Yawning as a Predictor of Survival in Critically III Mechanically Ventilated Patients

Abstract

Objectives: Yawning can be used as a functioning index for the central dopaminergic system and is part of a neural network involved in empathy. The presence of yawning indicates intact functioning in these brain areas. Since encephalopathy occurs frequently in critically ill patients and is associated with patient outcome, we hypothesized that the presence of yawning, as a measure of brain function, might be associated with mortality in critically ill patients. Material and Methods: A total of 99 consecutive patients who were admitted to a medical intensive care unit (ICU) at a tertiary-care hospital between July 1 and November 30, 2006 were prospectively investigated. The occurrence and frequency of yawning were recorded by ICU nursing staff. Multivariate logistic regression was used to determine the independent relationship between yawning and clinical outcomes. Results: About 50% of patients, whether they received invasive mechanical ventilation (MV) or not, had yawned during their ICU stay. Patients who never yawned in the ICU tended to have non-neurological diagnoses (p=0.035) or shock (p=0.045), or used vasopressors (p=0.035), and were more seriously ill as measured by the APACHE Ⅱ score (p=0.004), compared to those who had yawned during their ICU stay. In the logistic regression model, we found that only the presence of yawning (adjusted odds ratio [OR] 0.24, 95% CI 0.06-0.94, p=0.04) and use of vasopressors (adjusted OR 9.9, 95% CI 2.55-38.45, p=0.001) were independently associated with ICU mortality among MV patients. Conclusions: Yawning is a relatively uncommon behavior in the medical ICU, and its occurrence in MV patients predicts a better survival.