Different Doses Of Remifentanil Research Articles

ED50 of ciprofol combined with different doses of remifentanil during upper gastrointestinal endoscopy in school-aged children: a prospective dose-finding study using an up-and-down sequential allocation method.

This study aimed to determine the 50% effective dose (ED50) of ciprofol when combined with different doses of remifentanil for upper gastrointestinal endoscopy of school-age children and to evaluate its safety. This study involved school-aged children who were scheduled to undergo upper gastrointestinal endoscopy under deep sedation. The children were randomly assigned to two groups: remifentanil 0.3μg/kg (R0.3) and remifentanil 0.5μg/kg (R0.5). Anesthesia was induced with remifentanil, followed by ciprofol. The dose of ciprofol for each patient was determined using the Dixon up-down sequential method. If the MOAA/S score was ≤1 and the child did not exhibit significant movement or coughing during the endoscopy process, sedation was considered successful. The first patient in each group received 0.5mg/kg ciprofol. The dose of ciprofol was adjusted by 0.05mg/kg based on the response of the previous patient. The primary outcome was the ED50 of the ciprofol-induction dose. The total ciprofol doses, onset times, awakening times, and adverse reactions were recorded. 1) The Dixon method was used to collect crossovers data from each group, and the ED50 values of the R0.3 and R0.5 groups were calculated to be 0.390mg/kg (95% CI 0.356-0.424mg/kg) and 0.332mg/kg (95% CI 0.291-0.374mg/kg), respectively. The ED50 of ciprofol in the R0.3 group was significantly higher than that in the R0.5 group (p < 0.05). 2) The onset time and recovery time of the R0.5 group were shorter than those of the R0.3 group (p < 0.05). When the two groups were compared, the total dose of ciprofol in the R0.5 group decreased (p < 0.05). 3) Compared with the R0.3 group, the incidence of respiratory depression during induction in the R0.5 group increased (p < 0.05). This study explored the ED50 of ciprofol combined with different doses of remifentanil for successful sedation in upper gastrointestinal examinations in school-aged children. Compared to the use of remifentanil 0.3μg/kg, the combination of ciprofol with remifentanil 0.5μg/kg significantly reduced the ED50 required to prevent body movement or cough during endoscope insertion but increased the incidence of respiratory depression.

Conscious sedation anesthesia using different doses of remifentanil combined with dexmedetomidine for peritoneal dialysis catheter implantation

Background Conscious sedation anesthesia (CSA) is an anesthetic method during peritoneal dialysis catheter implantation. However, lack of optimal CSA strategies for patients with end-stage renal disease (ESRD). This study aimed to evaluate the analgesic effects and safety of CSA using different doses of remifentanil combined with dexmedetomidine during peritoneal dialysis catheter insertion. Methods Patients who underwent peritoneal dialysis (PD) catheter placement via open surgical incision were retrospectively analyzed and divided into three groups based on the tertile dose of remifentanil. The bispectral index (BIS) was used to monitor the depth of anesthesia. Data regarding clinical findings, the effects of anesthesia, and the incidence of drug-related adverse effects were collected. Results In total, 102 patients completed the surgery successfully and safely. The dose of remifentanil was 0.02–0.07 μg/kg/min, 0.08–0.13 μg/kg/min, and 0.14–0.20 μg/kg/min in Groups A, B, and C, respectively. Only seven patients reported mild pain during the surgery. No significant differences were observed among the numeric rating scale scores of the three groups (p > 0.05). Intraoperative hemodynamics were stable. The incidence of respiratory depression was 8.3%, 20.0%, and 41.9% in Groups A, B, and C, respectively (p < 0.01). The incidence of gastrointestinal symptoms in Group C (51.6%) was higher than that in Groups A and B (p < 0.05). Conclusion Low-dose remifentanil (0.02–0.07 μg/kg/min) combined with dexmedetomidine achieved satisfactory anesthetic effects with fewer adverse drug reactions during PD catheter implantation, indicating its potential for use in patients undergoing PD catheter placement.

Impact of different doses of remifentanil on chronic postsurgical pain after video-assisted thoracic surgery: A propensity score analysis.

