Optimal effect-site concentration of remifentanil for preventing cough during emergence from sevoflurane-remifentanil anaesthesia

Multimodal prevention of emergence cough following nasal endoscopic surgery under general anesthesia: a double-blind randomized trial

Purpose

Cough during emergence from anesthesia is a common problem and may cause adverse events. Monotherapy faces uncertainty in preventing emergence cough due to individual differences. We aimed to evaluate the efficacy and safety of multimodal intervention for preventing emergence cough in patients following nasal endoscopic surgery.

Methods

In this double-blind randomized trial, 150 adult patients undergoing nasal endoscopic surgery were randomly allocated into three groups. For the control group (n = 50), anesthesia was performed according to clinical routine, no intervention was provided. For the double intervention group (n = 50), normal saline 3 mL was sprayed endotracheally before intubation, 0.4 μg/kg dexmedetomidine was infused over 10 min after intubation, and target-controlled remifentanil infusion was maintained at an effect-site concentration of 1.5 ng/mL before extubation after surgery. For the multimodal intervention group (n = 50), 0.5% ropivacaine 3 mL was sprayed endotracheally before intubation, dexmedetomidine and remifentanil were administered as those in the double intervention group. The primary endpoint was the incidence of emergence cough, defined as single cough or more from end of surgery to 5 min after extubation.

Results

The incidences of emergence cough were 98% (49/50) in the control group, 90% (45/50) in the double group, and 70% (35/50) in the multimodal group, respectively. The incidence was significantly lower in the multimodal group than those in the control (relative risk 0.71; 95% CI 0.59 to 0.86; p < 0.001) and double (relative risk 0.78; 95% CI 0.63 to 0.95; p = 0.012) groups; the difference between the double and control groups was not statistically significant (relative risk 0.92; 95% CI 0.83 to 1.02; p = 0.20). The severity of sore throat was significantly lower in the multimodal group than that in the control group (median difference-1; 95% CI -2 to 0; p = 0.016). Adverse events did not differ among the three groups.

Conclusion

For adult patients undergoing endonasal surgery, multimodal intervention including ropivacaine topical anesthesia before intubation, dexmedetomidine administration after intubation, and remifentanil infusion before extubation after surgery significantly reduced emergence cough and was safe.

Comparison of dexmedetomidine and remifentanil on reducing coughing during emergence from anesthesia with tracheal intubation: A meta-analysis

Background: Dexmedetomidine and remifentanil are well known to suppress airway reflex during emergence from anesthesia, but which one is more effective is unclear. We conducted a meta-analysis to compare the effect of dexmedetomidine and remifentanil on reducing the occurrence of coughing.

Methods: We systematically searched PubMed, Embase, and Cochrane Library for randomized controlled trials (published between 1 January 1950, and 30 December 2021; no language restrictions) comparing dexmedetomidine infusion with remifentanil infusion. The primary endpoint was the incidence of moderate to severe coughing during the recovery period. The secondary endpoints were the time of recovery and extubation, and residual sedation. We assessed pooled data by using a random-effects model.

Results: Eight studies with 502 participants were included. The meta-analysis showed no statistically difference between dexmedetomidine and remifentanil in the occurrence of moderate to severe coughing during emergence from anesthesia (OR 1.45,95%CI 0.62–3.38), the extubation time (MD 0.93 min, 95%CI -0.28–2.14), and the residual sedation (OR 2.52, 95%CI 0.92–6.91). Compared with dexmedetomidine, the average recovery time of remifentanil was shorter (MD 3.88 min, 95%CI 1.01–6.75).

Conclusion: Dexmedetomidine and remifentanil infusion had no difference in the occurrence of moderate to severe coughing during emergence from anesthesia.

Clinical Trial Registration:https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42021239710

Comparison of remifentanil concentrations with and without dexmedetomidine for the prevention of emergence cough after nasal surgery: a randomized double-blinded trial

Background

Preventing emergence cough after nasal surgery is critical. Emergence cough can provoke immediate postoperative bleeding, which leads to upper airway obstruction. In the present study, we compared the effect-site concentration (Ce) of remifentanil to prevent emergence cough after propofol anesthesia for nasal surgery when remifentanil was or was not combined with dexmedetomidine.

Methods

Forty-seven patients with propofol-remifentanil anesthesia for nasal surgery were randomly assigned to a dexmedetomidine group (Group D, n = 23) or a saline group (Group S, n = 24). Group D and Group S were infused with dexmedetomidine (0.5 μg/kg) and saline, respectively, for 10 min before the completion of surgery. A predetermined Ce of remifentanil was infused until extubation. Remifentanil Ce to prevent cough in 50 and 95% of patients (EC₅₀ and EC₉₅) was estimated using modified Dixon’s up-and-down method and isotonic regression. Hemodynamic and recovery parameters were recorded.

Results

The EC₅₀ of remifentanil Ce was significantly lower in Group D than in Group S (2.15 ± 0.40 ng/mL vs. 2.66 ± 0.36 ng/mL, p = 0.023). The EC₉₅ (95% CI) of remifentanil Ce was also significantly lower in Group D [2.75 (2.67–2.78) ng/mL] than in Group S [3.16 (3.06–3.18) ng/mL]. Emergence and recovery variables did not differ between the two groups.

