Cardiac stroke volume predicts progressive central hypovolemia by three different non‐invasive methods

Abstract

BackgroundCardiac stroke volume (SV) has been proposed as a clinical tool to predict the magnitude of acute hemorrhage. Multiple non‐invasive measurement methods of SV exist, without a standard method. We aimed to investigate the development of SV during simulated hemorrhage, and examine differences between three non‐invasive methods of SV measurements.Methods10 healthy subjects underwent experimental central hypovolemia through lower body negative pressure (LBNP) until −60 mmHg or onset of presyncope (7/10 subjects). SV beat‐to‐beat was calculated by Ultrasound Doppler (SV_usd, SD 100), finger arterial blood pressure curve (SV_bpc, Finometer) and cardiothoracic impedance (SV_imp, Task Force). The non‐parametric median and 95% confidence intervals (CI) were calculated from epochs of 60 or 120 seconds for SV in 5 different LBNP levels.ResultsBaseline absolute values for the three methods were different: SV_usd 78 ml (95% CI: 68,93), SV_bpc 88 ml (77,99), SV_imp 103 ml (89,151). SV_usd decreased with 45% (52%, 37%), SV_bpc decreased with 39% (45%, 27%), while SV_imp decreased with 33% (48%, 21%). Differences between methods were not significant.ConclusionSV clearly reflects the development of a simulated hemorrhage. The three methods for non‐invasive SV measurements provide different absolute values of SV during LBNP, but they decrease in a comparable way. Financial support: University of Oslo.