A remifentanil infusion dose of >0.2 μg/kg/min is associated with hyperalgesia, leading to acute postsurgical pain; however, its contribution to the development of chronic postsurgical pain after video-assisted thoracic surgery remains unclear. This study aimed to evaluate the impact of different remifentanil doses on chronic postsurgical pain after video-assisted thoracic surgery. This study included inpatients aged ≥ 55 years who underwent video-assisted thoracic surgery under general anesthesia between April 2016 and December 2018. An inverse probability of treatment weighted using stabilized inverse propensity scores was adopted to minimize bias. After adjustments based on patient data, the outcomes of interest were compared with intraoperative covariates using a generalized estimating equation. The primary study outcome was chronic postsurgical pain 1 year after surgery, defined as a pain score ≥1 on a numerical rating scale. Of the 262 eligible patients, 258 with a mean age of 71.2 years were included in this analysis. Chronic postsurgical pain occurred in 23.6% of patients. The generalized estimating equation revealed that a remifentanil infusion dose >0.2 μg/kg/min was associated with chronic postsurgical pain at 1 year after surgery (odds ratio [OR] 1.52; 95% confidence interval [CI] 1.03-2.27), while remifentanil infusion doses >0.15 μg/kg/min (OR 1.12; 95% CI 0.79-1.59) and >0.175 μg/kg/min (OR 1.17; 95% CI 0.83-1.64) were not associated with our primary outcome. Remifentanil infusions >0.2 μg/kg/min were associated with chronic postsurgical pain 1 year after video-assisted thoracic surgery.

Comparative study of the effect of two different doses of remifentanil on bleeding control in lumbar fusion surgery: A randomized clinical trial.

ObjectivesSpinal fusion surgery completely prevents movement or friction between the two vertebrae. Remifentanil, a selective drug agonist, suppresses and decreases the vasomotor system upon release of histamine. In this study, the efficacy of remifentanil infusion at doses of 0.1 and 0.3 μg/kg/min in the control of low blood pressure was compared.MethodsIn this randomized clinical trial, 110 candidates for selective spinal fusion surgery were entered and randomized into 2 groups. The first group received 0.1 μg/kg/min and in the second group 0.3 μg/kg/min remifentanil. The systolic and diastolic blood pressure, pulse rate, SPO2, and surgeon's satisfaction were measured and compared between groups.Resultsthe systolic blood pressure was significantly lower in patients receiving 0.3 μg of remifentanil by the time 30, 45, 60, and 90 min during the surgeries (P < 0.05). No significant difference was observed in terms of PR (P = 0.19) and SPO2 (P = 0.41) between the two groups. We also observed significantly higher duration of surgeries (P = 0.002), duration of anesthesia (P = 0.009), significantly higher bleeding volume (P < 0.001), higher fluid intake (P = 0.01) and higher transfused blood (P = 0.01) in patients that received 0.1 μg remifentanil compared to other patients.ConclusionHere we showed that administration of 0.3 μg/kg/min remifentanil was associated with significantly lower systolic blood pressure during the surgeries. On the other hand, patients that received 0.1 μg/kg/min remifentanil had significantly higher duration of surgeries, duration of anesthesia, significantly higher bleeding volume, higher fluid intake, and also higher transfused blood.

Differential effects of remifentanil and sufentanil anesthesia on post-operative pain and cognitive functions

This study aimed to investigate the differential effects of remifentanil and sufentanil anesthesia on post-operative pain and recovery of cognitive functions following surgical resection of human colon cancer orthotopically transplanted in rats. Human colon cancer cells HT-29 were used to establish a rat model of orthotopically transplanted colon cancer on to the cecal wall of rats. The transplanted tumors were then surgically removed after 5 weeks, using different doses of remifentanil and sufentanil anesthesia. At 24 h after the surgery, von Frey test, hot plate test and voluntary wheel running test were used to evaluated post-operative pain in the rats. Morris water maze test and fear conditioning test were employed to assess cognitive functions. Serum and colon tissues of the rats were also subjected to ELISA to measure levels of stress response factors, while colon tissues were analyzed by RT-PCR and Western blot to measure expression of inflammation response factors and NF-κB pathway-related factors. Sufentanil showed better effect in reducing post-operative pain, while remifentanil showed better recovery of cognitive functions after surgery. In addition, remifentanil resulted in less stress and inflammation response, caused milder activation of NF-κB pathway-related factors after surgery. Remifentanil and sufentanil exhibited differential effects on post-operative pain and recovery of cognitive function. Specifically, remifentanil caused lower stress and inflammation response, associated with dampened activation of the NF-κB pathway. Our results could provide theoretical basis for adopting appropriate analgesic strategy and agents according to the characteristics of individual patients.

