How are Thermoregulation and Ventilatory Modes Linked? Some Methodological Views.

Dear Editor,

We have read with interest this original study, which analyzes two venilatory modes and the regulatory effect on body temperature mediated by the levels of positive end expiratory pressure (PEEP) presented by the authors (1). The direct effect of PEEP in this relationship might be questionable since it is shown as the only responsible mechanism in this complex scenerio (2). The authors also could not find this, and we believe that it has a significant impact on the prognosis of patients. Yet, there are some data, which are essential to be considered for better interpretation of the results.

The authors did not determine the type of humidification system that they have used during the study. We know that they can be either heated humidifiers in the breathing circuit or conventional filter humidification systems, and their ability to influence the body temperature is different (3).

Moreover, the system of control/analysis of the hemodynamic response in relation to the temperature used by the authors has limitations because it does not inform us about the essential parameters such as cardiac output and vascular resistance/peripheral constriction, which has an association with temperature (4). This would help us to understand the effects that the authors analyze in the study better.

Furthermore, the authors did not state the position of the operation table. In addition, the position of the patients and changes, if any, done during the surgeries need to be mentioned, as they can influence the thermoregulation, thus affecting the results (5).

We consider this study very interesting because of the impact of body temperature and its association with the ventilatory mode, but we believe that future studies should include a more direct method and other measurement elements of this association.