Basis for a hands free blood flow measurement with automated vessel focus

Cardiopulmonary resuscitation (CPR) is one of the essential tools to ensure oxygen supply during cardiac arrest. However, the precise effects of chest compression are not quantifiable to this day. This often results in a low quality of chest compressions even if performed by health-care professionals. One solution could be provided by quantification of blood flow via ultrasonic Doppler measurements, to guide first responders in their efforts. This paper presents an approach to address the issue of limited time, anatomical know how and limitations of system configuration during emergency scenarios. An approach for automated vessel identification with three different phases was developed, featuring a new sensor probe for ultrasonic measurements with non symmetrically angled piezo ceramics. The probe was used with prototype ultrasound hardware in a laboratory setup for Pulsed Wave Doppler (PW Doppler). In an initial measurement a qualitative flow was approximated to examine valuable measurement positions on a phantom. Afterwards an iterative mode was used for depth depending frequency measurements with score calculation of flow periodicity and signal power. The configuration with the best score was used for a prolonged monitoring mode. Flow values were compared to data of an industrial flow-sensor. Flow-sensor data showed an average coefficient of determination of 0.97 with an average root mean square error of 3.84 ml/s. With the proposed hardware and software solutions a basis for future developments was made, which could lead to a fully automated vessel identification during CPR. This device could provide first responders as well as clinical staff with vital information about CPR efficiency that has yet to be included into the therapy of people during cardiac arrest.