Conclusion

The remifentanil EC₅₀ to prevent cough after propofol-remifentanil anesthesia was significantly lower (approximately 19%) when a combination of remifentanil and 0.5 μg/kg dexmedetomidine was used than when remifentanil infusion alone was used in patients undergoing nasal surgery. Therefore, the Ce of remifentanil may be adjusted to prevent emergence cough when used in combination with dexmedetomidine.

Trial registration

ClinicalTrials.gov (NCT03622502, August 9, 2018).

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.

Antitussive effect of a magnesium infusion during anesthetic emergence in patients with double-lumen endotracheal tube: a randomized controlled trial

Background

A double-lumen endotracheal tube (DLT) inserted into the bronchus can stimulate the respiratory tracts, causing coughing. Opioids have been introduced to prevent emergence cough. However, the administration of a significant opioid dose at the end of surgery may result in undesirable events. Magnesium, common intracellular ion, suppress bronchial smooth muscle contraction and have antitussive effect. We investigated the antitussive effects of a magnesium infusion during anesthetic emergence in patients who underwent thoracic surgery requiring one-lung ventilation (OLV) anesthesia with a DLT.

Methods

One-hundred forty patients undergoing OLV anesthesia with a DLT were enrolled in this prospective, randomized double-blinded trial. In combination with a low dose of remifentanil, patients were randomly allocated to receive either magnesium sulphate (infusion of 15 mg/kg/hour after a single bolus of 30 mg/kg) or normal saline during the operation and emergence. Primary outcomes were the severity and incidence of cough during emergence.

Results

The severity of cough was assessed by the cough severity grading score: 0, no cough; 1, single cough; 2, cough persistence <5 seconds; 3, cough persistence ≥5 seconds. There was a significant difference in the severity score of cough between the groups [median (IQR): 2 (0 to 3) in control group vs. 0 (0 to 1) in magnesium group, P=0.003]. However, there was no significant difference in the overall incidence of cough between both groups [42 (64.6%) in control group vs. 31 (47.7%) in magnesium group, P=0.077].

Conclusions

Magnesium attenuated the severity of cough during emergence after OLV anesthesia using a DLT without adverse events.

Optimal effect-site concentration of propofol for tracheal suctioning during emergence from ophthalmic surgery

In ophthalmic surgery, coughing during emergence from general anesthesia may have a detrimental effect on intraocular pressure. Tracheal suction during emergence may elicit this reflex. The optimal effect-site concentration (EC) of propofol to prevent triggering of the cough reflex during tracheal suctioning is unknown. The aim of this study is to assess the optimal EC of propofol for tracheal suctioning during emergence in patients undergoing ophthalmic surgery.Twenty-one patients were enrolled, all of them American Society of Anesthesiologists (ASA) physical status I or II non-smokers undergoing ophthalmic surgery. Anesthesia was induced and maintained under total intravenous anesthesia using target-controlled infusion. During emergence from general anesthesia, tracheal suction was performed at different propofol concentrations as required for Dixon's up-and-down method with a step size of 0.2 μg/ml. A propofol concentration at which the cough reflex was not triggered during tracheal suctioning was considered successful.The EC50 of propofol for tracheal suction without cough was 1.4 μg/ml and the EC95 was 1.6 μg/ml.Tracheal suction may be accomplished without triggering the cough reflex when the propofol effect-site concentration is higher than 1.6 μg/ml.

A small dose of remifentanil pretreatment suppresses sufentanil-induced cough during general anesthesia induction: a randomized, double-blind, placebo-controlled trial

BACKGROUND

Intravenous use of sufentanil can elicit cough. This study aimed to evaluate the inhibitory effect of pre-injection of a mall dose of remifentanil on sufentanil-induced cough during the induction of general anesthesia.

METHODS

This prospective, randomized, controlled trial was conducted from January 10, 2019 to March 01, 2019. A total of 100 patients undergoing elective surgery under general anesthesia were enrolled, and at last 84 patients were included and randomly allocated into two equal size groups (n = 42): Patients in the Remifentanil group (R group) received an intravenous infusion of remifentanil 0.3 μg/kg (diluted to 2 ml) 1 min before sufentanil injection; patients in the Control group (C group) received 2 ml of normal saline (NS) at the same time point. Injections of patients in both groups were completed within 5 s. Then, sufentanil 0.5 μg/kg was injected within 5 s and the number of coughs that occurred within 1 min after sufentanil injection were recorded. One minute after sufentanil injection, etomidate 0.3 mg/kg and cisatracurium 0.15 mg/kg were given for general anesthesia induction irrespective of the presence or absence of cough. The mean arterial pressure (MAP) and heart rate (HR) at time points just before remifentanil pretreatment administration (T0), 3 min after administration (T1), 1 min after intubation (T2), and 3 min after intubation (T3) were recorded.

