Clinical assessment of propofol-induced yawning with heart rate variability: a pilot study

Study ObjectivesTo investigate the proportion of propofol-induced yawning and sympathovagal balance during propofol-induced yawning.DesignProspective, observational, clinical study.SettingUniversity hospital and 2400-bed tertiary medical center.Patients546 ASA physical status I and II patients undergoing elective surgery with general anesthesia.InterventionsStandard induction of anesthesia was performed with intravenous (IV) propofol two to four mg/kg (group P), or pretreatment with atropine 0.1 mg/kg (group AP) or with fentanyl 1 to 3 μg/kg (group FP) before propofol. Continuous standard electrocardiogram for heart rate variability (HRV) was performed in another 20 patients to investigate sympathovagal balance during propofol-induced yawning.Measurements and Main ResultsThe proportions of yawning were 53.5% (207/386), 61.1% (55/90), and 0% (0/50) in the P, AP, and FP groups, respectively. Propofol-induced yawning could be dramatically decreased by pretreatment with IV fentanyl (P < 0.001, χ2 test). Significant increased ratio of low-frequency/high-frequency power was detected during HRV monitoring in 9 patients with yawning in comparison with 11 patients without yawning (P < 0.05, Wilcoxon signed-rank test).ConclusionsPretreatment with fentanyl may inhibit propofol-induced yawning. Fluctuations in autonomic function have been noted during propofol-induced yawning.