Are you a North Carolina diver? DAN has a free talk tonight!

DAN is renowned for their educational lectures and they regularly put on a series of free seminars at the DEMA Show that all dive professionals can access.

Nick Bird, DAN, Chief Medical Officer, Divers Alert Network, Dr Richard D Vann, Dr Petar Denoble, Dr Neal W Pollock, Rosemary E Lunn, Roz Lunn, TUMC, The Underwater Marketing Company, diving medicine, DCS, DCI, diving physiology, bent diver, decompression sickness, decompression illnessFor the last three years, DAN HQ in Durham (North Carolina) has been running a bi-monthly diving medicine / research / safety series of lectures at their office in West Colony Place. The talk is held on the first Wednesday of every other month at 19:00. This programme provides an excellent opportunity for anyone with a thirst for diving knowledge to listen to a variety of local experts discuss dive medicine, research, and safety.

Tonight's lecture (Wednesday 3rd April 2013) is entitled "Managing DCS in Remote Locations" and given by Dr. Nicholas Bird.

"Decompression sickness often occurs in remote locations. In such environments, treatment options and local expertise may be lacking. This presentation covers a description of decompression sickness, diagnostic criteria and treatment options, and factors that may help guide decisions about treatment versus evacuation."

For those of you unfamiliar with Dr Nick, he is DAN's Chief Medical Officer.

Doors will open at 18:15 for a pre-event social, and 'Down Under' very kindly serve light refreshments. The presentation begins at 19:00 and will last approximately 45 - 55 minutes, followed by a question-and-answer session.

Admission to the lecture is free, and no registration is required. So come early, come hungry and hear Dr Nick wax lyrical about DCS logistics.

Upcoming Lectures in the Series:

June 5: "The Heart in Diving" presented by Dr. Petar Denoble

August 7: "Critical Thinking of Post-Dive Symptoms" presented by Dr. Matias Nochetto

DAN 2013 Internship Application Deadline closes this Tuesday

This is Jenna Wiley, a Research Associate I at Divers Alert Network. She's pictured here working on DAN's Project Dive Exploration doing field research at Innerspace 2012 (Grand Cayman). Once upon a time she was a DAN Research Intern.

DAN internship, Jenna Wiley, Research Associate I, research physiologist, Transthoracic Echocardiography, transthoracic echocardiogram, Project Dive Exploration, research phyInnerspace, Divetech, Grand Cayman, rebreather diving, TTE, DAN, Divers Alert Network, diving, scuba, scuba diving, diver safety, diving safety, dive safety, safety, Dan Orr, Dr Neal W Pollock, Neal Pollock, Dr Petar J Denoble, Petar Denoble, Dr Richard D Vann, Dick Vann, Rosemary E Lunn, Roz Lunn, The Underwater Marketing CompanyIf you have the burning ambition to be a DAN Research Intern, apply now. Applications for this close on Tuesday 15th January 2013.

Strong candidates for this competitive program will have excellent communication and organizational skills, meaningful personal accomplishments, an established commitment to diving and goals that would benefit from participation in the program. Whilst diving is not a required skill for this internship, candidates should be certified scuba divers.

The program runs primarily from late May through August, and interns are recruited largely from undergraduate students at colleges and universities across the United States (post-graduate students, students from other countries and periods other than summer will be considered, if appropriate). Following an initial week of training at DAN headquarters, research interns are placed with host facilities, including DAN, where they will participate in projects matched to their interests and ability. The range may include field, laboratory and/or epidemiological studies. Most research interns work closely with mentor experts to maximize their learning opportunities.

For more information follow this link

Attention CCR Instructors & Dive Centre Owners – we need your feedback

Pete Mesley of Lust4Rust ( will be doing a presentation at OZtek Tech Diving Conference in March this year "Are rebreathers ready for the recreational diving industry - is the recreational Diving Industry ready for rebreathers?"

He really need to hear from Instructors and Dive Store owners alike. He would appreciated getting as many comments as possible, where you personally stand, your thoughts and comments.