RESULTS

The incidence of cough in patients in the R group and C group was 4.8 and 31%, respectively. Compared with group C, the incidence and severity of cough in group R was significantly lower (P < 0.01). No significant differences were observed in MAP and HR at the time of general anesthesia induction between the two groups (P > 0.05).

CONCLUSION

Pretreatment with a small dose of remifentanil effectively and safely reduced the incidence and severity of cough induced by sufentanil during anesthesia induction and can be used as an alternative treatment to inhibit coughing caused by sufentanil.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR1900020587, registered date: January 9, 2019), http://www.chictr.org.cn.

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 transcutaneous electrical acupoint stimulation on the EC50 of remifentanil suppressing responses to tracheal extubation in elderly patients

Transcutaneous electrical acupoint stimulation (TEAS) is a emerging treatment which combines transcutaneous electrical nerve stimulation with traditional acupoint therapy. The present study was aimed to evaluate the effect of TEAS on the effective concentration (EC50) of remifentanil suppressing tracheal extubation response in elderly patients.Fifty-three patients undergoing spine surgery were randomly divided into 2 groups: control group (group C, n = 26) and transcutaneous electrical acupoint stimulation group (group TEAS, n = 27). The EC50 values for remifentanil TCI were determined using sequential method and probit analysis.The remifentanil EC50 of that suppressed responses to extubation during anesthetic emergence was 1.20 ng/mL in group TEAS, a value that was significantly lower than the 1.64 ng/mL needed by patients in group C.The TEAS can enhance the efficacy of remifentanil on suppressing responses to tracheal extubation in elderly patients, the EC50 of remifentanil can reduce approximately 27% compared with group C.

Comparison of sevoflurane and desflurane on effect-site concentration of remifentanil for preventing anesthetic emergence cough in elderly female patients undergoing laparoscopic cholecystectomy

Purpose

Among inhalational anesthetics, desflurane is widely believed to provoke upper airway irritation including coughing and laryngospasm. Remifentanil has been generally used to prevent cough due to its unique pharmacodynamics. However, there was no study that compared optimal remifentanil effect-site concentration (Ce) to prevent emergence cough according to the type of inhalational agent in elderly female patients. Thus, we investigated the Ce of remifentanil for preventing cough during emergence from sevoflurane and desflurane anesthesia in elderly female patients.

Methods

Forty-three female patients between 60 and 75 years of age undergoing laparoscopic cholecystectomy were randomly allocated to sevoflurane group (n=22) or desflurane group (n=21). The optimal remifentanil Ce using target-controlled infusion for 50% of patients (EC₅₀) and 95% of patients (EC₉₅) was assessed by Dixon’s up-and-down method or isotonic regression method with a bootstrapping approach.

Results

By Dixon’s up-and-down method, the EC₅₀ of remifentanil in sevoflurane group (2.08±0.47 ng/mL) was comparable with that in desflurane group (2.25±0.40 ng/mL) (P=0.385). The EC₅₀ (83% CIs) and EC₉₅ (95% CIs) by isotonic regression also did not show significant difference between two groups [2.06 (1.45–2.23) and 2.46 (2.35–2.48) ng/mL in sevoflurane group and 2.14 (1.45–2.56) and 2.88 (2.47–2.98) ng/mL in desflurane group, respectively].

Conclusion

There was no difference in the remifentanil Ce to prevent emergence cough between sevoflurane and desflurane anesthesia. Therefore, the clinicians may not need to adjust the remifentanil Ce to prevent emergence cough according to inhalational agents in elderly female patients.

Clinical and pharmacogenetics associated with recovery time from general anesthesia

AIM

Delayed recovery from general anesthesia is a well-known complication that requires predictive tools and approaches. This study aimed to determine significant factors associated with postanesthesia recovery and to develop an algorithm for estimating recovery time from general anesthesia.

MATERIALS & METHODS

The genotypes of patients were determined by SNaPshot or ARMS-qPCR. The algorithm was developed via machine-learning and tested by the worm plot.

RESULTS

Results showed that OPRM1 rs1799971 (p = 0.006) and ABCG2 rs2231142 (p = 0.041) were significantly associated with recovery time. Ten factors after random forest and stepwise selection were associated with recovery time. Ten factors after random forest and stepwise selection were associated with recovery time. Meanwhile, seven factors were associated with delayed recovery.

CONCLUSION

This study demonstrated that both clinical and pharmacogenetic data are significantly associated with recovery from general anesthesia and provide the basis for pre-emptive prediction tools.

Effects of age on effect-site concentration of remifentanil for suppressing anesthetic emergence cough in male patients undergoing laparoscopic cholecystectomy

Background

Remifentanil infusion during emergence lowers cough. Effect-site concentration (Ce) of remifentanil using target-controlled infusion (TCI) has been evaluated in previous studies. Recent studies revealed the existence of sex-related differences in remifentanil Ce in young and elderly patients. Thus, there was the need to re-evaluate the effect of age in single sex. We investigated the remifentanil Ce for suppressing emergence cough in young and elderly male patients and evaluated the age-related differences.

