Abstract Body: Background: The Advanced Life Support guidelines (AHA, ERC) emphasize immediate resumption of chest compressions for 2 minutes after defibrillation for ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT). In the presence of undetected return of spontaneous circulation (ROSC), chest compressions may increase the risk of recurrent VF.
Aim: To evaluate whether the novel, continuous, hands-free carotid Doppler ultrasound system, RescueDoppler, can detect successful defibrillation by identifying post-shock blood flow velocities indicative of ROSC.
Research Questions: Can RescueDoppler reliably detect carotid blood flow immediately following defibrillation?
Methods: Patients with pre- and in-hospital cardiac arrests are included from an ongoing multi-center study. The RescueDoppler probe was positioned over the left carotid artery by the cardiac arrest team. The team was blinded to the real-time ultrasound data. ECG recordings (Corpuls, Zoll, Lifepak) were synchronized with pulse-wave Doppler measurements of carotid blood flow velocity and analyzed using MATLAB. Informed consent was obtained post- cardiac arrest from relatives or the patient. ROSC was determined by observing post-shock ECG-synchronous carotid blood flow-velocity curves. The interval from shock to onset of peak systolic velocity (PSV) was measured.
Results: Thirteen cardiac arrest patients (7 men; mean age 71.1 ± 11.7 years) were included, treated either pre-hospital (n=4) or in-hospital (n=9). Causes were cardiac (n=8), trauma, pulmonary embolism, hypothermia, hyperkalemia (each n=1), and one unknown. Initial rhythms were VF (n=5), pulseless electrical activity (n=3), asystole (n=3), and pVT (n=2). A total of 36 shocks (1–12 per patient) were analyzed. Spontaneous circulation—either systolic-flow-only or full temporary ROSC (systolic and diastolic flow)—was observed in 12 patients, with a median shock-to-PSV time of 154 ms (IQR: 107–604) (Figure 1-2). One patient showed no carotid flow post-shock (Figure 3). Chest compressions resumed at a median (IQR) of 3.2 (2.5–4.4) seconds post-shock. Sustained ROSC was achieved in 8 patients, but only one survived to 30 days.
Conclusions: Hands-free, continuous monitoring of carotid blood flow may immediately detect ROSC, or the absence of blood flow following defibrillation. RescueDoppler could help identify successful defibrillation and delay resumption of chest compressions, potentially reducing the risk of recurrent arrhythmias.