Propofol requirement for insertion of I-gel versus laryngeal mask airway: A comparative dose finding study using Dixon's up-and-down method

Effective bolus dose of remimazolam for i-gel® insertion in nonparalyzed patients: a dose-finding study

PURPOSE

Remimazolam is a recently developed ultra-short-acting benzodiazepine used for anesthesia induction and maintenance. Nevertheless, the effective bolus dose of remimazolam for i-gel® (Intersurgical Ltd., Wokingham, Berkshire, UK) insertion without the use of neuromuscular blocking agents (NMBAs) has not been well established.

METHODS

This study included 25 adult patients scheduled for surgery under general anesthesia who were eligible for i-gel use. Anesthesia was induced with predetermined bolus doses of remimazolam, starting at 0.3 mg·kg-1 for the first patient, without the use of NMBAs. All patients concurrently received remifentanil using target-controlled infusion (TCI) at a fixed effect-site concentration (Ce) of 3.0 ng·mL-1. Insertion of the i-gel was attempted 90 sec after remimazolam administration, and insertion conditions were assessed. Subsequent doses of remimazolam were decreased or increased by 0.05 mg·kg-1, depending on the success or failure of i-gel insertion.

RESULTS

The mean (standard deviation) 50% effective dose (ED50) of a remimazolam bolus for successful i-gel insertion as determined by the modified Dixon's up-and-down method was 0.100 (0.027) mg·kg-1. The ED50 and ED95 estimated by isotonic regression were 0.111 (83% confidence interval [CI], 0.096 to 0.131) mg·kg-1 and 0.182 (95% CI, 0.144 to 0.195) mg·kg-1, respectively. None of the patients required treatment for hypotension or bradycardia during anesthesia induction.

CONCLUSION

Based on the ED95 of remimazolam bolus dose determined in our study, we recommend using 0.182 mg·kg-1 of remimazolam in combination with remifentanil TCI at a Ce of 3.0 ng·mL-1 for successful i-gel insertion without NMBAs in adult patients. This regimen seems effective with a low risk of hemodynamic instability during anesthesia induction.

STUDY REGISTRATION

ClinicalTrials.gov ( NCT05298228 ); first submitted 6 March 2022.

Predicted effect-site concentrations of remimazolam for i-gel insertion: a prospective randomized controlled study

This study is the first to report 50% and 95% effect-site concentrations (EC50 and EC95, respectively) of the new short-acting benzodiazepine, remimazolam, for the successful insertion of i-gels with co-administration of fentanyl. Thirty patients (38 ± 5 years old, male/female = 4/26) were randomly assigned into five groups to receive one of five different remimazolam doses (0.1, 0.15, 0.2, 0.25, and 0.3 mg/kg bolus followed by infusion of 1, 1.5, 2, 2.5, and 3 mg/kg/h, respectively, for 10 min), which were designed to maintain a constant effect-site concentration of remimazolam at the time of i-gel insertion. At 6 min after the start of remimazolam infusion, all patients received 2 µg/kg fentanyl. i-gel insertion was attempted at 10 min and the success or failure of insertion were assessed by the patient response. Probit analysis was used to estimate the EC50 and EC95 values of remimazolam with 95% confidence intervals (CIs). In the five remimazolam dose groups, two, two, four, five, and six of the six patients in each group had an i-gel successfully inserted. Two patients in the lowest remimazolam dose group were conscious at the time of i-gel insertion and were counted as failures. The EC50 and EC95 values of remimazolam were 0.88 (95% CI, 0.65-1.11) and 1.57 (95% CI, 1.09-2.05) µg/ml, respectively. An effect-site concentration of ≥ 1.57 µg/ml was needed to insert an i-gel using remimazolam anesthesia, even with 2 µg/kg fentanyl. Trial registration: The study was registered in Japan Registry of Clinical Trials on 19 April 2021, Code jRCTs041210009.

Laryngeal mask airway versus endotracheal intubation as general anesthesia airway managements for atrial fibrillation catheter ablation: a comparative analysis based on propensity score matching

BACKGROUND

The current evidence on the use of laryngeal mask airway (LMA) as an airway management technique for general anesthesia (GA) during atrial fibrillation (AF) catheter ablation (CA) is insufficient. This study aims to compare the feasibility, safety, and clinical benefits of LMA and endotracheal intubation (ETI) for airway management in AF CA.

