Automated Evaluation of Microvascular Blood Flow and Oxygenation following Trauma and Hemorrhage in Rats

Abstract

Studies evaluating blood flow and oxygen partial pressure (PO2) may not directly measure both parameters and may depend on investigator's selection of measuring sites. In addition, relevant systemic parameters may not be simultaneously recorded. Therefore, we implemented a new automated system for blood flow and PO2 acquisition in large tissue areas while collecting systemic information. In 10 animals anesthetized with isoflurane, cardio‐respiratory parameters were continuously recorded, in experiments lasting up to 4 h. Other data were collected at baseline, and after laparotomy and 30 min hemorrhage (40% of total blood volume). A cremaster muscle was spread over a thermostatically‐controlled pedestal fixed to a motorized stage. Sixteen noninvasive PO2 measurements using oxygen‐dependent phosphorescence quenching and fiber‐optics were performed during a computer‐controlled tissue scan. In the same areas used for PO2 measurements, microvascular blood flow was estimated employing laser speckle contrast imaging. Blood was sampled for extensive biochemistry and coagulation profiles. The system was used successfully by different operators. One set of flow and PO2 measurements was completed in less than 90 s. Changes in muscle flow correlated with local PO2 but several systemic parameters did not correlate with blood flow and PO2, emphasizing the importance of performing both local and systemic evaluations. System advantages include integration between local and multiple systemic parameters, unbiased data collection/analysis, easy implementation, improved performance, no need for customized programming, and simplified training compared to intravital microscopy.Support or Funding InformationSupported by US Army Medical Research and Materiel Command.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.