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Dive, Learn, Eat: Rebreather Meeting in Italy

How would you like to spend four days with a group of passionate adventurers on an island in southern Italy, diving rebreathers on submerged seamounts, getting briefed by some of the biggest diving brains on the planet, and eating to your heart’s content? Thought so! Unfortunately, you missed it. But here are the some of the highlights and takeaways presented by InDepth’s executive editor who was in attendance. Hey someone had to go.

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by Michael Menduno

May 1, 2019—Nearly three dozen rebreather aficionados made the biannual trek to Ponza, Italy, a picturesque island in the Tyrrhenian Sea about a three-hour journey from Rome. They were there for the sixth International Rebreather Meeting organized by Andrea Donati, owner of Ponza Diving Center, and his partner Daniela Spaziani. The goal of the four-day meeting, which was sponsored by a number of manufacturers and organizations, including JJ CCR, Shearwater, DAN Europe, Società Italiana Medicina Subacquea e Iperbarica (SIMI), and the Italian rebreather users’ association CCR Italia, was to provide the latest research and information to the rebreather community.

Photo by Peter Symes.

“They’re passionate tech divers hungry for information,” explained Dr. Simon Mitchell, a professor of anesthesiology at the University of Auckland, New Zealand, who was one of the presenters. “That’s what I love about these types of meetings. I am happy to be here and share what I know.”

Taking a cue from the hyperbaric medical community, the meeting was organized to appeal to diver sensibilities; diving in the morning (8:30 a.m.- 2:00 p.m.), and lectures and discussion in the afternoon (3:00 p.m. – 7:00 p.m.) followed by dinner and drinks (9:00p.m. – 11:30 p.m. or later).

Dive Right In!

Donati and his crew did a masterful job of supporting more than twenty rebreather divers bearing scooters, cameras, and bailout bottles, along with a few open circuit divers, without incident. Their enthusiastic attitude and thoughtful attention to detail, whether it was solving specific problems with individual’s rebreathers, or bringing in attendees dry suit underwear hanging on the exterior of the boat before the after dinner rain hit, helped the operation run smoothly and efficiently while feeling relaxed. They were aided by Ponza Diving’s ubiquitous mascot, an amicable large black matif named Ugo.

The boat, which was docked just outside of the dive shop, headed out each morning around 8:30 a.m., as divers huddled over Italian espresso and fresh bread after prepping their breathers. Interestingly, as we were loading up the boat on the first day there, Donati made a point of warning both me and Peter Symes, publisher of X-Ray magazine, to go easy on the coffee. “It can kill you,” he said with all seriousness, citing an American diver who had a heart attack underwater after consuming too many cups of espresso. The boat then made its way to one of the numerous submerged seamounts covered in soft corals surrounding the island, where it would anchor for the morning dive.

Photo by Marco Sieni.

Our morning dives were typically 165-261 ft/50-80m deep with one-to-two-hour run times. Visibility was 50-65 ft/15-20 m and water temperature was about 58-60°F/15-16°C. Following each dive, we were treated to a multi-course lunch, which usually included soup, fish, cephalopods, rice, pasta, bread, salad, and dessert, along with the requisite pitcher of wine and more espresso. After lunch, the boat headed back to port, where we prepped gear for the next day’s dive.

Where’s The Manzo, err Beef?

While rebreather diving in Ponza was clearly the attraction that brought people together, the presentations, given by some of the community’s leading scientists, engineers, and practitioners were the meat of the meeting. (Are you detecting a pattern here?) Our group met in an old stone chapel up the hill from the dive shop. Headphones were available for sequential English and Italian translation.

One of the themes that emerged from the meeting was the role of human factors, i.e. the way we process and act on and or fail to act on information, and its impact on diving safety. This is a deep body of knowledge that was developed in the aviation and healthcare fields and is now being applied to diving largely through the efforts of pioneer Gareth Lock at The Human Diver. Several of us noted that human factors were being discussed in the absence of the seemingly ubiquitous Lock, was a sign that this important work was beginning to gain traction. Here are some of the highlights.

Photo by Peter Symes.

Training Doesn’t Work: Technical Diving International (TDI) Rebreather Instructor, Instructor Trainer, and author Mark Powell began with a list of ten improvements in rebreather diving that he would like to see from a community perspective; things like better buoyancy control, the increased use of checklists, and more attention to bailout planning. He then asked the question, “Why hasn’t training made a difference?” That is, why hasn’t training produced permanent observable changes in divers’ behavior in these areas? The answer, documented by numerous studies, is that humans aren’t very good at retaining information.

