Optimal Effect-site Concentration Of Remifentanil Research Articles

Effects of smoking on the optimal effect-site concentration of remifentanil required for preventing cough during anesthetic emergence in male patients undergoing laparoscopic or robotic cholecystectomy.

Target-controlled infusion of remifentanil is known to reduce cough effectively during emergence from general anesthesia. The effect of smoking on emergence cough remains controversial. Therefore, we aimed to investigate the effect-site concentration (Ce) of remifentanil in the male patients undergoing laparoscopic or robotic cholecystectomy for suppressing emergence cough in smokers and non-smokers.Twenty smokers and 24 non-smokers (sex, male; age range, 20–65 years) were enrolled in this study. Anesthesia was maintained using sevoflurane and remifentanil. The Ce of remifentanil in 50% (EC50) and 95% (EC95) of the patients required for suppressing emergence cough were determined for each group (smokers and non-smokers) using Dixon up-and-down method and isotonic regression method with a bootstrapping approach.Dixon up-and-down method revealed that the EC50 value was significantly higher in smokers (3.51 ± 0.60 ng/mL) than in non-smokers (2.71 ± 0.30 ng/mL) (P < 0.001). In smokers and non-smokers, isotonic regression revealed EC50 to be 4.40 (83% CI, 4.17–4.58) ng/mL and 2.58 (83% CI, 2.31–2.87) ng/mL, respectively, and EC95 to be 4.76 (95% CI, 4.73–4.78) ng/mL and 3.15 (95% CI, 3.04–3.18) ng/mL, respectively.The Ces of remifentanil required to prevent cough during emergence were significantly higher in smokers than in non-smokers. Therefore, clinicians should pay attention to the smoking history of a patient to prevent cough during emergence.

Optimal effect-site concentration of remifentanil to prevent hemodynamic changes during nasotracheal intubation using a video laryngoscope.

BackgroundNasotracheal intubation is the most commonly used method to secure the field of view when performing surgery on the oral cavity or neck. Like orotracheal intubation, nasotracheal intubation uses a laryngoscope. Hemodynamic change occurs due to the stimulation of the sympathetic nervous system. Recently, video laryngoscope with a camera attached to the end of the direct laryngoscope blade has been used to minimize this change. In this study, we investigated the optimal effect-site concentration (Ce) of remifentanil for minimizing hemodynamic responses during nasotracheal intubation with a video laryngoscope.MethodsTwenty-one patients, aged between 19 and 60 years old, scheduled for elective surgery were included in this study. Anesthesia was induced by slowly injecting propofol. At the same time, remifentanil infusion was initiated at 3.0 ng/ml via target-controlled infusion (TCI). When remifentanil attained the preset Ce, nasotracheal intubation was performed using a video laryngoscope. The patient's blood pressure and heart rate were checked pre-induction, right before and after intubation, and 1 min after intubation. Hemodynamic stability was defined as an increase in systolic blood pressure and heart rate by 20% before and after nasotracheal intubation. The response of each patient determined the Ce of remifentanil for the next patient at an interval of 0.3 ng/ml.ResultsThe Ce of remifentanil administered ranged from 2.4 to 3.6 ng/ml for the patients evaluated. The estimated optimal effective effect-site concentrations of remifentanil were 3.22 and 4.25 ng/ml, that were associated with a 50% and 95% probability of maintaining hemodynamic stability, respectively.ConclusionNasotracheal intubation using a video laryngoscope can be successfully performed in a hemodynamically stable state by using the optimal remifentanil effect-site concentration (Ce50, 3.22 ng/ml; Ce95, 4.25 ng/ml).

Optimal effect-site concentration of remifentanil for preventing cough during removal of the double-lumen endotracheal tube from sevoflurane-remifentanil anesthesia: A prospective clinical trial.