Comparison of two different doses of intravenous remifentanil on cardiovascular response to endotracheal intubation: a randomized controlled trial

Background &amp; Objectives: Endotracheal intubation is one of the most potent stimuli as an integral part of general anesthesia with several risks such as a sudden increase in blood pressure and pulse rate. One of the drugs that can be used to prevent hemodynamic spikes in endotracheal intubation is remifentanil. It has rapid onset and peak effect with short duration of action. Various authors have used different doses of this drug. We compared the effect of two different doses of remifentanil on hemodynamic response to endotracheal intubation.&#x0D; Methodology: It was a randomized clinical trial on 35 patients, aged 19-65 y, physical status ASA I-II, body mass index (BMI) 18.5-29.99 kg/m2, who underwent elective surgery under general anesthesia. Subjects were randomly assigned into 2 groups, Group R1, who received remifentanil 0.5 µg/kg intravenously (IV), followed by an infusion @ 0.1 µg/kg/min; and Group R2, who received remifentanil 1 µg/kg followed by 0.1 µg/kg/min intravenously. Systolic, diastolic and mean arterial pressure, and pulse rates were noted on arrival in the operating room T0, then measurements were performed 2 min after induction (T1), 1 min after intubation (T2), and continued at 3 and 5 min after intubation (T3 and T4). The data was analyzed with SPSS v21.0 for Windows. T-test or Mann-Whitney U test was performed to analyze the data.&#x0D; Results: Based on this study, the hemodynamic parameters were significantly lower in systolic blood pressure (113.35 ± 4.66 vs. 107.83 ± 6.37, P = 0.008), diastolic blood pressure (68.88   vs. 61.83  P = 0.004), mean arterial pressure (83.76  vs. 77.28 ± 5.84, P = 0.001) and pulse rate (83.71 ± 8.20 vs. 76.11 ± 9.70, P = 0.013) after 1 min of endotracheal intubation in the remifentanil 1 µg/kg group compared to the 0.5 µg/kg remifentanil group.&#x0D; Conclusion: Administration of remifentanil 1 µg/kg followed by maintenance of 0.1 g/kg/min can cause a statistically significant decrease in blood pressure and heart rate compared to remifentanil 0.5 µg/kg followed by maintenance of 0.1 µg/kg/min, when administered for endotracheal intubation.&#x0D; Abbreviation: BMI: body mass index; IV: intravenously; SBP: Systolic blood pressure; DBP: Diastolic blood pressure; MBP: Mean arterial blood pressure;&#x0D; Key words: Endotracheal intubation; Hemodynamic insult; Remifentanil&#x0D; Citation: Suwarman, Prihartono MA, Azhari GA. Comparison of two different doses of intravenous remifentanil on cardiovascular response to endotracheal intubation: a randomized controlled trial. Anaesth. pain intensive care 2022;26(6):778−783; DOI: 10.35975/apic.v26i6.2047

Remifentanil reduces glutamate toxicity in rat olfactory bulb neurons in culture

BackgroundOpioids are widely used as an analgesic drug in the surgical setting. Remifentanil is an ultra-short acting opioid with selective affinity to the mu (μ) receptor, and also exhibits GABA agonist effects. The aim of this study was study of the neurotoxic or neuroprotective effect of different doses of remifentanil in glutamate-induced toxicity in olfactory neuron cell culture. Materials and methodsOlfactory neurons were obtained from newborn Sprague Dawley rat pups. Glutamate 10-5 mM was added to all culture dishes, except for the negative control group. Remifentanil was added at three different doses for 24 hours, after which evaluation was performed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), Total Antioxidant Capacity (TAC), Total Oxidant Status (TOS), and Annexin V. ResultsThe highest and lowest viability values were obtained from the low and high remifentanil doses at approximately 91% and 75%, respectively. TAC and TOS were correlated with the MTT results. TAC, TOS and MTT most closely approximated to the sham group values in the remifentanil 0.02 mM group. ConclusionsOur results suggest that remifentanil has the potential to reduce glutamate toxicity and to increase cell viability in cultured neuron from the rat olfactory bulb.

Study to evaluate the optimal dose of remifentanil required to ensure apnea during magnetic resonance imaging of the heart under general anesthesia.

Magnetic resonance (MRI) scanning of the heart is an established part of the investigation of cardiovascular conditions in children. In young children, sedation is likely to be needed, and multiple controlled periods of apnea are often required to allow image acquisition. Suppression of spontaneous ventilation is possible with remifentanil; however, the dose required is uncertain. To establish the dose of remifentanil, by infusion, required to suppress ventilation sufficiently to allow a 30-s apnea during MRI imaging of the heart. Patients aged 1-6years were exposed to different doses of remifentanil, and the success in achieving a 30-s apnea was recorded. A dose recommendation was made for each patient, informed by responses of previous patients using an adaptive Bayesian dose-escalation design. Other aspects of anesthesia were standardized. A final estimate of the dose needed to achieve a successful outcome in 80% of patients (ED80) was made using logistic regression. 38 patients were recruited, and apnea achieved in 31 patients. The estimate of the ED80 was 0.184µg/kg/min (95% CI 0.178-0.190). Post hoc analysis revealed that higher doses were required in younger patients. The ED80 for this indication was 0.184µg/kg/min (95% CI 0.178-0.190). This is different from optimal dosing identified for other indications and dosing of remifentanil should be specific to the clinical context in which it is used.

