Assessing Fluid-responsiveness Using Non-invasive Hybrid Diffuse Optics on Peripheral Muscle

Proof-of-concept observational study including ICU patients undergoing a PLR maneuver. Local microvasculature will be assessed with the hDOS platform on the brachioradialis muscle, deriving the microvascular blood flow index (BFI) and tissue oxygen saturation (StO2). CO will be assessed via an invasive hemodynamic monitor based on pulse waveform analysis through the patient's arterial line. The correlation over time between CO and microvascular parameters, and the ability of microvascular variables for predicting a positive CO response (increase \> 10%) will be assessed.