heart rate and end-tidal CO2 remained stable during the procedure and were comparable between the groups. After bolus injection of the study drugs, the respiratory rate and oxygen saturation values were lower in group R than in group P. Only one patient in group R required airway support. Pain and discomfort scores were better in group R than in group P. Sedation levels were higher in group P than in group R. Group P needed more supplemental doses than group R. The time to reach an Aldrete score of nine or more was shorter in group R, but discharge times were similar in the two groups. Amnesia was better in group P. Nausea and vomiting were more frequent in group R during the recovery phase. Low-dose remifentanil infusion with intermittent bolus injections can provide adequate sedation, amnesia and better analgesia than propofol infusion during colonoscopy. However, remifentanil-induced nausea and vomiting may be a problem during the recovery phase.

Low-dose remifentanil infusion does not impair natural killer cell function in healthy volunteers

Mu opioid agonists suppress natural killer (NK) cell activity in animal models. Studies in human volunteers, however, have yielded conflicting results, with morphine suppressing and fentanyl increasing NK cell activity. This study evaluated the effect of a constant 8-h infusion of remifentanil on NK cell number and function in human volunteers. After IRB approval and informed consent was obtained, 10 healthy volunteers underwent an 11 pm to 7 am infusion of saline, and at least 1 week later an infusion of 0.02-0.04 microg x kg(-1) min(-1) remifentanil. Blood was collected at 7 am for measurement of NK cell cytotoxicity using a (51)Cr release assay and measurement of NK cell number using fluorescent flow cytometry. Median and range of the total NK cell cytotoxicity (KU ml(-1)) was 745.0 (498.3-1483.6) on the control morning and 818.6 (238.5-1454.5) on the morning following the remifentanil infusion. Neither the number of NK cells ml(-1) (2.5 x 10(5) (1.4 x 10(5)-4.2 x 10(5)) vs 2.7 x 10(5) (1.1 x 10(5)-4.4 x 10(5))) nor the cytotoxicity per 1000 NK cells (KU 1000 NK cells(-1)) (3.0 (1.8-5.2) vs 2.9 (0.9-6.7)) changed between the control and remifentanil conditions. An 8-h infusion of remifentanil did not affect NK cell activity in normal volunteers. This result differs from previous findings of morphine-induced NK cell activity suppression and fentanyl-induced NK cell activity enhancement in normal volunteers.

A low-dose remifentanil infusion is well tolerated for sedation in mechanically ventilated, critically-ill patients.

To study the analgesic and sedative effects of remifentanil in critically-ill patients. Remifentanil infusion was started at 0.02 microg x kg(-1) x min(-1) in ten mechanically ventilated critically-ill patients, and the infusion rate was increased to 0.05, 0.10, 0.15, 0.20, and 0.25 microg x kg(-1) x min(-1) every 30 min. Basally and 25 min after each increase we measured: the Ramsey sedation score (RSS) and the respiratory response subscore of comfort scale (CSRR); the bispectral index (BIS) before and after lightly touching tracheal mucosa; heart rate and systemic arterial pressure; respiratory variables; plasma epinephrine and norepinephrine levels. Infusion rates up to 0.05 microg x kg(-1) x min(-1) were effective against agitation and achieved a good degree of adaption to the respirator in all patients (RSS 2 or more and CSRR 3 or less); BIS decreased significantly; respiratory and circulatory variables were unaffected; mean plasma epinephrine levels decreased. At infusion rates higher than 0.05 microg x kg(-1) x min(-1) RSS but not BIS decreased further and patient arousability caused by noxious stimuli was not prevented; respiratory drive suppression occurred at the infusion rates higher than 0.05 microg x kg(-1) x min(-1) in four patients; bradycardia and arterial hypotension was observed in three patients; plasma epinephrine levels decreased significantly, while norepinephrine was unaffected; severe itching was experienced by one patient. Low doses of remifentanil (up to 0.05 microg x kg(-1) x min(-1)) can be useful in critically-ill patients in order to achieve calm and sedation. Higher doses can inhibit respiratory drive and require controlled mechanical ventilation.

Remifentanil infusion as an adjunct to epidural anaesthesia for caesarean section

Introduction: A degree of intraoperative pain occurs in up to 50% of patients during caesarean section under epidural anaesthesia using 0.5% bupivacaine alone.t Expectations for pain-free surgery are high, leading to patient dissatisfaction and consequent medicolegal implications. The addition of epidural opioid improves the quality of epidural anaesthesia, yet up to 42% of women require additional intraoperative analgesia. 2 Intravenous remifentanil has been widely used in awake patients to supplement regional anaesthesia. 3 A low-dose remifentanil infusion may reduce discomfort during epidural caesarean section without causing significant adverse effects to mother or baby.