METHODS

One hundred fifty-two consecutive patients with AF who underwent CA under GA were included and divided into two groups based on different airway management methods (66 in the LMA group, 86 in the ETI group). After propensity score matching, a final analysis cohort of 132 patients was obtained to compare procedural parameters, adverse events, and prognosis between the two groups.

RESULTS

The LMA group exhibited significantly shorter total procedural time (p = 0.039), anesthesia induction time (p = 0.015), and recovery time (p = 0.006) compared to the ETI group. The mean arterial pressure (MAP) and heart rate were significantly lower in the LMA group during extubation and 1-min post-extubation (p < 0.05). Furthermore, the LMA group demonstrated lower MAP levels during intubation (p = 0.029). The incidences of intraoperative hypotension (p = 0.017) and bradycardia (p = 0.032) were significantly lower in the LMA group. The incidences of delayed recovery or delirium (p = 0.027), laryngeal or airway injury (p = 0.016), cough or bucking (p = 0.001), and sore throat (p < 0.001) were significantly lower in the LMA group. There were no statistically significant differences in catheter stability parameters and sinus rhythm maintenance rates between the two groups (p > 0.05).

CONCLUSION

LMA is feasible, safe, and effective in AF CA as an optimized airway management technique for GA.

High daily caffeine intake is associated with lower propofol requirements for anesthetic induction

Background and Aims

There is significant interindividual variation in the dose of propofol required for anesthetic induction. Factors dictating this are poorly described, but understanding them would be useful for anesthetic drug dosing. It has been shown in rats and recently in humans that caffeine administration accelerates recovery from anesthesia, but no study has assessed the effect on anesthetic induction.

Material and Methods

Forty American Society of Anesthesiologists (ASA)-I, 18-65-year-old patients, undergoing day case general anesthesia with propofol and fentanyl took part in this observational study. Total daily caffeine intake (mg) was estimated using the caffeine assessment tool and caffeine content values from the US Department of Agriculture National Nutrient Database. Pharmacokinetic-pharmacodynamic modeling was used to estimate the effect site concentration of propofol at loss of consciousness (Ce(p) LOC).

Results

Median (interquartile range [IQR]) daily caffeine intake was 106 (51-193) mg. Ce(p) LOC was lower in those with caffeine intake greater than or equal to the median of 106 mg (median (IQR) = 0.64 μg/ml (0.51-0.72) vs. 0.70 μg/ml (0.57-1.10), P = 0.04). The effect was robust when controlling for weight-adjusted fentanyl dose, age, smoking status, and alcohol intake (F (1,34) = 4.66, P = 0.04).

Conclusion

High daily caffeine intake is associated with lower propofol requirements for day case anesthetic induction. We propose that high daily caffeine intake may cause lower arousal levels prior to surgery due to a relative caffeine deficit caused by being nil by mouth. As such, assessment of daily caffeine intake preoperatively may aid anesthetic drug dosing.

Remimazolam dose for successful insertion of a supraglottic airway device with opioids: a dose-determination study using Dixon's up-and-down method

PURPOSE

Remimazolam, an ultra-short-acting benzodiazepine, was recently approved in numerous jurisdictions as an induction drug for general anesthesia. We aimed to determine the doses of remimazolam that would allow placement of a supraglottic airway device (SGD) in 50% and 95% of nonparalyzed patients (ED50 and ED95).

METHODS

In this prospective study, 30 American Society of Anesthesiology Physical Status I-II grade female patients scheduled for hysteroscopic surgery were enrolled. Anesthesia was induced with 1 μg·kg-1 of fentanyl and continuous infusion of remimazolam without neuromuscular blockade. An i-gel® SGD was inserted 2.5 min after the start of remimazolam infusion. We used Dixon's up-and-down method and isotonic regression to determine the ED50 and ED95 of remimazolam for insertion of an SGD.