Opioids are used as a treatment for coughing. Recent studies have reported an antitussive effect of remifentanil during recovery from general anesthesia by suppressed coughing. The coughing reflex may differ throughout the respiratory tract from the larynx to the bronchi. But the proper dose of remifentanil to prevent cough during double-lumen tube (DLT) extubation is unknown.Twenty-five ASA physical status 1 and 2 patients, 20 to 65 years of age who were undergoing video-assisted thoracoscopic lung surgery requiring 1-lung ventilation were enrolled. The effective effect-site concentration (Ce) of remifentanil for 50% and 95% of patients (EC50 and EC95) for preventing cough was determined using the isotonic regression method with a bootstrapping approach, following the Dixon up-and-down method. Recovery profiles and hemodynamic values after anesthesia were compared between patients with cough and patients without cough.EC50 and EC95 of remifentanil was 1.670 ng/mL [95% confidence interval (95% CI) 1.393–1.806] and 2.275 ng/mL (95% CI 1.950–2.263), respectively. There were no differences in recovery profiles and hemodynamic values after anesthesia between patients with/without cough. No patients suffered respiratory complications during the emergence period.Remifentanil can be a safe and reliable method of cough prevention during emergence from sevoflurane anesthesia after thoracic surgery requiring DLT. EC50 and EC95 of remifentanil that suppresses coughing is 1.670 and 2.275 ng/mL, respectively.

Optimal effect-site concentration of remifentanil for minimizing cardiovascular changes caused by fiberoptic nasotracheal intubation.

BackgroundEndotracheal intubation induces clinically adverse cardiovascular changes. Various pharmacological strategies for controlling these responses have been suggested with opioids being widely administered. In this study, the optimal effect-site concentration (Ce) of remifentanil for minimizing hemodynamic responses to fiberoptic nasotracheal intubation was evaluated.MethodsThirty patients, aged 18-63 years, scheduled for elective surgery were included. Anesthesia was induced with a propofol and remifentanil infusion via target-controlled infusion (TCI). Remifentanil infusion was initiated at 3.0 ng/mL, and the response of each patient determined the Ce of remifentanil for the next patient by the Dixon up-and-down method at an interval of 0.5 ng/mL. Rocuronium was administered after propofol and remifentanil reached their preset Ce; 90 seconds later fiberoptic nasotracheal intubation was initiated. Non-invasive blood pressure and heart rate (HR) were measured at pre-induction, the time Ce was reached, immediately before and after intubation, and at 1 and 3 minutes after intubation. The up-and-down criteria comprised a 20% change in mean blood pressure and HR between just prior to intubation and 1 minute after intubation.ResultsThe median effective effect-site concentration (EC50) of remifentanil was 3.11 ± 0.38 ng/mL by the Dixon's up-and-down method. From the probit analysis, the EC50 of remifentanil was 3.43 ng/mL (95% confidence interval, 2.90-4.06 ng/mL). In PAVA, the EC50 and EC95 of remifentanil were 3.57 ng/mL (95% CI, 2.95-3.89) and 4.35 ng/mL (95% CI, 3.93-4.45). No remifentanil-related complications were observed.ConclusionsThe EC50 of remifentanil for minimizing the cardiovascular changes and side effects associated with fiberoptic nasotracheal intubation was 3.11-3.43 ng/mL during propofol TCI anesthesia with a Ce of 4 ug/mL.

Optimal effect-site concentration of remifentanil for inhibiting response to laryngeal mask airway removal during emergence.

PurposeThis randomized, controlled, double-blind study was designed to determine the optimal dose of remifentanil for preventing complications associated with the removal of a laryngeal mask airway (LMA) without delaying emergence.Materials and MethodsThis study randomly assigned 128 patients to remifentanil effect-site concentrations (Ce) of 0 ng/mL (group R0), 0.5 ng/mL (group R0.5), 1.0 ng/mL (group R1.0), and 1.5 ng/mL (group R1.5) during emergence. The emergence and recovery profiles were recorded. Adverse events such as coughing, airway obstruction, breath-holding, agitation, desaturation, nausea, and vomiting were also evaluated.ResultsThe number of patients with respiratory complications such as coughing and breath-holding was significantly lower in the R1.0 and R1.5 groups than in the R0 group (p<0.05). Emergence agitation also decreased in the R1.0 and R1.5 groups (p<0.0083). The time to LMA removal was significantly longer in the R1.5 group than in the other groups (p<0.05).ConclusionMaintaining a remifentanil Ce of 1.0 ng/mL during emergence may suppress adverse events such as coughing, breath-holding, and agitation following the removal of LMA without delayed awakening.

