Dexmedetomidine reduces sevoflurane EC50 for supraglottic airway device insertion in spontaneously breathing morbidly obese patients
Received 25 December 2018
Accepted for publication 20 March 2019
Published 3 May 2019 Volume 2019:15 Pages 627—635
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Colin Mak
Peer reviewer comments 2
Editor who approved publication: Professor Deyun Wang
Lei Wan,1 Liu-Jia-Zi Shao,1 Yang Liu,2 Hai-Xia Wang,1 Fu-Shan Xue,1 Ming Tian1
1Department of Anesthesiology, Beijing Friendship Hospital, Capital Medical University, Beijing, People’s Republic of China; 2Department of General Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, People’s Republic of China
Purpose: This study aimed to assess the effect of intravenous dexmedetomidine (DEX) on sevoflurane EC50 for supraglottic airway device (SAD) insertion in spontaneously breathing morbidly obese patients.
Patients and methods: Thirty-eight morbidly obese patients with a body mass index 40–57 kg/m2, who were scheduled for bariatric surgery under general anesthesia requiring tracheal intubation were randomly allocated to two groups receiving the different treatments: group S, saline was given intravenously, and group D, a bolus dose of DEX 1 μg/kg was administered intravenously over 10 mins, followed by intravenous DEX infusion at a rate of 0.5 μg/kg/h. Five percent sevoflurane was initially inhaled for anesthesia induction and then end-tidal expiratory sevoflurane concentration (ETsev) was adjusted to a target value as to the modified Dixon’s up-and-down method. Patients’ response to SAD insertion was classified as “movement” or “no movement”. The average of the midpoints of all crossover points was defined as calculated sevoflurane EC50 for successful SAD insertion. Furthermore, the probit regression analysis was used to determine sevoflurane end-tidal concentrations where 50% (EC50) and 95% (EC95) insertions of SAD were successful. After the observation was completed, flexible bronchoscope-guided intubation was performed through the SAD.
Results: The calculated sevoflurane EC50 for successful SAD insertion was significantly lower in group D than in group S (1.75±0.32% vs 2.92±0.26%, p<0.001). By the probit regression analysis, EC50 and EC95 of sevoflurane for successful SAD insertion were 1.59% (95% CI, 1.22–1.90%) and 2.15% (95% CI, 1.86–3.84%) in group D, respectively, and 2.81% (95% CI, 2.35–3.29%) and 3.32% (3.02–6.74%) in group S.
Conclusion: When sevoflurane inhalational induction is performed in spontaneous breathing morbidly obese patients, intravenous DEX can reduce sevoflurane EC50 for successful SAD insertion by about 40%.
Chinese Clinical Trial Registry: No. ChiCTR1800016868
Keywords: obesity, inhalational induction, sevoflurane, dexmedetomidine, supraglottic airway device
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