Nitrox, Skin Bends and Cozumel

[michael-fisch]

What ever happened to surface decompression? I continue to breathe the O2 that I started breathing at 20' for about 10-15 minutes on the surface. Also learned that the maximum amount of bubbles found on doppler usually shows up 30-45 minutes after your ascent.
A good idea would be to get back on the boat, sitdown and drink as close to a quart of any uncarbonated non caffeine drink quickly while doing no exercise. Drinks containing alcohol, although widening your veins, also drop your blood pressure so are not a good idea.
The very worst thing you can do to yourself is haul your gear from the boat back to the diveshop within 90 minutes of surfacing while your body is working like a shook up Pepsi can. If you don't get skin bends doing that, remember it wasn't your fault that you didn't get a hit.
Multiple dives, closely spaced over many days, also results in a disproportionate number of hits, in my case it took weeks to relearn how to walk after 8 decodives involving at least 30 minutes of O2 deco each within a time frame of 76 hrs, followed by helicopter flight - 4hrs intensive care, another helicopter flight followed by a TT6 with 3hrs of O2 extensions, and 2 TT5s.
Learned that trying to convince ER and Intensive Care Physicians that the only treatment for what I've got is a hyperbaric chamber is very difficult unless one of your buddies is armed and demonstrating a willingness to use it.

Michael

 

[ljwillia]

Either of y'all know that not climbing the ladder with gear helps, or about the "silent safety stop"...?

Ok, I don't buy that one, either. I don't know what all caused Lynn's near-hit, and I hope she never has another similar scare. Diving nitrox on air settings or diving a more conservative puter or puter setting can be a misunderstood buffer, like 55 mph driving is safer than 70 mph driving - which is great for gas mileage but not a guarantee of safety. If you want to add buffers, cool - but ignoring the other safe practices minimizes those.

I have not heard of a silent safety stop. I did a google search but didn't find anything. Can you explain?

I think when the thread was moved it broke my notifications. I just realized there are a lot of responses to this.

What caused my hit? I've thought about this quite often. I don't think it was entirely "undeserved". Tired from airline travel and a very early morning. Probably did not hydrate well. Most importantly, I dove close to limits. I didn't think so at the time, but reviewing my computer I was complacent. Another factor that I will never repeat was deference to my dive master. We were doing 2 dives/day close to the same depth. I knew I should have objected but made the all to common assumption "He knows better than me. He's been doing this longer".

I also thought my computer (purchased my first year of diving) was conservative. Turns out, not so much. Unfortunately I can't change the algorithm but I can dive more conservatively.

Thanks to everyone on this thread. It has been a real education!

 

[DandyDon]

I have not heard of a silent safety stop. I did a google search but didn't find anything. Can you explain?

Effortlessly floating for a minute or more after surfacing as your body hits its peak in offgassing.

 

[JamesBon92007]

Another factor that I will never repeat was deference to my dive master. We were doing 2 dives/day close to the same depth. I knew I should have objected but made the all to common assumption "He knows better than me. He's been doing this longer".

Recently on a trip to Cozumel the DM said "anyone not diving with a computer just stay with me." That might work quite well if everything and everyone was equal. At one point I noticed, toward the end of the dive, that he was about 10 feet shallower than the rest of the group because he was leading and the bottom was sloping upward. I think the right answer is to watch out for yourself.

 

[Jay]

2. Is there any reason to be concerned about the depth limit on a Nitrox mix?!

I didn't notice a good answer for this and have also had this question for a while so I made this thread: OxTox (CNS) on Nitrox - what if you briefly exceed MOD significantly.

 

[leadduck]

From my post in another thread...

"This past summer, I worked 50-60 hrs/week the 2 months before my annual Cozumel dive trip to get my workload in order. The day before my flight, I picked up a college friend at the airport and we had dinner with a few other buddies about an hour away. Got home around 9:00PM, finished packing and got to bed about 11:00PM. Woke at 2:00AM to drive to the airport and catch my flight (Friday). Arrived in Coz about 12:30PM and had booked a refresher dive for that afternoon.

Saturday: 2 AM dives and a night dive
Sunday: 2 AM dives
Monday: 2 AM dives

Had some knee issues before the trip and it was bothering me that day. Had some trouble getting off the boat and I sat on the dock to rest for a minute. 10 minutes later, I realized something was very wrong. Had another guest call the manager who called an ambulance and I spent the next week doing 7 chamber rides for Type II DCS.

In retrospect, there were several factors that caused the illness even though I was diving Nitrox on an air setting on my computer and was well within NDL on every dive. Slow ascent rate with a minimum 15ft/5 min safety stop (usually longer).

Stress from a large workload before my trip
Little/no rest immediately before my flight
Dehydration (No alcohol but I didn't drink enough water)
Overweight/out of shape (My knee issue kept me out of the gym for about 6 months and I had gained almost 30lbs - probably stress eating was a factor also)
Trying to pack as many dives as possible in a short amount of time

Lesson learned - vacation is for relaxing. Don't try to do too much. Drink much more water than you are used to. Stay in shape with a regular exercise program. Don't stress myself out immediately before the trip."

IMO - the last several factors I listed had a greater effect/cause with regards to my DCS than were offset by diving Nitrox with my computer set to "Air".

Did your physician bring up the topic of a PFO? Severe undeserved type II DCS after an uneventful benign NDL dive could also be related to a PFO combined with exertion, coughing, sneezing, Valsalva maneuver, ...

 

[krbailey]

Did your physician bring up the topic of a PFO? Severe undeserved type II DCS after an uneventful benign NDL dive could also be related to a PFO combined with exertion, coughing, sneezing, Valsalva maneuver, ...

I brought the topic up with the doctors at the hyperbaric chamber. They didn't think it was likely. Subsequently, I went to my primary care physician back in the States who scheduled a test (echocardiogram, I think?). No indications of PFO.