Below is a few questions which he would be most grateful if you answered:


Pete Mesley, Lust4Rust, OzTek, tech divers, CCR divers, rebreather diver, CCR Instructors, rebreather instructor, resort diver, Dive Centre Owners, diving training agencies, Rosemary E Lunn, Roz Lunn, The Underwater Marketing CompanyTech divers have already embraced the technology. Training agencies and manufacturers are obviously going to directly benefit from expansion, but its in the trenches where Instructors are dealing with people all the time. I have categorized divers into 4 main groups (shown below), obviously there are more groups, but in the advent of simplicity and the relevance of the topic I have kept it to 4.

I would appreciate it if you could answer the questions below and any comments you might have on the topic. I have kept the questions to a minimum, but if you have any comments about the topic I would LOVE To hear them.

Can you please email me with all your comments.  Thank heaps, I really appreciate it.
- Pete


Categories of Diver

1. RESORT DIVER (only dive when on Holiday, little or no training, resort style diving)

2. AVERAGE DIVER (diver who does an average of 20 dives a year, goes on holiday with a few dives, own their own gear)

3. SERIOUS DIVING ENTHUSIAST (Diving is their main sport, heavily invested in diving, own their gear, but purely rec diving - no tech or deco)

4. Technical Diver (fanatical about diving, dives well beyond rec limits, does little else except dive, own all gear, invested lots of money in training, travel and gear)


1. Do you think CCR Rebreathers have a place in the Recreational Dive Market?

2. Where do you see, them fitting in the market (from the list above)?

3. Are you preparing to train CCR's in the Rec market? - Who do you see as your biggest market?

4. Do you have any personal comments about CCR's in the rec industry?


1. Would you mix CCR divers on boats with O/C divers?

2. If someone was a CCR diver who wanted to do a longer bottom time would you be able to accommodate them?

3. Are you happy to change the routine of your dive business to accommodate this?

4. What is the average time people spend underwater each dive?

5. How many dives do you offer in a day?

6. Do you think that CCR diving in the recreational market is upon us?

7. What challenges do you envisage if you adopted CCR diving in your operation?

8. Are you interested in looking at becoming a CCR friendly operation?

9. Do you think that investing in Rebreather Support/Training/Equipment & Service is is going to benefit your business?

Any feedback would be greatly appreciated.

Dr Richard D Vann receives the UHMS 2012 Premier Award

UHMS, Undersea & Hyperbaric Medical Society, Dr Richard D Vann, Dick Vann, DAN, Divers Alert Network, Duke Dive Medicine, Albert R Behnke Award, Al Behnke Award, Hyperbaric, Diving Medicine, Diving Physiology, arterial gas embolism, Rebreather Forum 3, RF3, Dr Dick Vann, Rosemary E Lunn, Roz Lunn, The Underwater Marketing Company, TUMC

The Undersea and Hyperbaric Medical Society (UHMS) is an international, non-profit organization serving over 2,400 members from more than 50 countries.  This society is considered a key source of scientific information for diving and hyperbaric medicine physiology worldwide.

The UHMS has just held their 45th Annual Scientific Meeting (Wednesday 20 - Sunday 24 June 2012) at the JW Marriott Desert Ridge Resort & Spa, Phoenix, USA.   During the event Dr Richard D Vann from the Center for Hyperbaric Medicine and Environmental Physiology (Duke University Medical Center), and a Consultant at Divers Alert Network received the Albert R Behnke Award.Technical Diving Conference Proceedings, Recreational Diving Fatalities, The Physiological Basis of Decompression, Proceedings of Rebreather Forum 2.0, Rebreather Forum 3, Flying After Diving Workshop, Report on Decompression Illness, Diving Fatalities, and Project Dive Exploration, No-stop enriched air (nitrox) diving with surface interval oxygen breathing - field validation, OXYGEN ENHANCED BREATH-HOLD: IMMERSION AND TEMPERATURE EFFECTS, Rosemary E Lunn, Roz Lunn, TUMC, The Underwater Marketing Company

The Albert R Behnke award is not presented every year, only when the Awards Committee deem it appropriate.  This is the premier award of the UHMS and is presented to an individual in recognition of outstanding scientific contributions to advances in the undersea or hyperbaric biomedical field. The award may be made for a single contribution of great importance or for many contributions over the years.

