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Words on squeeze from deeperblue.net

"Most of the competitive freedivers have at some point been spitting blood."

"I am not aware of any sport where bleeding is being accepted as a natural part of progression."

"Kirk Krack and Martin Stepanek talked about this ... They both felt that ruptures in the trachea that caused blood to drip down into the lungs."

"I had a cold anyway and hadn't got past 12m on my warm up - but rather stupidly just decided to storm it down to 35m on my comp dive... lots of orangey froth coughed up and short of breath for several days..."

"I did another 6 hours of almost perfect diving pushing myself to the comfort limit, but not beyond...One week later I suffered a 100% haemo pneumothorax (total lung collapse with heavy internal bleeding)"

"When Kirk & Mandy were training with Audrey for the 101m tandem dive, according to Kirk, Audrey would be coughing hard after every dive."

"Pipin and Audrey did not pack for their dives and they went down the fastest. They used salt water to equalize."

"After the swim back to shore I am physically exhausted...my throat gets dry. My heart beats 80-90% of max for at least 5 minutes ... I am coughing bright red blood, and I am at the point of muscular failure-"

"Its been 5 weeks since the squeeze occured, but still, every time i try to make a 100 % inhale it hurts a bit."

"I have a solid life history of taking excessive risks, and am content to keep tossing the dice."

"Theory says that getting a lung squeeze will leave some scarred tissue in your lungs, the scarred tissue is less flexible, so afterwards you are more prone to get a lung squeeze."

"I think those squeezes should NEVER be accepted as a normal risk of diving".

"I pretty much see this as a part of freediving as long as strength has returned in 24 hours."

"It is "set up" in the first 20m ... When you reach your residual volume, your blood shunt has not had time to come into full effect and thus squeeze ensues."

"Umberto Pelizzari dove over 80m without packing."

Squeeze -The last obstacle of deep freediving
text: Sebastian Naslund
Updated august and september 2006 - A story in swedish about squeeze here.

When you start freediving equalization usually sets the depth limit. After some training it is oxygen consumption. Then again equalization and after learning frenzel it will be lack of oxygen again. This has been the main obstacles for depth hungry freedivers to overcome - but there is a third problem.

In april 2006 I did my longest selfpropelled dive ever and it was also my deepest dive. FIM 72 meter in 2.48 minutes. A clear surfacing and happy ears at the bottom - but within seconds I started coughing. Soon I saw traces of blood. I had seen worse, but nevertheless on that day decided not to go deeper if I could not solve the issue of squeeze (lung/trachea).

I have 6 litres of VC and an RV of 1.9. On this dive I packed maybe a litre at the surface. In the old days my maximum depth would be defined in this equation: TLC/RV = depth in ATM.
In my case: 9/1.9=4.7 ATM. 4.7 ATM is reached already at 36 meters. Nowadays we know that Bloodshift reduces the RV (the volume of the compressed lung). My TLC of 9 was reduced to 1.1 litres at 72 metres. Bloodshift helps freedivers go deep - but in my case the RV seems not to have been reduced enough, or was there another problem? Negative pressure got so high that something inside me burst and I spit traces of blood in my saliva.

A suggestion for definition of squeeze:
"Pulmonary edema of immersion" which means that under pressure fluid will move from blood vessels into the breathing apparatus (lungs and trachea). In plain language: bloodvessels bursting in throat and/or lungs.

I would avoid categorizing blood from sinuses trickling down into the throat as bloodspitting caused by squeeze. In the equalization process blood vessels can break in the sinus area. Usually in conjunction with other health problems in this area, as a blocked sinus causing over- or underpressure in that area. Also remember that equalizing frenzel style puts the epiglottis at hard work - which could lead to soarness and even injuries.

Even though contradicted by some, I find the following description of squeeze useful: Diving below RV (RV as the volume after bloodshift has reduced it). If nothing else, it gives a simpler more pedagogic image of the problem.

But this would not be accurate if squeeze occurs due to rate of change instead of "maximum pressure limit reached". It could also be a fact that the pressure needed for squeeze can be produced by heavy contractions causing extra negative pressure. Which means it is about pressure, not an issue of volume. Another theory is that the actual damage caused is not at depth or on the way down - but on the way up. A lung that maybe has been packed above normal TLC, and then returning to the surface with this amount of air in a smaller lung - a lung that has been reduced by bloodshift that still remains - this lung most be enourmously overpressurized.

There is much investigation going into this area nowadays: packing (swollowing air), bloodshift and squeezerelated problems. Nothing is proven yet and what I write here is based on observation and speculation... and remarks from the deeperblue forum discussions with input from people as: Frank Pernett, Tyler Zetterstrom... among others.

