Type I Bends Hit in Chuuk

[Kevrumbo]

Note: Review sticky first before replying. Cynical non-objective, irrational, post-hoc, and ad hominem attacks will not be tolerated. . .

Overview, 12 Oct 2008:
DCS type I bends hit, left Shoulder/Upper Arm and Elbow suffered after non-optimal decompression profile time spent at depth. Ratio Deco 1:1 Schedule was recalculated at depth to account for an elective extension of Bottom Time, from originally 30 minutes to 50 minutes at an average depth of 48m/160'. Upon surfacing, the decompression profile was later determined to be 20 minutes too short (approximately 10min short at the Nitrox 50 segment from 21m/70 to 9m/30' and 10min short at the Oxygen Stop from 6m/20 to the surface). Deep Stop profile times on backgas turned out to be adequate and performed correctly. Backgas was Air in Double AL80's; Stage AL80 with Air; Deco gases were Nitrox 50 in a full AL80 and Oxygen in a half-full AL63. Original Depth & Bottom Time was planned for 54m/180 and 30 minutes respectively

This was my fourth career non-overhead Deep Air Dive on the San Francisco Maru, called the "million-dollar wreck" because of the amount of war material contained in her holds (Mines, Torpedoes, Aerial Bombs), and for three Tanks on her deck which are probably the most photographed deep wreck WWII fighting vehicle artifacts in the world. My Buddy and the rest of the group of three (two Open Circuit Divers and one on CCR) were going to be experiencing the effects of Deep Air diving beyond 39m/130 for the first time, so I initially planned to stay only on the forward deck areas where the Tanks were, eschewing the Grand Tour circumnavigating the deck from stem to stern. The bottom profile was conservatively planned for 54m/180 to account for my Buddy's higher SCR rate (21L/min or .75cf/min) using Ratio Deco 1:2 Schedule. I delegated the captaining of the Deco Profile to my Buddy. [Lesson Learned: since I had the most experience on this particular Deep Air dive, I should have been in control of the Deco Profile and not given the responsibility to my Buddy.]

Under partly sunny skies with gathering clouds, we dropped on a permanent surface buoy/mooring line, and finned over a distance of 15yds to the wreck's bow area. After resting a few minutes at the bow gun, we proceeded to the Tanks and then below to inspect the forward holds crammed full with ordnance & ammunition (depth range 45m/150 to a max of 51m/170')

Upon nearing the 30min Bottom Time mark, I looked at my buddy just as he exhausts his AL80 Stage and switches to his long-hose & Backgas Supply. Hmmm . . .wow I say to myself: He's relaxed & has a great breathing DCR (Depth Consumption Rate) going on. We kept a constant depth of around 45m/150 for the elapsed 30 minutes so far, and were just basically floating neutrally buoyant with very little finning while exploring the forward deck area . . .so I made the decision to extend the Bottom Time from 30min to 50min, or hitting MGR/Rock Bottom whichever came earlier.

I wrote in my wetnotes and communicated to my Buddy, "Re-calculate Ratio Deco 1:1 for 160 . . ." My Buddy signaled & acknowledged okay.
[Lessons Learned: 1) An Error of Omission: I should'vd wrote, "Re-calculate Ratio Deco 1:1 for 160 with Bottom Time 50 minutes. 2) An Error of Commission: Don't place a burden of re-calculating an entire Deco Profile on both yourself and your Buddy especially when you're both narced out-of-your-mind on Deep Air at max depth. At most, just figure out the Deep Stops to perform by looking at your WKPP Table in your wetnotes, then get to your Eanx 50 deco gas switch at 21m/70' and then as the narcosis eases, finally start re-calculating the required profile times needed on your Nitrox 50 and subsequent Oxygen Deco Stops. Better still, use a tech computer with a similar algorithm to your calculated decompression profile for back-up]

I exhausted my AL80 Stage bottle at around the 35min mark, and gave the Leader of the other group the sign, "Watch Me --Switching to Backgas", test purged my primary reg, breathed it and exchanged okay signs. I looked around for my Buddy and saw him finning towards the bow and caught up with him, both of us exchanging okay signals. Looking back, we lost sight of the others, so we finned back toward the bridge area almost to the aft facing end of the superstructure; they were long gone, probably exploring the engine room or aft cargo holds. I then signaled to my Buddy that we return to the bow at depth 45m/150'. Hopefully we would rendezvous with the other group before starting ascent.