RESULTS

Twenty-eight patients were included in the final analysis. The ED50 and ED95 of remimazolam required for successful i-gel insertion were 8.8 mg·kg-1·hr-1 (95% confidence interval [CI], 6.3 to 10.6) and 10.7 mg·kg-1·hr-1 (95% CI, 10.6 to 11.7), respectively. A nonfully relaxed jaw was found in 7/13 patients (54%) in the success group and 14/15 patients (93%) in the failure group (difference in proportions, 40%; 95% CI, 7 to 65; P = 0.02). Bucking or other movements during SGD insertion only occurred in the failure group (11/15, 73%).

CONCLUSION

In 95% of nonparalyzed female patients undergoing hysteroscopy, 10.7 mg·kg-1·hr-1 of remimazolam with 1 μg·kg-1 of fentanyl facilitates i-gel insertion. Remimazolam showed a high incidence of poor jaw relaxation and bucking or other movements during SGD insertion.

STUDY REGISTRATION

Clinical Trial Registry of the Republic of Korea (KCT0006527, https://cris.nih.go.kr ; registered 1 September 2021; principal investigator: Ji Seon Jeong).

Comparison of the ED50 propofol requirements during the insertion of laryngeal mask airway Ambu AuraFlex with Ambu AuraOnce in children undergoing strabismus surgery

WHAT IS KNOWN AND OBJECTIVE

Optimal airway management is crucial in strabismus surgery due to the inaccessibility of the airway throughout the procedure. Laryngeal mask airway offers advantages over tracheal intubation in ophthalmic surgery as it does not increase the intraocular pressure. The purpose of this study was to determine the median effective dose of propofol required, when combined with 0.2 µg/kg of sufentanil, for smooth insertion of Ambu AuraFlex in the first attempt in children undergoing strabismus surgery, and to compare it with that for Ambu AuraOnce.

METHODS

Forty-three paediatric patients undergoing strabismus surgery under general anaesthesia were recruited. For induction, the initial dosage of propofol was 2 mg/kg in the AuraOnce group or 3 mg/kg in the AuraFlex group. In accordance with Dixon's up-and-down method, the dose of propofol for consecutive patients in each group was adjusted in increments or decrements of 0.25 mg/kg based on the previous patient's "three-point, six-category scale" response to the first attempt of insertion of the randomized device. Insertion of the device was attempted when the bispectral index was ≤60 for 5 s after propofol administration without the use of neuromuscular blocking agents.

RESULTS AND DISCUSSION

The median effective dose (95% confidence interval) of propofol was significantly lower in the Ambu AuraOnce group than in the Ambu AuraFlex group (1.92 [1.50-2.32] mg/kg vs. 2.98 [2.49-3.94] mg/kg; p = 0.002). The incidence of dislodgement of the device was significantly higher with the use of the Ambu AuraOnce than with the use of AuraFlex (p = 0.023), whereas insignificant differences were observed between the two groups in the incidence of other perioperative adverse events.

WHAT IS NEW AND CONCLUSION

Ambu AuraFlex requires a significantly higher dose of propofol for insertion and provides more effective and stable airway management in strabismus surgery than AuraOnce.

Effect-site concentration of remifentanil for smooth emergence from sevoflurane anesthesia in patients undergoing endovascular neurointervention

During emergence from general anesthesia, coughing caused by the endotracheal tube frequently occurs and is associated with various adverse complications. In patients undergoing endovascular neurointervention, achieving smooth emergence from general anesthesia without coughing is emphasized since coughing is associated with intracranial hypertension. Therefore, the up-and-down method was introduced to determine the effective effect-site concentration (Ce) of remifentanil to prevent coughing in 50% and 95% (EC₅₀ and EC₉₅) of patients during emergence from sevoflurane anesthesia for endovascular neurointervention. A total of 43 participants, American Society of Anesthesiologists class I or II participants, aged from 20 to 70 years who were undergoing endovascular neurointervention through transfemoral catheter for cerebrovascular disease were enrolled. Using the up-and-down method with isotonic regression, the EC₅₀ and EC₉₅ of remifentanil to prevent coughing during emergence from sevoflurane anesthesia were determined. We also investigated differences of hemodynamic and recovery profiles between the cough suppression group and the cough group. In total, 38 of 43 patients were included for estimation of EC₅₀ and EC₉₅. The EC₅₀ and EC₉₅ of remifentanil to prevent coughing were 1.42 ng/mL (95% confidence interval [CI], 1.28–1.56 ng/mL) and 1.70 ng/mL (95% CI, 1.67–2.60 ng/mL), respectively. There was comparable emergence and recovery data between the cough suppression group (n = 22) and the cough group (n = 16). However, the Ce of remifentanil and total dose of remifentanil were significantly higher in the cough suppression group (P = 0.002 and P = 0.004, respectively). Target-controlled infusion of remifentanil at 1.70 ng/mL could effectively prevent extubation-related coughing in 95% of neurointervention patients, which could ensure smooth emergence.

