LAUSR

To the Editor: The study by Robert et al (1), in a recent issue of Critical Care Medicine, that evaluates the association between Paco 2 and survival to hospital discharge among patients diagnosed with sepsis is a current and well written effectual study. When sepsis is mentioned, mostly Pao 2 is assessed. This study brings a new dimension to the subject. In addition, Roberts et al (1) conducted the study on a very wide range of patients. This further increases the value of the study. However, it is not clear whether patients with chronic lung diseases (like chronic obstructive pulmonary disease) were included in the study or not. In the Procedures section of the study, it is stated that lung compliance was measured. Did Roberts et al (1) do any correlation study done between Paco 2 and static compliance? We believe that the data of a correlation study can reveal new points of view. The pH values were not changed as the Paco 2 values increased. How can Roberts et al (1) explain this? Roberts et al (1) state that they have administered lungprotective mechanical ventilation. What is the aim of administering a Fio 2 of 100% and positive end-expiratory pressure level of 5 cm H 2 O? We believe that the described mechanical ventilation variables do not comply with the classical lung-protective mechanical ventilation description (2). In the Discussion section, positive physiologic and clinical effect of increased Paco 2 levels are mentioned. According to the result of the study, an increase in Paco 2 levels has a negative impact on the discharge from the hospital. Addition to that, other studies are mentioned. which state that Paco 2 is related to dead space volume and this is a sign of lung damage and bad prognosis (3, 4). However, we were not able to encounter the data of dead space volume. By providing the readers with both the positive and negative effects of Paco 2 , a perception is created that profit and loss must be calculated. Can that profit and loss calculation be done according to a calculated cutoff value for the changes in the Paco 2 levels? The authors have disclosed that they do not have any potential conflicts of interest.