Richard Vann served as a Diving Engineer at Ocean Systems, and as a Diving Officer for US Navy Underwater Demolition Team 12 and various Naval Reserve SEAL units. 

After receiving a PhD in Biomedical Engineering, Dr Vann conducted research at the Duke Hyperbaric Center on bubble formation and inert gas exchange in divers and astronauts, developed decompression procedures for scientific and archeological diving, developed decompression methods for astronauts, and investigated oxygen breath-hold diving.

At the Divers Alert Network (DAN), he investigated fatal and non-fatal injuries and published on dive computers, nitrox diving, flying after diving, prognostic factors in DCS therapy, flying with DCS, flying after DCS therapy, and first aid oxygen for DCS.  He is Emeritus Assistant Professor in the Duke Anesthesia Department and a consultant to DAN.

Dick Vann is one of the nicest gentlemen in the diving industry.  He has endless enthusiasm, energy, drive and passion solidly backed by relevant knowledge.  Dick also firmly believes in mentoring, developing the next generation and nurturing talent.  In 1999 he established the DAN Research Internship Program.  Dick is wholly professional, supportive to colleagues, and his ethos focuses on the greater good.  He truly is ‘Mr. Nice Guy.’   


A Tripartisan look at the State of Rebreathers by ANDI, IANTD and TDI

The following data was announced today (Friday 19th May 2012) at Rebreather Forum 3 by Ed Betts, Brian Carney and Jo Dituri.


Rebreather Forum 3, RF3, Rosemary E Lunn, Roz Lunn, Rosemary Lunn, The Underwater Marketing Company, Simon Mitchell, Neal Pollock, Drew Richardson, Karl Shreeves, Mark Caney, Michael Menduno, Richard Pyle, Peter Denoble, DAN, PADI, AAUS, Richard Vann, rebreather safety, ANDI, IANTD, TDI, rebreather, training, diver training, rebreather market, experience, expertise, certification, Betts, Carney, Dituri, diver certification numbers, market analysis, diving data, total number of diving certs, international association of technical dives, technical dives international,


ANDI, IANTD, TDI Collective rebreather certification numbers and market analysis

Joseph Dituri (1), Brian Carney (2), Ed Betts (3*)

* corresponding author

1. IANTD World HQ
324 St Joseph ST STE 208
Rapid City, SD 57701
(605) 721-5600
2. TDI
1045 NE Industrial Blvd
Jensen Beach, FL 34957
(207) 729-4201
74 Woodcleft Avenue
Freeport, New York 11520
(516) 546-2026



ANDI, IANTD and TDI have combined their 65+ years of collective rebreather training experience and will brief the state and future of rebreathers with detailed certification numbers. We will trend this data and provide insight into market direction. Attendance at this lecture provides you with the opportunity to speak with the leaders in rebreather training. (Ed Betts, Brian Carney and Joseph Dituri.)

Keywords: ANDI, IANTD, TDI, rebreather, training, diver training, rebreather market, experience, expertise, certification, Betts, Carney, Dituri



The three largest rebreather certification agencies came together to understand the opportunities with respect to rebreathers and foster openness as well as discuss their individual responsibilities as industry leaders in the diving community. The need for knowledge of precise rebreather certifications numbers is overdue. This paper will summarize rebreather certification numbers and analyze their trend as well as mathematically predict the future of rebreather certifications.



