The biggest safety problem in diving?

[stadler_cj]

River Rat and Gene: Regarding CO2 buildup causing panic, you guys aware of any literature on that? Seems like it would be a big deal, as it should make you hyperventilate (based on the fact that increased respirations are based on CO2 buildup). I wonder how that fits into the panic thing.

Could panic be a purely psychological reaction to increased respirations?

And what causes CO2 buildup? In rebreathers, this could be the result of the systems inability to remove CO2 (when you exhaust your scrubber chemical). In open-loop SCUBA, maybe it's because the positive pressure doesn't allow the alveoli to fully exhale their CO2 (since the CO2 would be in the deepest place in the lungs, where gas exchange takes place).

These are educated guesses (or maybe ignorant ones). Please correct/confirm/ridicule, as appropriate.

 

[RiverRat]

River Rat and Gene: Regarding CO2 buildup causing panic, you guys aware of any literature on that? Seems like it would be a big deal, as it should make you hyperventilate (based on the fact that increased respirations are based on CO2 buildup). I wonder how that fits into the panic thing.

I'm sure there is literature on the panic cycle out there. I've researched it. I'd have to dig for it. The panic cycle was taught to me in my Rescue and Divemaster courses.
I know that as an OC diver, if I'm working hard or get anxious and feel stressed, just stopping, taking a few deep breathes and getting my breathing under control serves to blow off that excess CO2 and stops the "cycle" dead in its tracks.

Could panic be a purely psychological reaction to increased respirations?

There is a lot of literature on the panic subject out there. Seems there is still a lot we don't know for sure. Having knowledge and experience as a diver, as well as knowing how to break the panic cycle, is probably the best "cure" we have at the moment. Having said that, it's also understood that divers, even with thousands of dives and never having an attack, can suddenly get an attack that comes from "out of nowhere".

And what causes CO2 buildup? In rebreathers, this could be the result of the systems inability to remove CO2 (when you exhaust your scrubber chemical). In open-loop SCUBA, maybe it's because the positive pressure doesn't allow the alveoli to fully exhale their CO2 (since the CO2 would be in the deepest place in the lungs, where gas exchange takes place).

Speaking strictly OC, working too hard and not being able to "blow off" the extra gas causes a build up. Also, not paying attention to your breathing technique, or "skip breathing" (to try and conserve gas) can cause it.

I'm no expert, so back this up with current research, I'll send you some links etc. when I can get some time.

 

[Gene_Hobbs]

These are educated guesses (or maybe ignorant ones). Please correct/confirm/ridicule, as appropriate.

These are not bad...

There are good sections on CO2 and diver panic in:
"Stress and Performance in Diving", "The Physician's Guide to Diving Medicine" and "The Underware Handbook: A guide to physiology and performance for the engineer".

Other than these, work has been published on the "Panic Cycle" in the psychology literature.

As for CO2 in diving, it is a little different that normobaric conditions...
(From a post on another board) For most relaxed divers you will find hypoventilation resulting in inadequate CO2 elimination or hypercapnia. When I say hypoventilation, most divers start thinking that they blow through their tanks really fast so if anything they must be hyperventilating. The hypoventilation we are talking is alveolar hypoventilation and not to be confused with respiratory rate. You can have a high respiratory rate and still hypoventilate (all of us on every dive).

Lanphier and Camporesi describe Lanphier's (1-4) work at NEDU to answer the question 'why don't divers breathe enough?'

1. Higher Inspired Oxygen (PiO2) at 4 ata (404 kPa) accounted for not more than 25% of the elevation in End Tidal CO2 (etCO2) above values found at the same work rate when breathing air just below the surface.
2. Increased Work of Breathing accounted for most of the elevation of PACO2 (alveolar gas equation) in exposures above 1 ata (101 kPa), as indicated by the results when helium was substituted for nitrogen at 4 ata (404 kPa).
3. Inadequate ventilatory response to exertion was indicated by the fact that, despite resting values in the normal range, PetCO2 rose markedly with exertion even when the divers breathed air at a depth of only a few feet.

Beyond the respiratory physiology involved with diving in general, what about the idea of adding CO2. Most divers seem to know that CO2 is narcotic (5-6) and it can make nitrogen narcosis worse (6-7). We also seem to know that higher levels of CO2 are bad for CNS Oxygen Toxicity (8).

