Oxygen, glucose, carbon dioxide and lactate concentration gradients in different vascular compartments

• Grant number: 06/00561-9
• Support Opportunities: Regular Research Grants
• Start date: May 01, 2006
• End date: May 31, 2010
• Field of knowledge: Health Sciences - Medicine - Medical Clinics
• Principal Investigator: Eliezer Silva
• Grantee: Eliezer Silva
• Host Institution: Instituto do Coração Professor Euryclides de Jesus Zerbini (INCOR). Hospital das Clínicas da Faculdade de Medicina da USP (HCFMUSP). Secretaria da Saúde (São Paulo - Estado). São Paulo , SP, Brazil

Abstract

Some studies have shown a decreasing gradient in blood O2 saturation (SO2) and lactate concentration ([Lac]) from the right atrium to the pulmonary artery, defined as ΔSO2 and Δ[Lac], respectively. These concentration gradients are produced by mixing of RA blood with myocardial venous blood of lower O2 content and [Lac]. The possibility exists, however, that mixing with inferior vena cava (IVC) blood also could produce the observed changes in [Lac] and SO2. This could only happen, however, if IVC blood were to have lower SO2 and [Lac] than RA blood. ΔSO2 and ΔLac would have little clinical significance if produced by mixing atrial with IVC blood. Conversely, if produced by mixing atrial with coronary effluent blood, these gradients represent physiological signals of importance as they mirror alterations in myocardial metabolism. These signals could be monitored with relative ease in critically ill individuals who require a pulmonary artery catheter to aid with fluid management. The proposed research is designed to provide definitive information on the relative concentrations of O2, [Lac], CO2 and glucose in the inferior vena cava, superior vena cava, RA, coronary sinus ostium, right ventricle (RV), arterial circulation and pulmonary circulation in different tissue hypoxia models (sepsis, controlled bleeding, cardiac tamponade and isovolemic anemia). This information is expected to elucidate whether mixing right atrial blood with IVC or coronary venous blood produces the SO2 and [Lac] gradients and identify if CO2 and glucose gradients also exist. (AU)