Effects of Propofol and Propofol-Remifentanil Combinations on Haemodynamics, Seizure Duration and Recovery during Electroconvulsive Therapy.

ObjectiveThis study aimed to evaluate the effects of adding different doses of remifentanil to propofol treatment compared with propofol alone with regard to parameters, including the seizure duration, haemodynamic changes and recovery time, in patients undergoing electroconvulsive therapy (ECT).MethodsThis study was designed as a self-controlled, prospective, double-blind investigation of 17 patients between the ages of 20 and 65 years who had planned treatment with ECT at a psychiatric clinic. Group P (propofol) was administered 10 mL of normal saline after 0.5 mg kg−1 intravenous (IV) bolus of propofol. Group R I (propofol plus remifentanil-1) was administered 1.5 μg kg−1 of remifentanil, and group R II (propofol plus remifentanil-2) was given 2 μg kg−1 of remifentanil after 0.5 mg kg−1 IV bolus of propofol. The haemodynamic variables after seizure and the seizure duration were recorded. Time to return to spontaneous respiration, eye opening and achieving Aldrete score >9 were recorded.ResultsThe electroencephalography seizure duration was significantly longer in groups R I (34.7±13 s) and R II (34.9±12) than in group P (24±7.5). Motor seizure duration was longer in groups R I (29.70±12.8) and R II (28.1±10) than in group P (21±7.3). The amount of total propofol was 121±21 mg in group P, 69.4±2 mg in group R I and 67±17 mg in group R II. Times to eye opening, following simple commands, and achieving Aldrete score >9 were significantly shorter in groups R I and R II than in group P.ConclusionECT is a safe and effective treatment for patients with psychiatric disorders. Propofol-remifentanil anaesthesia prolongs the seizure duration and shortens the recovery time, suggesting that this combination may particularly be well suited for use in this patient group.

Effect of different doses of remifentanil on stress response during laparoscopic cholecystectomy.

An adequate perioperative analgesia reduces neuroendocrine stress response and postoperative complica-tions. Opioids are the most effective parenteral drugs to control pain and stress response. This is a prospective randomized double-blinded controlled study. Institutional tertiary level. Fifty patients underwent general anesthesia with desflurane for laparoscopic cholecystectomy. To compare two different doses of remifentanil (0.15 mcg/kg/min or 0.3 mcg/kg/min) in reducing markers of stress. Perioperative stress was assessed through the dosage of adrenocorticotropic hormone (ACTH), cortisol, growth hormone (GH), and prolactin (PRL). Three venous blood samples were collected from patients: before transferring the patient to the operating room (Time 0), at the trocar insertion (Time 1), and 1 hour after the end of the surgery (Time 2). Hemodynamic parameters showed no differences between the two groups. The authors observed an increase of GH and PRL in both groups at trocar insertion (Time 1) (p = 0.473 and 0.754, respectively). ACTH and cortisol showed a decrease at Time 1 and an increase after surgery (p = 0.586). The modification of stress parameters levels showed no significant differences between the two groups. The results of our study showed that a lower dose of remifentanil is equally effective in controlling stress hormones during laparoscopic cholecystectomy.

Influence of different doses of remifentanil on postoperative hemodynamics in patients undergoing laparoscopic total hysterectomy

