The microcirculatory response to compensated hypovolemia in a lower body negative pressure model.

Abstract

The objective of the present study was to test the hypothesis that controlled, adequately compensated, central hypovolemia in subjects with intact autoregulation would be associated with decreased peripheral microcirculatory diffusion and convection properties and, consequently, decreased tissue oxygen carrying capacity and tissue oxygenation. Furthermore, we evaluated the impact of hypovolemia-induced microcirculatory alterations on resting tissue oxygen consumption. To this end, 24 subjects were subjected to a progressive lower body negative pressure (LBNP) protocol of which 14 reached the end of the protocol. At baseline and at LBNP=-60 mm Hg, sidestream dark field (SDF) images of the sublingual microcirculation were acquired to measure microvascular density and perfusion; thenar and forearm tissue hemoglobin content (THI) and tissue oxygenation (StO2) were recorded using near-infrared spectroscopy (NIRS); and a vascular occlusion test (VOT) was performed to assess resting tissue oxygen consumption rate. SDF images were analyzed for total vessel density (TVD), perfused vessel density (PVD), the microvascular flow index (MFI), and flow heterogeneity (MFIhetero). We found that application of LBNP resulted in: 1) a significantly decreased microvascular density (PVD) and perfusion (MFI and MFIhetero); 2) a significantly decreased THI and StO2; and 3) an unaltered resting tissue oxygen consumption rate. In conclusion, using SDF imaging in combination with NIRS we showed that controlled, adequately compensated, central hypovolemia in subjects with intact autoregulation is associated with decreased microcirculatory diffusion (PVD) and convection (MFI and MFIhetero) properties and, consequently, decreased tissue oxygen carrying capacity (THI) and tissue oxygenation (StO2). Furthermore, using a VOT we found that resting tissue oxygen consumption was maintained under conditions of adequately compensated central hypovolemia.

• Authors: Sebastiaan A Bartels, Rick Bezemer, Dan M J Milstein, Matthijs Radder, Alexandre Lima, Thomas G V Cherpanath, Michal Heger, John M Karemaker, Can Ince
• Journal: Microvascular research (Microvasc Res) Vol. 82 Issue 3 Pg. 374-80 (Nov 2011) ISSN: 1095-9319 [Electronic] United States
• PMID: 21839097 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2011 Elsevier Inc. All rights reserved.

Chemical References

• Oxygen

Topics

• Adult
• Blood Volume
• Homeostasis
• Humans
• Hypovolemia (blood, physiopathology)
• Lower Body Negative Pressure
• Male
• Microcirculation
• Microscopy, Video
• Mouth Floor (blood supply)
• Netherlands
• Oxygen (blood)
• Oxygen Consumption
• Regional Blood Flow
• Spectroscopy, Near-Infrared
• Time Factors
• Upper Extremity (blood supply)