Words on squeeze from deeperblue.net

"I couldn't breathe properly for a month following my squeeze". Peter Scott on Squeeze

"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."

"If you squeeze your lungs you are an ignorant freediver. Plain and simple".

Squeeze -The last obstacle of deep freediving
text: Sebastian Naslund
Updated may 2008 - A story in swedish about squeeze here.
Basicly - the chart to the right says it all. It is from an abstract published 2008. It shows how gas exchange is impaired after deep dives. Explicitly - every third diver in this competition had squeeze - with another word pulmonary edema. You breath - but your body does not get access to all the oxygen. Your lungs are damaged. Squeeze has for many years been the secret of many freedivers, from beginners to high levele competititors.

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 to overcome  for depth hungry freedivers - but there is a third problem.

Personal experience
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 37 meters. Before learning frenzel/mouthfill that was my depth limit.
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 saliva with traces of blood. There was also a gurgling sound deep down the throat when breathing out hard.

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 (especially in addition to contractions).

Even though contradicted by some, I find the following description of squeeze useful: Diving below "bloodshiftRV" (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 must be enourmously overpressurized.

There is much investigation going into this area nowadays: packing (swollowing air), bloodshift and squeeze related 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. 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).

Near drowning
Where ever the blood comes from it can in both cases 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 decilitres  during a 30 minute period after a dive. In my experience "near drowning" is definitly a scenario if a diver is severly squeezed far from land and without any resting point.

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 the lungs can get squeezed in two ways: too 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. Gurgling sound in trachea when you breath out hard. Fever might occur. Similar symptoms as secondary drowning due to the blood and/or bloodplasma covering alveolis in the lung.

Treatment of squeeze: after a squeeze: Rest, stop diving, do not do anything. Lean forward and spit out as much salivablood as possible. But avoid coughing. Drink lots of water the following hours. In severe cases breath at least 5 minutes of oxygen (on land). Even 20 would not be overdoing it. 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).

How to avoid squeeze: Dive less deep. Slower increase of depth and seasonal PB´s. Stretch long term and short term (see below). Pack more air. Warm up with FRC´s. Dive without mask (access to more air). Do not dive or do physical work after a deep dive. Ventilate more, get contractions later. Use frenzel and mouthfill. Relax more. Relax even more. Do not stretch out at depth. Dive in a shorty (enhances central bloodflow). Do not over hydrate (slows bloodshift). Release some air just below surface. Avoid over pressurization when returning to surface. Slower descent. Slower ascent.
Unfortunately there are contradictory advice: more or less packing, more or less bloodshift (hard to cotrol but yet possible). Some even advice to be on the dehydrated side to avoid too much bloodshift (blood volume). In my experience contractions at depth are the main culprits. Which put you in a tight spot since contractions and high CO2 is what "keeps you conscious" in extreme dives.

- A lot of hard cardio has been said could cause thinner alveolis - and therefore more prone to break.

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.

How to measure squeeze
In a squuezed state your O2 levels are cleraly impared. With a finger meter you will se lower values. My sugestion is to define light squeeze as a state where O2 levels remain under 90 up to 10 minutes after surfacing. If saturation levels are under 80% it is a sever squueze. Keep on measuring, in the case of a really sever squeeze O2 levels are below 90 even hours afer surfacing. In the F.BIZ competitions (Bizzy Blue Hole and Nordic Deep) we will focus on detecting squeeze symptoms with direct observation and oximeter, since this might lead to increased risk of trouble in a possible second dive during the day (or next day). We will do this oxy test directly after a dive in certain cases and if need be a "pox" test under slight exercise later. We will evaluate every freediver individually. Oximeter

Personal tests 2006
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 feelings 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.

Johan Andersson one of the authors of the thesis mentioned above test FEV directly after dive.

Support science - answer questionaire about "bloodspitting" - here

Test 2007/2008
For half a year I have introduced more and more extrem lungstretches (see below). In 2009 I stepped up and introduced more and more advanced stretches. 2009 I did comfortable dives down to 65, on the other hand I got squeezed at 70 and on a 80 dive, both long dives, the last 3.20 with lots of contractions. On a VWT dive to 70 during the same period I got no squeeze whatsoever.

Stretches to prevent future squeeze for fit and experienced freedivers.
Stretches to be done slow, deliberate and with awareness. Softer approach the first weeks and somewhat less aggressive right before deep dive.

- Stretch ribcage and muscles around the lungs.
- Same stretches with air out.
- Same stretches but with packing.
- Ventilate, release all air down to RV, suck up diaphragm. Hold.
(in the Naoli or bastrika yoga position)
- Same but add contractions.
- Same but add negative pack and no contractions.
- Now add contractions.
- Ventilate, release all air down to RV, suck downwards against the epiglottis by pushing out your stomach.
Important exercise.
- Add contractions.

Rest after and in between.