Connect with us


Micro Bubbles, Macro Problems: New Research Brings Possible Solutions to DCS Quandaries

Diver Alert Network’s Reilly Fogarty geeks out on new research by University of North Carolina biomedical researcher and current R.W. Hamilton Grant recipient Virginie Papadopoulou, Ph.D. (That’s right, she received the “Dr. Bill” grant!!) Her potential paradigm-shifting work may help us to understand the actual link between bubbles and getting bent; our current models lack definitive causation.



By Reilly Fogarty

Our current understanding of decompression stress is binary—you are either symptomatic or you are not. This conceptualization is the result of decades of research done by driven individuals in an astonishingly complex academic niche. The field of bubble research ties together numerous academic fields and seems to survive solely on the dedication of those involved. Breakthrough advances in the field are rare and almost universally involve years of work and decades of experience. When they do happen, they have a way of discernibly shifting our understanding of the entire field. Research on microbubbles and ways to quantify decompression stress by bioengineer Virginie Papadopoulou, Ph.D., shows early signs that suggest such a shift.

A GIF showing decompression induced bubble growth on  tissue samples. Credit: Virginie Papadopoulou —2015. Originally published in this article.

Since the creation of this discipline, any explanation of how bubbles correlate to decompression sickness (DCS) from even the most experienced researchers has been a leading question or two away from, “well, we don’t actually know, but here’s our best guess.” The effects bubbles have on us are the product of an enormous (and constantly growing) list of factors, including dehydration and endothelial and inflammatory responses. Our current understanding of the link between “bubble populations” and DCS lacks definitive causation. Research up to this point has found that bubble counts may correlate to incidence of DCS, but they do not always, and some individuals seem not to bubble as much as others. This understanding of post-dive bubbling has led to a slew of theories about variance among individuals that cause some people to bubble more than others and increasingly elaborate modeling of decompression.

This video is of an ultrasound of a diver’s heart after an uneventful pool dive. The bright white spots moving against the dark background are bubbles moving to the venous chambers. Video: Virginie Papadopoulou, in joint experiments with DAN —2018.
This graphic of a human heart is to aid in understanding what can be seen in the sonogram of a divers heart. Credit to “Wapcaplet CC BY-SA 3.0 , from Wikimedia Commons”

Papadopoulou, who specializes in ultrasound imaging techniques and the creation and application of microbubbles and nanodroplets—tiny bubbles whose core has condensed to liquid through decrease in temperature or increase in pressure—for medical applications, has proposed that this correlation and the debate over why some divers bubble more than others is partly due to a failure in imaging technique rather than bubble production. Her techniques yield bubbles that are orders of magnitude smaller than previously imaged for scuba, or around 1-10 micrometers.

Her theory is that we will one day be able to correlate not just our binary understanding of decompression sickness but a quantifiable measure of decompression stress to bubble counts performed in new ways. Her most recent projects have involved imaging microbubbles using contrast ultrasound, and early evidence shows that with the type of imaging technology she applied, it may be possible to include microbubbles in post-dive bubble counts and show that signal increases (indicative of smaller bubble populations in this type of ultrasound imaging) are present in both divers who were previously considered “bubblers” and “non-bubblers”. These divers, imaged with traditional b-mode sonography, may bubble equally but in sizes that could not be imaged, leading researchers to conclude that they did not bubble at all. Papadopoulou found a signal increase across all seven subjects after identical dives, despite half of the subjects not showing significant counts of larger bubbles, and is currently working to refine her imaging technique, which is now capable of imaging not just moving bubbles but even smaller stationary bubbles as well.

Virginie Papadopoulou, Ph.D., in her lab. Photo by Megan May, UNC Office of Research Communications.

What this means for divers remains to be seen, but Papadopoulou hopes to advance our understanding of the relationship between bubbles and DCS, improve our understanding of how and where bubbles form, and change the narrative around DCS from a binary system focused on symptoms to a linear one that takes bubble count into consideration to improve both knowledge and diver safety. Her work is far from conclusively demonstrating cause and effect between bubble count and DCS, but it has gained significant ground in a matter of years. In fact, it is rapidly moving toward improving our mechanistic understanding of decompression and applying that to personalized decompression models. In the coming months, interested divers will be able to participate in a bubble counting research project created by Papadopoulou and available via

Dive Deeper:

If you’re interested in learning more about Papadopoulou and her work, visit Alert Diver Online or

Header Image by Sean Romanowski

Reilly Fogarty is media strategist at Divers Alert Network (DAN) and team leader for its risk mitigation initiatives. He is a USCG licensed captain and rebreather instructor whose professional background includes surgical and wilderness emergency medicine, and dive shop management.