Patients and methods

In total, 25 young (ages between 20 and 50 years) and 24 elderly (ages between 65 and 75 years) male patients undergoing laparoscopic cholecystectomy were enrolled. Anesthesia was implemented with remifentanil using TCI and sevoflurane. The remifentanil Ce for suppressing emergence cough was estimated for each group using Dixon’s up-and-down method and isotonic regression method with a bootstrapping approach.

Results

The remifentanil Ce for suppressing emergence cough in 50% (EC₅₀) and 95% (EC₉₅) of the patients was comparable between the young and elderly patients. Isotonic regression demonstrated that the EC₅₀ (83% confidence interval [CI]) of remifentanil was 2.56 (2.39−2.75) ng/mL in the young patients and 2.15 (1.92−2.5) ng/mL in the elderly patients. The EC₉₅ (95% CI) of remifentanil was 3.33 (2.94−3.46) ng/mL in the young patients and 3.41 (3.18−3.48) ng/mL in the elderly patients. Dixon’s up-and-down method also demonstrated that the EC₅₀ was comparable between the two groups (2.69±0.32 ng/mL vs 2.39±0.38 ng/mL, P=0.132).

Conclusion

The remifentanil Ce for suppressing emergence cough following extubation during general anesthesia was comparable between young and elderly male patients. It indicates that age-related differences in remifentanil requirement for suppressing emergence cough did not exist in male sex.

Predicting effective remifentanil concentration in 95% of patients to prevent emergence cough after laryngomicroscopic surgery

Smooth emergence or cough prevention is a clinically important concern in patients undergoing laryngomicroscopic surgery (LMS). The purpose of this study was to estimate the effective concentration of remifentanil in 95% of patients (EC95) for the prevention of emergence cough after LMS under propofol anesthesia using the biased coin design (BCD) up-down method.A total of 40 adult patients scheduled to undergo elective LMS were enrolled. Anesthesia induction and maintenance were performed with target-controlled infusion of propofol and remifentanil. Effective effect-site concentration (Ce) of remifentanil in 95% of patients for preventing emergence cough was estimated using a BCD method (starting from 1 ng/mL with a step size of 0.4 ng/mL). Hemodynamic and recovery profiles were observed after anesthesia.According to the study protocol, 20 patients were allocated to receive remifentanil Ce of 3.0 ng/mL, and 20 patients were assigned to receive lower concentrations of remifentanil, from 1.0 to 2.6 ng/mL. Based on isotonic regression with a bootstrapping method, EC95 (95% CI) of remifentanil Ce for the prevention of emergence cough from LMS was found to be 2.92 ng/mL (2.72-2.97 ng/mL). Compared with patients receiving lower concentrations of remifentanil, the incidence of hypoventilation before extubation and extubation time were significantly higher in those receiving remifentanil Ce of 3.0 ng/mL. However, hypoventilation incidence after extubation and staying time in the recovery room were comparable between the 2 groups.Using a BCD method, the EC95 of remifentanil Ce for the prevention of emergence cough was estimated to be 2.92 ng/mL (95% CI: 2.72-2.97 ng/mL) after LMS under propofol anesthesia.

Sex-related differences in effect-site concentration of remifentanil for preventing anesthetic emergence cough in elderly patients

Purpose

Cough on anesthetic emergence should be prevented considering its dangerous complications. Target-controlled infusion (TCI) of remifentanil can reduce emergence cough effectively, and sex-related differences in effect-site concentration (Ce) of remifentanil have been evaluated in young patients. In this study, we determined the Ce of remifentanil for preventing emergence cough following extubation in male and female elderly patients and evaluated the sex-related difference.

Patients and methods

Twenty-three male and 22 female elderly patients aged between 60 and 75 years were enrolled. Anesthesia was maintained with sevoflurane and remifentanil TCI. The Ce of remifentanil for preventing emergence cough was determined for each sex using isotonic regression method with a bootstrapping approach, following Dixon’s up-and-down method.

Results

The Ce of remifentanil for preventing emergence cough in 50% (EC₅₀) and 95% (EC₉₅) of the population was significantly lower in females than in males. Isotonic regression revealed the EC₅₀ (83% confidence interval [CI]) of remifentanil was 1.67 (1.55–1.83) ng/mL in females and 2.60 (2.29–2.91) ng/mL in males. The EC₉₅ (95% CI) of remifentanil was 2.30 (2.02–2.62) ng/mL in females and 3.41 (3.27–3.58) ng/mL in males. Dixon’s up-and-down method indicated that the mean EC₅₀ in females was lower than in males (1.56±0.26 ng/mL vs 2.56±0.37 ng/mL, P<0.001).

Conclusion

The remifentanil requirement for preventing emergence cough was lower in female than in male elderly patients, indicative of sex-related differences in Ce of remifentanil. Sex should be considered when using remifentanil TCI for preventing emergence cough in elderly patients.

Correlation of MDR1 gene polymorphisms with anesthetic effect of sevoflurane-remifentanil following pediatric tonsillectomy

BACKGROUND

The motive of this study was to investigate the collaboration between MDR1 gene polymorphisms and anesthetic effects following pediatric tonsillectomy.

