Appropriate sevoflurane concentration to stabilize autonomic activity during intubation with rocuronium in infants: a randomized controlled trial.
BACKGROUND
In infants, sevoflurane is commonly used for induction of anesthesia, following which a muscle relaxant is administered to facilitate tracheal intubation. When rocuronium is used as the muscle relaxant, intubation may be performed before reaching an adequate depth of anesthesia because of its rapid onset. The purpose of this study was to investigate the optimal sevoflurane concentration that would minimize the impact of intubation on hemodynamics and autonomic nervous system (ANS) activity in infants.


METHODS
Sixty-one infants aged 1-6 months, undergoing cleft lip repair, were enrolled. Patients were randomly assigned to three end-tidal sevoflurane concentration (E'Sevo) groups, 3%, 4% and 5%. Anesthesia was induced with 5% sevoflurane with 100% oxygen, and rocuronium (0.6 mg/kg) was administered. The concentration of sevoflurane was adjusted to the predetermined concentration in each group. Mechanical pressure control ventilation via a face mask was commenced. Five minutes after E'Sevo became stable at the predetermined concentration, tracheal intubation was performed. Immediately after tracheal intubation, ventilation was restarted at the same ventilator settings and continued for 150 seconds. Heart rate (HR) and mean arterial pressure (MAP) were measured 5 times in the 150 seconds after intubation. Normalized units (nu) of high frequency (HF: 0.04-0.15 Hz) and the ratio of low frequency (LF: 0.15-0.4 Hz) to HF components (LF/HF) of HR variability were calculated by MemCalc/Tonam2C™. Normalized units of HF (HFnu) and LF/HF reflect cardiac parasympathetic and sympathetic activity, respectively.


RESULTS
After intubation, HR increased slightly in all groups and MAP increased by 9.2% in the E'Sevo-3% group. LF/HF increased (p < 0.01) and HFnu decreased (p < 0.01) in all groups 30 seconds after intubation. HFnu was lower (p < 0.001) and LF/HF was higher (p = 0.007) in the E'Sevo-3% group than in E'Sevo-5% group. ANS responses to intubation were reduced in a dose-dependent manner.


CONCLUSIONS
Sympathomimetic and parasympatholytic responses to intubation in the E'Sevo-3% group were much greater than those in the E'Sevo-5% group. During tracheal intubation in infants, 4% or 5% sevoflurane is appropriate for prevention of sympathetic hyperactivation and maintenance of ANS balance as compared to 3% sevoflurane, when a muscle relaxant is co-administered.


BACKGROUND
The study was registered at UMIN-CTR ( UMIN000009933).
Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita, Osaka, 565-0871, Japan. hanamoto@dent.osaka-u.ac.jp.
Hiroshi
H
Hanamoto
Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita, Osaka, 565-0871, Japan. bokuaiji@dent.osaka-u.ac.jp.
Aiji
A
Boku
Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita, Osaka, 565-0871, Japan. morimoto@kdu.ac.jp.|Department of Anesthesiology, Graduate School of Dentistry, Kanagawa Dental University, 82, Inaoka-Cho, Yokosuka, Kanagawa, 238-8580, Japan. morimoto@kdu.ac.jp.
Yoshinari
Y
Morimoto
Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita, Osaka, 565-0871, Japan. smit@dent.osaka-u.ac.jp.
Mitsutaka
M
Sugimura
Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita, Osaka, 565-0871, Japan. ckudo@dent.osaka-u.ac.jp.
Chiho
C
Kudo
Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, 1-8, Yamadaoka, Suita, Osaka, 565-0871, Japan. niwa@dent.osaka-u.ac.jp.
Hitoshi
H
Niwa
D000732:Androstanols; D018685:Anesthetics, Inhalation / Q000008:administration & dosage* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002971:Cleft Lip / Q000601:surgery; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007223:Infant; D007442:Intubation, Intratracheal / Q000379:methods; D008297:Male; D008738:Methyl Ethers / Q000008:administration & dosage* / Q000494:pharmacology; D003473:Neuromuscular Nondepolarizing Agents; D000077123:Rocuronium; D000077149:Sevoflurane; D016037:Single-Blind Method; D013564:Sympathetic Nervous System / Q000187:drug effects*
D000732:Androstanols; D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D003473:Neuromuscular Nondepolarizing Agents; D000077149:Sevoflurane; D000077123:Rocuronium