A Theoretical Mathematical Model to Estimate Blood Volume in Clinical Practice.

Published

Journal Article

Perioperative intravenous (IV) fluid management is controversial. Fluid therapy is guided by inaccurate algorithms and changes in the patient's vital signs that are nonspecific for changes to the patient's blood volume (BV). Anesthetic agents, patient comorbidities, and surgical techniques interact and further confound clinical assessment of volume status. Through adaptation of existing acute normovolemic hemodilution algorithms, it may be possible to predict patient's BV by measuring hematocrit (HcT) before and after hemodilution. Our proposed mathematical model requires the following four data points to estimate a patient's total BV: ideal BV, baseline HcT, a known fluid bolus (FB), and a second HcT following the FB. To test our method, we obtained 10 ideal and 10 actual subject BV data measures from 9 unique subjects derived from a commercially used Food and Drug Administration-approved, semi-automated, BV analyzer. With these data, we calculated the theoretical BV change following a FB. Using the four required data points, we predicted BVs (BVp) and compared our predictions with the actual BV (BVa) measures provided by the data set. The BVp calculated using our model highly correlated with the BVa provided by the BV analyzer data set (df = 8, r = .99). Our calculations suggest that, with accurate HcT measurement, this method shows promise for the identification of abnormal BV states such as hyper- and hypovolemia and may prove to be a reliable method for titrating IV fluid.

Full Text

Duke Authors

Cited Authors

  • D'Angelo, M; Hodgen, RK; Wofford, K; Vacchiano, C

Published Date

  • October 2015

Published In

Volume / Issue

  • 17 / 5

Start / End Page

  • 478 - 486

PubMed ID

  • 25332464

Pubmed Central ID

  • 25332464

Electronic International Standard Serial Number (EISSN)

  • 1552-4175

International Standard Serial Number (ISSN)

  • 1099-8004

Digital Object Identifier (DOI)

  • 10.1177/1099800414555410

Language

  • eng