  • Halcyon Sidemount
  • Fourth Element
Click to comment

Leave a Reply

Your email address will not be published. Required fields are marked *


The Art of Risk: What We can learn from The World’s Leading Risk-Takers




One of the rescuers of the Thai soccer team (now the Netflix series ‘Thai Cave Rescue’) and former Australian of the Year explores why people are attracted to risky pursuits and what we can learn from their expertise. 

In June 2018, with the eyes of the world watching, Dr Richard Harris, or Harry to his mates, dived into a remote cave in northern Thailand in an attempt to rescue a Thai youth soccer team who had become trapped by flash flooding. He used his recreational skills in diving to traverse kilometres of the subterranean cave system, and his professional skills as an anesthetist to sedate the stranded boys so they could be dived and carried to safety. Despite incredible odds, all twelve boys, along with their coach, survived. 

Harry says he was able to succeed in the Thai cave because of decades of experience, comprising thousands of hours of careful planning, risk assessment and management. Often described as the most dangerous sport in the world, Harry never feels like he is doing anything particularly dangerous when he goes cave diving. Despite losing friends to the sport, in his mind the risks can be managed well enough to make the pastime extremely safe. And far from making him anxious or fearful, the planning and execution of potentially high-risk dives have been empowering and fulfilling. In his mind, carefully managed risk-taking gives him the courage to manage the day-to-day stresses of life in the 21st century.

In The Art of Risk, Harry talks to like-minded risk-takers about their adventures and asks them what is it about cheating death that makes them feel so alive. He aims to explore the active pursuit of risk through the lens of risk-takers and adventurers such as soldiers, pilots, mountaineers, rock climbers, deep-sea divers, sailors, big-wave surfers, firefighters, rally-car drivers – both professionals and amateurs. His conversations give us insights into what motivates these people and why a life without risk is no life at all. He believes that by doing ‘the hard things’ in life you can push yourself a little harder and become stronger, more courageous and resilient.

Selling Points

  • FASCINATING SUBJECT: why do deep-sea divers, free climbers and big-wave surfers take the risks that they do? How do soldiers and firefighters manage risk? What can we learn from how they prepare – and what they experience – that we can take into our own lives? Harris shows that in doing ‘the hard thing’, we become more resilient and courageous. Angela Duckworth’s Grit meets Alex Honnold film ‘Free Solo’
  • EXPERT AUTHOR: Dr Harry Harris was at the heart of the Thai Caves rescue, anesthetizing all the boys in order to get them out. A genuine hero and former Australian of the year, Harry Harris explores flooded caves deep underground for fun. For most people, this is the definition of a nightmare. Because Harry understands and can prepare for the risks, for him it’s a pleasurable – even meditative – experience. And, as he says, he feels ‘carefully managed risk-taking gives him the courage to manage the day to day stresses of life in the 21st century’.
  • FAMOUS INTERVIEWEES: Harry talks with people like climber Alex Honnold, sailor Jessica Watson, mountaineer James Scott, film director and deep-sea diver James Cameron and polar explorer Tim Jarvis, amongst many others. 
  • MAN BEHIND THE NETFLIX SERIES: ‘Thai Cave Rescue’ is fresh onto Netflix, further pushing awareness of the story.

The Book

Publication date: July 2023
288 Pages plus color inserts

The Author

Dr Richard ‘Harry’ Harris, SC, OAM and joint 2019 Australian of the Year, is an anaesthetist and cave diver who played a crucial role in the Tham Luang cave rescue in northern Thailand. He has more than thirty years’ experience as a cave diver and also works for the South Australian Ambulance Service’s medical retrieval service. He is the co-author, along with Craig Challen, of Against all Odds, the inside account of the Thai cave rescue and the courageous Australians at the heart of it. He lives in Adelaide, Australia.

  • Fourth Element
  • Halcyon Sidemount
Continue Reading