Effect-site concentration of propofol required for LMA-Supreme™ insertion with and without remifentanil: a randomized controlled trial

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.

Effective dose of propofol combined with intravenous esketamine for smooth flexible laryngeal mask airway insertion in two distinct age groups of preschool children

BACKGROUND

There is limited research on the combined use of propofol and esketamine for anesthesia induction during flexible laryngeal mask airway (FLMA) in pediatric patients, and the effective dosage of propofol for FLMA smooth insertion remains unclear. We explored the effective dose of propofol combined with intravenous esketamine for the smooth insertion of FLMA in two distinct age groups of preschool children.

METHODS

This is a prospective, observer-blind, interventional clinical study. Based on age, preschool children scheduled for elective surgery were divided into group A (aged 1-3 years) and group B (aged 3-6 years). Anesthesia induction was started with intravenous administration of esketamine (1.0 mg.kg- 1) followed by propofol administration. The FLMA was inserted 2 min after propofol administration at the target dose. The initial dose of propofol in group A and group B was 3.0 mg.kg- 1 and 2.5 mg.kg- 1, respectively. The target dose of propofol was determined with Dixon's up-and-down method, and the dosing interval of propofol was 0.5 mg.kg- 1. If there was smooth insertion of FLMA in the previous patient, the target dose of propofol for the next patient was reduced by 0.5 mg.kg- 1; otherwise, it was increased by 0.5 mg.kg- 1. The median 50% effective dose (ED50) for propofol was estimated using Dixon's up-and-down method and Probit analysis, while the 95% effective dose (ED95) was estimated through Probit analysis. Vital signs and adverse events during induction were recorded.

RESULTS

Each group included 24 pediatric patients. Using Dixon's up-and-down method, the ED50 of propofol combined with esketamine for smooth insertion of FLMA in group A was 2.67 mg.kg- 1 (95%CI: 1.63-3.72), which was higher than that in group B (2.10 mg. kg- 1, 95%CI: 1.36-2.84) (p = 0.04). Using Probit analysis, the ED50 of propofol was calculated as 2.44 (95% CI: 1.02-3.15) mg.kg- 1 in group A and 1.93 (95% CI: 1.39-2.32) mg.kg- 1 in group B. The ED95 of propofol was 3.72 (95%CI: 3.07-15.18) mg.kg- 1 in group A and 2.74 (95%CI: 2.34-5.54) mg.kg- 1 in group B. In Group B, one pediatric patient experienced laryngospasm.

CONCLUSION

The effective dose of propofol when combined with intravenous esketamine for smooth insertion of FLMA in children aged 1-3 years is 2.67 mg.kg- 1, which is higher than that in children aged 3-6 years (2.10 mg. kg- 1).

TRIAL REGISTRATION

Chinese Clinical Trial Registry Center (Registration Number: ChiCTR2100044317; Registration Date: 2021/03/16).

Effective dose of remimazolam co-administered with remifentanil to facilitate I-gel insertion without neuromuscular blocking agents: an up-and-down sequential allocation trial

BACKGROUND

Remimazolam is a new anesthetic drug developed and is an ultra-short-acting agent with rapid onset and offset. The pharmacology of this drug seems to be ideal for short surgeries eligible for I-gel insertion. Therefore, this study aimed to determine the optimal bolus dose of remimazolam for I-gel insertion when co-administered with remifentanil without neuromuscular blocking agents (NMBAs).

METHODS

Patients aged 19-65 years with American Society of Anesthesiologists physical status I or II scheduled for general anesthesia were enrolled. The first dose of remimazolam was 0.15 mg/kg and remifentanil was co-administered at an effect-site concentration (Ce) of 3.0 ng/mL. The dose of remimazolam for the following patient was decreased or increased by 0.05 mg/kg depending on the success or failure of I-gel insertion in the previous patient.

RESULTS

The remimazolam bolus dose required for successful I-gel insertion in 50% of adult patients using modified Dixon's up-and-down method with remifentanil Ce 3.0 ng/mL and no NMBAs was 0.280 ± 0.048 mg/kg. Isotonic regression analysis showed that the 50% and 95% effective doses were 0.244 (83% confidence interval [CI] 0.213-0.313) mg/kg and 0.444 (95% CI 0.436-0.448) mg/kg, respectively. The mean time to loss of consciousness (Modified Observer's Assessment of Alertness/Sedation score < 2) was 52.2 s. Three patients (12.0%) showed a reduction in systolic blood pressure of more than 30% from baseline.