50 minutes elapsed time was approaching and I was nearing MGR (Minimum Gas Reserve); my Buddy was past MGR and approaching Rock Bottom Limit (2000psi and 1500psi respectively on backgas), and still no sign of the other Group . . .I called ascent to Deco 36m/120 and made the pinky sign to my Buddy who emphatically signaled okay. We ascended up the forward mast.

Average Depth and Deep Stop Profile looked like this:
48m/160 50min
(ascent to 36m/120 @ 9m/min; 30'/min): 1.3min
36m/120 2min [75% Deep Stop]
33m/110 2min
30m/100 2min
27m/90 3min
24m/80 5min [50% Deep Stop]

(Note: at about the 33m/110 level of our Deep Stops, we noticed the other group signaling above us, as they had already started their deep stop deco sequence while swimming back from the aft cargo holds forward to the bow.)

And now, the Eanx 50 switch and the Fateful Blunder: I signaled seven minutes deco time. My buddy queried back, "Seven?" I signaled again definitely seven minutes. Buddy looks at me with a puzzled face; and this is where it all started to go wrong for me-- with the fist-to-forehead signal, I yielded and gave back control of the Deco Stops to my Buddy. He gets out his wetnotes and starts doing some scratch arithmetic, and then writes out a 4, 3, 3, 3, 4 minutes time sequence for the 21m/70 stop thru to the 9m/30 stop. [Lesson Learned: again I had the greater experience utilizing Ratio Deco on this particular dive and should have insisted on taking over lead and captaining the deco; I'm not quite sure why I conceded to this revised profile when it felt all wrong to me intuitively ("Deer in-the-Headlights Syndrome": you're overwhelmed cognitively and fail to act decisively, despite realizing an immediate threat to your safety.]

Nitrox 50 Segment revised profile was performed like this:
21m/70 4min (switch to Eanx 50)
18m/60 3min
15m/50 3min
12m/40 3min
9m/30 4min (or 2:2 with Backgas Break)

What I wanted to do was this:
21m/70 7min (switch to Eanx 50)
18m/60 6min
15m/50 6min
12m/40 6min
9m/30 7min (4:3 Backgas Break)

Or better yet, a S-Curve Sequence:
21m/70 9min (Eanx 50 switch)
18m/60 9min
15m/50 3min
12m/40 3min
9m/30 6min (3:3 Backgas Break)

So all in all for the Nitrox 50 Segment, only 17 to maybe 20 minutes total time was spent; it should have been at best an optimal 30 minutes!

 

[Kevrumbo]

By this time I now knew we were in trouble, and was praying we did enough time at the deep stops and at the sub-optimal Nitrox 50 segment to ward off a Type 2 Neuro or Spinal DCS Hit.

At the 6m/20 O2 switch, I was going to signal my Buddy to do a 30 minute Oxygen Segment, with the sequence 10:5:10:5 (i.e. 10min on O2:5min Backgas Break etc.) with an nice slow 1m/min or 3'/min ascent to surface on Oxygen. He immediately signs back at me a 12:6 sequence, so I think to myself, "Great . . .I'll just signal an additional 12 minute period on O2 after the 6 minute Backgas Break.

But after I shoot the SMB near the end of the 6 minute backgas break, he switches back to Oxygen and starts the slow ascent to the surface. Oh well I say to myself- guess we're both going for a Chamber Ride as soon as we get back to the dock. So then I start my ascent in my Buddy's wake. . .

. . . Only to shoot-up uncontrollably the last 3m/10 because of a large surface swell propelling me upward. I hit the surface in a maelstrom squall of pelting rain, 3-6' swells and low viz conditions. Luckily, the boatmen spotted all five divers and recovered us but with some difficulty. I held onto the boat ladder with my right arm while unclipping and handing up my stage & deco bottles with my left arm, all the while being slowly dragged in the water, as the boat driver kept the skiff from broaching into the swells. And I think it was this last uncontrolled ascent along with lifting my deco bottles up over the gunwale with my left arm; all that was the final straw-that-broke-the-camels-back. I started feeling the pain in my left shoulder about ten minutes into the boat ride back to the Dive Ops & Hotel Dock.

