Tracking DO2 with Compensatory Reserve during Whole Blood Resuscitation in Baboons

Abstract

BackgroundHemorrhagic shock can be mitigated by timely and accurate resuscitation designed to restore adequate delivery of oxygen (DO2) by increasing cardiac output (CO). However, standard care of using systolic blood pressure (SBP) as a guide for resuscitation has proven ineffective and can be associated with increased morbidity. We have developed a novel vital sign called the compensatory reserve (CRM) generated from analysis of arterial pulse waveform feature changes that has been validated in experimental and clinical models of hemorrhage. We tested the hypothesis that thresholds of DO2 could be accurately defined by CRM while avoiding over resuscitation during whole blood resuscitation following a 25% hemorrhage in non‐human primates.MethodsTo accomplish this, adult male baboons (n=12) were exposed to a progressive controlled hemorrhage that resulted in an average (± SD) maximal reduction of 601 ± 18 ml of their estimated circulating blood volume of 1,262 ± 64 ml based on body weight. Values of DO2 were calculated as the product of CO times O2 carrying capacity of hemoglobin (i.e., Hb content × 1.34).ResultsAverage (± SD) CRM increased from 6 ± 5 % at the end of hemorrhage to 70 ± 7 % at the end of resuscitation. DO2 of 12.1, 10.3, and 7.0 ml O2·kg−1 ·min−1 were calculated at 0% (baseline), 12.5% and 25% blood loss. By linear regression, CRM values of 6% (decompensation), 35%, and 68% corresponded to calculated DO2 values of 6.0, 9.2, and 12.1 ml O2·kg−1 ·min−1 during resuscitation. As such, return of CRM to baseline during resuscitation with only ~ 450 ml provided adequate DO2 (12.5 ml O2·kg−1 ·min−1) while total blood volume replacement (~600 ml) resulted in over resuscitation as indicated by an average increase in SBP (+17 mmHg) and CO (+0.1 L/min) over baseline values.ConclusionConsistent with our hypothesis, thresholds of DO2 were associated with specific CRM values. A target resuscitation CRM value of 70% minimized the requirement for whole blood, while avoiding over resuscitation. Furthermore, CRM at 0% provided a noninvasive metric for determining critical DO2 at approximately 5.4 ml O2·kg−1 ·min−1.Support or Funding InformationThis research was supported in part by appointment of Ms. Koons to the Postgraduate Research Fellowship Program at the US Army Institute of Surgical Research administered by the Oak Ridge Institute for Science and Education through an interagency agreement between the US Department of Energy and USAMRMC. Study funding was provided by a grant from the US Army Combat Casualty Care Research Program (D‐009‐2014‐USAISR). Linearregression of the relationship between DO2 and compensatory reserve during whole blood resuscitation in baboons. Data are expressed as mean ± SE.imageLinearregression of the relationship between DO2 and compensatory reserve during whole blood resuscitation in baboons. Data are expressed as mean ± SE.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.