Here is my analysis of the Blaine stunt.
I consider myself an expert in analyzing this because of the following reasons:
1. I have done static apnea at depth in pool (1-2m), and in the ocean (up to 20m of depth), and I have personally felt the dramatic differences which occur when performing static even at a slight depth (1-1.5m)
2. I have done static on 100% oxygen and I am aware of the changes this produces to the apnea
3. I have done many long statics and I have had hundreds of sambas (no kidding) and many blackouts as well. I have also witnessed countless sambas & BO's and rescued many people.
4. I have gone with no food for as long as 6 days and measured the effects on my statics in detail
Further, I heard with good certainty from reliable sources around Kirk that David Blaine's true 'air' pb was almost exactly 7 minutes flat prior to beginning the 8 day immersion in the water.
From this information, and from the visual evidence I can say pretty conclusively what happened. Regardless, all of this is still speculation on my part, and everything here should still be considered my *opinion* and nothing more.
First, I start with primary conclusions and then support those conclusions:
1. The stunt was performed on enriched O2, although there is not enough evidence to calculate the exact O2%.
2. David Blaine did not suffer a samba or blackout at the end of the static. He was genuinely in trouble, but he was suffering a different sort of problem which happens on enriched oxygen breath-holds.
Now, let's go into further depth:
STUNT WAS PERFORMED ON ENRICHED O2
1. The doctors said that David Blaine's plasma level had decreased by 20%. He was being fed gatorade during the stunt. I see little or no reason why the doctors would fabricate the change in the plasma level. It is, after all, consistent with fasting on gatorade. While fasting, with no protein in the diet, the body catabolizes muscle, creating massive amounts of uric acid, which promotes urination. This creates great dehydration, which reduces blood plasma volume. The blood becomes thicker. But, most importantly, the blood plasma is a huge buffer of CO2. With reduced blood plasma, the CO2 buffering capacity of the body is DRAMATICALLY reduced. I have personally experienced this after fasting for 6 days -- with each day the contractions came earlier and earlier. So, with David's plasma volume reduced, we would expect his CO2 buffering capacity to be reduced dramatically. We would therefore expect to see contractions STRONG, and EARLY.
2. David did the stunt at a depth of 1-2m. This creates a massive increase in the CO2 pressure in the lungs. At a depth of 1m, the CO2 concentration in the lungs is 10% higher, and at 2m, 20% higher. Given that the lung CO2 varies from about 4 to 6.5% on a max apnea, the 10-20% increase when doing static at 1-2m is enough to bring contractions FAR earlier. In my case, getting contractions at 5'00" on surface apneas, they would come at 3'30" when doing apnea at 1.3m. Thus, with David doing his static at 1 to 2m of depth, we would expect to see contractions STRONG and EARLY.
So, we have a diver (David Blaine) with a pb of 7'00", who is doing his static with reduced plasma volume, and at depth. The combination of these factors would bring contractions incredibly early, possibly as early as 1'30" or 2'00". I mean BODY BUCKLING CONTRACTIONS. Yet, in the footage, David doesn't appear to get any major contractions until at least 6'00", and more like 6'30". This is absolutely inconsistent with what should have happened, even allowing for an extreme CO2 tolerance on David's part. However, any apnea done on enriched oxygen creates a dramatic delay of the contractions. I can see no other way that he could have delayed contractions that long (given the situation), except with enriched O2. I will continue evidence for this in the next section.
Further, the top of the sphere was closed during his final breathe up. This would be absolutely detrimental if he had been breathing regular air (the air would become stale and high in CO2). I can't see any reason to close the sphere until after the apnea had started. Unless pure O2 was being diffused in that area by a regulator or something else.
DAVID DID NOT SUFFER A SAMBA OR BLACKOUT
1. As David starts to release bubbles, Kirk orders Martin and Mandy to perform the rescue. David is still moving during the rescue, making swimming movements with his arms. His movements, though confused, are not the characteristic spasms and convulsions of a real samba or blackout. His diaphragm is fluttering with rapid contractions, so badly that I don't think it could be faked. So, we know he is getting extremely powerful and rapid contractions (normally a sign a BO could be happening), yet his body language does not indicate a real blackout.
2. If the breath-hold were done on highly enriched oxygen, a blackout is not possible. When doing apnea on enriched oxygen, you cannot hold your breath until you black out. The CO2 level becomes so high that it is simply no longer possible to hold the breath. If, somehow, a person's mouth and nose were glued shut during an O2 breath-hold, blackout would eventually occur from CO2 narcosis, not hypoxia, and this would happen after an incredibly long time. The famous Duke university study on pure O2 apnea for the Navy showed that subjects could not and would never blackout from hypoxia. A few subjects (while exercising vigorously), experienced CO2 narcosis to the point where they could no longer cycle effectively (confusion and confused body movements).
3. It appears to me that David Blaine simply could not hold his breath any longer. His contractions, which came suddenly around 6 - 6'30", became extreme, to the point where he was losing air. The urge to breathe was simply too big. This is again consistent with an enriched oxygen breath-hold. At some point, you simply can't hold your breath any longer, and you start to lose air. However, you do not go into samba-like convulsions because you are not that hypoxic.
So, in my opinion, ALL the evidence points to an enriched O2 apnea which did not end in a samba or BO.
Now, David was a bit blue after the apnea but this can also be easily explained. During a pure O2 apnea, high CO2 shifts your hemoglobin affinity curve, creating a certain level of hemoglobin desaturation, enough to turn you blue, but generally not enough for a blackout. Alternatively, with the pure O2 diffusing through the upper sphere, David could have been doing his apnea on something like 40% O2. In that case, he would have been somewhat hypoxic (making him even more blue), but still not enough for a real blackout -- but enough to delay the contractions dramatically.
As a final piece of evidence, given that David's pb was near 7'00" on the surface (while motionless), if we consider that he did his apnea at depth, while moving to undo the chains, I would expect a dramatic reduction in the apnea time, surely no more than 5 minutes or maybe 6, even in the best of conditions -- however in that case the contractions would have come very early and very hard, which they did not.
After they rescued David, they sat him up on the edge of the sphere. A long time after he had recovered, he did a bunch of samba-like shakes. These shakes occurred WAY after he had recovered.... which doesn't happen in real life. Either those shakes were faked, or he suddenly experienced stabbing pains in his hands, feet, or other muscles as he had described earlier. Perhaps the stabbing pains caused him to shake suddenly.
Now, the event can be analysed on an even higher level. What was the plan? Many people (including me) thought the plan was a blackout with spectacular rescue. However, given his pb of 7'00" on land, and the fact that is extremely likely that enriched O2 was used, I actually think they were planning a success. They may have planned a simulated BO after 9 minutes, but I still think the plan was to go over the 8'58". However, David's dramatically reduced plasma volume (and high uric acid levels) reduced his CO2 tolerance so much that he couldn't hold his breath long enough to finish the stunt. I think that is why he was so upset after it was over.
Nevertheless, I still have great respect for the stunt. Seven days underwater with only gatorade, plus fasting 6 days before, plus a difficult stunt with no mask or nose clip trying to undo chains, with millions of people watching, to the point where you can't hold your breath any longer... it is all very impressive regardless.