Objective To study the influence of different doses of remifentanil on postoperative hemodynamics in patients undergoing laparoscopic total hysterectomy. Methods Ninety patients underwent laparoscopic total hysterectomy in Weihai Municipal Hospital were selected as the subjects, and they were divided into A group(0.2μg/kg·min remifentanil), B group(0.3μg/kg·min remifentanil), C group (0.5μg/kg·min remifentanil) according to the random number table method, with 30 cases in each group.The relative operative indicators(including operation time, anesthesia time, extubation time and analgesia time) of the three groups were compared, and compared the heart rate (HR) and mean arterial pressure (MAP) in the three groups at different stages (T0: preoperation, T1: immediately after operation, T2: one day after operation, T3: three days after operation). The adverse reactions were recorded and compared. Results There were no statistically significant differences on relative operative indicators among the three groups (F=1.278, 1.346, 0.987, 2.232, all P>0.05). The levels of HR and MAP in A group, B group and C group at T1 were (94.68±8.51)times/min and (105.84±11.37)mmHg, (81.82±9.17)times/min and (97.14±9.02)mmHg, (75.24±8.29)times/min and (82.39±10.87)mmHg, respectively.The levels of HR and MAP in A group were higher than those in B group and C group (t=5.630, 3.283, 8.962, 8.165, all P 0.05, t=0.480, 0.430, 0.437, all P>0.05). There was no statistically significant difference in the total incidence of adverse reactions among the three groups (χ2=3.069, P>0.05). Conclusion Different doses of remifentanil have great impact on postoperative hemodynamics undergoing laparoscopic total hysterectomy, while the dose of 0.3μg/kg·min is stable, which is worthy of attention. Key words: Laparoscopy; Hysterectomy; Hemodynamics; Remifentanil

Pharmacokinetics and -dynamics of intramuscular and intranasal naloxone: an explorative study in healthy volunteers

This study aimed to develop a model for pharmacodynamic and pharmacokinetic studies of naloxone antagonism under steady-state opioid agonism and to compare a high-concentration/low-volume intranasal naloxone formulation 8mg/ml to intramuscular 0.8mg. Two-way crossover in 12 healthy volunteers receiving naloxone while receiving remifentanil by a target-controlled infusion for 102min. The group were subdivided into three different doses of remifentanil. Blood samples for serum naloxone concentrations, pupillometry and heat pain threshold were measured. The relative bioavailability of intranasal to intramuscular naloxone was 0.75. Pupillometry showed difference in antagonism; the effect was significant in the data set as a whole (p < 0.001) and in all three subgroups (p < 0.02-p < 0.001). Heat pain threshold showed no statistical difference. A target-controlled infusion of remifentanil provides good conditions for studying the pharmacodynamics of naloxone, and pupillometry was a better modality than heat pain threshold. Intranasal naloxone 0.8mg is inferior for a similar dose intramuscular. Our design may help to bridge the gap between studies in healthy volunteers and the patient population in need of naloxone for opioid overdose. clinicaltrials.gov : NCT02307721.

Remifentanil effects on respiratory drive and timing during pressure support ventilation and neurally adjusted ventilatory assist

We assessed the effects of varying doses of remifentanil on respiratory drive and timing in patients receiving Pressure Support Ventilation (PSV) and Neurally Adjusted Ventilatory Assist (NAVA). Four incrementing remifentanil doses were randomly administered to thirteen intubated patients (0.03, 0.05, 0.08, and 0.1μg·Kg−1·min−1) during both PSV and NAVA. We measured the patient's (Ti/Ttotneu) and ventilator (Ti/Ttotmec) duty cycle, the Electrical Activity of the Diaphragm (EAdi), the inspiratory (Delaytrinsp) and expiratory (Delaytrexp) trigger delays and the Asynchrony Index (AI).Increasing doses of remifentanil did not modify EAdi, regardless the ventilatory mode. In comparison to baseline, remifentanil infusion >0.05μg/Kg−1/min−1 produced a significant reduction of Ti/Ttotneu and Ti/Ttotmec, by prolonging the expiratory time. Delaytrinsp and Delaytrexp were significantly shorter in NAVA, respect to PSV. AI was not influenced by the different doses of remifentanil, but it was significantly lower during NAVA, compared to PSV. In conclusion remifentanil did not affect the respiratory drive, but only respiratory timing, without differences between modes.

Continuous postoperative infusion of remifentanil inhibits the stress responses to tracheal extubation of patients under general anesthesia.

