Effects of rotational head position on the minimum alveolar concentration for tracheal intubation in children under inhalation anesthesia induction during tonsillectomy and adenoidectomy

Abstract

Objective To investigate the minimum alveolar concentration of sevoflurane for endotracheal intubation in children who underwent tonsillectomy and adenoidectomy under inhalation anesthesia induction without the use of muscle relaxants. Methods A total of sixty-three patients [American Society of Anesthesiologists(ASA) Ⅰ or Ⅱ] undergoing tonsillectomy and adenoidectomy were divided into two groups: a neutral head position group (n=27) and a rotary head position group (n=36) according to the random number table. General anesthesia was induced with 8% sevoflurane. After the loss of the eyelash reflex, the vapourizer was adjusted, so that the end-tidal sevoflurane concentration reached the preset concentration, and maintain for 10 min, followed by endotracheal intubation. The intubation score was assessed using Helbo-Hansen score scale. For each group, the concentration of sevoflurane used for each consecutive patient was increased or decreased using the Dixon′s up-and-down method based on the success or failure to achieve adequate conditions for intubation in the previous patient. The adjacent concentration gradient was 0.5%. Results In the neutral head position group, the minimum alveolar concentration (MAC) of sevoflurane for endotracheal intubation was (4.30±0.44)%, where the median effective dose (ED50) was 4.30%, and the 95% effective dose (ED95) was 4.99%. In the rotary head position group, the MAC of sevoflurane for endotracheal intubation was (3.45±0.54)%, where the ED50 was 3.45%, and the ED95 was 4.62%. Conclusions The head position of rotating 45° was superior to the neutral head position, which can significantly reduce the MAC of sevoflurane for endotracheal intubation in children undergoing tonsillectomy and adenoidectomy. Key words: Children; Sevoflurane; Anesthesia induction; Endotracheal intubation; Minimum alveolar concentration; Tonsillectomy and adenoidectomy