2022 Strategic - Predicting bubbles in recreational scuba divers
Applications open: 19/07/2021
Applications close: 13/08/2021
About this scholarship
Just over 1% of US and Australian residents scuba dive in any particular year, making an average of 10 dives per person. Scuba divers are subjected to increased ambient pressure at depth and they absorb inert gas while breathing underwater. During ascent the ambient pressure falls and bubbles commonly form inside divers’ blood and/or tissues. These bubbles are detectable in vivo using echocardiography, and they can be seen passing through the heart. Bubbles are associated with post-dive vascular dysfunction, decreased Flow Mediated Dilation (FMD) and increased inflammatory responses. A meta-analysis identified that a decrease of 1% FMD increases the risk of a cardiovascular event (e.g. stroke, myocardial infarction) by 13%, and cardiovascular events are a leading cause of death in divers. It is especially important for divers with an atrial-septal defect or a patent foreman ovale (a hole in the heart) to avoid bubbles, which pass through the heart and enter the arterial circulation without being filtered out by pulmonary capillaries, leading to decompression sickness. Around one quarter of divers have a hole in their heart and, whilst it is common for divers to produce detectable bubbles without decompression sickness, it is far more common for divers with decompression sickness to have detectable bubbles.
The first depth-time tables to prevent decompression sickness (the “bends”) were produced by JS Haldane in 1908. Since then, Haldanean tables have undergone a number of “tweaks” and newer tables have been experimentally designed. The most recent algorithms for predicting risk of decompression sickness, based on probability of bubbles, are founded on theoretical physics and not on human data. Only limited experimental trials have been conducted on bubble models and half were stopped early due to adverse outcomes. While we are able to successfully predict the risk of decompression sickness by using personal underwater diving computers, we are not yet able to accurately predict the probability of bubbles forming in recreational divers. Predicting the probability of decompression sickness allows defining a threshold to limit the probability of that outcome occurring. Without being able to predict the probability of bubbles, divers cannot reliably limit the volume of bubbles they produce and it is not known how changing the personalised settings available within current dive computers affects the volume of bubbles produced.
This project will collate existing human bubble data recorded in vivo in recreational divers, using published research and existing datasets in Australia, Europe and North America. A bubble “score” is given after observing the quantity of bubbles passing through the right ventricle of the heart, using 2D echocardiography. The partial pressure of inert gas dissolved in the divers will be estimated using software authored by the research team. An algorithm will be developed with three possible outcomes: no detectable bubbles, low bubbling or high bubbling. The independent predictor variables will be a set of classic Haldanean tissue pressures, which are already well-established in popular dive computers. In this way, divers and dive computers of the future will be able to simultaneously predict the probability of both decompression sickness and bubble formation. We will then validate our algorithm by recording bubbles in recreational divers in Western Australia and comparing their bubble scores with those predicted by the algorithm, (based on the recorded depth-time dive profiles). A second validation set of dives will be made in the Fiona Stanley Hyperbaric Medicine Unit, in a custom-built pool inside the hyperbaric chamber.
- Future Students
- Faculty of Health Sciences
- Higher Degree by Research
- Australian Citizen
- Australian Permanent Resident
- New Zealand Citizen
- Permanent Humanitarian Visa
- International Student
- Merit Based
Total value of the annual scholarships (stipend and fees) is approx. $60,000 - $70,000 p.a. Curtin PhD Stipends are valued at $28,597 p.a. for up to a maximum of 3.5 years.
Successful applicants will receive a 100% Fee offset.
All applicable HDR courses
Statistical skills would be an advantage but can be learned, and the successful candidate will apply themselves to the analysis of data to contribute to the health of Western Australian recreational divers. We are looking for someone who will get on well with the other PhD students, be mentored by them, and mentor future PhD students. You will present at a conference, but we will help you develop presentation skills. Familiarity with MS Office (WORD and Excel), fluency in English and previous research experience (e.g. honours degree) are essential. Certification as a scuba diver would also be an advantage.
If this project excites you, and your research skills and experience are a good fit for this specific project, you should complete the Expression of Interest (EOI) form now.
You will need to ensure you accurately select the Project lead (listed below) as your nominated supervisor and provide details for at least one referee.
Eligible to enrol in a Higher Degree by Research Course at Curtin University by March 2022
To enquire about this project opportunity contact the Project lead (listed below).
Name: Dr Peter Buzzacott
Contact Number: 9266 3041