Any risk from PFO test?

[Dr Deco]

Dear Paul:

Erect vs. Horizontal on the Boat

I did not initially note that there was apparent confusion in my reply. I was commenting on body position when the diver has returned to the boat and climbing the ladder or during the surface interval. Here, blood pools and Valsalva maneuvers are affected by gravity.

Position in the Water

Apparently the initial question also concerned body position during the deco stop. I missed that part.

When in the water, the hydrostatic gradient in the body is compensated by the external water pressure. There is no increase in augmentation of rebound flow when recumbent vs. erect in this situation – as you stated.

Since blood flow is not as influenced by venous pressure as it is by the muscle pump (moving the arms and legs during the stop), I doubt that the horizontal position is a big contributor to washout. While we have not yet measured "the position effect" at NASA (in space, everyone is recumbent), we do not put much emphasis on position as an augmenter of washout; we rely instead on muscle activity through exercise.

Dr Deco :doctor:

 

[bluebanded goby]

Thanks to Dr. Deco for the clarification re position during safety stops.

Also thanks to Paul for the mention of Raynaud's phenomenon. (I wonder what the protocol is in the medical world for determining whether the thing they name after you is a "phenomenon" vs. a "syndrome"? ;-)

Just to say a bit more about my situation in response to Paul's interest, I'm of the belief that I probably have a couple of different causes of neuropathies. One set of sensations/pains appear and move around in my hands and arms, and sometimes up to my neck and head. These occur and remit during periods of time when I haven't been scuba diving for months. They also remit when I put a cold pack on my neck. This suggests strongly to me that I have a neck injury that is responsible for the pains and sensations. I note that five years ago I had a neck whiplash injury (Dr. Deco will be interested to know that it occurred while driving down A1A in Cocoa Beach while attending an ELV launch) that took quite a while to heal. The hyperbaric doctor has recommended a head/neck MRI to look for a lesion. My HMO doctor feels that an MRI is "overkill" and authorized a neck X-ray instead. If you have any opinions about the relative merits/sensitivities of MRI's vs. X-rays for a situation like this, I'd be very interested.

As a secondary issue, during one examination of me last year, the hyperbaric doctor noticed that I have a detectable insensitivity to vibration in my feet. He suggested at the time that I be seen by a neurologist. I saw the head of neurology at my HMO hospital, who examined me briefly and said, essentially, "Yes, you have a certain amount of insensitivity in the nerves in your feet, but you don't have diabetes or risk factors for it, which would be the main thing we'd be concerned about. So we'll just take this as a benchmark and track it." The hyperbaric doc noted this insensitivity again while examining me recently, and suggested several blood tests to look for other causes (RPR, Hep B, HIV, folate, B12, heavy metal screen, thyroid studies). My HMO family doc again felt that all this was overkill, but arranged to have most or all of these done, and they're all coming up negative so far. Although I have occasional very faint sensations in my feet, and an interesting "ghost" sensation in one calf (a small patch of skin sometimes feels like a hot liquid has been squirted on when there is no reason for this sensation; usually goes away in a few minutes), the lower-body neuropathies haven't been issues during diving.

So that's a bit more background. I figure I'll try to run it to ground as much as possible between the hyperbaric doctor and HMO resources, then figure out a long-term plan. In the meantime I've developed quite an affection for freediving . ;-)

 

[The Iceni]

Yes, lets see what your own doctors say.

 

[bluebanded goby]

Paul: "Yes, lets see what your own doctors say."

Roger that.

One last question, though, if you or any other M.D.s here might have some comment. If a patient came to you with hand/arm/shoulder sensations and pains that appeared to be related to an issue with the neck, which test would you prefer to look for a lesion: an MRI, or an X-ray? How much more sensitive might one be than the other?

Thanks again for all the help on this.

 

[The Iceni]

bluebanded goby once bubbled...
One set of sensations/pains appear and move around in my hands and arms, and sometimes up to my neck and head. These occur and remit during periods of time when I haven't been scuba diving for months. They also remit when I put a cold pack on my neck. This suggests strongly to me that I have a neck injury that is responsible for the pains and sensations. I note that five years ago I had a neck whiplash injury.

Ah! I used to act as an expert witness/examiner in personal injury claims the majority of which where long term problems consequential to "whiplash" injuries, mostly caused by rear-end shunts.

I got bored with it! (and the money was not that great either)

X-rays are cheap and cheeful but show only changes in bone, such as fractures, arthritic erosions or sclerosis; or possibly a narrowing of the vertebral disc space.

An MRI is very expensive but it is a much more sensitive imaging technique and will show all bone and soft tissues including the disruption to the disc (such as a prolapse) which may have caused the narrowing of the disc space seen on the original X-ray.

So? examination, X-rays and blood tests first.

MRI later but only if needed.

Hope this is useful BB G.