Relationship of oxygen delivery and mixed venous oxygenation to lactic acidosis in patients with sepsis and acute myocardial infarction

Abstract

Critical decreases in oxygen delivery (Do₂) and mixed venous oxygen saturation (Svo₂) are associated with anaerobic metabolism and, therefore, lactic acidosis. We studied 50 consecutive patients with sepsis and 50 consecutive patients with acute myocardial infarction (AMI) in whom the arterial blood lactate was > 1 mmol/ L in order to determine critical thresholds of Do₂ and Svo₂. In both groups, critical values of Do₂ or Svo₂ associated with lactic acidosis could not be identified. The Do₂ ranged from 136 to 811 ml/min m² and Svo₂ ranged from 28% to 73% in the patients with sepsis. The Do₂ ranged from 115 to 434 ml/min m² and Svo₂ from 17% to 72% in patients with AMI. The absence of threshold values for Do₂ Svo₂ and probably reflects the influence of distributive flow abnormalities as well as differences in metabolic requirements in these critically ill patients.