Completely normal nitrox dive to 25m gave me DCS

[Duke Dive Medicine]

I can confirm that the oxygen was administered by a head mask, which was poorly fitting. The time was less than 3.5 hours. I measured the ascent rates at 0.5 metres per minute, both from 18m to 9m and 9m to surface.

SFJCody,

From your description, there is little reason to suspect decompression sickness from the dive. Your symptoms resolved spontaneously and are more likely related to alternobaric vertigo or motion sickness.

However, the fact that you were using a poorly fitting oxygen mask on a hyperbaric treatment and are experiencing symptoms that COULD be decompression sickness is extremely concerning. Whatever they were treating you on, it wasn't a US Navy table 6. Regardless, if you were at 60 feet for longer than 60 minutes, you incurred a decompression obligation according to US Navy tables. A hyperbaric treatment table is designed with the assumption that the patient is on oxygen for the majority of the time and therefore isn't on-gassing nitrogen. However, if your mask didn't fit well it's possible that it was not delivering oxygen to you, in which case you were breathing chamber air and WERE on-gassing and are therefore at risk for DCS. I would certainly make the chamber crew aware that the mask does not fit well. I assume that you were using something that looks like one of these:

Amron International 450M BIBS Mask

Scott 801238 Series Oxygen BIBS Mask System - Hyperbaric Chamber Accessories

If so, these are demand masks and depend on a good seal against the user's face in order to deliver oxygen at the appropriate concentration. You should hear a hiss every time you breathe in, just as if you were using a scuba regulator. If you are still experiencing symptoms I recommend you follow up immediately with the chamber physician and ensure that he or she is aware that your mask was not fitting properly. Please feel free to PM or have your physician call our 24-hour emergency consult line at (919) 684-8111 if there are any questions.

Best regards,
DDM

 

[SFJCody]

Thanks everyone.

I underwent a further short 2.5 hour session today with significant improvement. I think I have identified the cause of the early negative results: the technician didn't properly open the oxygen valve. With each breath during the 20 minute o2 phase I was taking in significant amounts of n2 from the surrounding air. This time I made sure the valve was open properly (a rush, not a light hiss). Post treatment i noticed a substantial improvement on my condition compared to yesterday. No confusion, hands no longer feel arthritic. One further 2.5 hour session tomorrow. Hopefully that will eliminate any remaining bubbles.

 

[RyanT]

I'm seriously concerned that you as the patient were in charge of regulating O2 flow. This seems like a serious problem and indeed, in light of what you and Duke Diving Medicine said, could be the source of your problems.

 

[Duke Dive Medicine]

Ditto RyanT - that's very troubling. You could very well have been getting DCS during the treatment. I'm glad you figured out the problem - good lesson in self-advocacy. I hope your recovery continues uneventfully.

Best regards,
DDM

 

[tc]

Cody, what chamber are you being seen at? Very curious to see what table they're using there.

 

[SFJCody]

Now at a different facilty. Underwent table 6 alpha to 60m- seemingly complete recovery. But 16 hours later the symptoms have been creeping back. First the nausea, now joint aches and dizziness and clouded thinking.

Amateur physical speculation: could the bubbles be forming in a part of my body that doesn't have a strong connection to the nitrogen free blood I'm receiving? Should I take a vasodilator and do more intense exercise in the chamber? What about continuing to breathe o2 after each session, could that stop the symptoms returning? Concerned for my future.

 

[SFJCody]

More amateur physical speculation: I go to the gym a lot and often take a pretty workout supplement that includes a strong vasodilator. Could this be a contributing factor both to the hit and my inability to recover, in that my body is now so used to the vasodilator that on days I'm not using it my circulation isn't up to task? I've heard rumours that gym rat types seem to have a higher than expected rate of unjustified hits, could this be the cause?

 

[SFJCody]

Edit: pretty should read pre

 

[Kevrumbo]

Now at a different facilty. Underwent table 6 alpha to 60m- seemingly complete recovery. But 16 hours later the symptoms have been creeping back. First the nausea, now joint aches and dizziness and clouded thinking.

Amateur physical speculation: could the bubbles be forming in a part of my body that doesn't have a strong connection to the nitrogen free blood I'm receiving? Should I take a vasodilator and do more intense exercise in the chamber? What about continuing to breathe o2 after each session, could that stop the symptoms returning? Concerned for my future.

Can you tell us the medical justification from the attending hyperbaric physician at the different facility to now undergo a Treatment Table 6A???

 

[SFJCody]

Justification: continued symptoms including numbness, nausea, vertigo affecting the CNS.