Primary in our minds was the validity of the data. As seems evident, there may be cross certifications between agencies. That is to say, some divers may seek certifications in two or more certification agencies which would effect the resulting certification agency’s numbers. To alleviate this, our respective agencies opened our certification files to one another. We traded all unit specific agency’s numbers. To alleviate this, our respective agencies opened our certification files to one another. We traded all unit specific certification data on rebreather training. We combined our numbers and confirmed the accuracy of the data for a statistically relevant number of years and cross checked each person by name that was certified in a geographical area, by year, unit and level of training. This process allowed each agency to personally verify numbers of certifications. From that we determined a 1% duplication effort. We then applied that duplication decrement number (γ) across all the 22 years of numerical data. All data presented represented the γ reduced data which indicates zero duplication in data. The training agencies know the units on which the training is being completed for each year. Due to potential financial implications we are not sharing unit specific information.

The resultant data was analyzed for the mean by summing the total number of certifications and dividing by the number of years, yielding the mean over the spread of years. Since the early years of rebreather certifications were very low and manufacturers were not regularly producing rebreather, the mean did not contain 1990-1995. The mean was calculated using the following equation:


Standard deviation shows how much variation or “dispersion” exists from the mean value. A high standard deviation indicates that the data points are spread out over a large range of values. Standard Deviation was calculated using the following equation:


Our three companies have slightly different methods for classifying rebreather certifications. Basic includes any entry level program to CCR’s and SCR’s as well as no stop diving and depths not greater than 30 meters. Intermediate qualifications comprises any training with minimal decompression. Advanced qualifications include dives that generate both hard and soft ceilings that are significant in nature such as trimix, cave and exploratory qualifications.

Since forecasting the market data was an important consideration, we turned to the Holt analysis. Holt’s linear exponential smoothing captures information about recent trend and time series data that is non-seasonal. For any statistical test, the probability of making a Type I error is denoted by the Greek letter alpha (α), and the probability of making a Type II error is denoted by Greek letter beta (β). Type I errors, also known as false positives, occur when you see things that are not there. Type II errors, or false negatives, occur when you don’t see things that are there (see Figure below). Alpha (α) was chosen to be 0.3 and beta (β) which was chosen to be .03. The equations are:


Lt and bt are respectively (exponentially smoothed) estimates of the level and linear trend of the series at time t, while Ft+m is the linear forecast from t forward. The group understands the Holt analysis continues to have less validity each year after projections are incorporated to determine another year of trend data. That is why the forecast was stopped after four years.


This data that reflects over 30,000 divers have been certified on 27 different types of rebreathers at varying levels from 1990-present. The mean certified per year is 1852 divers (number based only on developmental years 1996-present). The Standard Deviation is 707. Further study of the data reveals that greater than 66% of the years studied reflected a number at or greater than the mean which indicates the market is continually growing and has significant recent growth. A comparison of the SCR to CCR certifications, as shown in Figure 1, indicates a growing trend of CCR certifications although a minor resurgence is noted in SCR certifications toward the end of the data recording period.


As demonstrated in Figure 2, basic rebreather certifications (new rebreather divers) total more almost 18,000 divers. Over 12,000 divers carried on to continuing education classes on rebreathers. (50% at the intermediate level and 50% at the advanced level.) New rebreather divers are at almost an all time high in the market save a single year in 2001.


The Holt analysis projections depicted in Figure 3 indicate the market will generate between 2400 and 3100 rebreather diver certifications each year. This trend continues upward and as expected, the calculation error boundaries converge on a Holt analysis because the result calculated from one prediction is fed into the next year’s prediction. The raw data used for all calculations depicts the duplicate certifications removed and is contained in Table 1 below.

Rebreathers are a growth market. The basic rebreather divers are at a high and climbing. CCR certifications continue to grow, but we have noticed a minor resurgence of SCR in the last two years. ANDI, IANTD and TDI are three different training agencies. We have similarities and differences in the conduct of our individual businesses. Together we have a successful training methodology with 65+ years of experience. We thoroughly enjoyed working together and we will continue to work together in the future to foster openness as well as discuss our individual responsibilities as industry leaders in the diving community. While we may have minor differences as competitors, we agree on a few training items. The most important of which is that the rebreather instructor’s experience matters when choosing an instructor.