Optimal effect-site concentration of remifentanil when combined with dexmedetomidine in patients undergoing cystoscopy

BackgroundCystoscopic procedure is a very common practice in the field of urology due to its ability to survey the bladder for a variety of indications. However, patients who undergo cystoscopy feel intense pain and discomfort. This study investigated the half maximal effective concentration (EC50) of remifentanil in preventing cystoscope insertion pain under sedation using dexmedetomidine.MethodsThe study was prospectively conducted on 18 male patients, aged 18 to 65. Remifentail infusion was initiated together with dexmedetomidine, and started at a dose of 2.4 ng/ml on the first patient. The effect-site concentration (Ce) of remifentanil for each subsequent patient was determined by the previous patient's response using Dixon's up-and-down method with an interval of 0.3 ng/ml. Patients received a loading dose of 1.0 µg/kg dexmedetomidine over 10 minutes, followed by a maintenance dose of 0.6 µg/kg/hr. After the patient's OAA/S score (Observer's Assessment of Alertness/Sedation scale) reached 3-4, and the Ce of remifentanil reached target concentration, the urologist was allowed to insert the cystoscope and the pain responses were observed.ResultsThe effect-site concentration of remifentanil required to prevent cystoscope insertion pain in 50% of patients under sedation using dexmedetomidine was 1.30 ± 0.12 ng/ml by Dixon's up-and-down method. The logistic regression curve of the probability of response showed that the EC50 and EC95 values (95% confidence limits) of remifentanil were 1.33 ng/ml (1.12-1.52 ng/ml) and 1.58 ng/ml (1.44-2.48 ng/ml), respectively.ConclusionsCystoscopic procedure can be carried out successfully without any pain or adverse effects by optimal remifentanil effect-site concentration (EC50, 1.33 ng/ml; EC95, 1.58 ng/ ml) combined with sedation using dexmedetomidine.

Effect‐site concentration of remifentanil to prevent cough after laryngomicrosurgery

The aim of this study was to discover the optimal effect-site concentration of remifentanil for cough prevention that does not delay awakening or cause respiratory depression during emergence from anesthesia with propofol and remifentanil in laryngomicrosurgery patients. Prospective, randomized, controlled trial. One hundred five patients were randomly assigned to maintain an effect-site concentration (Ce) of remifentanil at a predetermined value of 1 (R1), 1.5 (R1.5), and 2 (R2) ng/mL during emergence. The incidence and grade (0, no coughing; 1, single cough; 2, more than one episode of nonsustained coughing; 3, sustained and repetitive coughing with head lift) of cough, emergence time, blood pressure (MAP), heart rate (HR), spontaneous respiratory rate, oxygen saturation, and postoperative nausea and vomiting (PONV) were recorded during emergence and recovery. The total number of patients with coughing during emergence was lower in groups R1.5 and R2 than in group R1. The cough grade during tracheal extubation was lower in groups R1.5 and R2 than in group R1. In group R2, emergence time was longer and postanesthesia care unit score was lower than in groups R1 and R1.5. Also in group R2, transient hypoventilation and PONV were more frequent compared to group R1. There were no differences in MAP and HR among the three groups during emergence and recovery. Maintenance of remifentanil at Ce 1.5 and 2 ng/mL suppressed coughing without serious adverse events during emergence from anesthesia with propofol and remifentanil in patients undergoing laryngomicrosurgery.

The optimal effect-site concentration of remifentanil to attenuate the pain caused by propofol

