Jihad Mallat
Cleveland Clinic Abu Dhabi, UAE
Title: Use of PCO2-Gap to guide resuscituation therapy in septic shock patients
Biography
Biography: Jihad Mallat
Abstract
The mixed venous-to-arterial carbon dioxide (CO2) tension difference [P (v-a) CO2] is the difference between carbon dioxide
tension (PCO2) in the mixed venous blood (sampled from a pulmonary artery catheter) and the PCO2 in arterial blood. P (va)
CO2 depends on the cardiac output and the global CO2 production, and on the complex relationship between PCO2 and
CO2 content. Experimental and clinical studies support the evidence that P (v-a) CO2 cannot serve as an indicator of tissue
hypoxia, and should be regarded as an indicator of the adequacy of venous blood to wash out the total CO2 generated by the
peripheral tissues. P (v-a) CO2 can be replaced by the central venous-to-arterial CO2 difference (ΔPCO2), which is calculated
from the simultaneous sampling of central venous blood from a central vein catheter and arterial blood and, therefore, more
easy to obtain at the bedside. Determining the ΔPCO2 during the resuscitation of septic shock patients might be useful when
deciding when to continue resuscitation despite a central venous oxygen saturation (ScvO2) > 70% associated with elevated
blood lactate levels. Because high blood lactate levels is not a discriminatory factor in determining the source of that stress, an
increased ΔPCO2 (> 6 mmHg) could be used to identify patients who still remain inadequately resuscitated. Monitoring the
ΔPCO2 from the beginning of the reanimation of septic shock patients might be a valuable means to evaluate the adequacy of
cardiac output in tissue perfusion and, thus, guiding the therapy. In this respect, it can aid to titrate inotropes to adjust oxygen
delivery to CO2 production, or to choose between hemoglobin correction or fluid/inotrope infusion in patients with a too
low ScvO2 related to metabolic demand. The combination of P (v-a) CO2 or ΔPCO2 with oxygen-derived parameters through
the calculation of the P (v-a) CO2 or ΔPCO2/arteriovenous oxygen content difference ratio can detect the presence of global
anaerobic metabolism.