915

Abstract

Introduction: In critical illness, increasing oxygen delivery (DO2) in an attempt to raise oxygen consumption (VO2) was previously thought to be beneficial. Further studies however showed that while patients whose VO2 increased with increased DO2 did well, those whose VO2 did not increase in spite of high DO2 had extremely poor outcomes. This suggests that oxygen extraction is critical in these patients. Hypothesis: Thiamine, a co-factor of pyruvate dehydrogenase and necessary for aerobic metabolism, may increase oxygen extraction in critically ill patients. Methods: This was an open-label, pilot study. 20 critically ill, mechanically ventilated adult patients were enrolled in the medical and surgical ICU’s at our tertiary care medical center. 4 were excluded from analysis due to incomplete data collection. All patients were connected to the Cheetah non-invasive cardiac output monitor for continuous cardiac index(CI) monitoring, and to the GE Compact Anesthesia monitor for continuous measurement of VO2. After baseline CI and VO2 data were collected for 3 hours, a single dose of 200mg IV thiamine was administered. VO2 and CI were monitored for an additonal 6 hours after thiamine was given. Thiamine levels and lactate were collected at the beginning and end of the study. Results: The primary outcome was change in VO2. 16 patients were included in the analysis. There was a statistically significant increase in VO2 after thiamine (average increase of 16ml/min +/- SE 8, p= 0.049). These results remained the same after adjusting for changes in cardiac index (CI). In patients with an average CI greater than our cohort’s median value of 2.9L/m2, there was an increase in VO2 of 71ml/min (+/- 16, p<0.0001) after thiamine administration. Thiamine had no effect on VO2 in patients with reduced CI(<2.5L/m2). Thiamine levels ranged from undetectable in one patient to 73nmol/L (reference range 9-44nmol.L). There was no association between initial thiamine level and change in VO2 after thiamine administration. Conclusions: We found that thiamine administration increases VO2 in critically ill patients. There was a larger effect in patients with higher than average CI. These effects were not associated with baseline thiamine level.