Altered Microvascular Reactivity During a Skin Thermal Challenge Is Associated With Organ Dysfunction and Slow Recovery After Cardiac Surgery

Abstract

ObjectivesTo assess microvascular reactivity during a skin thermal challenge early post-cardiac surgery and its association with outcome. DesignNon-invasive physiological study. SettingThirty-five-bed department of intensive care. ParticipantsPatients admitted to the ICU post-cardiac surgery. InterventionsThermal challenge. Measurements and Main ResultsForty-six patients were included; 14 needed vasoactive support or ventilatory support for at least 48 hours (slow recovery) and 32 had a more rapid recovery. Skin blood flow (SBF) was measured on the anterior proximal forearm using skin laser Doppler (SLD). A thermal challenge was performed by abruptly increasing local skin temperature from 37°C to 43°C while monitoring SBF. The ratio between the SBFs at 43°C and 37°C was calculated as a measure of microvascular reactivity. SBF at 37°C was not significantly different in patients with a slow recovery and those with a rapid recovery, but SBF after 9 min at 43°C was lower [48.5 (17.3-69.0) vs 85.1 (45.2-125.7), p<0.01], resulting in a lower SBF ratio [2.8 (1.5-4.7) vs 4.8 (3.7-7.8), p<0.01]. Patients with lower SBF ratios were more likely to have dysfunction of at least 1 organ (as assessed using the sequential organ dysfunction [SOFA] score) 48 hours post-cardiac surgery than those with higher ratios: 88% vs 40% vs 27% (p<0.01), respectively, for the lowest, middle, and highest tertiles of SBF ratio. In multivariable analysis, lower SBF ratio was an independent risk factor for slow recovery. ConclusionsEarly alterations in microvascular reactivity as evaluated by a skin thermal challenge are correlated with organ dysfunction. These observations may help in the development of new, simple, non-invasive monitoring systems in postoperative patients.