The Rough Guide to Florida. Part 1 – Filling the Tank

The lengths some people will go to, to attend Rebreather Forum 3 (  The following is taken from a blog written by Sport Diver UK writer, Martin Sampson.

Got out of the airport on Sunday and picked up the hire care. First time in a left hand drive car on the wrong side of the road for over 25 years so with some trepidation I ventured onto the highway, well turnpike actually. No I’ll stick with highway because I still haven’t got a clue what turnpike means. The first task was to get some fuel. The first gas station was a matter of yards away so I pulled onto the forecourt and read the sign on the pump saying ‘please pre-pay’. I put my credit card into the slot but the pump couldn't recognise my post code. Remove card, walk into shop, and say to the girl on the counter "please can I get some fuel?”
“How much would you like” she asked. Cue confused tourist expression.

Rebreather Forum 3, RF3, Sport Diver UK, Martin Sampson, Anglesey Divers, Rosemary E Lunn, Roz Lunn, Rosemary Lunn, The Underwater Marketing Company, Simon Mitchell, Neal Pollock, Drew Richardson, Karl Shreeves, Mark Caney, Michael Menduno, Richard Pyle, Peter Denoble, DAN, PADI, AAUS, Richard Vann, rebreather safety“I don’t know” I replied, “I want to fill up so I don’t know how much it will take”.

“Well you can leave your card, fill up and then pay” she said helpfully, oblivious to the fact that she was helping a simple process get complicated.

I walk out to the pump, lift the nozzle and waited. Nothing. After two mins I walk back into the shop. “What am I doing wrong?” I asked.

“Are you waiting for gas?” she asked still sounding delightfully helpful.

“Er... yes”.

She pressed a button on the touch screen in front of her, “Ok the pump’s on now”.

Back out to the pump and 'Hey Presto' I fill the tank up. Back to the shop again to pay.  She hands me back my card which I dutifully slide into the card reader.
“Mileage please”, she asks.

“Eh?” Looking down at the card reader the word ‘odometer’ was displayed. Why did the credit card company need to know the mileage? Was it that, by some conspiracy, that the car rental company had informed Google, who had informed Mastercard that I was on the road?

“I’ll be back in a moment”, I shot out of the shop, ran to the car and opened the door. The steering wheel had been stolen – er no, wrong bloody side. Run round to other side. Look at the odometer which is digital. The ignition needed to be on. Where are the keys? In the shop. Bugger!  Back to shop looking flustered. Grab keys, run to car, get mileage, run back. The transaction had timed out and my card was lying on the counter and another guy was now paying for fuel, coffee, muffins, and who knows what else.

“45657, 45657, 45657,” I started muttering to myself, willing myself not to forget the number. By now the bloke with the muffins thinks I'm cracked.  At last! Card in slot, mileage?.............45657........YeeeeeSS!

“Driver number”.

Driver number? What the f... is a driver number?

The girl shrugged her shoulders.

“Can you tell I’ve only just arrived in the USA?” Rough translation: “please help me out here because I haven’t got a clue what’s going on”.

“I don’t know” said the girl doing her level best to be nauseatingly helpful.

“Well I’ll just make one up shall I?”


“I’ll tell you what, I’ll just try my pin number”

I type in four numbers and........the transaction goes through.

Back to the car, and I sit in the drivers seat.......exhausted.

“Where’s the bloody steering wheel?”
Oh no not again.

Finally, sat in the right seat I gave the gas station a cheery wave goodbye. I didn’t actually want to do that but my right hand was flapping around trying to find the seat belt. That's on the left stupid. Meanwhile, my left leg was in spasm trying to find the clutch. Oh didn’t I say? They drive automatics out here.

