packing

[Mark Jeffery]

After reading several posts about "packing" I have come to understand what it really is. Packing causes the amount of air in your lungs to increase without any (or very little) increase in volumn. By applying commonly known gas laws of physics, this must increase the PRESSURE in your lungs. And if you dive with increased pressure in your lungs, then you are in effect doing the same type of dive a scuba diver does. I wonder if this could cause embolism problems if a person were to "pack" too much. If a diver goes down "under pressure" and stays down awhile his blood may adjust to the "packed" pressure. Then when he resurfaces to normal air pressure, has blood could embolize. Any comments?

[Erik]

Hi Mark, packing forces more air into your lungs than your diaphragm can take in. While there is a small extra amount of pressure near the last packs because of the resistance of the lungs to stretch, it is not substantial enough to cause an embolism at the surface. Also, you are mistaken about the pressure/volume relationship. The volume of the lungs increases greatly. You can watch and feel your ribcage stretch as you fill your lungs. This is in fact the main limiting factor- the flexibility of the rib cage, intercostals , etc, not the elasticity of the lungs.
If you pack your lungs as full as possible, it will be slightly uncomfortable. As soon as you dive,usually at 3 metres or so, the pressure of the water begins to collapse the lungs, and the discomfort dissapears. It does not matter what depth you go to; let's say 30 metres. At this depth , your lungs are now about the size of a cantaloupe. When you reascend, there will not be more air in your lungs than when you began the dive, so there is no possibility of embolism (air into the circulatory system or subcataneously).
Cheers,
Erik Y.

[Crispin]

Erik,

I recently ruptured some of my diapragm muscles (some of the fibres within the muscle) by packing too much - a tad painful...

[Erik]

Ouch, that's gotta hurt! Hope you're healed up. I have never heard of evidence that one could break the lung barrier by packing, and I think that Crispins experience shows that. If muscles and tendons tear first, then I don't think there's much possibility of lung tear.
Cheers,
Erik Y.

[Crispin]

One of Umbertos guys tore some part of his lung packing I believe. In my humble opinion packing can be both useful and dangerous. Kirk Krack reckons on a gain of around 1.5 - 2 litres if you are proficient at it, I personally am sticking to around 7 or 8 very quick packs to get around a litre (ish) in whereas before i was packing around 15 - 20 times after my last inhalation, this made me feel extremely uncomfortable for a very short period of time (till around 5m depth) till volume decreased enough to relieve the discomfort.....

I guess the moral of the story (for me anyway) is: Travel light - i.e. don't pack too much....

[Erik]

Hi Crispin....I stand corrected on that. That's the first I've heard of a lung tear from packing. I pack 50 or 60 times. I watched Eric Fattah pack 70 times through a snorkel. I believe Eric said he gets an extra 3 litres that way.
I think it's a matter of working up to it, just like any stretching of hamstrings or lower back tendons and muscles.
For divers who are not attempting anything really deep, then heavy packing is not neccesary, but is still helpful. Deep divers use packing primarily for deep equalisation, but the extra O2 helps as well, despite the time it takes to pack at the surface.
I would say for anyone using packing to give themselves time to let their lungs, tendons, and muscles adapt over time to the stretching.
Cheers,
Erik Y.

[Pekka]

Hi Erik how long does it take you to pack 50 times?
I pack sometimes but only for a 3-6 times it seems to consume time and precious oxygene nore than it is good for when actually diveing?
I can pack with and without snorkel, but when packing snorkel in my mouth one pack is smaller than doing it without snorkel. is there any special technique to pack with snorkel?

[Erik]

Hi Pekka, it takes me around 25 to 30 seconds to fully pack. I can't pack through a snorkel, which pisses me off a bit. I am going to make a concerted effort to learn though. My packs are reasonable sized ones, but not as efficient as Kirk Krack's for instance. I think he packs about 20 to 25 times, but he is very efficient with them. Eric F. packs through a snorkel, around 70 times. Tom Lightfoot also packs with a snorkel.
The evidence I have seen shows that there is an oxygen benefit to packing. The time it takes is not as significant as the time you gain. If you pack heavy though, you must dive to a depth that will compress your lungs enough that there is not a great effort to hold the air in.
For rec diving to 20 metres, I pack around 20 times.
Hope that helps,
Erik Y.