ABSTRACT
PURPOSE: Stridor during emergence from anesthesia is not rare in children managed with supraglottic airway (SGA). However, we know little about the mechanisms of stridor and behavior of the vocal cords (VC). This study aimed to clarify patterns of VC movement and laryngeal airway maintenance function during recovery from anesthesia in children with SGA. METHODS: This is a secondary analysis of data collected from an observational study involving 27 anesthetized children. Using a multi-panel recording system, endoscopic VC image, vital sign monitor, multi-channel tracings of respiratory variables and respiratory sound and patient's view were simultaneously captured in one monitor. Inspiratory and expiratory VC angles formed by lines connecting anterior and posterior commissures were measured at the first spontaneous breath and the breath one minute after the first breath. VC narrowing and dilation were assessed by differences of VC angles. RESULTS: Inspiratory VC narrowing (median (IQR): 5.3 (2.7, 9.1) degree at the first breath) and dilation (- 2.7 (- 3.8, - 1.7) degree at the first breath) were observed in 15 and 12 out of 27 children, respectively. The former group achieved greater tidal volume compared to the latter in one minute. Five children (19%) temporarily developed stridor-like sound from outside with inspiratory VC narrowing. The stridor-like sound was captured by microphones attached to the neck and anesthesia circuit, but was not evident from the chest. CONCLUSION: Laryngeal narrowing occurs in half of the children with SGA during emergence from anesthesia, and temporal stridor-like sound is relatively common. CLINICAL TRIAL REGISTRATION: UMIN (University Hospital Information Network) Clinical Registry: UMIN000025058 ( https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000028697 ).
