Immersion pulmonary edema/lung squeeze---HELP!

[cdavis]

Kurt,
Thanks for the detailed reply. Your description of PE explains much if not all of what I have experienced. Too many things fit for it not to be part of the problem. The difference in recovery times could be individual, or age related (I'm 57) or maybe mine is more than PE. Either way, I'm going to be more careful with exhale diving.

I agree with you on the math re: negatives in the pool. I've done the same math with the same results, but it still feels like much shallower. I know one other diver, capable of 60 m dives, who says the same is true for him. When diving 1/2 exhale, it feels to me the same as around 65 ft. If I push it, I'll get "squeezed" for sure. I've played with the math assumptions, residual capacity, throat/nasal volume, mask volume, etc and can come up with scenarios that yield much shallower simulated depth for negatives, but those are just scenarios. I don't know what the real answer is. But I know I can't equalize to 50 meters, no matter what happens in the pool.

Demasoni,

Preasure Contractions. So that's what that weirdness was. I get'em too, but very seldom now. I guess my stretch receptors have been reset. The first time was the first dive deeper than 70 that I ever attempted. Felt like my chest was going berserk, heaving, trying like crazy to inhale at 90 ft. Very fast, like you describe. Extremely odd! Once I figured out what was happening, I could control it with concentration. Over time it has pretty much disappeared.

Laminar,

I could not agree more about simulating much deeper than you can dive. Negatives are tricky and need to be approached with great care. That said, at least in my individual case, what I can simulate is not deeper than I can dive, no matter what the math says.

I get a chance to do real diving much less than I prefer, maybe once very two months, not near enough to maintain any sort of ability, especially exhale ability. I use pool practice three or so times a week, to stay in shape,dynamics for apnea and negatives for depth and exhale diving.

Can you suggest another training mode that will improve my exhale diving ability without negatives?

Any idea why exhale negatives feel like such shallow depth for me?

Connor

 

[Phil C]

This is a very interesting post, and it looks like you are getting advice from people much more qualified than me. However, while reading your symptoms and the irregular nature of these events I wondered if you had considered the possiblility of something along the lines of saltwater aspiration irritating the lungs causing these squeeze like symptoms.

 

[Bill]

'throat/nasal volume'

What did you come up with Conner? On a very good day I can go from sfc to 38' (1-2 atm) or 100-230' (4-8 atm) on a mouthfull of air but no matter how I juggle the numbers, it doesn't make any sense.

 

[demasoni]

Frank,

Thanks for chiming in, your response is very interesting to me. When you fill your mouth, how do you do it to create negative pressure with your tongue? I never thought that the WAY in which you fill your mouth for the mouthfill is a cause for P.E. - i.e. - creating positive pressure with diaphragm filling (good?) vs. negative pressure with tongue (bad?).

I cannot BTV, so I just fill my mouth by "exhaling" into my cheeks at around 30m on the descent. I can do this without using my diaphragm, maybe I should consciously use it?

 

[laminar]

Great summary, Frank, as always.

Another way to look at this in terms of the three paths to lung injury is in prevention:

1-Pulmonary hypertension: This is due to volume of blood in the pulmonary system, and vascular resistance. The last one increases with very high or very low alveolar volumes at the beginning of immersion. FRC is the best option to avoid high pulmonary pressure among others.

-Avoid packing and seek good overall fitness (less vascular resistance)

2-Negative Interstitial pressure: This is transmitted from negative pleural pressure. The biggest problem here is strong contractions and ribcage stiffness.

-Strive for flexibility without risky negative pressure dive practice or stretching "cold" (I see this ALL the time!) and, more importantly, adequate time for long term adaptation and dive response stimulation.

3-Negative airway pressure: This comes from tongue mouth filling. Specially reverse packing.

-Avoid reverse packing while trying to equalize or, in short, don't dive deeper than your body can handle! The mouthfill, for example, is an expert technique. Just because we can all learn it from a document, doesn't mean that the body is ready for it.

I get a chance to do real diving much less than I prefer, maybe once very two months, not near enough to maintain any sort of ability, especially exhale ability. I use pool practice three or so times a week, to stay in shape,dynamics for apnea and negatives for depth and exhale diving.

Can you suggest another training mode that will improve my exhale diving ability without negatives?

Any idea why exhale negatives feel like such shallow depth for me?

