mise à jour du
23 février 2006
Br. J. Anaesth
Yawning during thiopentone induction
Morton HJV
Hillingdon Hospital
Middlesex. GB.


Some patients yawn whilst being rendered unconscious with thiopentone, and it has been remarked that those who do so are usually those who have not been given opiate premedication. As I am not aware of any published numerical data bearing on this matter, I offer the following results, derived from adult, general surgical patients.
In a series of 100 consecutive patients given atropine only 45 (45%) yawned. In a further series of 500 consecutive patients given an opiate and hyoscine or atropine 5 (1%) yawned. The difference between the proportions is highly significant. It might be thought that the 5 who had been given opiate and nevertheless yawned were patients whose premedication has been mistmied, but this was true only for 3.
Yawning was much commoner in the aged, though not due to old age per se: the aged had been given atropine only much more commonly. When a comparaison with respect to age was restricted to individuals all given atropine only, the difference in results became small, and not sigificant.

Relationship between clinical endpoints for induction of anesthesia and bispectral index and effect-site concentration values.
Kim DW, Kil HY, White PF.
J Clin Anesth. 2002 Jun;14(4):241-5.
Department of Anesthesiology, The Catholic University of Korea, Seoul, Korea.
STUDY OBJECTIVE: To assess the relationship between clinical endpoints for induction of anesthesia and the electroencephalographic (EEG) bispectral index (BIS) and effect-site concentration (C(E)) values when using a target-controlled infusion (TCI) of either thiopental sodium or propofol, by hypothesizing that yawning may be a useful alternative to other commonly used clinical signs for determining loss of consciousness.
DESIGN: Randomized observational clinical study. SETTING: Operating room of a university-based hospital.PATIENTS: 60 healthy adult patients (aged 20-50 yrs) scheduled for elective surgery with general anesthesia.
INTERVENTIONS: During a TCI of propofol (n = 30) or thiopental (n = 30), clinical endpoints for loss of verbal responsiveness (LOV), loss-of-eyelash reflex (LOE), occurrence of yawning, and apnea were assessed at 15-second intervals. In addition, BIS and C(E) values were recorded at each of the endpoints.
MEASUREMENTS AND MAIN RESULTS: In both anesthetic groups, the sequence of occurrence of the clinical endpoints was similar, namely LOV, LOE, yawning, and, lastly, apnea. Compared with LOV and LOE, yawning was associated with lower BIS and higher C(E) values with both anesthetics. The frequency of yawning was higher with thiopental than propofol (83% vs. 63%, respectively). However, the frequency of apnea was higher with propofol than thiopental (77% vs. 53%, respectively).
CONCLUSION: The correlation of the clinical endpoints with BIS and C(E) values was highest for LOV. Yawning was as unreliable as LOE for determining the onset of unconsciousness during induction of anesthesia. This clinical sign failed to be observed in 17% and 37% of patients induced with thiopental and propofol, respectively.

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
Does yawning represent a transient arousal-shift during intravenous induction of general anesthesia?
Kasuya Y, Murakami T, Oshima T, Dohi S.
Anesth Analg. 2005 Aug;101(2):382-384
Division of Anesthesia, Gifu Red Cross Hospital, Japan.
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.
IMPLICATIONS: Yawning elicited by IV anesthetic induction was related to a transient increase during the continuing decrease in the electroencephalographic bispectral index value (sensitivity and specificity, 77% and 80%, respectively). This type of yawning may be a clinical indicator of a transient arousal-shift during progressive loss of consciousness.

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Sato-Suzuki I, Kita I, Oguri M, Arita H
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Ghisi D, Fanelli A, Tosi M, Nuzzi M, Fanelli G.
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Leslie K, Myles PS, Forbes A, Chan MT, Short TG, Swallow SK
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Osborne GA, Bacon AK, Runciman WB, Helps SC.
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David E Bateman
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