Usefulness of central venous saturation as a predictor of thiamine deficiency in critically ill patients: a case report

Background Central venous oxygen saturation (ScvO2) reflects the balance of oxygen delivery and consumption. Low ScvO2 indicates the presence of inadequate oxygen delivery, while high ScvO2 indicates reduced oxygen consumption and is sometimes associated with a high mortality rate in critically ill patients from dysoxia. Thiamine is an essential cofactor in cellular aerobic metabolism. Thiamine deficiency is more prevalent than was previously thought, and underlies severe conditions in critically ill patients. However, currently, there is no rapid diagnostic test for thiamine deficiency. Considering oxygen flux, high ScvO2 might be associated with thiamine deficiency. Case presentation A 70-year-old man admitted to the hospital with chief complaint of malaise and edema. He was diagnosed with heart failure with preserved ejection function and was treated with loop diuretics, which resulted in shock. Venoarterial extracorporeal membrane oxygenation and intra-aortic balloon pumping was indicated. The right heart catheter showed high ScvO2, normal cardiac output, and low systemic vascular resistance. Thiamine deficiency was suspected and we started the thiamine infusion. His hemodynamic status improved after thiamine replacement. After his recovery, it was discovered that he had a 1-month history of anorexia and thiamine deficiency. His final diagnosis was beriberi. Conclusions The current case showed the relation between thiamine deficiency and high ScvO2. A literature review also suggested that thiamine deficiency is associated with high ScvO2. Thiamine deficiency causes impaired tissue oxygen extraction, which could lead to high ScvO2. In this context, high ScvO2 might serve as a predictor of thiamine deficiency in critically ill patients.