The optimal exhaled concentration of sevoflurane for intubation without neuromuscular blockade using clinical bolus doses of remifentanil: A randomized controlled trial

50% effective concentration of sevoflurane for immobility in cerebral palsy children undergoing botulinum toxin injection

BACKGROUND

This prospective study aimed to determine the optimum end-tidal sevoflurane concentration required for immobility during botulinum toxin injection in spontaneously breathing children with cerebral palsy (CP).

METHODS

Twenty-three children with spastic CP, aged 3 to 12 years, with American Society of Anesthesiologists (ASA) physical status I and II, scheduled to receive botulinum toxin type A injection were enrolled in the study. After induction of deep sedation using pre-filled 8% sevoflurane in oxygen and maintenance of the predetermined end-tidal sevoflurane concentration, the botulinum toxin was injected in spontaneously breathing children. The response to the botulinum toxin injection was classified as "movement" or "no movement" by an independent investigator who was blinded to the predetermined end-tidal sevoflurane concentration and bispectral index (BIS) value. The end-tidal sevoflurane concentration was predetermined, initiating at 2.0% with 0.2% as a step size in the next patient depending on the previous patient's response using the modified Dixon's up-and-down method.

RESULTS

Of 21 children, 12 (57.1%) showed "no movement" in response to the botulinum toxin injection. By Dixon's up-and-down method, the 50% effective end-tidal concentration (EC50) of sevoflurane for successful botulinum toxin injection was 1.76 ± 0.15% (95% CI 1.62-1.90). Based on the dose-response curve using probit analysis, the predicted EC50 and 95% effective end-tidal concentrations (EC95) of sevoflurane without movement were 1.77% (95% CI 1.59-2.35) and 2.09% (95% CI 1.89-5.80), respectively.

CONCLUSION

Botulinum toxin injection can be successfully accomplished at an end-tidal sevoflurane concentration of 1.76 ± 0.15% in 50% of spontaneously breathing children with CP aged 3-12 years.

Minimum Alveolar Concentration-Awake of Sevoflurane is Decreased in Patients with Parkinson's Disease: An Up-and-Down Sequential Allocation Trial

Background

An increasing number of patients with Parkinson’s disease (PD) will have surgery under general anesthesia. A previous study demonstrated that propofol requirement for inducing unconsciousness in PD patients was lower than that in non-PD (NPD) patients. However, the requirement of inhaled anesthetics in PD patients has not been clarified. The aim of this study was to investigate the minimum alveolar concentration-awake (MAC_awake) of sevoflurane in patients with PD compared to NPD patients.

Patients and Methods

The current study is an up-and-down sequential allocation trial. The initial end-tidal concentration of sevoflurane (CETsevo) was estimated by the response of the previous patient to verbal command using the Dixon’s up-and-down method. The first patient in each group received CETsevo at 1%, and the step size between patients was 0.2%.

Results

Forty-one patients including 20 PD patients and 21 NPD patients were enrolled. Patients’ characteristics and arterial blood gas parameters (except blood sodium) were comparable between two groups. The MAC_awake of sevoflurane estimated by the Dixon’s up-and-down method in PD patients (0.47% ± 0.08% [Mean ± S.D.]) was significantly lower than that in NDP patients (0.64% ± 0.10%) (P=0.003). The estimated difference in means was 0.17% (95% CI, 0.10–0.24%). Probit analysis showed that the MAC_awake of sevoflurane in PD and NPD patients was 0.49% (95% CI, 0.42–0.57%) and 0.67% (95% CI, 0.59–0.76%), respectively. The relative median potency was 0.73 (95% CI, 0.38–0.94).

Conclusion

Patients with PD exhibit a significantly lower MAC_awake of sevoflurane compared with NPD patients. Clinicians should avoid an overdose of sevoflurane in patients with PD.

Trial Registration

Registered at ChiCTR1900026956.

LncRNA Rik-203 contributes to anesthesia neurotoxicity via microRNA-101a-3p and GSK-3β-mediated neural differentiation

The mechanism of anesthesia neurotoxicity remains largely to be determined. The effects of long noncoding RNAs (LncRNAs) on neural differentiation and the underlying mechanisms are unknown. We thus identified LncRNA Rik-203 (C130071C03Rik) and studied its role on neural differentiation and its interactions with anesthetic sevoflurane, miRNA and GSK-3β. We found that levels of Rik-203 were higher in hippocampus than other tissues and increased during neural differentiation. Sevoflurane decreased the levels of Rik-203. Rik-203 knockdown reduced mRNA levels of Sox1 and Nestin, the markers of neural progenitor cells, and decreased the count of Sox1 positive cells. RNA-RNA pull-down showed that miR-101a-3p was highly bound to Rik-203. Finally, sevoflurane, knockdown of Rik-203, and miR-101a-3p overexpression all decreased GSK-3β levels. These data suggest that Rik-203 facilitates neural differentiation by inhibiting miR-101a-3p's ability to reduce GSK-3β levels and that LncRNAs would serve as the mechanism of the anesthesia neurotoxicity.