METHODS

All together 178 children undergoing tonsillectomy with preoperative sevoflurane-remifentanil anesthesia were selected. In order to determine MDR1 gene polymorphisms of 3435C > T, 1236C > T, and 2677G > T/A, polymerase chain reaction-restriction fragment length polymorphism was used. Mean arterial pressure (MAP), diastolic blood pressure (DBP), systolic blood pressure (SBP), and heart rate (HR) at T0 (5 mins after the repose), T1 (0 min after tracheal intubation), T2 (5 mins after the tracheal intubation), T3 (0 min after the tonsillectomy), T4 (0 min after removal of the mouth-gag) and T5 (5 min after the extubation) were observed. The visual analog scale (VAS), the face, legs, activity, cry, and consolability (FLACC) pain assessment, and Ramsay sedation score were recorded after the patients gained consciousness. The adverse reactions were also observed.

RESULTS

As compared to the CT + TT genotype of MDR1 1236C > T, the time of induction, respiration recovery, eye-opening, and extubation of children with the CC genotype was found to be shorter (all P <.05); the MAP, SBP, DBP, and HR were significantly reduced at T5 in children that possessed the CC genotype (all P <.05), the VAS at postoperative 1, 2, 4, and 8 hours and Ramsay sedation score were decreased, while the FLACC score increased (all P <.05). It was found that the adverse reaction rate was lower in children bearing the CC genotype (P <.05).

CONCLUSION

It could be concluded that anesthetic effect in patients with the MDR1 1236C > T CC genotype was found to be superior to those carrying the CT + TT genotype.

Swallowing action immediately before intravenous fentanyl at induction of anesthesia prevents fentanyl-induced coughing: a randomized controlled study

PURPOSE

Fentanyl is a strong µ-opioid analgesic which attenuates the stimulation of surgical invasion and tracheal intubation. However, intravenous fentanyl often induces coughing [fentanyl-induced coughing (FIC)] during induction of anesthesia. We found that the swallowing action, when requested at induction of anesthesia, attenuated FIC. In the current study, we investigated the relationship between the occurrence of FIC and the swallowing action.

METHODS

The study included American Society of Anesthesiologists physical status I or II patients, aged 20-64 years, who were undergoing elective surgery. They were divided into two groups-one group was urged to perform the swallowing action immediately before intravenous fentanyl (S group), and the other group performed no swallowing action (non-S group). The patients first received intravenous fentanyl and were observed for 90 s. Each patient's background, dose of fentanyl and occurrence of coughing were investigated from their records and a motion picture recording. The incidence of FIC was evaluated by chi-squared test, and severity was tested by Wilcoxon rank-sum test. P < 0.05 was considered statistically significant.

RESULTS

The incidence of FIC in the S group and non-S group was 14.0 and 40.4%, respectively. The risk of FIC was reduced in the S group by 75%; risk ratio (95% confidence interval) was 0.35 (0.20, 0.60). The number of coughs in the S group were less than in the non-S group (P < 0.001).

CONCLUSION

The swallowing action immediately before intravenous fentanyl may be a simple and clinically feasible method for preventing FIC effectively. Clinical trial number: UMIN000012086 ( https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=Rn000014126&language=J ).

Comparison of Dexmedetomidine and Remifentanil on Airway Reflex and Hemodynamic Changes during Recovery after Craniotomy

PURPOSE

During emergence from anesthesia for a craniotomy, maintenance of hemodynamic stability and prompt evaluation of neurological status is mandatory. The aim of this prospective, randomized, double-blind study was to compare the effects of dexmedetomidine and remifentanil on airway reflex and hemodynamic change in patients undergoing craniotomy.

MATERIALS AND METHODS

Seventy-four patients undergoing clipping of unruptured cerebral aneurysm were recruited. In the dexmedetomidine group, patients were administered dexmedetomidine (0.5 μg/kg) for 5 minutes, while the patients of the remifentanil group were administered remifentanil with an effect site concentration of 1.5 ng/mL until endotracheal extubation. The incidence and severity of cough and hemodynamic variables were measured during the recovery period. Hemodynamic variables, respiration rate, and sedation scale were measured after extubation and in the post-anesthetic care unit (PACU).

RESULTS

The incidence of grade 2 and 3 cough at the point of extubation was 62.5% in the dexmedetomidine group and 53.1% in the remifentanil group (p=0.39). Mean arterial pressure (p=0.01) at admission to the PACU and heart rate (p=0.04 and 0.01, respectively) at admission and at 10 minutes in the PACU were significantly lower in the dexmedetomidine group. Respiration rate was significantly lower in the remifentanil group at 2 minutes (p<0.01) and 5 minutes (p<0.01) after extubation.

CONCLUSION

We concluded that a single bolus of dexmedetomidine (0.5 μg/kg) and remifentanil infusion have equal effectiveness in attenuating coughing and hemodynamic changes in patients undergoing cerebral aneurysm clipping; however, dexmedetomidine leads to better preservation of respiration.

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.

