I've been waffling about posting this but talking with another tech diver who's also had a DCS episode, it seems like we generally don't talk about these things, so I'll just file this under "maybe the purpose in one's life is to serve as a warning to others."
So this is basically the story...last October a group of us headed to Key Largo for some wreck diving. And just for background, I had about 700 total dives since 1984, 200 CCR dives and about 250 hours on the unit including trimix to 200' with no issues. On day one, we dove the Spiegel Grove, all of us on CCR (air Dil) with 2x 40cf BO bottles, and had a nice dive with max 134' for 95 minutes with about 20 minutes of deco. Second day was a dive on the Duane, 121' for 111 minutes, exact same average depth (77') as the previous day, with a couple more minutes deco, with all deco cleared normally. From here it gets interesting.
After 15-20 minutes of climbing the ladder, my stomach felt off, like a case of motion sickness. Gear was stored for the ride back and I basically just found a place to rest while the nausea continued for the 50 minutes back to the dock. Like most divers, I figured it was just a case of motion sickness (which I don't normally get). DCS really didn't cross my mind as I had no joint pain or tingling/numbness. By the time we got back, I was fairly weak with the nausea. My buddies got my gear off the boat and I got on some 50% O2 to see of that helped, but unfortunately it didn't. By the time we were back to the shop, we swapped out the 50% for 100%, and by that time I had a little tingling in the right thumb. Time to head to the medical shop, which was a 20 minute drive.
We pulled up at the ER for Mariners Baptist in Key Largo and within 5 minutes, the staff had me off to an exam room, on to medical O2, plugged in with IVs, obligatory Covid test, blood draw and chest X-Ray. We also noticed some skin marbling in the trunk and chest region at this time, and within about 20 minutes we had a hyperbaric doc on hand with a call out to the chamber technician. Another 30 minutes or so and I was rolling into the chamber for a Table 6 session.
The chamber itself wasn't too bad, they had a TV showing through a window with some sound-powered headsets, while the O2 mask is strapped to your noggin. I've been in a chamber a long time ago for USAF physiological training so this wasn't new, but after a couple cycles of 20 on - 5 off for pure O2 under pressure, you get tired of breathing out against the positive pressure, and after 5+ hours, you're pretty beat. Soon after starting, I was actually feeling much better, nausea was going away (as this was now late afternoon, I was hungry!), rash was disappearing, and thumb tingling was gone. The folks had provided a turkey sandwich and a bunch of water, which was well needed. Overall, I had a couple liters of IV so I was certainly dehydrated. After 5 hours, I was released and advised to watch for other symptoms and no diving for a while, and no flying for 72 hours (no problem, that worked with my schedule). The next day was fine, but I was basically just fatigued! With the chamber session, I had about 7 hours under pressure that day.
The biggest question was what happened; dives weren't particularly aggressive, warm water, and not strenuous. I won't say it was an undeserved hit, but initially, it was of unknown origin. I was a bit dehydrated, coming from Pacific Northwest, the 90 degrees and 90% humidity had us sweating a lot, and I just didn't have enough water. Once back home I checked in with the local hyperbaric doc (Doc Jim Holm), and due to the skin bends and nausea, Doc thought a PFO test was in order, but I was cleared back for conservative diving. After scheduling, I had a transthoracic doppler bubble check done and that had some interesting results. Yep, I was getting a small amount of right to left shunting, but it was delayed. After some further discussions with Pulmonary medicine, we agreed to do a chest CT scan to check for and arterial-venous malformation (AVM). The delay in bubbles indicates presence of the AVM, and if they can find it, it can potentially be fixed. Unfortunately, CT didn't identify an AVM, so the consensus it that it's microscopic, and thus no fix available.
So this was actually a DCI incident with the nausea, tingling, and rash, and like a lot of DCS, I had a theory. We dove with 2 40cf bailout bottles, and on first day, we handed up the bottles. On second day, we climbed the ladder with the extra 40+ pounds of bottles. In a PFO test, you basically hold breath and strain, I'm convinced that I had somehow strained a bit climbing the ladder, and it didn't take much, and timing of symptom onset seems to support this. I've climbed ladders with all the junk before, no issues in years of diving, but somehow this triggered a small shunt through an unknown AVM.
Conclusion: I'm fortunate that a first rate chamber was available and staffed within a short drive, and for follow-ups, our local Hyperbaric/Cardio/Pulmonary at Seattle Virginia Mason is well versed on diving issues. From Doc Doug Ebersole's presentation on Diving for Older Divers, I'm probably classified as one of those. I'll keep diving CCR as it does provide for increased PPO2, but I'm watching SfGF more. I surfaced with 69% on the incident dive, which is well aligned with other deco dives I've done. Previous GF was 65/80, but I've pulled that back to 55/70, and plan to further extend time at end of deco. I probably came up from last deco stop at 20' a little quicker than normal, so that's something to watch as well. I have about 30 dives since returning home, but haven't worked back into deco dives quite yet. So far, no recurring issues.
If there's one thing this incident shows, it's that you can think you're doing everything correctly, or as you've been doing for years, and still be impacted. And they always tell you don't strain, exercise, or lift after diving, this is why. Oh…and make sure you keep DAN up to date! You just never know when you'll need that! available.
