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mise à jour du
11 août 2005
Anesth Analg
2005;101(2):382-384
lexique
Does yawning represent a transient arousal-shift during intravenous induction of general anesthesia?
Kasuya Y, Murakami T, Oshima T, Dohi S.
Department of Anesthesiology and Pain Medicine, Gifu University Graduate School of Medicine, Japan.

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Abtsract : Although yawning occurs frequently during the IV induction of general anesthesia, the significance of this response remains unknown. In this study, we induced 30 surgical patients with 4 mg/kg thiopental IV, and 30 patients with 2 mg/kg propofol IV. Thereafter, the occurrence of yawning was continuously assessed, as the only clinical end-point, for 1 min. The electroencephalographic bispectral index was monitored throughout the observation period. The criterion for an arousal response was a transient increase during a continuing decrease in the bispectral index value. On the basis of this criterion, the sensitivity and specificity of the yawning response as an arousal sign were 77% and 80%, respectively. If a patient exhibited a yawning response, the chance of arousal was 84% (positive predictive value). With no yawning response, the chance of nonarousal was 71% (negative predictive value). According to simple logistic regression, the yawning response was predictive of a transient arousal-shift with an odds ratio of 13.5 (95% confidence interval: 3.8-48; P < 0.001). The occurrence of a yawning response during IV induction may be a clinical indicator of a transient arousal-shift during progressive loss of consciousness.

One of the most frequently encountered clinical situations during which yawning occurs is the IV induction of general anesthesia (1). A typical yawn is characterized by a single large inspiration with simultaneous mouth opening and stretching of the trunk (2Ð 4). Yawning can also be accompanied by changes in autonomic function, such as lacrimation and penile erection (5Ð7). Furthermore, yawning has been established as a phenomenon that subserves arousal (8). Although a transient arousal-shift during the yawning behavior has been demonstrated in awake humans as measured by skin conductance (9), sympathetic nerve activity (10), and behavior (11), we thought it important to know whether this phenomenon also applies to humans during IV induction, a clinical situation in which relevant information is still lacking. We hypothesized that a yawning response during IV induction is associated with a transient arousalshift during continuing loss of consciousness in humans. To examine this hypothesis, we recorded the electroencephalographic (EEG) bispectral index (BIS) during IV induction achieved using a single bolus induction dose of thiopental or propofol.

Discussion

The principle finding in this study was that, in humans, a yawning response was related to a transient increase during the continuing decrease in the BIS value seen after IV administration of thiopental or propofol. This phenomenon, observed using BIS monitoring, may reflect a transient arousal-shift during the progressive loss of consciousness caused by IV induction. We therefore focus the following discussion on the arousal-shift that seems to be related to the yawning response. In our study, the yawning response elicited during IV induction had positive and negative predictive values of 84% and 71%, respectively, for predicting a transient increase in the BIS value, with the sensitivity and specificity being 77% and 80%. Moreover, simple logistic regression indicated that the odds ratio of the yawning response as a prediction of a transient increase in the BIS value was 13.5 (95% confidence interval: 3.8Ð48; P 0.001). These statistical values are all consistent with our hypothesis that the yawning response might represent a transient arousal-shift during continuing loss of consciousness and on the assumption that the BIS monitor is capable of detecting rapid changes in arousal or consciousness or whatever it actually measures. On the BIS record, a transient increase during a continuing decrease was consistently observed 15Ð20 seconds after the occurrence of a yawning response. However, because the BIS value that actually correlates with a given event is the value recorded after a 20-second delay to compensate for the time delay in calculating the BIS value (1), the underlying phenomenon may occur either before or during the yawning response. This arousal effect may be of considerable significance because the data were obtained under general anesthesia. A few years ago, Sato-Suzuki et al. (12) recorded the electrocorticogram to evaluate arousal responses during yawning in anesthetized rats. During both spontaneous yawning and yawning responses evoked by chemical stimulation of the paraventricular nucleus, electrocorticogram arousal (represented by lower voltage and faster rhythms) occurred before the actual yawning behavior. However, Concu et al. (8) demonstrated that EEG arousal and yawning appeared concomitantly in cats. When taken together with these findings in animal experiments (8,12), the present data suggest that yawning-induced EEG arousal does not result from the stretching of the trunk. Although the BIS monitor is capable of rejecting the electromyographic artifacts, we cannot exclude the possibility that the transient increase in the BIS value may incorporate electromyographic activity which could have increased because of muscle activity during opening of the mouth. Further studies using a multichannel EEG with electrodes over the mandible are needed to solve this problem. Although the BIS monitor involves this limitation, this study is the first to indicate an arousal-shift associated with yawning during induction of general anesthesia in humans

 
See baillements iatrogènes

Kasuya Y, Murakami T, Oshima T, Dohi S. Does yawning represent a transient arousal-shift during intravenous induction of general anesthesia? Anesth Analg 2005;101(2):382-3
 
Morton HJV Yawning during thiopentone induction Br. J. Anaesth 1962;34:133-134
 
Oshima T et al. Inhibitory effects of landiolol and nicardipine on thiopental-induced yawning in humans J Anesth 2010