References:
1. Lanphier. Nitrogen-Oxygen Mixture Physiology, Phases 1 and 2. NEDU Report 1955-07. RRR ID: 3326
2. Lanphier, Lambertsen, and Funderburk. Nitrogen-Oxygen Mixture Physiology - Phase 3. End-Tidal Gas Sampling System. Carbon Dioxide Regulation in Divers. Carbon Dioxide Sensitivity Tests. NEDU Report 1956-02. RRR ID: 3327
3. Lanphier. NITROGEN-OXYGEN MIXTURE PHYSIOLOGY. PHASE 4. CARBON DIOXIDE SENSITIVITY AS A POTENTIAL MEANS OF PERSONNEL SELECTION. PHASE 6: CARBON DIOXIDE REGULATION UNDER DIVING CONDITIONS NEDU Report 1958-07. RRR ID: 3362
4. Lanphier. Nitrogen-Oxygen Mixture Physiology. Phase 5. Added Respiratory Dead Space (Value in Personnel Selection tests) (Physiological Effects Under Diving Conditions). NEDU Report 1956-05. RRR ID: 3809
5. Henning et. al. Behavioral effects of increased CO2 load in divers. Undersea Biomedical Research 1990. RRR ID: 2540
6. Lanphier EH (ed). Unconscious Diver: Respiratory Control and Other Contributing Factors. 25th Undersea and Hyperbaric Medical Society Workshop. UHMS Publication Number 52WS(RC)1-25-82. Bethesda: Undersea and Hyperbaric Medical Society; 1982; 160 pages. RRR ID: 4278
7. Fothergill et. al. Effects of CO2 and N2 partial pressures on cognitive and psychomotor performance. Undersea Biomedical Research 1991. RRR ID: 2576
8. Natoli and Vann. Factors Affecting CNS Oxygen Toxicity in Humans. MS Thesis (Duke) 1996. RRR ID: 26

 

[scubapro50]

The biggest problem in diving is divers not knowing their limits. A diver may not be properly trained, may not be in physical shape or he doesn't know the conditions of the dive before entering the water. In my 30 years plus of diving I have seen many divers get into trouble due to one of these reasons.

 

[Tomeck]

My opinion:

for equipment:

1. abuse by user;
2. lack of service;
3. not used properly (i.e. using a non-cold water certified reg on an ice dive);


for divers:

1. complacency (i.e. diving beyond their training and limits);
2. ignorance ( i.e. getting into a situation such as hitting fire coral or surfacing in boat traffic);
3. not physicall fit for diving (i.e. heart problems);
4. using wrong or insufficient gear (i.e. small smb on a distant, choppy dive site);
4. dork (most the above - bad buddy and a danger to all around)

non-divers:

1. boaters ( not recognizing dive flags)
2. legislators (not enforcing boater safety and education - regarding SCUBA divers)

dive shops:

1. inexperienced staff ( make bad or dangerous repairs or servicing on dive gear)
2. selling their products, even if it isn't proper or correct.

Do you think dork divers are bad?

In Switzerland, we dive in very cold water at 40°F, even in summer, we often dive with decompression, because we often dive more than 130 feet to see pictturesque wall, water is often dark, visibility is not always good, but there are not more accidents than in the tropical sea. I think when there are dangerous things, one is more prudent.

 

[RiverRat]

Back on the CO2 subject, here is a great video for all divers on what CO2 can do. Aimed at rebreather divers but still shows the effects and what the end result can be for CC or OC. This guy came real close to his last dive.

CO2: The rebreather incident

 

[stadler_cj]

RiverRat: Thanks for the video.

 

[leapfrog]

Back on the CO2 subject, here is a great video for all divers on what CO2 can do. Aimed at rebreather divers but still shows the effects and what the end result can be for CC or OC. This guy came real close to his last dive.

CO2: The rebreather incident

Awesome video. Can't figure out the stuff about reusing your lime. Freaky! Ten they go and blame "the military". He could have blamed Mickey Mouse!Rebreathers are real simple. It's the people who screw up, not the system.

 

[RiverRat]

Awesome video. Can't figure out the stuff about reusing your lime. Freaky! Then they go and blame "the military". He could have blamed Mickey Mouse! Rebreathers are real simple. It's the people who screw up, not the system.

Sounds like you never want to repack or remix it in any way. Someone taught them to reuse the stuff and they took it as gospel. The heck with that. If I had the money to dive an RB you'd bet I'd just refill it everytime it's due. Many of the RB accidents I've heard about were just that, divers messing with the hardware or jury rigging something. Diving with faulty sensors, pushing the limits of the lime or whatever it's called. Crazy. What's your life worth

 

[GLOC]

For the last 2 years I have been working on a paper which takes the Human Factors Analysis and Classification System (HFACS) devised to investigate the root cause of incidents and accidents in aviation and apply it to Sport Diving, covering both recreational and technical diving. The application of the HFACS to US Navy and US Marine Corps aviation accident analysis reduced accidents whose root cause was violations of rules or regulations from approximately 44% to approximately 12% over a 9 year period ending in 2000.

The paper looks at how incidents develop and whilst it includes the individual’s actions to ‘create’ the event, it also looks at the influence of the supervisor or organisation on how the incident develops. By identifying those influences, future incidents may be prevented. This work has been the baseline for my presentations on Human Factors and Diving Incidents which I have presented at DiverSE ’10, Eurotek 2010, LIDS and TEK 2011 and a few BSAC clubs. (More presentations planned this year too, including the Global Diving Conference in Germany in November).

Some of the reviewers have commented that such a system will not be adopted within a recreational sport because it costs money and therefore drawing comparisons with an activity (aviation or medicine) which is well funded, is not a valid comparison. I leave that to the readers to decide, but the drivers must come from the topdown, rather than the bottom up.

The paper has been written as a discussion paper and over the next few weeks I will be putting together a more accessible version forthose who are not interested in reading a long technical paper. The full paper can be found on the Cognitas website here Cognitas Incident Research and Management Human Factors in Sport Diving Incidents Paper

Happy Reading!

Regards

Gareth