The feasibility of monitoring trauma patients with a wireless, wearable Doppler ultrasound

Abstract

Background: Early detection of reduced stroke volume (SV) or cardiac output (CO) may expedite resuscitative interventions during traumatic hemorrhage; corrected carotid artery flow time (ccFT) has been proposed as a surrogate for SV during blood volume loss.

Study design and methods: We conducted a prospective cohort study to assess the feasibility of using a wireless, wearable Doppler ultrasound capable of measuring ccFT in traumatically injured patients at a level 1 trauma center. A convenience sample of 33 patients was enrolled. We assessed device placement, data transfer and capture, and signal quality by assessing the ability to capture at least 15 consecutive cardiac cycles in the minute prior to blood pressure monitor cycling. A post hoc analysis examined ccFT variations between transfused and non-transfused patients.

Results: Device placement succeeded in 94% of patients (n = 31) and the data were captured and transferred from all 31. The consecutive cardiac cycles before blood pressure measurement exceeded 15 (p = .015) in 93% of patients (n = 28). We observed ccFT below 270 ms and longer time spent under this threshold during resuscitation in transfused patients. Patients with low ccFT experienced more severe injuries and longer hospital and ICU stays.

Discussion: This is the first study that demonstrates the feasibility of using a wearable Doppler ultrasound in trauma patients on admission to the trauma bay. Although findings suggest that ccFT could serve as an early marker of hemodynamic compromise, further large-scale, multicenter studies are needed to validate its predictive value and clinical utility in guiding trauma resuscitation.

Keywords: Doppler ultrasound; RBC transfusion; blood management; corrected carotid flow time; transfusion practices (adult); wearable technology.

FIGURE 1

Picture of wireless, wearable Doppler and spectrograms. (A) The wearable Doppler adhered to the neck under a cervical collar (over the anatomical right carotid artery) and (B) the common carotid artery and internal jugular Doppler spectrograms. The equation of Wodey is shown. (C) Boxplots indicate the number of consecutive cardiac cycles collected with wearable Doppler device in the minute prior to a non‐invasive blood pressure (NIBP) recording. In 28 of 30 patients, at least one instance of 15 consecutive cardiac cycles were recorded prior to NIBP recording.

FIGURE 2

Analyses in 31 patients comparing corrected continuous flow time of the common carotid artery (ccFT), injury severity score (ISS), and length of hospital stay (LOS) between patients receiving blood products (orange) during their resuscitation in the trauma bay and those that did not (blue). (A) Patients who received blood products showed a trend toward lower ccFT, higher ISS and LOS. (B) Histograms (not shown) reveal a natural breakpoint in the average ccFT at 270 ms which contributed to a subsequent analysis based on this dichotomy. Overlapping temporal waveforms and more saturated colors of ccFT indicate that a higher density of patients receiving blood products (yellow) experienced a below 270 ms ccFT (red line) compared with those that did not (blue).