Connor

To answer your first question, Connor, I would say that it may be that given how seldom you dive, you'll need to scale back the depths you aim for when in open water. So the question is not "how can I improve my exhale diving/equalizing/depth in the pool or otherwise" but rather "how can I modify my diving habits/goals to stay safe and healthy given that I can't dive more often." It may feel like a step backward, but believe me 20m without ever having issues with lung squeeze is way more enjoyable than 40m with injuries.

Another possibility for staying "in shape" is to pursue good a cardio fitness regime. I have no idea what you do yourself, but heavy breathing is good for developing elastic muscles and tissues in the chest and no doubt improves lung function overall. I think some forget that staying in good shape has benefits that are more important for most of us than trying to be super specific with our apnea training.

And as for your last question, the first thing that comes to mind is that you might have a high residual volume.

Overall, I think many underestimate the time that should be allowed for becoming truly comfortable at new depths. It's hard when you see new divers on the scene achieving great depths in a short time. But if you dig a little, you'll find that many of the "stars" have had squeezes or some sort of bleeding and just prefer not to mention it in their interviews.

I think diving once or twice a month and expecting to go deeper than 20m is unrealistic unless you've already spent a significant amount of time diving more frequently. Lately, I've been away from diving for a month or two at a time, and each time, I maintain a floor of 20m and then slowly extend that if I get back into diving more frequently. It may seem overly cautious but I haven't had a squeeze of any kind in several years.

Hope this helps.

Pete

 

[azapa]

Great thread. I must disclose that I am a beginner with 1 years diving under my weight belt but:

-pressure contractions: I like the "hiccups" description, they are fast and light, and I definitely get them. Martin on the FIT II course mention they occur as the pressure separates lungs/diaphragm/ribcage area from it's resting position and the triggers are sent to breathe. He said "swim though them, they will go away" I must agree, but I have aborted many dives being fooled into thinking they were the real thing, only to realize on the surface that I had not even had a single diaphragm contraction. Hence: they are quite convincing.

- squeeze: I shrugged this off at the weekend due to the meager depth (50ft,) but I ended up spitting a little blood after about 20 dives to this depth, in the ocean, and some 5 hours later at home. I had been very tense during the dives as the water was very murky, my bottom times were awful. Could this have been squeeze? Martins recommendation: more phlegm than blood > don't dive for a week. More blood that phlegm, and two weeks out, and probably see a doc.

Regards

 

[naiad]

I feel obliged to advise all of you who are practicing with negatives and negatives with reverse packing to ease off a little. I very much doubt that these exercises help your deep diving ability. You do know that doing a full negative and sinking to the bottom simulates pressures on your lungs and within your chest that you'll never experience while diving? You are simulating a descent that is nearly impossible in terms of speed and you most likely are not ready for the rapid change of condition within your thoracic cavity. If you come up with some coughing and wheezing, however mild, it is too much, in my opinion. I really disagree with PFI doing this with new or even intermediate freedivers, but that's just my opinion. I really don't see how it's relevant.

There is really little use in simluating 100m of depth in a 4m pool. :duh Especially if you want to enjoy diving for the rest of your life.

I agree. Negatives and reverse packing in the pool are some of those things that scare me. They should definitely be done with great care and only by experienced freedivers.

I sometimes do negative dry statics, but not in the pool. If I want to practice equalisation, what I do is exhale on the surface, but NOT a full forced exhale, and then sink to the bottom and equalise. That way I think it is safer. I have to equalise using Frenzel, but without the extreme negative pressure in my lungs caused by the full forced exhale at the surface.

 

[Ol Dirty Diver]

He said "swim though them, they will go away"

I think you want to avoid pressure contractions altogether. These are so strong that they may provide the force necessary to rupture alveoli and cause a squeeze. If you are doing a relaxed dive within your limits, these should not occur. If they do, I would be wary and consider aborting that dive.

Could this have been squeeze?

Did you feel like crap afterward? Did you feel very exhausted for the next few hours or rest of the day, and perhaps develop a bad headache? If so, this might indicate that you weren't getting enough oxygen after the injury due to fluid in your lungs impeding gas exchange. This is what always happens to me during and after my PE, and what happens to victims of lung squeeze.

If, instead, you didn't feel abnormal after the dive, the blood may be coming from the trachea (or even sinuses) rather than the lungs, and you had not experienced lung squeeze (see my recent post).

