Oxygen Consumption as an Early Warning System in the Critically ill

Abstract

Introduction In this study, we assessed whether changes in oxygen consumption (VO2) and other metabolic parameters could be used as an early warning system for detecting clinical deterioration in mechanically ventilated patients. Methods This was a prospective cohort study of adult patients requiring mechanical ventilation between February 2016 and March 2019. We looked for changes in VO2, carbon dioxide production (VCO2), respiratory quotient (RQ), and end-tidal carbon dioxide (EtCO2), occurring prior to clinical deterioration. Clinical deterioration was pre-defined as a requirement of vasopressor, an increase in serum lactate by 20% where at least one value was above 3 mmol/L, or a decrease in hemoglobin by 20% in the four hours prior to clinical deterioration. Results A total of 141 patients were included. There were no detectable changes in VO2, VCO2, and EtCO2 within the four hours prior to any clinical deterioration. RQ increased significantly within the four hours prior to an increase in lactate as compared to no increase in lactate but there were no detectable changes prior to other clinical deteriorations. Conclusions RQ has the potential to be an early marker of tissue hypoperfusion or mitochondrial dysfunction. However, future studies are necessary to evaluate the use of RQ as a bedside monitor in critical care settings.

Carotid artery ultrasound for assessing fluid responsiveness in patients undergoing mechanical ventilation with low tidal volume and preserved spontaneous breathing

“…For patients with acute circulatory failure, fluid resuscitation is like a double-edged sword. Proper fluid replacement can effectively increase cardiac output and improve tissue perfusion (1)(2)(3). However, excessive fluid loading can lead to increased complications, prolonged intensive care unit (ICU) stay, and significantly raise the mortality rate in shock patients (4)(5)(6)(7)(8).…”