Towards real-time decompression sickness mitigation using wearable capacitive micromachined ultrasonic transducer arrays

Abstract

Decompression sickness (DCS) due to inert gas supersaturation remains one of the major risks for scuba divers and can occur despite adherence to prevention schedules for staged decompression. Post-dive echocardiography for venous gas emboli (VGE) detection has low sensitivity for DCS outcome and is unable to provide real-time physiological monitoring underwater. Alternatively, we present progress towards collecting ultrasound data while at pressure and an exploration into a quantitative assessment for decompression stress. Ultrasound data of an imaging phantom were collected in a hyperbaric chamber up to 9 ATA using a Verasonics V1 system and custom capacitive micromachined ultrasonic transducer (CMUT). The DC voltage requirement for CMUT operation decreased as ambient pressure increased. Separately, a mouse model was used to simulate an extreme pressure profile and echocardiograms were collected every 20 min over 2-h post-decompression. Towards enhancement of DCS assessment, a quantitative analysis of the murine echocardiograms was implemented. Preliminary results show an increase in signal intensity within the venous blood from pre- to post-dive, indicating potential gas presence despite VGE absence. Our findings demonstrate the ability to obtain ultrasound data at pressure and a potential continuous assessment method, which may provide a practical direction for real- time decompression stress quantification.