Anyone who spits up blood should note whether they felt strangely exhausted afterward. This is a way to identify whether PE/lung squeeze happened or not.

 

[azapa]

Hi Kurt, Thanks for the valuable reply. I did not feel any more tired than normal afterwards. I left the water after seeing the blood in my spit. It was a about 25 dives to 50ft in a 2 1/2 hour period, each dive was about 1:30 average, recovery times were average 2x that. In the whole session I only really enjoyed and felt relaxed on two or three dives. Not a relaxing day in general.

I have had blood in sinuses before (when I started and could not equalize properly) but my time my snot was clear. Blood only on spitting. My throat was (and still is even, 4 days later) sore.

I could have strained my neck whilst looking for the bottom, causing a pull in the trachea?

 

[fpernett]

Frank,

Thanks for chiming in, your response is very interesting to me. When you fill your mouth, how do you do it to create negative pressure with your tongue? I never thought that the WAY in which you fill your mouth for the mouthfill is a cause for P.E. - i.e. - creating positive pressure with diaphragm filling (good?) vs. negative pressure with tongue (bad?).

I cannot BTV, so I just fill my mouth by "exhaling" into my cheeks at around 30m on the descent. I can do this without using my diaphragm, maybe I should consciously use it?

I don't know if you are familiar with reverse packing. It's like gulping, you move your tongue from the roof of the hard palate to the bottom of the mouth. There is only 2 way of filling your mouth 1) Creating negative pressure in the mouth or 2) Increasing pressure in your lungs. When you "exhale" into your cheeks you have to create a pressure gradient. When we exhale we are using our diaphragm, this is unconscious. I think is worth to work on diaphragm function, because it´s the safer way to equalize.

Pete

Can´t agree more with you. I agree totally.

 

[feign]

Kurt and all,

I was glad to finally read this thread of your experience. I missed it the first time. There are a few things that have come to my mind. I have had a similar experience of 'pulmonary edema' while diving several times. The first was a few years ago and I have tried to find an explanation for it in myself. The first thing that bothered me about it was that there was a 100% correlation with being cold and also breathing cold air. Exertion played a role as well, but the depth of diving has not been consistent. I even had one day in a river where I dove no more than 5 feet down when it occurred, but it was very cold water and I had been in for some time. There were two leading diagnosis that were coming to my mind during analysis of my symptoms and the events, pulmonary edema and bronchospasm. After the river episode I was at my father's (emergency and anesthesia physician) place within about 2 hours and I immediately asked him to auscultate my chest, as it is doesn't work to listen to your own. There were very faint crackles present (rales). Most of my symptoms had resolved, so I imagine that whatever process had been going one would be less evident clinically. After discussing with my father, we felt I should consider cold induced bronchospasm as a potential cause for my symptoms. I had never really been plagued by symptoms like this at other times, but my father and younger brother both have exercise and cold induced bronchospasm and reactive airway diseases can have a familial association. Bronchospasm is when the small airways in the lungs constrict down in response to a stimulus. The most well known version of this is garden variety asthma. Commonly we think of dust, pollen, smoke etc. as triggers for bronchospasm, but there are many others including cold and exercise.

Here are some things to consider:

Bronchospasm is an acute inflammatory reaction to a stimulus and generally there is also some hypersecrection of fluid within the airways during the process - what, if any, could this process be contributing to the increasing amount of fluid in the airways during an edema episode.

Typically, we don't think of pulmonary edema as a consequence of asthma, but the negative pleural pressures created during acute asthma (bronchospastic) attacks has been documented to result in pulmonary edema. I don't know, but speculate that possibly freediving during an acute bronchospastic episode could accentuate this phenomenon. For example, the relative negative intrathoracic pressure created with contractions.

Cold is a common denominator in many of our experiences. In addition to potentially being a trigger for bronchospasm, peripheral vasoconstriction from the cold can possibly shunt blood centrally and result in increased pulmonary pressures, which may also be a component in the development of pulmonary edema.

Hypoxia itself can increase pulmonary microvascular hydrostatic pressure through constriction of pulmonary arterioles, which has been speculated to be a contributor to pulmonary edema. A study with anesthetized dogs who were subjected to repetitive apneas, the majority of the subjects developed a degree of pulmonary edema. The finding was attributed to the increased pulmonary hydrostatic pressure and significant negative intrathoracic pressure from breathing efforts against a closed airway (rings a bell with contractions). In addition to pulmonary microvascular constriction, hypoxia can contribute to peripheral vasoconstriction, which further supports central shunting and possibly elevates pressures in the pulmonary system.

