An increase in skin blood flow induced by fluid challenge is associated with an increase in oxygen consumption in patients with circulatory shock

Purpose: To investigate whether an increase in skin blood flow (SBF) after fluid challenge was associated with an increase in oxygen consumption (VO2) in patients with circulatory shock. Materials and methods: We studied 62 patients with shock who required fluid challenge. Using laser Doppler, we measured finger SBF at basal temperature (SBFBT) and after a thermal challenge test (SBFTCT), before and after a fluid challenge (500 ml of Plasmalyte (R)). In fluid responders (i.e., increase in cardiac index >= 15%), VO2 responders (VO2R) were those with a >= 15% increase in VO2. Results: Of the 62 patients, 33 were fluid responders and 16 of these were VO2R. At baseline, VO2R had lower SBFBT (21[14-52] vs 83[24-116] PU, p = 0.03) and SBFTCT (2.1[1.2-3.3] vs 4.4[2.2-5.6] PU/degrees C, p = 0.02) than VO2 non-responders (VO2NR); hemodynamic variables were not significantly different. The increase in SBFBT (Delta SBFBT) after fluid challenge was greater in VO2R than in VO2NR (141[83-174] vs 57[17-150]%, p = 0.03). Areas under the curves for baseline SBFTCT (0.83 +/- 0.07 [0.68-0.98]) and Delta SBFBT (0.90 +/- 0.05 [0.75-1.0]) to predict Delta VO2 >= 15% were higher than for other variables. Conclusion: A lower baseline SBFTCT and a greater Delta SBFBT can identify patients in whom VO2 will increase after fluid challenge, suggesting an improvement in cellular metabolism. (C) 2022 Elsevier Inc. All rights reserved.