Abstract 11489: Respiratory Quotient Correlates With Blood Lactate During Hemorrhage
Background: Cellular energy productions shifts from oxidative phosphorylation to glycolysis during periods of hypoxia, a symptom common to both shock and rigorous exercise. In critical care, serum excess lactate is measured as a marker of increased anaerobic metabolism. In exercise physiology, the respiratory quotient (RQ), defined as the ratio of the number of carbon dioxide molecules produced to the number of oxygen molecules consumed in a single breath, is used to track shifts between aerobic and anaerobic metabolism. We hypothesized that the respiratory quotient could be used to track the metabolic status of animals in shock.
Methods: To compare lactate and RQ during two states of shock, 5 swine (~30kg) were subjected to 2 minutes of untreated VF followed by ACLS (2 minutes of CPR followed by defibrillation). After successful resuscitation and hemodynamic stabilization, 1 L of blood volume was removed through a femoral introducer sheath. In addition to standard physiological monitoring, we measured airway flow, oxygraphy, and capnography. Blood chemistry was measured at baseline, 1.5 minutes into arrest and at 3 time points after resuscitation. Serum lactate values were aggregated across all animals and fit with a least squares linear regression. The respiratory quotient was calculated using breath by breath values of oxygen consumption and carbon dioxide production.
Results: All animals were successfully resuscitated. Blood pressures and heart rates normalized within 30 minutes of resuscitation for all animals. All animals died within 100 minutes of the initiation of hemorrhage. During and after hemorrhage, the serum lactate model increased 60% and the respiratory quotient increased 7%. The Pearson correlation coefficient between the serum lactate model and the mean respiratory quotient was R = 0.69 with p = 0.02.
Conclusions: We have developed a stable model of altered hemodynamics and metabolic injury. Both serum lactate and the respiratory quotient increased monotonically with time, and were strongly correlated. These data suggest that the combination of volumetric capnography and volumetric oxygraphy can be used to track patient metabolic status in real time during shock.
Author Disclosures: J.W. Lampe: Employment; Significant; University of Pennsylvania. Research Grant; Significant; NIH funding in hypothermia. Other Research Support; Significant; ZOLL Medical Corporation, Philips Therapeutic Care, Nihon Khoden. Ownership Interest; Significant; Helar Technologies, LLC. Consultant/Advisory Board; Significant; Philips Therapeutic Care. R. Wijshoff: Employment; Significant; Philips Research. J. Muehlsteff: Employment; Significant; Philips Research. M. Bartula: Employment; Significant; Philips Research. M. Fuller: Employment; Significant; Philips Therapeutic Care. D. Jorgenson: Employment; Significant; Philips Therapeutic Care. L.B. Becker: Employment; Significant; University of Pennsylvania. Research Grant; Significant; NIH funding in hypothermia. Other Research Support; Significant; Philips Therapeutic Care, ZOLL Medical, Nihon Khoden, Medtronic, Benechill. Ownership Interest; Significant; Helar Technologies, LLC. Consultant/Advisory Board; Significant; Philips Therapeutic Care.
- © 2015 by American Heart Association, Inc.