Hands-free continuous carotid Doppler ultrasound for detection of the pulse during cardiac arrest in a porcine model

Real-time feedback on chest compression efficacy by hands-free carotid Doppler in a porcine model

Aim

Current guidelines for cardiopulmonary resuscitation (CPR) recommend a one-size-fits-all approach in relation to the positioning of chest compressions. We recently developed RescueDoppler, a hands-free Doppler ultrasound device for continuous monitoring of carotid blood flow velocity during CPR. The aim of the present study is to investigate whether RescueDoppler via real-time hemodynamic feedback, could identify both optimal and suboptimal compression positions.

Methods

In this model of animal cardiac arrest, we induced ventricular fibrillation in five domestic pigs. Manual chest compressions were performed for ten seconds at three different positions on the sternum in random order and repeated six times. We analysed Time Average Velocity (TAV) with chest compression position as a fixed effect and animal, position, and sequential time within animals as random effects. Furthermore, we compared TAV to invasive blood pressure from the contralateral carotid artery.

Results

We were able to detect changes in TAV when altering positions. The positions with the highest (range 19 to 48 cm/s) and lowest (6-25 cm/s) TAV were identified in all animals, with corresponding peak pressure 50-81 mmHg, and 46-64 mmHg, respectively. Blood flow velocity was, on average, highest at the middle position (TAV 33 cm/s), but with significant variability between animals (SD 2.8) and positions within the same animal (SD 9.3).

Conclusion

RescueDoppler detected TAV changes during CPR with alternating chest compression positions, identifying the position yielding maximal TAV. Future clinical studies should investigate if RescueDoppler can be used as a real-time hemodynamical feedback device to guide compression position.

Evaluation of hemorrhagic shock and fluid resuscitation in pigs using handless Doppler carotid artery ultrasound

OBJECTIVE

This study aimed to utilize a hemorrhagic shock pig model to compare two hemodynamic monitoring methods, pulse index continuous cardiac output (PiCCO) and spectral carotid artery Doppler ultrasound (CDU). Additionally, we sought to explore the feasibility of employing CDU as a non-invasive hemodynamic monitoring tool in the context of hemorrhagic shock and fluid resuscitation.

DESIGN

Animal experiments.

SETTING AND SUBJECTS

Female pigs were selected, and hemorrhagic shock was induced by rapid bleeding through an arterial sheath.

INTERVENTIONS

Hemodynamic monitoring was conducted using both PiCCO and CDU during episodes of hemorrhagic shock and fluid resuscitation.

MEASUREMENTS AND MAIN RESULTS

Among the 10 female pigs studied, CDU measurements revealed a significant decrease in carotid velocity time integral (cVTI) compared to baseline values under shock conditions. During the resuscitation phase, after the mean arterial pressure (MAP) returned to its baseline level, there was no significant difference between cVTI and baseline values. A similar trend was observed for carotid peak velocity (cPV). The corrected flow time (FTc) exhibited a significant difference only at the time of shock compared to baseline values. In comparison to PiCCO, there was a significant correlation between cVTI and MAP (r = 0.616, P < 0.001), stroke volume (SV) (r = 0.821, P < 0.001), and cardiac index (CI) (r = 0.698, P < 0.001). The carotid Doppler shock index (cDSI) displayed negative correlations with MAP (r =  - 0.593, P < 0.001), SV (r =  - 0.761, P < 0.001), and CI (r =  - 0.548, P < 0.001), while showing a positive correlation with the shock index (SI) (r = 0.647, P < 0.001).

CONCLUSIONS

Compared to PiCCO, CDU monitoring can reliably reflect the volume status of hemorrhagic shock and fluid resuscitation. CDU offers the advantages of being non-invasive, providing real-time data, and being operationally straightforward. These characteristics make it a valuable tool for assessing and managing hemorrhagic shock, especially in resource-limited settings.