Comparison of Train-of-four Response between Adductor Pollicis and Orbicularis Oculi to Determine the Optimal Time for Endotracheal Intubation after Vecuronium Administration. |
Hong Sik Lee, Chong Kweon Chung, Yong Deog Cha, Dong Ho Park, Chung Hoon Song, Sung Keun Lee |
Department of Anesthesiology, Inha University College of Medicine, Inchon, Korea. |
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Abstract |
BACKGROUND Ideal condition of endotracheal intubation after administration of non-depolarizing muscle relaxants like vecuronium is the time when the diaphragm and upper airway muscles are completely relaxed. But these muscles are difficult to determine the degree of relaxation.
Neuromuscular response of these muscles are similar to that of orbicularis oculi (OO), but adductor pollicis (AP) is different. However, it is sometimes difficult to monitor OO response. The purpose of this study was to monitor the upper airway muscle relaxation using AP other than OO. METHODS Fourty-four adult patients of ASA class 1 schaduled for elective surgery under general anesthesia were examined.
Anesthesia was induced with fentanyl 2 mcg/kg, and 2 minutes later followed by thiopental sodium 5 mg/kg. After supramaximal stimulation for control twitch height, vecuronium 0.1 mg/kg was intravenously injected and applied continuous train-of-four (TOF) facial nerve stimuli. The TOF response of OO was closely observed with examiner's naked eyes. When complete relaxation of OO achieved, TOF ratio of AP and the time after vecuronium injection were recorded.
Thereafter, tracheal intubation was performed and the intubating condition scores was recorded. Ulnar nerve stimuli were continuously applied until complete relaxation of AP was achieved. The time of complete relaxation of AP after vecuronium injection was also recorded. RESULTS The onset time of complete relaxation was significantly faster in OO (181.3+/- 47.4 secs) as compared with that of AP (265.0+/-67.8 secs). The average TOF ratio of AP was 47.3+/-17.2% and the condition of intubation performed after complete relaxation of OO was satisfied. CONCLUSION The optimal time for endotracheal intubation was about 3 min after vecuronium 0.1 mg/kg injection, when TOF ratio of AP was about 50%. |
Key Words:
Monitoring, neuromuscular function; Neuromuscular relaxants, vecuronium; Intubation, tracheal, technique |
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