Determination of EC95 of remifentanil for smooth emergence from propofol anesthesia in patients undergoing transsphenoidal surgery

BACKGROUND

In patients undergoing pituitary surgery using a transsphenoidal approach, anesthesia emergence should be smooth with minimal coughing. Recent studies demonstrated that a target-controlled infusion of remifentanil effectively suppresses coughing induced by the endotracheal tube. We investigated the EC95 of remifentanil for smooth emergence without coughing from propofol anesthesia in patients undergoing transsphenoidal hypophysectomy.

MATERIALS AND METHODS

A total of 41 patients undergoing transsphenoidal hypophysectomy, aged 20 to 65 years, with an ASA physical status of I or II, were enrolled. For all participants, anesthesia was induced and maintained with a target-controlled infusion of remifentanil and propofol using predicted effect-site concentration (Ce). A biased coin design up-and-down sequential allocation and isotonic regression method were used to determine the remifentanil EC95 to prevent emergence coughing. In addition, we observed recovery profiles after anesthesia.

RESULTS

According to the study design, 19 patients received remifentanil 2.6 ng/mL Ce and 22 patients received a lower Ce, ranging from 1.0 to 2.2 ng/mL. The EC95 of remifentanil to prevent coughing was estimated as 2.51 ng/mL (95% confidence interval, 2.28-2.57 ng/mL). Despite the exclusion of 1 case because of delayed emergence, 17 of 18 patients receiving 2.6 ng/mL of remifentanil had bradypnea (<10 breaths/min) until 3 minutes after extubation. However, end-tidal carbon dioxide was maintained below 55 mm Hg during anesthetic emergence and respiratory rate recovered within 20 minutes of admission to the postanesthetic care unit.

CONCLUSIONS

The EC95 of remifentanil for smooth emergence from anesthesia was 2.51 ng/mL after transsphenoidal hypophysectomy.

Comparison of emergence after deep extubation using desflurane or desflurane with remifentanil in patients undergoing general anesthesia: a randomized trial

STUDY OBJECTIVE

To compare recovery times and respiratory complications during emergence after deep extubation using either desflurane alone or a lower concentration of desflurane with remifentanil.

DESIGN

Prospective randomized double-blind clinical trial.

SETTING

Intraoperative.

PATIENTS

A total of 62 patients between the ages of 20 and 60 years with American Society of Anesthesiologists class I or II and who underwent low- to intermediate-risk surgery of 2- to 4-hour duration were enrolled.

INTERVENTIONS

Randomly assigned either 1.5 minimum alveolar concentration desflurane (group D; n = 31) or 1.0 minimum alveolar concentration of desflurane and 1.0 ng/mL effect-site concentration of remifentanil (group DR; n = 31).

MEASUREMENTS

Recovery times, from the time of extubation to the time when the patients could breathe without assistance, were awake enough to maintain the airway independently, and exited the recovery room, as well as respiratory complications were compared between the groups.

MAIN RESULTS

Recovery times were significantly reduced in the group DR (P < .001). The incidence of respiratory complications was also lower in group DR than in group D (48% vs 3.8%; P < .001).

CONCLUSIONS

The combined use of remifentanil while lowering the concentration of desflurane improves recovery profiles during emergence after deep extubation.

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

PURPOSE

This 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 METHODS

This 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.

RESULTS

The 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).

CONCLUSION

Maintaining 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.

Does the type of anesthetic agent affect remifentanil effect-site concentration for preventing endotracheal tube-induced cough during anesthetic emergence? Comparison of propofol, sevoflurane, and desflurane

STUDY OBJECTIVE

To investigate whether the type of anesthetic agent administered affects the antitussive effect of remifentanil.

DESIGN

Prospective randomized study.

SETTING

Operating room of a university hospital.

PATIENTS

78 ASA physical status 1 and 2 women, aged 20 to 65 years, who were scheduled to undergo a thyroidectomy.

INTERVENTIONS

Patients were randomly assigned to three groups to receive anesthesia with propofol (Group P), sevoflurane (Group S), or desflurane (Group D). The main anesthetics were titrated to maintain a target Bispectral Index for hypnosis of 40 to 60. Remifentanil was administered via effect-site target-controlled infusion (TCI). To determine the effective remifentanil effect-site concentration (Ce) to suppress coughing in each group, the up-and-down sequential allocation design was used.

MEASUREMENTS

The half maximal effective concentration (EC50) values of remifentanil for preventing coughing in the groups were estimated using isotonic regression and compared among the groups.

MAIN RESULTS

The EC50 of remifentanil for cough suppression in Group P [1.60 ng/mL (98.3% CI, 0.92-1.75 ng/mL)] was statistically lower than in Group D [1.96 ng/mL (98.3% CI, 1.81-2.50 ng/mL)]. The EC50 in Group S was 1.75 ng/mL (98.3% CI, 1.39-2.13 ng/mL), which was higher than in Group P and lower than in Group D, but did not differ significantly from either group.

CONCLUSIONS

Remifentanil administration for cough suppression during emergence should be customized to the anesthetic agent.

