This study aims to evaluate two different methods for calculating physiological dead space in adult patients undergoing invasive mechanical ventilation in the intensive care unit (ICU). Physiological dead space refers to the portion of air that is ventilated but does not participate in gas exchange due to impaired perfusion or ventilation-perfusion mismatch. Traditionally, dead space is calculated using the end-tidal carbon dioxide (EtCOâ‚‚) method, which estimates the difference between arterial and exhaled COâ‚‚ values. However, this method may be influenced by circulatory failure or abnormal COâ‚‚ distribution. An alternative method using the alveolar-arterial oxygen gradient \[P(A-a)Oâ‚‚\] has been proposed, as it may provide a more stable measurement under critical conditions by relying on oxygenation efficiency rather than COâ‚‚ elimination. In this prospective observational study, patients receiving mechanical ventilation in a tertiary ICU will be monitored. Physiological dead space will be calculated using both the EtCOâ‚‚-based method and the P(A-a)Oâ‚‚-based method. Various respiratory and clinical parameters, including arterial blood gases, ventilator settings, and severity scores, will be recorded. The correlation between the two methods will be assessed, and their relationship with ICU mortality will be analyzed. The results of this study may help determine whether the P(A-a)Oâ‚‚ method can be used as a reliable alternative for estimating dead space in ICU patients and whether it has prognostic value in predicting patient outcomes.
See this in plain English?
AI-rewrites the medical criteria so a patient or caregiver can understand them. Always confirm with the trial site.
Correlation between EtCOâ‚‚- and P(A-a)Oâ‚‚-based dead space calculations
Timeframe: Within the first 72 hours of ICU admission