Rebreather Forum 3 Speakers

Rebreather Forum 3 Speakers - Friday 18th May 2012
Caribbean Ballroom III, Caribe Royale Convention Center


Dr Drew Richardson, PADI, Professional Association of Diving Instructors, Rebreather Forum 3 Speaker, TUMC, The Underwater Marketing Company, Rosemary E Lunn, Rosemary Lunn, Roz Lunn, Rebreather Forum 2.0, Rubicon Foundation, Rebreather Forum 2.0 Conference Proceedings





Dr Drew Richardson

07:30 Rebreather Forum 3 Welcome
15:00 Rebreather Forum 3 Orientation



Michael Menduno, Rebreather Forum 3 Speaker, RF3, Lessons learned from Rebreather Forum 2, Rosemary E Lunn, Rosemary Lunn, Roz Lunn, The Underwater Marketing Company, TUMC, aquCORPS magazine, technical diving, diving conference,





Michael Menduno

15:15 Lessons Learned from Rebreather Forum 2



Richard Harris, Harry Harris, Rebreather Forum 3 Speaker, RF3, cave diving, cave diver, Australian, Rosemary E Lunn, Rosemary Lunn, Roz Lunn, The Underwater Marketing Company, TUMC, anaesthetist, physician, Diving and Hyperbaric Medicine, Royal Adelaide Hospital





Dr Richard 'Harry' Harris

16:30 Rebreathers - Overcoming Obstacles in Exploration



Martin Robson, Rebreather Forum 3 Speaker, RF3, Rosemary E Lunn, Roz Lunn, Rosemary Lunn, The Underwater Marketing Company, TUMC, Christian McDonald, Evan Kovacs, Mark Caney, Phil Short, Lamar Hires, CCR communities





Martin Robson

17:20 CCR Communities

A Tri-partisan look at the state of Rebreathers by ANDI, TDI and IANTD @ RF3

One week today CCR Pioneer’s ANDI, IANTD and TDI will release historical training data at Rebreather Forum 3.  The three agencies have worked together and will announce the total number of divers certified on rebreathers.  This has not been done before, and it will give the Industry some idea of just how big the CCR (Closed Circuit Rebreather) market is.

Brian Carney, TDI President, TDI, SDI, ERDI, Rebreather stats, Rebreather Forum 3, RF3, Rosemary Lunn, Roz Lunn, TUMC, The Underwater Marketing Company, rebreather diver numbers, safety, rebreaher stats“There has been a lot of speculation out there about just how many people lean to dive on CCR’s”, stated TDI’s President Brian Carney.  “I am really glad to participate with Ed Betts of ANDI and Joe Dituri of IANTD and release our certification numbers”.

Joe Dituri, Tom Mount, IANTD, International Association of Nitrox and Technical Divers, TUMC, The Underwater Marketing Company, Rosemary Lunn, Roz Lunn, Rosemary E Lunn, Rebreather Forum 3, RF3, CCR, SCR, certified diver numbers“The rebreather industry is fickle and I laud the other big rebreather certification agencies getting together and setting the record straight,” stated IANTD’s Vice President Joe Dituri.  “I have never been more excited to be part of this growing culture.  Our cooperation is a win for the diving public”.

“Our corroboration will hopefully provide some clarity and result in a stronger, safer industry for all of us”, said Ed Betts, President of ANDI.  “Rebreather Forum 3 should be about improving safety and understanding.  Safety should not be a competitive issue”.

Ed Betts, Edward Betts, ANDI, American Nitrox Divers Inc, Dick Rutkowski, TUMC, The Underwater Marketing Company, Rebreather Forum 3, RF3, Rosemary E Lunn, Roz Lunn, Rosemary Lunn, rebreather stats, safety stats, diving safety informationDue to the fact that ANDI, IANTD and TDI have slightly different ways of classifying rebreather certifications the numbers will be broken down as ‘Basic’, ‘Intermediate’ and ‘Advanced’ certifications by year.  Basic qualifications will include any entry level program to SCR’s (Semi-Closed Rebreather) and CCR’s.  Intermediate qualifications will include any training that includes minimal decompression.  Whilst Advanced qualifications will include Trimix and exploratory qualifications.  The companies will also be showing the difference between SCR and CCR certifications.