Personally, I have had a couple chest x-rays, electrocardiogram and complete pulmonary function testing. I have also had a multitude of pulmonary and cardiac clinical exams over the years from colleagues. I have normal heart and lungs on a day to day basis. I had no evidence of bronchoconstiction in pulmonary testing when I am feeling normal on land.

In order to help the hypothesis that bronchospasm could be a contributor to my episodes while diving, I started pretreating myself with Ventolin (Albuterol), a beta 2 agonist, which inhibits bronchospasm. I have been more mindful to do this in repetitive diving situations or when it is colder water. Interestingly, I have not had any episodes of diving pulmonary edema/bronchospasm when using the Albuterol. I have also been more conscious of getting cold and breathing cold air, but it is unavoidable at times up here in Canada, so in my anecdotal case, I seem to have a positive result while using the medication. I am nervous however to not use the Albuterol in situations that I believe would result in symptoms. To not use it and re-introduce the symptoms would be the next step in the experiment, but I am hesitant, as the edema experience is very unpleasant. Though, I also noted that while diving in Hawaii last spring (when I was always comfortably warm the whole time) I never used the Albuterol and never had an episode. During that time in Hawaii however, I was using a low dose inhaled steroid to suppress any inflammation in my lungs; as low grade inflammation in the lung can go unnoticed symptomatically, but result in a much more severe response when an acute trigger is introduced.

I believe that the physiology and mechanisms behind pulmonary edema associated with diving is complex and is likely a combination of factors. I think that we should also consider that bronchospasm (constriction of the airway) may be playing a role in this process.

lee

 

[katwoman]

Hey Guys - thought I'd drop in an update here... I'm not a diver, but a triathlete who gets IPE, also known as SIPE in the swim portion of an event.

To summarize, my first occurance of SIPE was at Mooseman in 2007, then again at IM Lake Placid that same year. For 2008, I raced SIPE free at Ironman Germany and Ironman Florida... Then, I got it again in 2009 at The Canadian Iron 226 in Ottawa. I thought after good races at IM Cozumel in 2009 and IM Brazil in 2010 that I had it figured out, but it was BAAACK at Ironman France - one month after Brazil.... Then I raced Ironman Canada in August and was fine.

So, basically I have had SIPE in 4 out of 11 Ironmans - only 1 DNF (the 2007 race in LP) - the other times I was able to keep racing. I do not reccommend this strategy to anyone, and I will say it's very difficult to race with fluid in the lungs, but I have been learning how to cope with it. I am on a quest to find the answers, and I think my pre-race routine has been helpful in preventing the onset of SIPE. In the races where it happened, it seems as though the physical contact and crush of the swim, combined with no warm-up prior to the start may have contributed to it.

I have posted updates on the SIPE page of my website at : http://www.endurancetriathletes.com/sipe.html

One area of research currently being done by Dr. Richard Moon at Duke University is looking at Pulmonary Arterial and Pulmonary Artery Wedge Pressure in those of us who have experienced IPE/SIPE. The study is being done at the Hyperbaric Chamber where they test divers for this same condition. They are also looking at a possible DNA link as part of the study. I was fortunate enough to participate in this clinical trial on Feb 14 & 15, 2011 and have posted a report on my experience there on my site as well at: http://www.endurancetriathletes.com/duke_ipe_sipe_study.pdf

Dr. Moon will have to test more participants and gather more data before he can make any final conclusions. In the meantime, he will share the findings of my testing with me so that we can reveiw the data and share that with my cardiologist and perhaps implement some additional pre-race strategies into my routine.

If you have suffered from IPE while diving, this is very dangerous and I urge you to contact Dr. Moon to perhaps be included in this study.

Feel free to check it out and contact me if you have any questions.
Be safe,
Kat

 

[trux]

If you are not familiar with the following study of SIPE at triathlon competitors, you may interested in reading it:

Elsevier

Besides others, it identifies hypertension and fish oil in particular as risk factors

 

[katwoman]

Thanks. I co-authored that particular study...

