A new method to evaluate carotid blood flow by continuous Doppler monitoring during cardiopulmonary resuscitation in a porcine model of cardiac arrest.

AIM: We used a wearable carotid Doppler patch to study carotid blood flow patterns in a porcine model of cardiac arrest to identify return of spontaneous circulation (ROSC) and hemodynamics associated with different arrhythmias and the quality of compressions.

METHODS: Twenty Landrace pigs were used as models of cardiac arrest following a standard protocol. Carotid blood flow was monitored continuously using noninvasive ultrasound. Carotid spectral waveforms were captured during various arrhythmias and CPR. Typical carotid blood flow waveforms were recorded at the time of ROSC, and hemodynamic changes were compared with carotid blood flow parameters.

RESULTS: The results showed that the carotid blood flow waveforms varied with ventricular arrhythmia type. During CPR, compression depth correlated significantly with carotid maximal velocity (Vmax) (Spearman correlation coefficient (r)=0.682, P<0.001) and velocity-time integral (VTI) (r=0.794, P<0.001). Vmax and VTI demonstrated moderate predictive value for survival. The regular carotid blood flow pattern towards the brain was observed during ROSC, concurrent with compression waveforms. After ROSC, VTI and carotid pulse volume (cPV) showed similar trends as stroke volume (SV). The carotid minute volume (cMV) exhibited a similar trend as cardiac output (CO).

CONCLUSIONS: Carotid blood flow monitoring could provide valuable information about different arrhythmias as well as the quality of CPR. Carotid flow monitoring allows for timely and effective identification of ROSC. In addition, it may provide valuable hemodynamic information after ROSC.