CONCLUSIONS

Selecting the appropriate dose of remimazolam/remifentanil without NMBAs makes it feasible to insert the I-gel.

TRIAL REGISTRATION

This study protocol was registered at http://cris.nih.go.kr (KCT0007801, 12th, October, 2022).

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).

Comparative evaluation of i-gel® insertion conditions using dexmedetomidine-propofol versus fentanyl-propofol - A randomised double-blind study

Background and Aims:

i-gel^® insertion necessitates adequate depth of anaesthesia to prevent laryngospasm, gagging or limb movements. We aimed to compare i-gel^® insertion conditions with propofol induction after pre-treatment with dexmedetomidine or fentanyl.

Methods:

Eighty ASAI/II patients undergoing general anaesthesia were randomised into Groups D (n = 40) and F (n = 40). Group D received 1 μg/kg dexmedetomidine over 10 minutes followed by 5ml of 0.9%normal saline (NS) over 2 minutes. Group F received 10 ml of 0.9%NS over 10 minutes followed by fentanyl 1 μg/kg over 2 minutes. Thirty seconds after study drugs, propofol 2 mg/kg was given. Ninety seconds after propofol, i-gel^® was inserted. Overall insertion conditions were assessed by Modified Scheme of Lund and Stovener. Heart-rate (HR) and mean arterial pressure (MAP) were noted at baseline, after study drug, propofol induction and 1,3,5,10 minutes after i-gel^® insertion. Respiratory rate and apnoea times were recorded.

Results:

Insertion conditions were comparable between both groups. Moderately relaxed jaw, coughing and movement was observed in more patients of Group F. Incidence of apnoea was significantly higher (P < 0.0001) in group F (18/40) than group D (3/40).Mean duration of apnoea in group F (284.5 ± 11.19 sec) was significantly higher than group D (217.17 ± 16.48 sec). Percentage drop in MAP from baseline after propofol was more in group F (10.3%) than group D (5.6%). MAP after induction was significantly lower in group F compared to group D (P = 0.002), but similar after i-gel^® insertion, 1,3,5 and 10 minutes after insertion. After propofol (P = 0.003) and i-gel^® insertion (P < 0.001), HR was significantly lower with dexmedetomidine.

Conclusion:

Dexmedetomidine and fentanyl provide comparable conditions for i-gel^® insertion with propofol.

The optimum sevoflurane concentration for supraglottic airway device Blockbuster™ insertion with spontaneous breathing in obese patients: a prospective observational study

BACKGROUND

Airway management of the obese patient presenting for surgery is more likely to be a challenging problem. Supraglottic airway device has been adopted as a bridge to connect ventilation and tracheal intubation in obese patients who would be suffered with difficult intubation. The optimum sevoflurane concentration for supraglottic airway device insertion allowing spontaneous breathing in 50% of obese patients (ED₅₀) is not known. The purpose of this study was to determine the ED₅₀ of sevoflurane for supraglottic airway device Blockbuster™ insertion with spontaneous breathing in obese patients requiring general anesthesia.

METHODS

Thirty elective obese patients (body mass index 30-50 kg/m²) undergoing bariatric surgery were recruited in this study. The predetermined target sevoflurane concentration (initiating at 2.5% with 0.5% as a step size) was sustained for >5 min using a modified Dixon's up-and-down method, and then the supraglottic airway device Blockbuster™ was inserted. The patient's response to supraglottic airway device insertion was classified as either 'movement' or 'no-movement'. The ED₅₀ of sevoflurane were determined by calculating the midpoint concentration of crossover point from 'movement' or 'no-movement' response.

RESULTS

The ED₅₀ of sevoflurane for supraglottic airway device Blockbuster™ insertion in obese patients calculated using up-and-down method were 2.50 ± 0.60%. The ED₅₀ and ED₉₅ (95% confidence interval) obtained by probit regression analysis were 2.35 (1.28-3.42) % and 4.03 (3.16-17.83) % for supraglottic airway device Blockbuster™ insertion, respectively.

CONCLUSION

We conclude that the optimum end-tidal sevoflurane concentration required for the supraglottic airway device Blockbuster™ insertion allowing spontaneous breathing in 50% of obese patients (ED₅₀) is 2.5 ± 0.6%.

TRIAL REGISTRATION

Chinese Clinical Trial Registry, ChiCTR-IPR-16009071 , Registered on 24 August 2016.