 

[Ol Dirty Diver]

There were two leading diagnosis that were coming to my mind during analysis of my symptoms and the events, pulmonary edema and bronchospasm.

Your theory on the involvement of bronchospasm certainly makes sense, but in my own personal case I feel it probably hasn't been involved because I have no personal or familiar history of asthma.

Cold is a common denominator in many of our experiences. In addition to potentially being a trigger for bronchospasm, peripheral vasoconstriction from the cold can possibly shunt blood centrally and result in increased pulmonary pressures, which may also be a component in the development of pulmonary edema.

I absolutely believe being cold is a major risk factor, with the mechanism being as you mentioned, peripheral vasoconstriction. I would be curious to learn what proportion of IPE victims have very low body fat, like myself (5.1%), because I feel that this is responsible for me becoming many orders of magnitude colder than others who have normal body fat percentage. While others may complain of feeling cold but still be able to function, I am shivering within 5 minutes in 80F water and have to wear a 5mm open cell suit most of the year in the "balmy" water of Hawai'i. Since I'm usually wearing wetsuits in some state of losing their insulation due to use, I can still get cold while diving nowadays and have realized another resulting health concern: being cold makes me urinate so much and so frequently (uncontrollable urge every 15min or less) that I get extremely dehydrated from diving. This is again because of the peripheral constriction: my fluids pool up in my cavity so much that my kidneys are deceived into thinking I'm overhydrated and they force me to urinate unnecessarily.

However, certainly there have been cases of IPE in individuals who didn't feel they were cold, but I'd still be curious to know if such individuals had very low body fat percentage, because I think "feeling cold" may be relative and those of us with very low insulation can become so much colder than others with only a few points more body fat percentage.

I believe that the physiology and mechanisms behind pulmonary edema associated with diving is complex and is likely a combination of factors. I think that we should also consider that bronchospasm (constriction of the airway) may be playing a role in this process.

A combination of factors indeed. My own personal factors seem to be:

• - Being cold
• - Being stressed/heartrate elevated (as while diving in tough conditions)
• - Being in the midst of serious cardiovascular training (*will discuss this more in my next post)
• - Genetic?

So, basically I have had SIPE in 4 out of 11 Ironmans - only 1 DNF (the 2007 race in LP) - the other times I was able to keep racing.

As a former serious triathlete myself, I must say I can't believe your determination! I couldn't imagine continuing a race in that state.

If you have suffered from IPE while diving, this is very dangerous and I urge you to contact Dr. Moon to perhaps be included in this study.

I emailed Dr. Moon back in 2008 and have to say I was disappointed in his response at the time. He first asked me if I had ever experienced IPE while swimming or scuba diving, rather than while freediving, to which I replied that I had not (I don't scuba dive, but I've been an avid ocean swimmer). His reply then was pretty much a dismissal of my case as being IPE, instead being 'lung squeeze'. I'm not sure of his definition of lung squeeze, but I would not classify any of my cases as such, and it's pretty clear based on my symptoms that my cases are one and the same with IPE. Lung squeeze, to me, entails fluid in the form of blood, not just plasma, entering the airway due to rupturing of the alveoli due to surpassing a negative pressure threshold. Most of my cases occurred in depths far too shallow to provide enough negative pressure (as shallow as 10m, and I'm a 70m diver), and I've never seen blood, so I dispel having ever experienced lung squeeze.

I feel like I'd be a perfect guinea pig for their studies since I have experienced IPE so much and can do so almost predictably, but I guess they're discriminating against freedivers!

 

[Ol Dirty Diver]

Here's an update of what I have experienced and learned since several years ago:

Thankfully, my incidence of IPE has drastically reduced to almost nil. There have been maybe only four incidents in the last three years. Interestingly, three of these coincided with blackouts in serious freediving efforts, so they were probably avoidable, but there was one that occurred in moderate depth on a typical spearfishing day.

Regarding the IPE as a result of the blackouts, in all three cases I BO'd before reaching the surface due to very hard limit-surpassing efforts of depth and/or duration, and the IPE was severe. Losing consciousness underwater, of course, could have allowed me to inhale water and confuse that with IPE, but there are some reasons I suspect I didn't inhale water in all of these cases. For one, we know that the protective reflex of the laryngospasm is supposed to protect against this during a BO. However, I will admit that I really don't trust it to always happen! I have had other BOs in which I did inhale water and dealt with the serious consequences of having water enter the lungs. That's actually another of my reasons to suspect I didn't inhale water in those cases: the risk of infection is high, and I had such complications in other cases, but not these. As for why I experienced severe IPE in conjunction with BOs, my only theory is that before blacking out I likely had serious contractions that provided a significant negative pressure in my lungs, along with very high stress.