The solution: deliberate practice of essential skills. “People tend to practice things they like and are good at, which is not very helpful,” Powell explained, noting that practicing things that are very difficult to do doesn’t work either. “The sweet spot,” he said, “is practicing things that are challenging.” He recommended that divers practice something on every dive! Sounded very GUE to me.

In-water Recompression (IWR): The use of in-water recompression to treat divers at remote locations has long been controversial, and until recently the hyperbaric medical community has failed to reach a conclusion regarding its efficacy. But as Simon Mitchell explained, the situation has now changed as a result of a new paper, “In-Water Recompression”, he co-authored with Dr. David Doolette, a decompression physiologist at the U.S. Navy Experimental Diving Unit (and a GUE diver). The two were able to find evidence not previously reported that answers two key questions:

  1. Does early recompression improve outcomes? (i.e. recompressing an injured diver within minutes vs hours)
  2. Is shallower, shorter recompression effective? (Note that IWR typically compresses the diver on 100% oxygen to 30 ft/9 m vs. a USN Table 6 to 60 ft/18 m.)

Based on U.S. Navy data derived in part from early research on treatment protocols, Mitchell and Doolette were able to answer both questions strongly in the affirmative. The new recommendation: A diver should be treated with IWR if a chamber is more than two hours away and the team is set up to provide IWR (i.e. has proper equipment such as full face mask and training, support, environmental conditions, and appropriate patent status).

Defensive Dive Profiling/Concerns for Aging Divers

Dr. Neal Pollock, research chair in hyperbaric and diving medicine at Université Laval, gave a pair of eye-opening lectures on the potential long-term impacts of decompression stress, what can be done, and the prospects for aging divers. Was he talking about us?

Photo by Marco Sieni.

Pollock began by citing studies that found lesions in the brain and spinal cord have been observed with higher frequency in individuals with a history of repeated decompression stress. Bone lesions have also been found in commercial divers. The factors shown to increase the risk of dysbaric osteonecrosis in commercial divers were: a history of inadequate or experimental decompression, diving deeper than 165 ft/50 m, and a history of decompression sickness (DCS). The conclusion: while dysbaric osteonecrosis has largely been eliminated in commercial diving due to procedural changes, decompression stress poses a potential long-term risk factor for technical divers! Divers need to think about immediate and long-term risk.

As a result, Pollock, who is known for doing extra deco, encouraged divers to do longer shallow decompression adding, “It can’t hurt. It can only help.” Specifically, he recommended several ways of adding conservatism: using conservative gradient factors, primarily reducing GF-high, buffering the dive by slowing down on the final ascent to the surface following the last high pO2 stop, delaying exercise post-dive, extending surface intervals to add more time for recovery, using appropriate gasses (Yes, “air is for tires!”), choosing appropriate partners with similar risk tolerances, and maintaining good physical fitness.

The bottom line for aging divers; there is no upper age limit, though there may come a point where you need greater support. Be forewarned! Note, there were several post 65-year-old divers making the plunge at Ponza!

Presenters: L to R: Dott. Pasquale Longobardi, president of SIMI, TDI instructor trainer Mark Powell, Dr. Simon Mitchell, professor of anesthesiology, University of Auckland, New Zealand, Dr. Neal Pollock, research chair in hyperbaric and diving medicine at Université Laval, Dott. Alessandro Marroni, president of DAN Europe, Shearwater founder Bruce Partridge, DAN Europe research supervisor Massimo Pieri and Eduardo Pavia, owner of Sea Dweller Divers.

Human Factors In Rebreather Diving: Mitchell began by noting that human factors were the most important, but also the hardest, path to improving safety in rebreather diving. He then posed the question: Is there a safety problem with rebreather diving?

Mitchell began by reviewing what we know about rebreather safety based on the ground-breaking 2012 paper by Dr. Andrew Fock analyzing recreational rebreather deaths 1998-2010, to wit: There were approximately 20 deaths/year for 2000-2010 from a population, which was then estimated to be about 18,000 rebreather divers based on agency certifications. That means that the fatality rate for rebreather diving was estimated to be about 133 deaths/100,000 divers/year compared to about 16 deaths/100,000 divers/year for open circuit diving. The conclusion: rebreather diving was about 10x more hazardous than open circuit scuba. Note, there is currently a follow up study underway to determine if things have improved.

Mitchell broke down the causes of rebreather fatalities into three buckets:  

• Hazards of advanced diving

• Rebreather equipment failures

• Diver error and violations

Overwhelmingly, most incidents arose from diver errors (Trying to do the right thing but doing the wrong thing) and violations (Knowingly creating unnecessary risk of harm to yourself and others, and expecting to get away with it). “I have made errors and violations in my rebreather diving,” Mitchell offered to the assembled group of divers, “and I bet you have too.”

