Assessing Skeletal Muscle Variations in Microvascular Pressure and Unstressed Blood Volume at the Bedside. (October 2014)

• Record Type: Journal Article
• Authors: De Blasi, Roberto Alberto; Arcioni, Roberto
• Is Part Of: Microcirculation. Volume 21:Number 7(2014:Oct.)
• Page Start: 606
• Page End: 614
• Publication Date: 2014-10
• Subjects: Biological transport -- Periodicals; Microcirculation -- Physiology -- Periodicals; 612.135
• DOI: 10.1111/micc.12139
• Languages: English
• ISSNs: 1073-9688

Abstract

<abstract abstract-type="main" id="micc12139-abs-0001"> <title>Abstract</title> <sec id="micc12139-sec-0001" sec-type="section"> <title>Objective</title> <p>Quantitative NIRS measurements for MBV partitioning inside microvessels are of current physiologic and clinical interest. In this study, in healthy subjects, we sought new bedside NIRS variables for noninvasively measuring <italic>V</italic><sub>u</sub> and <italic>P</italic><sub>i</sub> changes.</p> </sec> <sec id="micc12139-sec-0002" sec-type="section"> <title>Methods</title> <p>Fifteen healthy subjects underwent graded venous congestion for MBV measurements with NIRS and the reference technique strain‐gauge plethysmography. From ΔMBV we calculated vascular compliance, blood flow, and new NIRS variables including <italic>V</italic><sub>u</sub> and <italic>P</italic><sub>it</sub> and <italic>P</italic><sub>crit</sub>.</p> </sec> <sec id="micc12139-sec-0003" sec-type="section"> <title>Results</title> <p>Extrapolating MBV changes to 0 yielded <italic>P</italic><sub>it</sub> 4.19 ± 0.5 mmHg corresponding to a <italic>V</italic><sub>u</sub> of 2.53 ± 0.43 mL/100 mL T. The slope for MBV began steeper at values below 18 mmHg (<italic>P</italic><sub>crit</sub>). Microvascular compliance measured with NIRS or with strain gauge gave matching results. The change in MBV depended on the oxyhemoglobin increase. No correlation was found between <italic>V</italic><sub>u</sub> and microvascular compliance or the overall ΔMBV. Cumulative pressure steps showed higher linearity in ΔMBV than that induced by discontinuous steps.</p> </sec> <sec id="micc12139-sec-0004" sec-type="section"> <title>Conclusions</title> <p>The new NIRS variables we report could be a practical bench‐to‐bedside tool to assess venous driving pressure for systemic perfusion and measure changes in <italic>V</italic><sub>u</sub> within the microvascular bed.</p> </sec> </abstract>