PurposeThe study aimed to assess the combined effects of parecoxib with three different doses of remifentanil and its effect on the stress and cough responses following tracheal extubation under general anesthesia.MethodsA total of 120 patients with American Society of Anesthesiologists (ASA) scores of I or II, undergoing selective thyroidectomy with total intravenous anesthesia (propofol-remifentanil) and tracheal intubation, were randomly allocated to be treated with an intravenous injection of parecoxib and a continuous infusion of remifentanil at 0.1 μg/kg/min (R1), 0.2 μg/kg/min (R2), 0.3 μg/kg/min (R3), or an isotonic saline injection (the control group). Hemodynamic vital signs, emergence time, extubation time, sedation-agitation scale (SAS) score, pain visual analog scale (VAS) score, occurrence of coughing, and side effects were recorded before surgery and during the peri-extubation period. The vital signs included blood pressure (BP), heart rate (HR), respiratory rate (R), and peripheral arterial oxygen saturation (SPO2).ResultsBP, HR, the occurrence rate of coughing, and extubation awareness decreased with the dose of remifentanil, and the differences among the groups were significant (P < 0.05). Emergence and extubation time increased with the dose of remifentanil, and the differences among the groups were significant (P < 0.05). The occurrence rates of respiratory depression and bradycardia in group R3 were significantly higher than those in other groups (P < 0.05). SAS and VAS were lowest in group R3, and the differences among the groups were significant (P < 0.05). BP, HR, SAS, and VAS increased with time in the remifentanil groups.ConclusionThe combined use of parecoxib and a moderate dose of remifentanil can effectively suppress the stress and coughing responses during the peri-extubation period. The appropriate quantity of remifentanil was found to be 0.2 μg/kg/min, as this dosage caused no side effects.

Sedative-analgesic activity of remifentanil and effects of preoperative anxiety on perceived pain in outpatient mandibular third molar surgery

The aim of this study was to assess the sedative-analgesic activity of different doses of remifentanil and effects of preoperative anxiety on intraoperative pain levels in patients attending a dental clinic. The patients (n=60) were divided into two groups according to the remifentanil infusion dose given: group R1: 0.05μg/kg/min; group R2: 0.1μg/kg/min. The following were evaluated: haemodynamic parameters, State-Trait Anxiety Inventory (STAI) TX-I score, pain level due to local anaesthesia injection, time to reach a Ramsay Sedation Scale (RSS) score of 3, amount of bolus dose, total drug consumption, recovery period, patient and surgeon satisfaction, and complications. The patient satisfaction score on a visual analogue scale (VAS) was 90 in group R1 and 100 in group R2 (P=0.008); the surgeon satisfaction score was 80 in group R1 and 90 in group R2 (P=0.004). The time to reach an RSS score of 3 and the amount of bolus dose were significantly lower in group R2 than in group R1. High levels of anxiety did not affect intraoperative pain levels. In conclusion, high doses of remifentanil can safely be used for various same-day dental surgery interventions.

Effects of different doses of remifentanil on hemodynamic response to anesthesia induction in healthy elderly patients

Objective: We compared the effects of three different doses of remifentanil infusion, which were performed for the induction of anesthesia in elder patients, on cardiovascular response.Research design and methods: The present study was designed as a randomized, prospective and double-blind study. A total of 90 ASA I–II patients over the age of 65 years were enrolled. The patients were randomly (by lot) assigned to receive one of the three doses of remifentanil infusion (0.1, 0.2 or 0.3 μg/kg/min) for two minutes. Subsequently, 0.5 mg/kg propofol was administered via IV route and 0.5 mg/kg rocuronium was administered via IV route at the time eyelash reflex disappeared. Intubation was performed after 2 minutes. Patients who had an allergy against opioids, were chronic substance users, were obese, expected to have difficult airway, had hypertension, or were receiving any drug influencing the cardiovascular system were excluded.Main outcome measures: In this study after recording baseline values of heart rate (HR), systolic arterial pressure (SAP), diastolic arterial pressure (DAP) and mean arterial pressure (MAP), these values were recorded at the 1st, 2nd, 3rd, 4th and 5th minutes of induction.Results: A significant increase was observed in heart rate at the 1st and 2nd minutes of induction versus baseline in the Remi 0.1 group and at the 2nd minute of induction versus baseline in the Remi 0.2 group, with no additional significant change in heart rate. A significant decrease was determined in the systolic, diastolic and mean arterial pressures in all groups from the 1st minute of induction of anesthesia to the pre-intubation period compared to baseline (p < .05).Conclusions: It was determined that each dose of remifentanil used was quite high for patients of this age-group.ClinicalTrials.gov trial number: NCT02763098.

The effect of two different doses of remifentanil on postoperative pain and opioid consumption after cardiac surgery--a randomized controlled trial.