What’s to be done?

Mitchell reviewed several fatalities involving violations, like diving with two-year old oxygen sensors, or using a type of sorb not specified by the manufacturer. He said that we needed to remove the motivation for violations. This involves a culture change: Make safe choices be seen as a strength versus a weakness. Training, mentoring, and role modeling are critical in this regard.

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Typical errors might include forgetting to analyze one’s gas, forgetting to turn on the rebreather or open the oxygen valve, or leaving out an O-ring on the scrubber. In fact, each of these errors has resulted in multiple fatalities. Mitchell said that pre-dive checklists are the primary means for preventing errors. As a testament to the power, he cited a study analyzing the impact of using checklists in surgical suites: Deaths were reduced by 50% after the introduction of checklists, and as Mitchell pointed out, these were among highly trained professionals. He then cited a DAN study of some 2041 dives examining the impact of pre-dive checklist use on scuba mishaps; mishaps, including rapid ascents and low/out of air were reduced by 36%.

Photo by Michael Menduno.

The barriers to using checklists?

First, misunderstanding about their purpose; checklists are not meant to replace a manual! Second, arrogance/ignorance; I can do it from memory, or I don’t make mistakes. Checklists can be supported by training, practice, and engineering.

Interestingly, after the meeting I asked one of the Italian rebreather divers if he used a checklist on our dives. “My instructor taught me to do it by memory,” the diver told me, “So that is what I do. I haven’t had any problems.” Until he does, and therein lies the problem.

Bruce Partridge, founder of Shearwater Research, also focused his talk on human factors and changing divers’ behaviors. He began by talking a little about the history of Shearwater, which got it start making rebreather controllers before venturing into dive computers. He then discussed the work involved in assuring that rebreather sub-systems like controllers meet safety requirements as part of the CE 14143 standard, which they published in a 2013  IEEE paper. Partridge said he believed that the CE 14134 standard was a really good thing for the rebreather industry. Interestingly, he pointed that there were approximately 600 failure modes possible on a rebreather, however, only 40 were equipment related; the remainder involve diver errors.

Explorer Edoardo Pavia, owner of Sea Dweller Divers, also spoke passionately about rebreather safety in light of human factors from his personal experiences. He began by speaking about British expedition leader Carl Spencer’s tragic death on the 2009 Britannic Expedition. Spencer mistakenly breathed an unmarked, high-oxygen content bailout cylinder at depth and convulsed and drowned. Pavia shared his views about the importance of following manufacturers’ rules and recommendations regarding checklists, oxygen sensors lifetime, scrubber duration, using proper sorb, and the importance of bailout out valves (BOV). He concluded that ignorance was “the hardest monster to defeat.”

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DCI Research/Telemedicine

Massimo “Max” Pieri, research supervisor for DAN Europe, presented their research focusing on preventing decompression illness (DCI) using DAN’s diving database of some 66,000 dives ranging in depth from 16-628 ft/5-192 m, average depth 100 ft/30 m. Some of the factors they have considered include: gradient factors, hydration, genetic disposition, and hematological parameters. They are also conducting a decompression study with a local (Italian) GUE group in cooperation with instructor Mario Arena, examining the efficacy of so-called “deep stops” vs shallow decompression profiles [See Dr. David Doolette’s post, “Gradient Factors in a Post-Deep Stops World,” in this blog issue for additional data].

Next, DAN Europe president Dr. Alessandro Marroni discussed his visionary program dubbed Advanced Virtually Assisted Telemedicine in Adverse Remoteness (AVATAR). Their goal is to develop tools and procedures to enable real-time monitoring of divers during their dives—think Fitbits on steroids! Marroni described his vision of a DAN doctor able to assess a diver who’s still in the water, and communicate directly with that diver via an underwater communications system. In fact, they have already tested prototypes.

Courtesy of DAN Europe.

Dott. Pasquale Longobardi, president of SIMI, also presented SIMI’s research examining the biochemical mechanisms involved in decompression stress.  He concluded with a set of best practices, namely to run pO2s at 1.3 bar or less, maintain pN2s at 3.16 bar (the equivalent of breathing air at 100 ft/30 m) or less and run pHe as high as possible; Longobardi stated that helium in the form of trimix protects divers from oxidative stress (inflammation) compared to diving air (kick those tires again!). A colleague in the audience told me he had questions about the supporting data.