Where does the blood come from:
This has not been proven scientificly. Lungs, throat or sinuses? (or several places). Fact is that the lungs are very flexible and prone to bloodshift while the throat is made out of cartilage. Under pressure the throat folds into itself (this has been seen in magnetic scan). I think it is likely that it is here that the bloodvessels mainly break. A so called trachea squeeze.
I also believe that it doesnt take that many broken bloodvessels in the throat to procuce enough blood to scare a freediver. All in all I dont think it will be more than 50ml in a severe case, but this is a guess (based on some experience). It is my experience that this is a sharper red of blood coming from the trachea.

Note that different types of blood can appear. Small specks of blood in saliva or more foaming pink salivablood. Could it be that the foaming type come from bloodplasma and therefore is caused by a rupture in the lungs?
There can also be small quantities of what looks like only blood. This is usually a brighter red, probably from arteries (recently oxygenated).
Whereever the blood comes from it can in both options trickle down into the lungs and produce signs of near drowning. But ENT doctors have said that it would take quite a lot to produce these symptoms. I know of cases of foamingsalivablood, probably from the lung, that has amounted to 3-4 decileters during a 30 minute period after a dive.

Scenarios where squeeze can be triggered:
Realy at any depth. A negative or FRC dive can get you squeezed at very shallow depths as 10 meters.
One theory is that Squeeze can only occur when you have mastered frenzel equalization fully and the "mouthfill" efficiently. Otherwise you would be stopped by failing equalization much earlier than you get squeezed, but this has been contradicted by some very shallow dives showing symptoms of squeeze. Even swimmers at the surface has shown symptoms, specially after OVER-hydrating themselves.

It is important to note that teh lungs can get squeezed in two ways: to little bloodshift and "too much" bloodshift. Scientists claims that if you are too hydrated you have more bloodplasma and during vasoconstriction concentration and pressure gets to high in torso/lungs. This last scenario is more likely in cold waters (increased vasoconstriction)

Description of symptomps:
Couching, higher breathrate, soarness in throat, traces of blood in the saliva. A continious state where you breath at a higher rate (A high shallow breathing), being tired for hours, maybe even days. Fever might occur. Similar symptoms as secondary drowning due to the blood and/or bloodplasma covering alveolis in the lung.

Treatment of squeeze:
Stop diving. Rest. Lean forward and spit out as much salivablood as possible. Drink lots of water the following hours. In severe cases breath at least 5 minutes of oxygen (on land). Eat vitamins, get extra hours of sleep. Drink more.
In severe cases you might need many days of rest, even weeks. When the risk/effects of near drowning is dealt with, there are still small internal wounds that has to heal (and scar).

Suggestions on how to avoid squeeze:
- First and foremost have a slow progress to depth every season.
- Do not pack air. Rapid changes in lung volumes could be a factor, but latest indications is that packing does not increase the likelyhood of squeeze.
- If possible: turn before contractions - indications say that heavy contractions might be the main cuplrit.
- Slow ascent (some suggests the first 10-15 meters are the most important).
- Do not stretch out at depth.
- A general relaxed approach all through the dive.
- Warm up with (at first) gentle FRC or negative dives
- Drink less before diving deep.
- Breath out well before the surface

If you want to go deep you have to facilitate bloodshift as much as possible. Also note that your RV can differ from day to day.


Overpressurized at surface.
Maybe the blood is not the result of squeeze in all cases but rather of lung overexpansion. When you return to surface you may well be in bloodshift state. That is a reduced lung volume. At the same time your air is expanding back to the volume you had when leaving the surface - did you pack maximum? With bloodshift and packing you are way above a pressure you have ever experienced before. Peter Lindholm (KI, apnearesearcher) or Johan Anderson (apneamamal researcher) does not believe in this theory.
Personal tests
I have during a three week period tried to explore my reactions to squeeze. I have dived these dives: 55,50,55,56,63,66,65 - seeking out different factors and focusing at relaxing and feeling changes at depth, taking spirometer test afterwards. These are some of my conclusions.
- I believe that you seldom can feel that you are squeezed until after the dive.
-
I believe that contractions are a major factor when it comes to trachea squeeze.
-
I believe that the ascent rate is not a major factor (but still a factor). Fast or slow, you can still get squeezed.
- I believe that packing is not a major culprit when it comes to lungsqueeze.

On my last dive to 65 I get sinussqueeze and get delayed. The whole dive lasts 2.55 (my longest) (heavy contractions) but good relaxed feelins at depth (somewhat narced). At the surface I experience my first BO in deepdiving (thus forgeting to release air deeper). I experience my most severe squeeze ever. All the worst symptoms. 7 days later I try a relaxed dive to 55 without any problems, but when measuring my VC (6 litres before) it is reduced to 5 litres for several minutes after the dive. Scientist made this measurement and they do not believe that it is a bloodshift that has not retrieved. They believe that the reduction is because of a light pulmonary oedema.

Support science - answer questionaire about "bloodspitting" - here