What I really want to share, though, is that one particular risk factor has become more eminent than all of the others now that I have several years of experiences to look back on. This risk factor is being in the midst of serious cardiovascular training at the same time as diving. The way that I arrived at this notion is that I retired from racing triathlons in 2007 (and all the training that went with it), and since then I have experienced almost no IPE (except for the few cases I mentioned that were mostly associated with extenuating circumstances). I believe that all of the cardiovascular training I was doing while racing (2004 - 2007) kept my body in a state more susceptible to IPE. I suspect that the mechanism of this was having an adaptation of increased alveolar membrane permeability (thinner alveolar membrane walls?) to facilitate gas exchange, which, unfortunately, also made the lungs more susceptible to filling with fluid under the right circumstances. When I raced I trained twice a day, much at high effort levels; after retiring I've done almost nothing, save for a few spurts of very light running. I can definitely tell that I've lost a great deal of fitness, and probably a great deal of that enhanced gas exchange capability. But at least I'm nearly IPE-free!

It should be pointed out that the incidence of swimming-induced PE lends to my theory; obviously most of the victims of this are highly fit individuals competing in a race. That risk factor as well as the one of being stressed/heartrate elevated are in place. It's hard to believe that such limited submersion underwater could enhance the negative pressure in the lungs sufficiently, but obviously it's possible. But still, why do only a few individuals succumb to it? Is there a genetic risk factor?

The one other case of IPE I experienced since 2007 unassociated with a BO is worth mentioning, because it lends strong support to my theory. Several months after ending my racing and training, I guess I experienced withdrawal and began running again. I kept at it for a few months at moderate level, and what do you know, I experienced another instance of IPE on a typical spearfishing dive. I was simply diving to 15m repetitively, though I added the risk factor of being stressed/heartrate elevated by performing these dives with too short of a recovery interval. Due to my irresponsibility after finding that lobster hole I spent the rest of the day feeling miserable and diving horribly, but I'm convinced that the underlying factor was the fact that I had resumed running.

Since then I've been off and on with cardiovascular training, but always at very light levels, and I haven't noticed any IPE associated with it. I'm sure there are plenty of other divers out there who exercise while diving at the same time, perhaps even at high levels, but we're all different and perhaps they just aren't susceptible to IPE.

I'll provide another update when/if I resume racing or otherwise training hard (yeah right!) and I start experiencing IPE regularly again. :head

 

[scott]

I posted earlier to this thread about coughing up blood after diving as shallow as 50'. I later replied that all seemed to be well, after implementing a diaphragm stretching routine. Well, probably in 2009, the problem reoccurred and so I started to monitor other factors.

While this is far from scientific, I have found that, for me, any dairy products the night before or day of diving results in almost 100% chance of coughing up blood on even shallow dives. When I avoid the dairy and warm up properly, I almost never have the problem.

Not sure if this will apply to any others, but, for now at least, I seemed to have isolated the problem as it relates to me.

Thanks,

Scott

 

[katwoman]

Interesting point Kurt.

Dr. Moon does think there is a genetic predisposition to IPE/SIPE in some individuals, and part of the study is looking into that susceptibility. They took my DNA, which will be analyzed along with other individuals who have had IPE to see if there is a link. They will also test individuals who have not experienced IPE and compare the DNA.

In addition, there is some concern about 'interval' training, which is primarily what I do, and it's affect on susceptibility to IPE/SIPE, but it's not yet proven.

Understanding the mechanisms behind IPE will require more testing of individuals in controlled settings to try to find the common links.

The Duke Center for Hyperbaric Medicine is quite a unique facility and his testing is very specific. I know they were not sure if I would qualify for the study either, and it took some time for them to review my occurrences, medication and medical history before giving me the 'green light'. I would recommend you contact Dr. Moon again, just to be sure...

Keep me posted and let me know if you have any more questions... I really am trying to figure this one out - but science will be the key to revealing the links I think...

