Category Archives: 2022 Dr. Glen H. Egstrom DAN

Alex Balan

Why Do We Bubble: My Involvement in DAN’s New Bubble Study

Initially, my reaction to working every Saturday with the DAN research team was probably similar to most who are accustomed to having weekends off — “So… every Saturday?” But my outlook quickly changed after having the opportunity to be a part of what I feel is a critical step toward our understanding of individual variability in decompression stress, which is something that concerns all divers. In other words, why do some people get decompression sickness (DCS) when others don’t, even when diving similar dive profiles? This was a focus of the DAN research team’s primary bubble study for which I helped both as a researcher and participant. It also undoubtedly helped that it was an excuse to go diving every Saturday.

A map of the drive out to Mystery Lake

Myself and fellow interns bubble watching during the study at Mystery Lake.

Before I go further, I think it is useful to explain why bubbles (specifically venous gas emboli) are important when discussing decompression stress. As you may know from an open water class, DCS is a known risk of scuba diving and is currently managed by adhering to no-decompression limits, or decompression schedules, and slow ascent rates dictated by decompression models. DCS in diving is caused by dissolved gasses that form bubbles as they come out of solution due to a decrease in pressure on ascent.

What you may not know, or at least I didn’t know before my internship, is that bubbles can still form without the presence of “clinical DCS.” These bubbles are also known as venous gas emboli (VGE) and are detectable using ultrasound imaging. VGE provide a marker of decompression stress and have been associated with the probability of DCS (although it is not a direct relationship). Interestingly, like DCS, VGE appear at different rates both for different divers and for the same diver on different days. This could be due to a variety of factors, including hydration levels, inflammatory status, nutrition, age, sex, and weight to name a few.

Myself debriefing with Dr. Frauke Tillmans after a dive as a participant in the study

With all that in mind, the way that we investigated VGE differences between divers and within divers was by having a standard dive profile in a local quarry called Mystery Lake over the course of 6 weeks.

Pictured is the visibility at Mystery Lake (I promise that the image has loaded in correctly)

We also take some anthropomorphic measures (i.e., measures of body size), blood (for signs of inflammation), saliva (for stress and other factors), urine (for hydration status) and a 24-hour dietary recall. It was interesting to take part in the study from both the perspective of a researcher and a participant because you feel more empathy for some of the measures: namely the pinching from the caliper body fat measurements and the frustration of forgetting to log your meals from the previous day. Before and after each dive, we would take ultrasound images of participants’ hearts. While I can’t speak to the results of the study (because DAN will still be recruiting and collecting data for at least a few more years), I can speak to some of the interesting anecdotal results we had.

DAN Research team members taking some ultrasound measurements on a participant

There was evident variation in bubbling depending on the dive and the diver. For instance, I did not show much bubbling (if any) on any of my six dive days. In contrast, my colleague bubbled every single dive and for varying lengths post-dive (up to 3 hours later). A different participant noted anecdotally that they think they bubbled more on weeks where they were menstruating, which could be an interesting finding if further investigated, especially given the lack of representation of women in most scientific research (not excluding dive physiology research).

All in all, I was not at all disappointed to have “lost” my Saturdays to DAN’s new bubble study, because it was an opportunity to really contribute to some of the early research that may one day lead us to more personalized decompression models and safer diving. I’m excited to hear more about the upcoming findings over the next few years, and I hope that it was interesting to hear a bit about DAN’s new bubble study! If you’re in the Durham, North Carolina, area, DAN is still recruiting. Volunteering to participate in the study is not only a chance to help advance dive safety and science, but it’s also an excuse to have a great time with great people and go diving (for free) for six weekends.

DAN Research Team Members at Mystery Lake. From left to right Front Row: Enya Marx, Katherine Eltz, Virginie Papadopoulou Back Row: Myself, Robert Furberg, Gabe Graf, Shannon Sunset, Rhiannon Brenner, David Charash, Grant Dong


Growth as a Researcher, Diver, and Instructor

As a research intern at Divers Alert Network, there is an opportunity to learn at every corner. In my time with the research team, I received incredible mentorship as a young scientist to hone my data collection, analysis, and knowledge translation skills. Going into the internship, I knew the quality of research DAN produces, so I was eager to learn as much as I could from the team. But the amount I learned exceeded all expectations.

In addition to DAN’s commitment to training me to be a better scientist, I was provided with a wealth of opportunities for continuing education, allowing me to increase my capacity to act as a steward and leader in the diving field.

I am proud to now hold certifications as a Professional Scuba Inspector/Professional Cylinder Inspectors (PSI/PCI) Visual Cylinder Inspector, Oxygen Cylinder Cleaning Technician and Valve Repair Technician. This course consisted of didactic learning portions and tank and valve disassembly, as well as a tour of a facility where compressed gas cylinders are made. We were incredibly fortunate to have the CEO of PSI/PCI, Mark Gresham, to lead us through learning the intricacies of ensuring safety when working with compressed gas.

I am using a specially designed light and picking tool to peek into a scuba cylinder to inspect the integrity of the walls

A photo showing the thickness of a typical scuba cylinder wall in relation to the shoulder.

As research interns, we were also given the opportunity to participate in a regulator clinic at the headquarters of Dive Rite. This was a first for many of us, to open up such a critical part of our life-support equipment. The experience gave me a better understanding of the system and while it was complex in some sense, it could be broken down into a relatively simple system.

Beth Jones and I taking apart the second stage of a regulator as a part of a regulator clinic at Dive Rite.

During my time at DAN, I also became certified as an instructor for the Divers Alert Network First Aid for Professional Divers (DFA Pro) Course. For the course, we were guided through general first aid, emergency oxygen, CPR, neurological assessment and first aid for hazardous marine life injuries. These skills were first taught at the provider level with the help of our instructors Christine Tamburri and Wally Endres from Risk Mitigation and Safety Services.

This course gave us the foundations and knowledge to apply to our DFA Pro instructor training, which was done with the help of Jim Gunderson, the director of training at DAN. Working with Jim, we were able to better understand the teaching methodology DAN employs to provide some of the most robust training in CPR and first aid available while making it applicable to divers.

Some of the training materials used for the DAN DFA Pro Course.

Each of these certifications has aided in my professional development immensely, as I am able to bring them back to my home dive shop. I am excited to teach new students about the importance of first aid training for divers. I also have gained a deeper understanding of how my equipment works when diving and am therefore better equipped to solve problems above and below the water.