Effects of remifentanil with or without midazolam pretreatment on the 95% effective dose of propofol for loss of consciousness during induction: A randomized, clinical trial

BACKGROUND

Propofol is a rapid, efficient hypnotic agent with antiemetic effects. However, a high dosage is related to hemodynamic abnormalities such as hypotension and bradycardia. Pretreatment with remifentanil can decrease injection pain and stabilize hemodynamics during the induction period. Remifentanil or midazolam in combination with propofol can provide synergistic or additive effects during anesthesia induction. However, the hypnotic doses of propofol required in patients who receive pretreatment with remifentanil or midazolam remain unclear.

METHODS

Patients aged 20 to 50 years who were scheduled to undergo surgery under general anesthesia were enrolled in this study. The patients were randomized into 3 groups using a computer-generated randomization table. Patients in Group P (Propofol) received only propofol for loss of consciousness, those in Group PR (Propofol-Remifentanil) received remifentanil prior to propofol, and those in Group PMR (Propofol-Midazolam-Remifentanil) received remifentanil and midazolam prior to propofol. After propofol administration, loss of both the eyelash reflex and verbal response represented success. The 95% effective dose of propofol for loss of consciousness in each group, which was the primary outcome, was determined using a modified biased coin up-and-down method.

RESULTS

A total of 124 patients were initially enrolled. Of these, 4 were excluded, and the remaining 120 patients were randomized to each (n = 40) of the 3 groups. The 95% effective dose of propofol for loss of consciousness was 1.74 , 1.38, and 0.92 mg/kg in Groups P, PR, and PMR, respectively. Blood pressure decreased at 2 minutes after propofol administration in all the groups. However, compared with Group P, Groups PR and PMR exhibited a significant decrease in blood pressure.

CONCLUSIONS

The effective dose of propofol for loss of consciousness could be decreased by 21% and 47% when remifentanil pretreatment was used without and with midazolam, respectively. However, the decrease in blood pressure was greater with pretreatment than sole propofol use. These findings suggest that the combination of remifentanil with or without midazolam may have no benefit on hemodynamic stability during induction using propofol.

TRIAL REGISTRATION

NCT02536690 (clinicaltrials.gov).

Optimum end-tidal concentration of sevoflurane to facilitate supraglottic airway device insertion with propofol at induction allowing spontaneous respiration in obese patients: A prospective observational study

Obese patients are more likely to encounter with difficult airway management, and supraglottic airway device has been adopted to facilitate tracheal intubation. The optimum anesthetic concentration for obese patients to insert a supraglottic airway device with spontaneous respiration has not been investigated. This study was designed to determine the end-tidal concentration of sevoflurane that would provide acceptable condition for supraglottic airway device insertion with propofol at induction in obese patients without using neuromuscular blockade.Thirty elective obese patients [body mass index (BMI) 30-50 kg/m] scheduled for bariatric surgery were enrolled in this study. Sevoflurane was inhaled at a concentration of 5% after infusion of 1 mg/kg propofol (within 1 minute) according to lean body weight. The target concentration of sevoflurane was initiated at 2.5% with 0.5% as a step size using a modified Dixon up-and-down method. Five minutes after target concentration achieved, the insertion of supraglottic airway device was attempted.The minimum alveolar concentration of sevoflurane for successful insertion of supraglottic airway device calculated using up-and-down method were 2.25 (0.53) % for obese patients. The values of the effective concentration of sevoflurane for successful supraglottic airway device insertion in 50% (EC50) and 95% (EC95) of the obese patients obtained by probit regression analysis were 2.09% (95% confidence interval 1.48-2.68) and 3.31% (95% confidence interval 2.70-8.12), respectively.We conclude that sevoflurane at a minimum alveolar concentration of 2.25% can provide optimal conditions for insertion of supraglottic airway device with spontaneous respiration in obese patients with 1 mg/kg propofol at induction.