NEW Bubble Study: Inter- and intrasubject variability in post-dive venous gas emboli

Venous gas emboli (VGE) are bubbles that can appear in the blood after a dive due to decompression. These bubbles are detectable using ultrasound imaging and provide a measure of decompression stress. VGE appear at different rates both for different divers and for the same diver on different days. Reasons for variation in VGE and decompression stress have yet to be identified. In this study, DAN researchers will collect data on participants diving the same profile each week for 6 weeks in a row to determine how much variation exists within and between divers, and to attempt to narrow down what factors contribute to increased decompression stress.

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Decompression Sickness (DCS) is a known risk of SCUBA diving. Inert gas from the compressed breathing gas is absorbed by the body when the diver is breathing pressurized gas under pressure. When a diver begins to surface, the surrounding pressure decreases. The decrease in pressure forces the absorbed inert gas from the tissues back into the bloodstream to be expired out of the body and can sometimes cause bubbles to grow in tissues or in the bloodstream. Decompression bubbles in blood can be detected using ultrasound as venous gas emboli (VGE). These VGE are a marker of decompression stress and are associated with the probability of DCS (although it is not a direct relationship).

DCS risk is currently managed by adhering to no-decompression limits, or decompression schedules, and slow ascent rates dictated by decompression models. These models do not account for documented differences in VGE post-dive and DCS risk between people. There is also a lack of information regarding DCS risk and VGE incidence post-dive of for repeated exposures of a single subject. This study aims to collect ultrasound recordings pre- and post-dive across six weeks (six dive days) in order to evaluate individual VGE susceptibility in the absence of repeated diving that has previously been shown to result in acclimation. Data from this study will therefore compare the presence and count of VGE between different divers (inter-subject variability) and whether individual divers are consistent in their VGE incidence (intra-subject variability). Variability in VGE incidence will also be compared with a multitude of factors including nutritional intake, anthropometrics (body measurements), hydration status, and stress and inflammation levels.