I looked at my Buddy and asked, "You feelin okay??" He replied, "Yeah . . .how 'bout you?" I just shook my head and mumbled something about a muscle strain from manipulating all those deco bottles at depth. Well, at least he wasn't experiencing any symptoms (and thankfully so for his sake; it was he and his wife's anniversary the next day!).

Started breathing the remainder of my Oxygen bottle before we reached the dock, and everyone now knew I had a problem. The shoulder discomfort was a constant 6 on a scale of 1-to-10, and the O2 was dulling the pain somewhat. I had a fleeting thought of possibly trying an In Water Recompression Table at 6m/20 (I wrote the Pyle In Water Treatment Table in my Wetnotes), but the continuing rain squall and rough surface conditions would have made that a dangerous endeavor.

After landing at the dock, I rinsed & put away all my gear as usual; all while breathing my O2 bottle, and continued in a 20min O2 and 5min air break pattern until dinner. I finally went to bed with the discomfort at a constant 5, took two Tylenol Caplets with the notion of continuing standard ambient surface O2 breathing in the morning and the whole day to further treat & cure the symptoms. [Lesson Learned: Go immediately to the Chamber for evaluation and probable recompression treatment, even if suffering from non-neurological/pain only symptoms which seem to respond favorably to surface Oxygen breathing. Those soft tissue & muscle bubbles will start to collect residual Nitrogen overnight and begin to grow again, as well as aggregating at the nerve ends and joint spaces around the affected area, possibly causing additional tissue & nerve damage.]

Woke up the next morning with a constant 6 pain, with intense stabbing impulses of +10 every few minutes (now I know why they call it the Bends; you literally double over in excruciating pain --when the spasms hit!!!). Even breathing Oxygen would not take the edge off the pain spasms. I waited too long, and should've gone to the Chamber on the evening beforehand, saving myself from the agony of the overt, classic and acute DCS type 1 symptoms. . .

Lastly, I made one last altruistic gesture . . .I decided to painfully hold-off treatment until my buddy group came back from their morning 60m/200 dive on the Aikoku Maru, with the hope that none of them would need to utilize the Chamber more urgently than my current malady (i.e somebody else suffering a more serious Type 2 Neuro/Spinal Hit or worse, a full-arrest AGE) . . .they all "appreciated" the gesture by shooting video of my journey to Truk's Hyperbaric Chamber, much to my chagrin. . .

Post Script: further related sequela (DVT, PE and continuing treatment in Honolulu) are posted in this thread.

 

[nereas]

This is not in the DIR section, although the issues are DIR issues.

First, this is why I avoid 10 ft stops, utilizing 20 ft with O2 or 15 ft with anything else instead. You just never know when a swell or wave is going to sweep you up from a 10 ft stop. In cave diving at a spring, a 10 ft stop is just an opportunity to watch the crayfishes, so no issues there. But the open ocean is different.

Another good rule is to say on the anchor or mooring line for deco. Especially if there is a current. But even so, sometimes drift deco is unavoidable.

This is also why I advocate doing your own deco, rather than debating with your buddy. I would have exhaused my O2 bottle at 20 ft if I though that was needed to fully decompress. I am surprised he was fine afterwards while you were not, but everyone is different, I suppose.

This is further why I prefer to use a technical dive computer, with deco capability and gas switches, rather than an in-your-head method. Just a personal preference. Not that a computer is always going to save you. Just that these tend to be conservative and they do not make mistakes, like the human brain can.

I have done a fair amount of EAN25 and air dives to 150 ft, so I think that is fine, when you have no other choice. As long as you are cognizant of the narcosis, and keep your dive plan simple, as you did. It's too bad that trimix is not available everywhere.

Sounds like you had fun though, even though you paid for it.

 

[Kevrumbo]

Yeah I paid for it all right --the DAN and Primary Health Insurance paperwork is just as painful and further motivation to not get bent again. . .

