Carotid artery velocity time integral and corrected flow time measured by a wearable Doppler ultrasound detect stroke volume rise from simulated hemorrhage to transfusion

Abstract

Objective Doppler ultrasonography of the common carotid artery is used to infer stroke volume change and a wearable Doppler ultrasound has been designed to improve this workflow. Previously, in a human model of hemorrhage and resuscitation comprising approximately 50,000 cardiac cycles, we found a strong, linear correlation between changing stroke volume, and measures from the carotid Doppler signal, however, optimal Doppler thresholds for detecting a 10% stroke volume change were not reported. In this Research Note, we present these thresholds, their sensitivities, specificities and areas under their receiver operator curves (AUROC). Results Augmentation of carotid artery maximum velocity time integral and corrected flowtime by 18% and 4%, respectively, accurately captured 10% stroke volume rise. The sensitivity and specificity for these thresholds were identical at 89% and 100%. These data are similar to previous investigations in healthy volunteers monitored by the wearable ultrasound.

The time cost of physiologically ineffective intravenous fluids in the emergency department: an observational pilot study employing wearable Doppler ultrasound

“…For instance, in the investigation by Barjaktarevic et al a + 4 ms absolute ccFT ∆ was as accurate as + 7 ms, however, + 4 ms traded improved sensitivity for specificity. Further, in previous research on healthy volunteers performing a simple preload modifying maneuver [ 20 ] or undergoing moderate-to-severe central hypovolemia and simulated blood transfusion [ 21 , 31 ], we found that 2% and 4% ccFT ∆ , respectively, best identified a 10% SV ∆ . Hence, we studied these thresholds as well.…”

“…Furthermore, ccFT is a promising surrogate for % SV ∆ [ 35 – 43 ], even in the critically ill [ 22 , 44 ], as mentioned in a recent systematic review [ 45 ]. Further, our data in healthy volunteers undergoing moderate-to-severe central hypovolemia, followed by simulated blood transfusion—induced by lower body negative pressure (LBNP) and release—demonstrated a strong, linear relationship between SV ∆ and ccFT ∆ [ 21 , 31 ]. This LBNP analysis comprised approximately 50,000 cardiac cycles making it, to our knowledge, the largest known physiological comparison between SV ∆ and ccFT ∆ .…”

“…Therefore, applying the ccFT ∆ thresholds determined by Barjaktarevic and colleagues may not be physiologically appropriate given that their patient population was undifferentiated shock in the ICU [ 22 ]. Nevertheless, we applied various thresholds for detecting a 10% SV ∆ including from healthy volunteers performing a simple preload modifying maneuver [ 20 ] and those in an LBNP chamber [ 31 ] which may more closely approximate the spectrum of hemodynamic duress in the ED. Despite this, for all thresholds studied, we observed a clinically significant fraction of ED patients, early in their care, demonstrating a fluid ‘unresponsive’ or ‘refractory’ phenotype.…”

Assessing Fluid Intolerance with Doppler Ultrasonography: A Physiological Framework

“…A final implication of this novel framework is that emerging technology may help automate ultrasonographic assessments of both preload (e.g., venous Doppler) and stroke volume (e.g., arterial Doppler), simultaneously ( Figure 4 ) [ 97 ]. We have developed a wireless, wearable Doppler ultrasound that concurrently insonates the jugular vein and common carotid artery [ 98 , 99 , 100 , 101 , 102 , 103 , 104 ]. To our knowledge, we have first reported synchronous venous and arterial Doppler during a dynamic assessment, both in a volume-responsive, healthy volunteer and critically ill, septic patient [ 99 ].…”

A wireless ultrasound patch detects mild-to-moderate central hypovolemia during lower body negative pressure

“…As previously reported, we recruited 11 healthy adult volunteers 9 , 10 , 12 in a physiology laboratory. Exclusion criteria were known cardiovascular history and/or taking regular cardiovascular medications.…”