Mangia Mangia

Having gotten our daily dose of brain food, attendees retired to their hotels and apartments  to catch up on email, clean up, and later walk to the ristorante du jour that had been chosen for that evening. There we were greeted by our attentive hosts, Andrea and Daniela, accompanied by Ugo, who had arranged for a family-style dinner with wine and made sure that everyone had enough to eat and drink. If you had trekked to the meeting for the food alone, you would have not been disappointed.

Photo by Michael Menduno.

“Mangia,” Dani told me gesturing emphatically with her hands and pointing to my empty plate, after the second, or was it the third course? “Please, you must eat some more,” she insisted passing me a bowl of mussels.” It felt like a family gathering—a family of passionate, geeky divers who were there to commune with their peers in celebration of l’arte e pratica che amiamo. And the eating and drinking and sharing of stories continued into the night.

Header Image: Marco Sieni.

Dive Deeper:

X-Ray International Dive Magazine will be featuring more about the meeting and Ponza diving including some compelling images in their June issue.

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Michael Menduno is InDepth’s executive editor and, an award-winning reporter and technologist who has written about diving and diving technology for 30 years. He coined the term “technical diving.” His magazine “aquaCORPS: The Journal for Technical Diving”(1990-1996), helped usher tech diving into mainstream sports diving. He also produced the first Tek, EUROTek, and ASIATek conferences, and organized Rebreather Forums 1.0 and 2.0. Michael received the OZTEKMedia Excellence Award in 2011, the EUROTek Lifetime Achievement Award in 2012 and the TEKDive USA Media Award in 2018.


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The Risk and Management of Record Chasing

The pursuit of deep diving records is an unsettling but accepted facet of tech diving culture. On the one hand, we are driven as a species by our genetic predisposition to “Go Where No One Has Gone Before.” Blame it on our DRD4-7R explorer gene! On the other, many question the value and legitimacy of conducting a high risk, touch-and-go line dive for recognition and bragging rights alone. Where and how do we reconcile the two? Here diving physiologist Neal Pollock seeks to answer those questions in a compelling, principled exposition that may help you to sharpen your beliefs.

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By Neal W. Pollock, PhD. Header image: Nuno Gomes getting ready to make his 2005 world record dive to 318.25m m/1039 ft in the Gulf of Aquaba.

Humans have probably been chasing records as long as we have existed. Og was almost certainly proud of discovering that two stones could be rubbed together to make fire, and it likely resulted in a solid community standing for at least a while. Tempting though it may be, we cannot blame our interest in records on the advent of the Internet or social media. The Guinness Book of World Records, a small example of documenting novelty, was first published in Great Britain in 1955. The Internet and social media, however, have made the striving for and tracking of new records more intense. 

Record making is well established in diving as well as in most other communities. There are interminable lists of the first makers of equipment, the first to implement or explore, and the most extreme doers of deeds. History shows them to be pivotal, meaningful, or trivial as it unfolds. Keeping the record straight is important, but the decision as to why and whether to pursue records is worth debating. 

I am a fan of documenting meaningful events, but I have concerns over an excessive focus on arbitrary milestones. When a community puts more weight on records than actual achievements, the drive can become pointless or problematic. The pointless includes many Guinness records, such as the most number of people brushing their teeth simultaneously and the largest rubber band ball.

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While some in the diving community have pursued fairly pointless but low risk records, it is the problematic ones that are a much greater concern. Underwater activities involve greater risk than many other endeavors, relying on equipment, training, technique, and practice to produce an envelope in which reasonable levels of safety can be maintained. Pursuing records is generally about pushing boundaries, and when the boundaries are set by the interaction of physics and physiology, the erosion of safety buffers can produce serious risk. The pursuit of targets can overwhelm well-founded safety concerns and common sense. 

“Record chasing can produce good outcomes, and some meaningful achievements, but when going forward is reliant on misplaced beliefs that personal motivation and superiority can overcome unforgiving limits, the outcome can be bad for both individual and community, even if considered successful.” 

Record chasing can produce good outcomes, and some meaningful achievements, but when going forward is reliant on misplaced beliefs that personal motivation and superiority can overcome unforgiving limits, the outcome can be bad for both individual and community, even if considered successful. 

Nuno Gomes’ support team for his 2005 Guinness World Record Dive to 318.25m/1039 ft

One of the chief challenges in diving is that the interaction of physics and physiology creates difficult-to-define limits. There are differences in tolerance between individuals and often between exposures. Different breathing gas mixtures can alter narcotic potential, respiratory gas density, decompression stress, and susceptibility to oxygen toxicity and high pressure nervous syndrome, among other concerns. Differences in workload, stress, physical fitness, and physical skill can also alter the response to other more fixed stressors. Practically, the interactions between the host of factors is complex and can make the element of chance more important than people would like to admit. A scary reality of many boundary-pushing events is the fact that getting away with something once, or even multiple times, does not necessarily make it safe, and almost certainly not safe for all. 