Kat

 

[sai]

I saw some of you mentioning "pressure contractions". I get exactly the same when diving below a certain depth. Fast and intense hiccups occur as early as 20 seconds after submerging. I could easily confirm that hey have nothing to do with CO2, because intense hyperventilation did nothing to postpone them.I have a really hard time at the bottom with those contractions. (and got trachea squeezed 2 times)
How did you get rid of this problem? If at all...

 

[Ol Dirty Diver]

I saw some of you mentioning "pressure contractions". I get exactly the same when diving below a certain depth. Fast and intense hiccups occur as early as 20 seconds after submerging. I could easily confirm that hey have nothing to do with CO2, because intense hyperventilation did nothing to postpone them.I have a really hard time at the bottom with those contractions. (and got trachea squeezed 2 times)
How did you get rid of this problem? If at all...

"Pressure contractions", I believe, are simply an expectable response to excessive negative pressure in the lungs. There is an element of the nervous system around the chest wall called stretch receptors, which serve to measure the distension and compression of the chest wall, primarily to regulate breathing. If one causes enough compression of the chest wall (such as from normal diving, negative pressure/exhale diving, or even stretching exercises outside of the water), he may surpass some threshold of chest compression, which the stretch receptors report to the brain and which may trigger the abrupt and rapid contraction of the respiratory muscles (especially other than the diaphragm). As you mentioned, this feels quite different than "normal" (CO2) contractions, which are usually exclusive to the diaphragm.

Susceptibility to pressure contractions varies significantly among individuals, probably dependent mostly on chest flexibility (along with a freediving experience component). They have never happened to me in normal diving up to 70m, but I can readily trigger them with a deep enough negative pressure dive (simulating some depth that feels much greater than 70m, thus surpassing my chest flexibility threshold). I can also stimulate them out of the water when doing aggressive negative diaphragm stretching including reverse packing. But I recently had a student that experienced them on a normal inhalation dive in relatively shallow water (50'), which I can only guess is attributable to poor chest flexibility (he was into weight lifting) and relative inexperience (had only been freediving for a few months). But I'm sure there's a mental component as well...Relaxation is beyond just physical; being tense mentally (as when doing something new or difficult) probably contributes.

I have never gotten injured from mine, but the possibility is certainly there since they happen at the worst time...when your lungs are the most negative at the apex of a dive (since that is what triggers them). Your lungs are already very negative, then they are subjected to rapid and forceful instances of even more negative pressure, making injury due to squeeze more likely. This risk is also associated with having "normal" (CO2) contractions at depth, which is why there is general advice to avoid having contractions at depth on deep dives (obviously harder to avoid the pressure contractions since they are somewhat unpredictable). My student actually did get quite squeezed from that dive to 50' because he hung out on the line tolerating them for some duration (due to his inexperience he wasn't aware of the different kinds of contractions, thinking instead they were normal/CO2). His injury didn't seem to happen in the lower lungs, fortunately, instead closer to the trachea (it recurs now and he says he can feel where, and he coughs up the blood immediately instead of after some delay).

Note: I was not instructing my student when he injured himself! This was just the circumstances he shared before seeking my instruction. But as I mentioned, his trachea squeezes do recur regularly now and he can still have pressure contractions on normal dives, perhaps due to incomplete recovery and the general increased susceptibility individuals tend to have from having been squeezed before, and/or he still possesses the same risk factors...poor chest flexibility and relative inexperience. Sounds like you're in the same boat. My recommendations:

• Cease laying on the bottom tolerating the pressure contractions! As I mentioned, this causes injury. As soon as they happen, head up to make them stop. If you want to lay on the bottom or otherwise hang out at depth, you're going to have to do it shallower until you improve your situation.

• Work on improving your chest flexibility. I'm sure there is plenty of specific advice for this around DB. I'm also aware that Stepanek produced a DVD that guides you through his own personal stretching routine; I've been through it and it definitely includes lots of effective chest stretching.

• Take it easy. Like the student I mentioned, it sounds like you are continuing to subject yourself to the same uncomfortable situation and experiencing the injury resulting from it, which should never be a requisite of freediving. I'm no stranger to being determined and "pushing through the pain", but in this particular instance it isn't appropriate and you are probably only reducing your freediving potential and longevity (squeeze injuries are very hard to completely overcome). You have to be smart and patient enough to dive shallower now and progress back to and hopefully through the troublesome depth gradually.

Hope that helps and good luck.