BackgroundThe injection pain of propofol is a frequent and well-known adverse effect. This study was designed to determine the optimal effect-site concentration of remifentanil for minimizing injection pain during induction with propofol.MethodsA total intravenous anesthetic technique was used for patients undergoing general anesthesia and remifentanil was pretreated to reach a certain target concentration before propofol injection. Using Dixon's up-and-down method, the degree of pain described by the patient was used to adjust the target concentration of remifentanil for the next patient. Ten success-failure curves (crossovers) were sought to find the effect-site concentration (EC) of remifentanil for minimizing injection pain of propofol.ResultsThe EC of remifentanil in 50% and 95% of adult female population (EC50 and EC95) for minimizing injection pain of propofol were 3.09 ng/ml (95% confidence limits [CI] 2.92-3.30 ng/ml) and 3.78 ng/ml (95% CI 3.45-3.95 ng/ml), respectively. Clinically significant hemodynamic compromise or respiratory complications were not found during remifentanil infusion.ConclusionsMaintaining 3.78 ng/ml EC of remifentanil during induction with propofol attenuate propofol injection pain without serious adverse events in female patients undergoing general anesthesia and this method may provide the patient's comfort without preparing other drugs for pain relief.

The optimal effect-site concentration of remifentanil for lightwand tracheal intubation during propofol induction without muscle relaxation

Study Objective To determine the most suitable effect-site concentration of remifentanil during lightwand intubation when administered with a target-controlled infusion (TCI) of propofol at 4.0 μg/mL without neuromuscular blockade. Design Prospective study using a modified Dixon's up-and-down method. Setting Operating room of an academic hospital. Patients 28 ASA physical status 1 and 2 patients, aged 18-65 years, scheduled for minor elective surgery. Interventions Anesthesia was induced by TCI propofol effect-site concentration to 4.0 μg/mL, and the dose of remifentanil given to each patient was determined by the response of the previously tested patient using 0.2 ng/mL as a step size. The first patient was tested at a target effect-site concentration of 4.0 ng/mL of remifentanil. If intubation was successful, the remifentanil dose was decreased by 0.2 ng/mL; if it failed, the remifentanil dose was increased by 0.2 ng/mL. Successful intubation was defined as excellent or good intubating conditions. Measurements and Main Results The remifentanil effect-site concentration was measured. The optimal effect-site concentration of remifentanil for lightwand tracheal intubation during propofol induction using 2% propofol target effect-site concentration to 4 μg/mL was 2.16 ± 0.19 ng/mL. From probit analysis, the effect-site concentration of remifentanil required for successful lightwand intubation in 50% (EC50) and 95% (EC95) of adults was 2.11 ng/mL (95% CI 1.16-2.37 ng/mL) and 2.44 ng/mL (95% CI 2.20-3.79 ng/mL), respectively. Conclusion A remifentanil effect-site concentration of 2.16 ± 0.19 ng/mL given before a propofol effect-site concentration of 4 μg/mL allowed lightwand intubation without muscle relaxant.

Optimal effect-site concentration of remifentanil for preventing development of hypertension during tracheal intubation with inhaled desflurane induction.

BackgroundThe aim of the present study was to determine the effect-site concentration of remifentanil needed to prevent haemodynamic instability during tracheal intubation with inhaled desflurane induction.MethodsOne hundred American Society of Anesthesiologists I and II female patients were randomized to receive an effect-site concentration of remifentanil of 0, 1, 2, 3, or 4 ng/ml. Induction of anaesthesia was started with intravenous injection of propofol 2 mg/kg. Ninety seconds after the completion of propofol injection, rocuronium (0.8 mg/kg) and remifentanil were administered simultaneously with 3% desflurane inhalation. Tracheal intubation was attempted 150 sec after the commencement of remifentanil administration.ResultsA probit model of remifentanil concentration was predictive of successful intubation without development of hypertension (P for goodness-of-fit = 0.419). The effect-site concentration of remifentanil needed to achieve successful intubation without development of hypertension in 95% of the patients was 3.3 ng/ml (95% confidence interval, 2.6-4.8 ng/ml).ConclusionsThe effect-site concentration of remifentanil of 3.3 ng/ml is effective in blunting the haemodynamic response in 95% of the patients when 2.0 mg/kg of propofol induction was followed by 3% desflurane inhalation.

What is the optimal effect-site concentration of remifentanil for minimizing the cardiovascular changes to endotracheal intubation during induction with propofol in elderly patients?.

