The 50% and 95% effective doses of desflurane for removal of the classic laryngeal mask airway in spontaneously breathing anaesthetised adults

Comparison of ED95 of Butorphanol and Sufentanil for gastrointestinal endoscopy sedation: a randomized controlled trial

Background

Butorphanol, a synthetic opioid partial agonist analgesic, has been widely used to control perioperative pain. However, the ideal dose and availability of butorphanol for gastrointestinal (GI) endoscopy are not well known. The aim of this study was to evaluated the 95% effective dose (ED₉₅) of butorphanol and sufentanil in GI endoscopy and compared their clinical efficacy, especially regarding the recovery time.

Methods

The study was divided into two parts. For the first part, voluntary patients who needed GI endoscopy anesthesia were recruited to measure the ED₉₅ of butorphanol and sufentanil needed to achieve successful sedation before GI endoscopy using the sequential method (the Dixon up-and-down method). The second part was a double-blind, randomized study. Two hundred cases of painless GI endoscopy patients were randomly divided into two groups (n = 100), including group B (butorphanol at the ED₉₅ dose) and group S (sufentanil at the ED₉₅ dose). Propofol was infused intravenously as the sedative in both groups. The recovery time, visual analogue scale (VAS) score, hand grip strength, fatigue severity scores, incidence of nausea and vomiting, and incidence of dizziness were recorded.

Results

The ED₉₅ of butorphanol for painless GI endoscopy was 9.07 μg/kg (95% confidence interval: 7.81–19.66 μg/kg). The ED₉₅ of sufentanil was 0.1 μg/kg (95% CI, 0.079–0.422 μg/kg). Both butorphanol and sufentanil provided a good analgesic effect for GI endoscopy. However, the recovery time for butorphanol was significantly shorter than that for sufentanil (P < 0.05, group B vs. group S:21.26 ± 7.70 vs. 24.03 ± 7.80 min).

Conclusions

Butorphanol at 9.07 μg/kg was more effective than sufentanil for GI endoscopy sedation and notably reduced the recovery time.

Trial registration

Chinese Clinical Trail Registry (Registration number # ChiCTR1900022780; Date of Registration on April 25rd, 2019).

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.

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.

End-tidal desflurane concentration for tracheal extubation in adults

OBJECTIVE

To determine the end-tidal desflurane concentration required for tracheal extubation in anaesthetised adults.

MATERIAL AND METHODS

After hospital Ethics Committee approval, eighteen ASA I-II adult patients (19-65 years of age), who had been scheduled for elective ambulatory surgery were included in the study. Anaesthesia was induced with propofol 2.5mg.kg^-1, fentanyl 2μg.kg^-1, and rocuronium 0.6mg.kg^-1 for intubation. Maintenance of anaesthesia was provided by desflurane in oxygen and air (40:60), and remifentanil at 0.05-0.25μg.kg^-1.min¹. Neuromuscular function was monitored with train-of-four (TOF) nerve stimulation and acceleromyography. At the end of the surgery neuromuscular blockade was reversed with sugammadex 2-4mg.kg^-1 in accordance with the TOF ratio. The concentration of desflurane at which extubation was attempted was determined by using Dixon's up-and-down method with 0.5% as a step size. Smooth extubation was defined as one without coughing, teeth clenching, gross purposeful movements, and no breath-holding or laryngospasm within 1min of tracheal extubation.

RESULTS

It was found that the end-tidal concentration of desflurane was 3.17±0.18% (95% CI: 3%-3.35%) for successful extubation in 50% of adults.

CONCLUSION

Extubation in patients receiving desflurane may be feasible at 0.62 minimum alveolar concentration.

End-tidal concentrations of sevoflurane and desflurane for ProSeal laryngeal mask airway removal in anaesthetised adults: a randomised double-blind study

BACKGROUND

The optimal end-tidal sevoflurane and desflurane concentration for successful ProSeal laryngeal mask airway (PLMA) removal in unpremedicated anaesthetised adults has not been determined.

OBJECTIVES

We determined end-tidal sevoflurane and desflurane concentration in 50% of anaesthetised adults (EC50: concentration at which there is 50% chance of patients showing 'no movement' response) for smooth PLMA removal.

DESIGN

Randomised controlled double blind study.

SETTING

Operating theatre of a government tertiary care institute. The study period was December 2011 to January 2013.

PATIENTS

Thirty nine unpremedicated American Society of Anesthesiologists (ASA) physical status I and II women with cervical carcinoma (aged 30 to 60 years) scheduled for implantation of intracavity caesium under general anaesthesia with PLMA as an airway device were included in the study.

INTERVENTIONS

The participants were randomised to one of the two groups receiving either desflurane or sevoflurane for anaesthesia maintenance. Anaesthesia induction was performed with intravenous propofol. Predetermined end-tidal sevoflurane concentration (initiating at 2%) or desflurane (initiating at 4%) was sustained for 10 min before PLMA removal was attempted. End-tidal concentrations were increased/decreased (step-size 0.2% for sevoflurane and 0.5% for desflurane) using Dixon and Massey up and down method in the next patient depending upon previous patient's response. Patient responses to PLMA removal were classified as 'movement' or 'no movement'.

MAIN OUTCOME MEASURES

EC50 was calculated as the mean of the crossover pairs' midpoints in each group and further confirmed by probit regression analysis.

RESULTS

EC50 (95% confidence interval) of sevoflurane and desflurane for PLMA removal were 1.58% (0.669 to 2.060) and 2.79% (2.733 to 2.841), respectively.

CONCLUSION

Predicted EC50 and EC95 of sevoflurane and desflurane for smooth removal for the PLMA were 1.58 (0.669 to 2.060), 2.27 (1.859 to 21.16), 2.79 (2.733.2.841) and 3.27% (3.173 to 3.395), respectively.

TRIAL REGISTRATION

Registered with Clinical Trial Registry of India (URL: http://www.ctri.in), Registry ref no: CTRI/2012/12/004285.

Effect of headphones on sevoflurane requirement for MRI

BACKGROUND

Acoustic noise may have adverse effects, even in patients under general anesthetic.

OBJECTIVE

We aimed to determine the effect of headphones on sevoflurane requirements in children undergoing general anesthesia for an MRI scan.

MATERIALS AND METHODS

Children scheduled for MRI were enrolled in the study. Sevoflurane was used for general anesthesia in all children. Patients were randomly divided into two groups, one to wear headphones and the other none. After reaching a predetermined end-tidal concentration, the MRI scan was initiated, and the patient was evaluated by an observer blinded to the concentration of sevoflurane. Awakening was defined as eye opening, onset of continued purposeful movement or phonation. Using the Dixon up-and-down method, each target concentration was determined by the response of the previous child in the same group.

RESULTS

The study included 28 children undergoing MRI. There was a significant difference in ED50 between the two groups (0.92, 0.81-1.02, vs. 0.47, 0.42-0.63; P < 0.001). The times to spontaneous arm and leg movements, eye opening and discharge from the post-anesthesia care unit were significantly shorter in patients with headphones than in those without (P < 0.001). However, there was no difference in times to hospital discharge (P = 0.056).

CONCLUSION

Noise-concealing headphones decrease inhalational anesthetic requirements and facilitate recovery. We recommend the routine use of headphones in children undergoing an MRI scan.