Dexmedetomidine does not reduce emergence agitation in adults following orthognathic surgery

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Sex differences in remifentanil requirements for preventing cough during anesthetic emergence

PURPOSE

Target-controlled infusion (TCI) of remifentanil can suppress coughing during emergence from general anesthesia; nevertheless, previous studies under different clinical conditions recommend significantly different effective effect-site concentrations (effective Ce) of remifentanil for 50% of patients (EC₅₀). The differences among these studies include type of surgery and patient sex. In recent years, study of sex differences in regards to anesthetic pharmacology has drawn greater interest. Accordingly, we attempted to determine the effective Ce of remifentanil for preventing cough for each sex under the same clinical conditions.

MATERIALS AND METHODS

Twenty female and 25 male ASA physical status I-II grade patients between the ages of 20 and 46 years who were undergoing thyroidectomy were enrolled in this study. The effective Ce of remifentanil for preventing cough was determined for each sex using the isotonic regression method with a bootstrapping approach, following Dixon's up-and-down method.

RESULTS

Isotonic regression with a bootstrapping approach revealed that the estimated EC₅₀ of remifentanil for preventing coughing during emergence was significantly lower in females {1.30 ng/mL [83% confidence interval (CI), 1.20-1.47 ng/mL]} than in males [2.57 ng/mL (83% CI, 2.45-2.70 ng/mL)]. Mean EC₅₀ in females was also significantly lower than in males (1.23±0.21 ng/mL vs. 2.43±0.21 ng/mL, p<0.001). Mean arterial pressure, heart rate, and respiratory rate over time were not significantly different between the sexes.

CONCLUSION

When using remifentanil TCI for cough prevention during anesthetic emergence, patient sex should be a considered for appropriate dosing.

Prevention of perioperative and anesthesia-related complications in facial cosmetic surgery

Although office-based anesthesia for facial cosmetic surgery remains remarkably safe, no anesthesia or sedation performed outside the operating room should be considered minor. Proper organization, preparation, and patient selection, close collaboration with the surgeon, and expert and effective anesthesia care will increase patient safety and improve perioperative outcomes and patient satisfaction. This article presents a comprehensive overview of anesthesia in terms of facial plastic surgery procedures, beginning with a broad review of essentials and pitfalls of anesthesia, followed by details of specific anesthetic agents, their administration, mechanism of action, and complications.

Effect-site concentration of remifentanil to prevent cough after laryngomicrosurgery

OBJECTIVES/HYPOTHESIS

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.

STUDY DESIGN

Prospective, randomized, controlled trial.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

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.

Comparison of the antitussive effect of remifentanil during recovery from propofol and sevoflurane anaesthesia

This prospective randomised study compared the antitussive effect of remifentanil during recovery from either propofol or sevoflurane anaesthesia. Seventy-four female patients undergoing thyroidectomy were anaesthetised with either propofol and remifentanil or sevoflurane and remifentanil. During recovery, remifentanil was maintained at an effect-site concentration of 2 ng.ml(-1) until extubation and the occurrence of coughing, haemodynamic parameters and recovery profiles were compared between the two groups. During recovery, neither the incidence nor the severity of cough (incidence 20% with propofol; 24% with sevoflurane, p = 0.77), nor the haemodynamic parameters were different between the two groups. Time to awakening and time to extubation were significantly shorter in the propofol group (4.7 min, 6.1 min min, respectively) compared with the sevoflurane group (7.9 min and 8.9 min respectively) (p < 0.001 and p = 0.002, respectively). An effect-site concentration of 2 ng.ml(-1) of remifentanil was associated with smooth emergence from both propofol and sevoflurane anaesthesia.

Smooth emergence in men undergoing nasal surgery: the effect site concentration of remifentanil for preventing cough after sevoflurane-balanced anaesthesia

BACKGROUND

Suppression of cough during emergence after nasal surgery is practical to avoid bleeding from the surgical site. Previously recommended effect-site concentration of remifentanil for preventing cough during emergence is restricted to female patients undergoing thyroid surgery, so we evaluated effective effect-site concentration of remifentanil for preventing cough during emergence for men undergoing nasal surgery.

METHODS

Twenty-four American Society of Anesthesiologists (ASA) physical status I or II, between the ages of 18 and 60 years old, non-smoker male patients undergoing nasal surgery were enrolled in this study. The effective effect-site concentration for 50% of patients (EC(50) ) and and that for 95% of patients (EC(95) ) of remifentanil for preventing cough were determined by Dixon's up-and-down method and by isotonic regression method with a bootstrapping approach. Haemodynamic variables were compared in patients with cough and without cough during emergence.

RESULTS

The EC(50) of remifentanil for preventing cough during emergence by Dixon's method was 2.17 ng/ml [standard deviation (SD) 0.38]. The estimated EC(50) and EC(95) of remifentanil using isotonic regression model with a bootstrapping approach were 2.35 ng/ml [95% confidence interval (CI) 1.89-2.66] and 2.94 ng/ml (95% CI 2.83-2.97), respectively. Mean arterial pressure and heart rate were significantly higher in patients with cough during emergence. Three out of 13 patients that received more than 2.5 ng/ml of remifentanil experienced a brief episode of bradypnea.