The addition of remifentanil during propofol TCI (target controlled infusion) attenuates the hemodynamic changes induced by endotracheal intubation. This study examined the optimal effect-site concentration of remifentanil to minimize the cardiovascular changes to endotracheal intubation in elderly patients. Fifty ASA 1 or 2 elderly patients scheduled for elective surgery under general anesthesia were assigned randomly to one of two groups according to the effect-site concentration of remifentanil. Each group was administered 4 microgram/ml of propofol TCI with 1 ng/ml (group R1) or 3 ng/ml (group R3) of remifentanil. The heart rate (HR), systolic (SAP), mean (MAP) and diastolic arterial pressure (DAP) were measured at pre-induction, before and after endotracheal intubation. After intubation, the HR, SAP, MAP and DAP increased significantly in the two groups compared with the pre-intubation values. However, the HR, SAP, MAP and DAP for group R3 were lower than group R1 for 5 min after intubation. In elderly patients administered 4 microg/ml of propofol TCI, we suggest that the optimal effect-site concentration of remifentanil to minimize the cardiovascular changes to endotracheal intubation is 3 ng/ml rather than 1 ng/ml.

What is the Optimal Effect-site Concentration of Remifentanil for Minimizing the Cardiovascular Changes to Endotracheal Intubation during Induction with Propofol?

Background: In this study, the optimal effect-site concentration of remifentanil for blunting hemodynamic responses to endotracheal intubation during total intravenous anesthesia using propofol were evaluated. Methods: 137 ASA class I and II patients, aged 18�� 60 years, were randomly allocated to one of six groups according to the effect-site concentration of remifentanil. Remifentanil was then infused at a target effect-site concentration of 0, 1, 2, 3, 4 or 6 ng/ml in groups R0, R1, R2, R3, R4 and R6, respectively. Anesthesia was induced with propofol infusion at a target effect-site concentration of 4μg/ml endotracheal intubation was performed 5 minutes after remifentanil administration. Blood pressure (BP), heart rate (HR) and cardiac index (CI) were recorded at the baseline and then every 30 seconds until 3 minutes after intubation. Results: BP and HR in groups R0, R1 and R2 increased significantly after intubation when compared with the baseline values. The CI in group R0 also increased significantly after intubation when compared with the baseline values. Incidences of hypertension and hypotension were 50% and 5% in R0, 32% and 14% in R1, 18% and 32% in R2, 10% and 48% in R3, 8% and 54% in R4, and 0% and 81% in R6. There were also 2 cases in which the mean blood pressure was less than 50 mmHg in group R6. Conclusions: We suggest that the optimal target effect-site concentrations of remifentanil for blunting hemodynamic responses to endotracheal intubation are 3 or 4 ng/ml during total intravenous anesthesia using propofol at an effect-site concentration of 4μg/ml. (Korean J Anesthesiol 2008; 54: 30∼6)

Predicted Effect-site Concentration of Remifentanil for Facilitating Laryngeal Mask Airway Insertion with Propofol Target-Controlled Infusion

Background: The addition of remifentanil during the propofol induced anesthesia facilitates the insertion of laryngeal mask airway (LMA) with minimal adverse hemodynamic disturbances. This study predicted the optimal effect-site concentration of remifentanil for LMA insertion with propofol target-controlled infusion (TCI). Methods: In 25 adults patients, aged 18-60 years, anesthesia was induced with propofol TCI at the effect-site concentration of 4μg/ml. Two minutes later, the predetermined effect-site concentration of remifentanil was started. The remifentanil concentration was determined using modified Dixon's up-and-down method (0.5 ng/ml as a step size). The first patient was tested at 2.0 ng/ml remifentanil. The insertion of LMA was attempted 3 min after remifentanil TCI began. The response of the patients to the insertion of LMA was classified as either 'movement' or 'no movement'. Results: The remifentanil concentration at which there was a 50% probability of successful LMA insertion (EC50) was 3.18 - 0.53 ng/ml. From probit analysis, the EC50 of remifentanil was 3.10 ng/ml (95% confidence limits, 2.55-4.11 ng/ml), and the EC95 was 4.31 ng/ml (95% confidence limits, 3.64-11.11 ng/ml). Conclusions: The predicted effect-site concentration of remifentanil for facilitating LMA insertion was 3.18 ng/ml in 50% of adults during propofol TCI at an effect-site concentration of 4μg/ml without premedication.