Ahmed Gabr’s 2014 Guinness World Record Deep Dive remains under controversy

Records achieved with a large helping of good luck still count, but they can be extremely troubling if others are encouraged to try to surpass them. Not only can tolerance and good fortune differ, the lessons learned in building to “record” performance may not be appreciated by those who follow, potentially magnifying the risks. 

Care is warranted to decide on what “records” are truly worth pursuing and what should be left alone. A simple practical test is whether an activity serves any purpose beyond the record attempt. If there is no other benefit or purpose, the value in it may not be sufficient to continue, especially when the associated risks may be high. 

Source: Nuno Gomes

Record attempts are sometimes pursued by relative newcomers to a field. It is unclear how much of this is due to simple enthusiasm or a desire to stand out, but all such efforts are best met with counsel before encouragement. The field needs leaders, and the next generation of leaders, but this requires keeping those with potential both healthy and engaged. This may come down to mindset—finding what is most important and appropriate to pursue as part of personal growth. 

Leaders who want to establish themselves are best served by ensuring that they have the best understanding, skill, and experience within the realm of what they will need to do rather than pushing the envelope for increased fame. Chasing records by sacrificing safety margins and/or ignoring compromised states of affairs is not compatible with accepted best practice. Those looking up to leaders for inspiration may not fully appreciate the issues and concerns, but the best leaders will be conscious of the total impact their efforts can have on others. 

Karen van den Oever after she dived to a depth of 246.65 m/809 ft in Bushmansgat cave, South Africa, representing the women’s world record deep cave dive. 

Bragging about exceptional or record exploits is problematic in that it can encourage others who may be inadequately prepared to follow suit. It may be a hard reality for the keen, hungry, and superbly confident instructor to accept, but they can provide a much better service to their students by encouraging them to stay within the accepted realm of operational safety. This is often most effectively demonstrated through example. The goal should be to promote a long and healthy diving life, effectively achieved by solid training and an instilled appreciation for the value of robust safety buffers and a constant revisiting of “what if” preparation. 

We should recognize the meaningful efforts in the community, but without losing sight of the implications of such endeavors. Promotion of a positive safety culture requires questioning whether things should be done, and how things that should be done can be done with appropriate safety margins. If meaningful efforts result in record achievements they should be applauded, but always with an appropriate framing of any associated value, limitations, hazards, and implications.

Reporting the exceptional is important, but a high priority should also be put on recognizing activities and efforts that are unexceptional in outcome due to appropriate preparation and execution within safe boundaries. Efforts to improve training, awareness, and operational safety must always be promoted. Safety programming is challenging since, when it is effective…, nothing happens. Ongoing commitment is required to ensure that it continues to be effective. 

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I would posit that the best record attempts are those pursued without fanfare, moving quietly from concept through to safe workup stages and then safe completion. The reporting of record efforts should always consider the value and relevance of the activity. Achievements that violate the criteria for safe performance should be neither encouraged nor glorified. 

We live in a time when the pursuit and promotion of records can be expected to continue, but appropriate framing can help to ensure that the community benefits from a sustained focus on safety and thoughtfulness.

See Companion Story: I Trained Doc Deep by Jon Kieran

Dive Deeper

InDEPTH: Fact or Fiction? Revisiting Guinness World Record Deepest Scuba Dive by Michael Menduno

InDEPTH: Karen van den Oever Continues to Push the Depth at Bushmansgat: Her New Record—246m by Nuno Gomes

InDEPTH: South African Cave Diver Karen van den Oever Sets New Women’s Deep Cave Diving Record by Nuno Gomes

InDEPTH: Opinion: Don’t Break That Record by Dimitris Fifis

InDEPTH: Diving Beyond 250 Meters: The Deepest Cave Dives Today Compared to the Nineties by Michael Menduno and Nuno Gomes

InDEPTH: Extending The Envelope Revisited: The 30 Deepest Tech Shipwreck Dives by Michael Menduno

InDEPTH:  High Pressure Problems on Über-Deep Dives: Dealing with HPNS by Reilly Fogarty


Neal Pollock holds a Research Chair in Hyperbaric and Diving Medicine and is an Associate Professor in Kinesiology at Université Laval in Québec, Canada. He was previously Research Director at Divers Alert Network (DAN) in Durham, North Carolina. His academic training is in zoology, exercise physiology, and environmental physiology. His research interests focus on human health and safety in extreme environments.

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