Remifentanil, an ultra-short-acting opioid, provides intensive analgesia without prolonged respiratory depression and is widely used in cardiac surgery. Diminished dosing may also offer stable hemodynamics, even during sternotomy and sternal retraction. However, increased postoperative pain and induced opioid tolerance after remifentanil dosing during abdominal surgery was reported. We tested whether remifentanil 0.3μg/kg/min infusion increased postoperative opioid consumption and pain compared to 0.1μg/kg/min dosing. Ninety coronary artery bypass grafting or heart valve surgery patients were randomized to remifentanil 0.1μg/kg/min or 0.3μg/kg/min infusions during surgery. All patients received oxycodone bolus 0.15μg/kg postoperatively, and patient-controlled analgesia (PCA) with oxycodone thereafter. Postoperative pain was estimated thrice daily by visual analogue scale, and 48-h opioid consumption was recorded from the PCA-device. Total remifentanil dosing was 64μg/kg in the higher and 22μg/kg in the lower dosing group during the 3-h cardiac operations. Mean postoperative opioid consumption was 107 (SD 36)mg in the lower and 104 (SD 33)mg in the higher dose remifentanil groups. Postoperative pain did not differ between groups, at rest or during deep breathing, at any time (P=0.110 and 0.941, respectively). Remifentanil 0.3μg/kg/min infusion did not increase postoperative pain or opioid consumption after cardiac surgery compared to the 0.1μg/kg/min infusion. Remifentanil infusion 0.1-0.3μg/kg/min during cardiac surgery was safe, with no exaggerated postoperative pain or opioid consumption.

Effects of different doses of remifentanil on postoperative analgesic in patients underwent upper abdominal surgery

Objective To assess the effects of intraoperative administration of different doses of remifentanil on postoperative analgesic in patients underwent upper abdominal surgery.Methods Sixty patients underwent upper abdominal surgery were randomly divided into two groups (n=30).They were intraoperatively administrated of high-dose remifentanil 0.4 μg· kg-1· min-1 (group H) or low-dose 0.2 μg·kg-1·min-1 (group L),respectively.Anesthesia was maintained with i.v.propofol,remifentanil and muscle relaxant.Postoperative analgesia was provided by patient-controlled intravenous analgesia (PCIA) with sulfentanyl.The visual analogue scale (VAS) and sedation score were measured at 2,4,12,24,48 h postoperatively.Sulfentanyl consumption was recorded and PCIA effect was observed in postoperative 48 h.Results VAS in group L(24±6,29±6,25±6,21±7) were significantly lower than in the group H(42±7,55±6,33±6,30±6),while the sedation score(2.7±0.3,2.3±0.4,2.5±0.3,2.0±0.1) were higher than in the group H (1.7±0.2,1.5±0.3,1.2±0.2,1.5±0.3) at 2,4,12,24 h postoperatively (P＜0.05).The postoperative total consumption of sulfentanyl (155±9) and the number of PCIA successfully delivered doses (5.6±0.9) in group L were decreased by 12％ and 43％ respectively compared with group H(176±13) μg and(9.9±0.6) (P＜0.05).There was no significant difference on side effects in two groups (P＞0.05).Conclusions Intraoperative administration of low-dose remifentanil can improve postoperative analgesia with no obvious side effects. Key words: Remifentanil; Patient-controlled intravenous analgesia

Comparison of efficacy of different doses of remifentanil combined with propofol for colonoscopy

Objective To compare the efficacy of different does of remifenanil combined with propofol for colonoscopy.Methods Ninety ASA Ⅰ or Ⅱ patients,aged 35-63 yr,weighing 45-72 kg,scheduled for elective painless outpatient colonoscopy,were randomly divided into 3 groups (n =30 each):remifentanil 0.2 μg/kg group (group Ⅰ),remifentanil 0.5 μg/kg group (group lⅡ) and remifentanil 1.0 μg/kg group (group Ⅲ).In groups Ⅰ-Ⅲ,remifentanil 0.2,0.5 and 1.0μg/kg were injected over 60 s,respectively,and then propofol 1.0 mg/kg was injected intravenously for induction.The colonoscope was inserted after loss of eyelash reflex.When body movement appeared during examination,remifentanil 0.1 μg/kg + propofol 0.5 mg/kg,remifentanil 0.25 μg/kg + propofol 0.5 mg/kg,and remifentanil 0.5μg/kg+ propofol 0.5 mg/kg were added in groups Ⅰ,Ⅱ and Ⅲ,respectively.The operation time,induction time,emergence time,examination room discharge time,and body movement,hypotension,bradycardia,hypoxemia and respiratory depression during operation were recorded.Results There was no significant difference in the operation time,induction time,emergence time,and examination room discharge time between the three groups (P ＞ 0.05).Compared with group Ⅰ,the incidence of body movement was significantly decreased,and the incidences of hypotension and respiratory depression were increased in group Ⅱ,and the incidence of body movement was significantly decreased,and the incidences of hypotension,hypoxemia,bradycardia and respiratory depression were increased in group Ⅲ (P ＜ 0.05).The incidences of hypoxemia,bradycardia and respiratory depression were significantly higher in group Ⅲ than in group Ⅱ (P ＜0.05).Conclusion The optimum dose of remifentanil is 0.5 μg/kg when combined with propofol for colonoscopy. Key words: Piperidines; Propofol; Colonoscopy

