Abstract
Assessment of microcirculatory functional capacity is considered to be of prime importance for therapy guidance and outcome prediction in critically ill intensive care patients. Here, we show determination of skin microcirculatory oxygen delivery and consumption rates to be a feasible approach at the patient’s bedside. Real time laser-doppler flowmetry (LDF) and white light spectrophotometry (WLS) were used for assessment of thenar skin microperfusion, regional Hb and postcapillary venous oxygen saturation before and after forearm ischemia. Adapted Fick’s principle equations allowed for calculation of microcirculatory oxygen delivery and uptake. Patient groups with expected different microcirculatory status were compared [control (n = 20), sepsis-1/2 definition criteria identified SIRS (n = 10) and septic shock patients (n = 20), and the latter group further classified according to sepsis-3 definition criteria in sepsis (n = 10) and septic shock (n = 10)], respectively. In otherwise healthy controls, microcirculatory oxygen delivery and uptake approximately doubled after ischemia with maximum values (mDO2max and mVO2max) significantly lower in SIRS or septic patient groups, respectively. Scatter plots of mVO2max and mDO2max values defined a region of unphysiological low values not observed in control but in critically ill patients with the percentage of dots within this region being highest in septic shock patients. LDF and WLS combined with vasoocclusive testing reveals significant differences in microcirculatory oxygen delivery and uptake capacity between control and critically ill patients. As a clinically feasible technique for bedside determination of microcirculatory oxygen delivery and uptake, LDF and WLS combined with vasoocclusive testing holds promise for monitoring of disease progression and/or guidance of therapy at the microcirculatory level to be tested in further clinical trials.ClinicalTrials.gov: NCT01530932.
Highlights
Assessment of microcirculatory functional capacity is considered to be of prime importance for therapy guidance and outcome prediction in critically ill intensive care patients
Preoperative otherwise healthy control patients, patients suffering from non-infectious systemic inflammation after trauma or major surgery, and septic shock patients were tested for differences in microcirculatory flow dependent oxygen delivery and oxygen consumption rates upon vasooclusive testing
Three cohorts were enrolled from August 2012 to April 2014: non-infected control patients listed for elective minor surgery, patients suffering from non-infectious systemic inflammatory response syndrome (SIRS) following major trauma or surgery and septic shock patients as defined by sepsis-1/2 definition criteria10, respectively
Summary
Assessment of microcirculatory functional capacity is considered to be of prime importance for therapy guidance and outcome prediction in critically ill intensive care patients. LDF and WLS combined with vasoocclusive testing reveals significant differences in microcirculatory oxygen delivery and uptake capacity between control and critically ill patients. Transpulmonary cardiac output monitoring became popular und global oxygen consumption / delivery balance was estimated by central venous oxygen s aturation4 All these approaches focus on the macrocirculatory level and do not directly provide information of what happens at the microcirculatory and cellular level. In the present study we set out to investigate the technical feasibility and clinical relevance of skin microcirculatory oxygen balance measurements To this end, preoperative otherwise healthy control patients, patients suffering from non-infectious systemic inflammation after trauma or major surgery, and septic shock patients were tested for differences in microcirculatory flow dependent oxygen delivery and oxygen consumption rates upon vasooclusive testing
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