Abstract 44: Use of a Hands-Free, Noninvasive Doppler Ultrasound Device to Measure Carotid Blood Flow During Resuscitation From Cardiac Arrest
Background: The ability to non-invasively detect a clinical response during resuscitation efforts remains elusive. A novel hands-free, noninvasive Doppler ultrasound device was developed to detect carotid blood flow during resuscitation.
Hypothesis: The device will detect and quantify the widely variable blood flow seen during return of spontaneous circulation (ROSC) in cardiac arrest.
Methods: Five anesthetized, intubated swine were instrumented with aortic and right atrial pressure transducing catheters. The Doppler device was adhered to the neck over the carotid artery. EKG, pressure readings and Doppler signal were digitized and recorded to disk. Ventricular fibrillation was induced with a pacing catheter. Several fibrillation and resuscitation cycles were performed in each animal. Time-averaged peak Doppler frequency was correlated with the mean aortic systolic blood pressures over the range of ROSC values up to 90mmHg, using 2.5 second data intervals.
Results: Doppler signal data was available for 11 of 27 ROSC episodes. Device attachment and placement issues accounted for the uncaptured signal events. The range of systolic blood pressures detected during these ROSC events was 34–90 mmHg. There was good correlation of the carotid Doppler measurement with systolic blood pressure (R = 0.78). Waveform morphology obtained from the Doppler signal had similar characteristics to that of the aortic waveform tracing by visual inspection.
Conclusion: This hands-free, noninvasive Doppler device is able to detect and measure carotid blood flow over a wide range of values in a similar fashion as that obtained by invasive arterial monitoring. The Doppler waveform morphology will be visually useful to clinicians. Future work will focus on improving device attachment and placement.