Optimal propofol dosage for i-gel® insertion in healthy paralyzed patients

Background

Propofol is used for supraglottic airway device insertion, often with the i-gel. However, the propofol requirement for i-gel insertion has not been explored in paralyzed patients. This study was performed to explore hemodynamic changes and sedation level with different propofol doses in healthy paralyzed patients when the i-gel was inserted.

Methods

A total of 141 patients undergoing a urologic operation were randomly allocated to three groups depending on the propofol dose (1.5, 2, and 2.5 mg/kg; Groups P1.5, P2, and P2.5, respectively). After patients had been administered each propofol dose and rocuronium, the i-gel was inserted and changes in hemodynamic parameters and bispectral index were evaluated.

Results

Group P2 showed a lower incidence of complications (17%) such as hemodynamic instability and inadequate sedation than Group P1.5 (55.3%, P < 0.001) or Group P2.5 (40.4%, P = 0.012). The incidence and dose of additional propofol increased in Group P1.5 (51%, median [range]; 20 [0–50]) compared with those in the other groups (0%, 0 [0–0] in Group P2 and 8.5%, 0 [0–50] in Group P2.5, all P < 0.001), and the incidence and dose of additional ephedrine were significantly higher in Group P2.5 (31.9%; 0 [0–20]) than in Group P1.5 (10.6%, P = 0.012; 0 [0–5], P = 0.007, respectively).

Conclusions

For the stable maintenance of hemodynamic parameters and proper sedation level during i-gel insertion, 2 mg/kg propofol has an advantage over 1.5 mg/kg or 2.5 mg/kg propofol in healthy paralyzed patients.

Comparison of remifentanil EC50 for facilitating i-gel and laryngeal mask airway insertion with propofol anesthesia

OBJECTIVE

Each supraglottic airway requires different anesthetic depth because it has a specific structure and different compressive force in the oropharyngeal cavity. We designed the study to compare the effect-site concentration (Ce) of remifentanil in 50 % of patients (EC50) for successful insertion of the i-gel second-generation supraglottic airway device with that for laryngeal mask airway (LMA) insertion during target-controlled infusion (TCI) of propofol.

METHODS

Forty-one female patients were randomized to the i-gel group (n = 20) or the LMA group (n = 21). Anesthesia was induced with propofol Ce of 5 μg/ml and the predetermined remifentanil Ce, and the i-gel or LMA was inserted 5 min later. The remifentanil Ce was estimated by modified Dixon's up-and-down method (initial concentration: 3.0 ng/ml, step size: 0.5 ng/ml). The patient's response to device insertion was classified as either "success (no movement)" or "failure (movement)".

RESULTS

Using the Dixon's up-and-down method, EC50 of remifentanil Ce for the i-gel (1.58 ± 0.41 ng/ml) was significantly lower than that for LMA (2.25 ± 0.55 ng/ml) (p = 0.038). Using isotonic regression, EC50 (83 % CI) of remifentanil in the i-gel group [1.50 (1.37-1.80) ng/ml] was statistically lower than that in the LMA group [2.00 (1.82-2.34) ng/ml]. EC95 (95 % CI) of remifentanil in the i-gel group [2.38 (1.48-2.50) ng/ml] was statistically lower than that in the LMA group [3.35 (2.58-3.48) ng/ml].

CONCLUSIONS

We found that EC50 of remifentanil Ce for i-gel insertion (1.58 ng/ml) was significantly lower than that for LMA insertion (2.25 ng/ml) in female patients during propofol TCI without neuromuscular blockade.