Utilizing indirect calorimetry to assess oxygen consumption in shock patients

Document Type

Conference Proceeding

Publication Date


Publication Title

Crit Care Med


INTRODUCTION: Regardless of etiology, shock is a failure of the circulatory system to supply enough oxygen carrying blood to peripheral tissues to maintain normal function. This peripheral hypoxemia impairs oxygen dependent cell functions and contributes to changes in metabolism, impaired mitochondrial and energy metabolism. Indirect calorimetry can be used to measure the volume of oxygen consumption (VO2) and volume of expiratory carbon dioxide (VCO2) quickly and accurately at the bedside. The mismatch of oxygen (O2) delivery andO2demand andO2consumption in shock provides insight into the severity and progression of shock in critically ill patients. This may aid the evaluation of patients at risk for adverse outcomes, including mortality, length of ICU and hospital stay. METHODS: This is an IRB approved research project (IRB 11012). Data was collected from 12/2018 to 08/2019. To assess the DO2-VO2 status in shock patients with a mobile open-circuit indirect calorimeter (IC) (CCM Express, MGC Diagnostics, St Paul, MN, USA) was utilized to continuously sample inspired and expired gases from a pitot flow sensor connected to the subject's endotracheal tube and face tent. The sampled gas is drawn through galvanic and nondispersive infrared sensors that measure the concentrations ofO2and CO2 and provide measured values of VO2 and VCO2. IC as a method of VO2 determination was used as it considers oxygen consumption by the lung and reduces artifacts. Data for 29 consecutive shock patients was analyzed using Student t-test. A p-value of 0.05 was considered statistically significant. RESULTS: We analyzed 29 patients in shock with an observed mortality of 51.7%. VO2 for the survivors and nonsurvivors was 325 mL/min and 267 mL/min, respectively (p< 0.05). Further comparison of the two groups showed no statistically significant differences between lactate (4.3 vs 6.1 mmol/L), shock index (0.8 vs 0.9), or oxygen consumption normalized to body surface area (159 vs 137 mL/min/m2). CONCLUSION: Patients who survive shock have significantly higher VO2 values than patients who do not survive. We did not observe other significant differences in clinical parameters for these patients, highlighting the significance of oxygen consumption in shock.

PubMed ID

Not assigned





First Page