CONCLUSIONS

The EC(95) of remifentanil for preventing cough in men after nasal surgery is 2.94 ng/ml. Remifentanil target-controlled infusion with established effect-site concentration could suppress cough in men during emergence from sevoflurane anaesthesia after nasal surgery, though reversible respiratory depression might arise at high effect-site concentration of remifentanil.

Target controlled remifentanil infusion for smooth laryngeal mask airway removal during emergence from desflurane-remifentanil anesthesia

PURPOSE

Administration of remifentanil can be a reliable method for preventing airway reflex responses during emergence. We therefore investigated the effect of maintaining target controlled infusion (TCI) of remifentanil for smooth cLMA removal during emergence from desflurane-remifentanil anaesthesia.

METHODS

Forty-one patients undergoing uretero-renoscopy under general anesthesia with desflurane and at 1-4 ng/ml TCI remifentanil infusion were randomly assigned to a control group (n = 20) or a remifentanil group (n = 21). At the end of the surgery, desflurane and remifentanil infusion were stopped in group C and remifentanil was maintained at the effect-site concentration of 1.5 ng/ml TCI in group R. When LMA removal was accomplished without coughing, teeth clenching, gross purposeful movements, breath holding, laryngospasm, and desaturation to SpO(2) less than 90%, removal was regarded as smooth (successful). The emergence and recovery profiles were also evaluated.

RESULTS

The incidence and number of complications (coughing, teeth clenching, gross purposeful movements, breath holding, laryngospasm, desaturation to SpO(2) <90%) were significantly higher in the control group than in the remifentanil group (p = 0.002).

CONCLUSION

Maintaining effect-site TCI of remifentanil at 1.5 ng/ml during emergence from anaesthesia enabled smooth removal of cLMA without any delay in recovery time.

Comparison of the Optimal Effect-Site Concentrations of Remifentanil for Preventing Cough during Emergence from Desflurane or Sevoflurane Anaesthesia

OBJECTIVE: To compare the effect-site concentrations of remifentanil target-controlled infusion (TCI) that produced 50% and 95% of the maximal effect (EC50 and EC95, respectively) for preventing cough during emergence from desflurane or sevoflurane anaesthesia, in patients undergoing elective thyroidectomy. METHODS: Adults undergoing elective thyroidectomy were randomized to receive anaesthesia with desflurane or sevoflurane. The EC50 and EC95 values for remifentanil TCI were determined using Dixon's up-and-down method and probit analysis with sigmoid curve. RESULTS: In total, 48 patients aged 20 – 64 years were enrolled in the study. The EC50 ± SD of remifentanil TCI, determined by Dixon's up-and-down method, were 1.54 ± 0.70 and 1.11 ± 0.24 ng/ml for desflurane and sevoflurane, respectively. The EC95 of remifentanil TCI, analysed by probit analysis, were 2.88 ng/ml and 2.29 ng/ml for desflurane and sevoflurane, respectively. The effect-site concentration of remifentanil TCI for preventing cough during emergence from desflurane anaesthesia was not significantly higher than that observed for sevoflurane. CONCLUSIONS: During emergence from anaesthesia, variations in effect-site concentrations of remifentanil for preventing cough are of limited importance as they do not generate significant differences in results.

Dose-dependent attenuation by fentanyl on cough during emergence from general anesthesia

BACKGROUND

Although fentanyl suppresses tracheal tube-induced cough during anesthetic recovery, it has not been proven if its antitussive effect is dose dependent and complication free. The purpose of this study is to evaluate the relationship between fentanyl doses and cough suppression during emergence from sevoflurane anesthesia.

METHODS

Sixty patients undergoing thyroidectomy were randomly allocated to one of four groups (F0, F1, F1.5, and F2) according to the fentanyl dose (0 mcg/kg, 1 mcg/kg, 1.5 mcg/kg, or 2 mcg/kg). Fentanyl was administered immediately after sevoflurane discontinuation. Coughing was assessed throughout the periextubation period. The relationship between fentanyl dose and incidence of cough was analyzed using Cochran-Armitage trend test. Incidence of more than 30% elevation of mean arterial pressure (MAP) and heart rate (HR), awakening time, extubation time, and respiratory rate after extubation were recorded and compared using Mantel-Haenszel chi-square test and one-way analysis of variance.

RESULTS

Fentanyl suppressed emergence cough in a dose-related manner (P = 0.002), and the ED(50) and ED(90) were 1.1 mcg/kg and 2.1 mcg/kg, respectively. The higher dose of fentanyl further reduced the number of patient with MAP and HR elevation (P = 0.003 and 0.005, respectively). Awakening time (8.4 ± 1.9 min) in F2 was comparable with that in F1 and F1.5. Respiratory rate (9 ± 2 bpm) and extubation time (11.9 ± 1.8 min) in F2 were only different from those in F0 (13 ± 3 bpm and 10.4 ± 1.1 min, respectively).

CONCLUSIONS

Fentanyl suppressed cough in a dose-related manner during recovery from general sevoflurane anesthesia, and 2 mcg/kg may be considered as a proper dose.