This information will be released post RF3 for anyone not able to attend this event and will be included in the published Conference Proceedings.

"20 Years of CCR Training Data from ANDI, IANTD and TDI" will be presented on Friday 18th May 2012 at 11:30 in Boca Room IV, Caribe Royale by Ed Betts, Brian Carney and Joe Dituri


"RF3 is the premier worldwide CCR event" states Tony Davis

Tony Davis, Aqua Tech Australia, CCR Technologies, Dive Rite Australia, The Underwater Marketing Company, TUMC, Roz Lunn, Rosemary Lunn, Rosemary E Lunn, RF3, Rebreather Forum 3, CCR physiology, Simon Mitchell, Petar Denoble, Neal PollockTony Davis, CEO of Aqua Tech Australia & CCR Technologies is flying in from down under to attend RF3.  We asked him why.

“When I read the agenda I knew I had to attend.  RF3 is the premier worldwide CCR event, and I want to learn more about the CCR’s I distribute in Australia, whilst making business contacts to grow the CCR component of my company. I also want to learn more about CCR specific physiology, and the business of CCR’s in recreational diving.”

The three day programme is divided into sessions to cover different aspects of rebreathers.   Topics up for discussion include;

- Hazard Analysis and Human Factors
- CO2 Scrubber Technology
- CO2 Sensors
- O2 Sensors and O2 Control
- Pre-Market Testing
- Post-Market Monitoring
- Post-Incident Testing
- Semi-Closed Systems
- Operations and Training

If you want to join Tony, book your tickets now by logging onto and be part of this key rebreather event.


Duke Research Team wins NASA Award; Preventing DCS in Astronauts

A research team at the Duke University Hyperbaric Centre, (North Carolina, USA) has won a Johnson Space Center (JSC) Group Achievement Award from NASA. The Durham based team comprising Dr Neal Pollock, Dr. Richard Vann, Mike Natoli and Dr Richard Moon. Dr Neal W. Pollock and Dr Richard D. Vann developed an in-suit light exercise pre-breathe regime to prevent decompression sickness developing in astronauts.

Dr Neal Pollock, Dr Neal W Pollock, Dr Richard Vann, Dr Richard D Vann, Dr Dick Vann, Duke University, Astronaut, DCS, Decopression Sickness, NASA, Duke University Hyperbaric Center, Dr Richard Moon, Mike Natoli, pre-breathe protocol, space walking hazards, Rosemary E Lunn, Roz Lunn, Rosemary Lunn, TUMC, The Underwater Marketing Company, Rebreather Forum 3, RF3, Rebreathers
Dr Neal W Pollock and Dr Richard D Vann

Although it might not seem immediately obvious, there is a strong link between astronauts, rebreathers, diving physiology and physics. A space suit is effectively an oxygen rebreather with the contents of the suit recirculated through a CO2 scubber. However the helmet doesn’t suffer the same CO2 retention problems that some diving helmets can, mainly because the gas is far less dense, therefore it circulates easily around the system.

“When an astronaut transitions from Space Station pressure (1 bar) and dons a space suit (0.29 bar), the pressure on them drops by 0.71 bar”, stated Neal Pollock. “It’s the same effect as instantly going from ground level to a thousand feet above Everest. Consequently one of the dangers of space walking is that decompression sickness will result if there is no intervention or treatment. Although the astronaut hasn’t been diving, he does have nitrogen in his tissues - in equilibrium with the content at ground level pressure. With an immediate drop in pressure the gas comes out of solution forming bubbles and possibly symptoms of decompression sickness, just like diver experience. We needed to wash out nitrogen from the astronauts’ tissues by having them breathe pure oxygen; an old trick used since World War II by bomber and fighter crew."

The full story can be found here, see page 6 of X-Ray Magazine, May Issue, # 48

Dr Neal W Pollock and Dr Richard V Vann also work at DAN Headquarters in Durham, respectively as Research Director and Consultant.  They are two members of the team behind Rebreather Forum 3.