Can't Intubate, Can't Ventilate

Stefanutto et al. in this issue of Anesthesia & Analgesia continue the long quest to develop an optimal anesthetic induction protocol. A technique that assures good-to-excellent conditions for tracheal intubation upon loss of consciousness, yet assures that if “can’t intubate, can’t ventilate” (CICV) conditions are encountered, then adequate spontaneous ventilatory exchange will recover before significant arterial oxygen desaturation supervenes. In healthy patients, apneic intervals of 5 to 7 minutes may elapse before desaturation ( 90% arterial saturation) following preoxygenation in the presence of a patent airway, although in patients with decreased functional residual capacity or venous admixture, this interval may be significantly shorter. The protocol of Stefanutto et al. was designed so that their subjects retained the greatest chance of maintaining oxygenation during propofol/opioid-induced apnea: they received optimal preoxygenation (end-tidal oxygen 90%), and a tightly fitted facemask with insufflated oxygen flow at 6 L/min was kept in place. Assuming a patent airway, the authors’ subjects thus benefited from some degree of “apneic oxygenation.” The authors chose to avoid the use of succinylcholine to facilitate intubation because there is convincing evidence that significant arterial hemoglobin desaturation may take place before recovery of adequate respiratory mechanics occurs after a traditional “intubating dose” of this relaxant. For example, Heier et al. were able to demonstrate that, after induction with thiopental and succinylcholine (no opioid), spontaneous recovery from succinylcholine-induced apnea frequently did not occur quickly enough to prevent arterial desaturation. The present authors hypothesized that perhaps substituting a short-acting opioid in lieu of succinylcholine might result in a shorter apneic interval. In the present investigation, they studied an induction dose of propofol (2.0 mg/kg) combined with 2 different doses of remifentanil. The first dose they selected, remifentanil 2 g/kg, resulted in arterial hemoglobin saturations 80% in one-third of subjects, although it offered acceptable intubating conditions in 11 of 12 subjects. This time course of respiratory depression and resulting arterial desaturation is consistent with remifentanil’s pharmacokinetic/pharmacodynamic profile. In another session, they reduced the dose of remifentanil to 1.5 g/kg and successfully shortened the apnea time by approximately 1 minute, but 4 of 12 subjects had unacceptable conditions for tracheal intubation. The present study thus demonstrates the limitations of a relaxant-free intubation technique using what are certainly only modest doses of propofol and remifentanil. As pointed out by Sneyd and O’Sullivan, in the absence of a good clinical reason for doing so, “attempting tracheal intubation without a neuromuscular blocking agent represents substitution of an inferior technique for one with greater efficacy.” In the “real world” of unexpected CICV, a patent airway by definition would not be present, and the adequacy of preoxygenation may be questionable. Thus, the study by Stefanutto et al. probably represents a “best case” scenario. Nevertheless, the arterial O2 saturations in 14 of 24 subjects decreased to 90% at some point. Actual patients would likely experience a faster onset of arterial oxygen desaturation during apnea than the present authors observed. An induction sequence designed to facilitate tracheal intubation ideally should do more than simply induce hypnosis and abet mechanical placement of the endotracheal tube. It should also ensure reflex suppression and cardiovascular stability. Thus, significant reductions in the authors’ doses of propofol/opioid may not be realistic. In young, healthy subjects, perhaps the propofol dosage could be decreased to 1.5 mg/kg, but doses less than remifentanil 1.0 g/kg or fentanyl 2 g/kg are unlikely to suppress the hemodynamic response to intubation. Thus, it appears that muscle relaxant-facilitated intubation is here to stay. An ideal neuromuscular blocker used for intubation should have fast onset and either rapid elimination or the potential for prompt and complete antagonism of its effect. Succinylcholine is still the “gold standard” in this regard. After a 1 mg/kg dose, succinylcholine establishes complete block at the adductor pollicis in 70 20 seconds and first twitch (T1) height recovers to 10% of control in approximately 6 minutes and to 25% of control in 7 minutes. Diaphragmatic recovery takes place approximately 2 minutes earlier, and 50% recovery of this muscle’s strength is seen in 5 to 6 minutes. These data correlate nicely with From the *Department of Anesthesiology, Weill Cornell Medical College, New York, New York; and †Department of Anesthesia, Kyoto University Graduate School of Medicine, Kyoto, Japan.