Another Lesson Learned: always make sure your primary carrier insurance contact information is up-to-date so you're not stuck with an initial $2000 Emergency Room bill on hospital discharge:shocked2:

 

[Ayisha]

Hey Kev,

Your buddy abandoned you when you made your gas switch and then argued about and reduced all your deco times. He then pretty much abandoned you in the final ascent as well. I'm sure that you felt that you had to follow to keep the team together, but he didn't seem to have much of a team or safety mentality. I don't know if this is a regular buddy, but I'd be very cautious about ever diving with him again, even on less demanding dives.

If you felt that you would be going for a chamber ride long before even that final part of the ascent, you have the right to demand that you spend more time doing deco. If you had enough gas, why not be sure that you're being safer and use it? No harm done in off-gassing more, but I know you know that. Sometimes it's hard to argue, especially u/w, and we tend to follow when we're in doubt. If you're pretty sure that the shortened stops are not going to cut it, demand that he stay with you until you're sure you're as safe as possible. Any reasonable buddy would allow you to finish your deco.

I hope that you don't have any residual difficulties.

 

[Kevrumbo]

No onus on the inexperienced dive buddy, Ayisha --he made a mistaken decision in hindsight that wasn't acted on and duly corrected by me at that particular moment in time, of which I passively accepted and am held culpable for.

He just happened to perform a profile which left no margin for error on ascent rates (and kudos to him for executing a slow controlled ascent to the surface, despite the rain squall) . . .which I unfortunately broke through.

 

[grazie42]

Not to "armchair" this too much but...
I can understand you yielding on the first 21m stop but you really should have spent the rest of it recalculating your obligation to make sure you had it right. Ascending from deco to the surface should never be done without prior communication in the team. Going to bed on a pain level of 6, after "shoddy" deco really isn´t a good idea.

But I know you knew that already so I can only whish you a full recovery...thank you for sharing, maybe it will help someone be more assertive on the next dive the deco doesen´t feel right or to get treatment faster...

 

[Kevrumbo]

Well grazie42 . . .going to the chamber meant a premature end to the dive vacation --and all diving for a month per Dr's orders (could've been worse though, eh?). The motivation was to try and treat the symptoms with oxygen to resolve the pain, and then continue diving for the remainder of the week. After all, "my buddy turned out okay" and was diving afterward (albeit at recreational depths and within NDL) --which was my rationalization at that time.

In retrospect, that was a very bad decision as well to delay Hyperbaric Oxygen Therapy (HBOT) as noted above (the Hyperbaric Doc's in Hawaii, and my Supervisor Karl Huggins at the Catalina Hyperbaric Chamber really reprimanded me hard for that one!). Even with resolution of symptoms just by breathing O2 at 1atm for a day, it still would have been risky & foolish to continue diving after such an injury, with potential pathological bubbles still residing in my circulatory system. . .

 

[drl]

Nice analysis. Thanks for sharing so we can all learn from it.

 

[Rick Murchison]

An interesting read.
Our (my little tech circle) approach to deep air is considerably different; I'll hit the high points for your consideration.
I'll start with this caveat: we don't dive deep air at all unless it's the only option to make the dive. The only thing worse than deep air is to not do the dive at all
(1) Narcosis is detrimental to sound thinking. We plan to avoid making decisions at depth - that is, we make the decisions on the surface, including contingencies. Pretty much every move is part of the plan (or one of the contingencies) before we ever hit the water, including plans for CRACTEMERS (CRitical ACTion EMERgencies). With the exception of emergencies, we do not accept on-the-fly deviations from the plan. No matter how tempting or how benign a plan change may seem at depth, we have an absolute proscription on that issue - plan changes will be made after the dive, on the surface, with the full benefit of our faculties and hindsight.
(2) Keep plans simple; keep goals conservative.
(3) Make abort criterea tight, clear and immutable.
(4) Everybody works out deco schedules independently (primary, lost gas and contingency). We compare schedules before the dive and decide on the team schedules before the dive. We plan a couple of extended bottom time schedules as contingencies. The only thing that would make us stay beyond a planned bottom time would be an emergency.
(5) I (this is just me) keep the Navy air tables "in my back pocket." Whatever flaws they may have, they can "forgive" all sorts of deep errors if you have enough gas to extend your shallow stops to meet them.
--
Another of my personal preferences/procedures - if I blow a shallow stop for whatever reason, I go back to it and stay there as long as I can stand it (at least five extra minutes), or until gas supply forces me to surface.
Rick