Ultrasound treatment for DCS

[Charlie99]

I recently stumbled across a US patent whose abstract is

Decompression sickness in human patients is treated by administering to the patient in the region affected by decompression sickness ultrasound energy having a frequency in the range of 1 to 15 MHz in an amount and time sufficient to alleviate the symptoms of decompression sickness.

ref: Patent 6,361,510

Has anybody heard of any further development of this technique? Any further studies to confirm the claims of this patent ---- that a portable ultrasound generator can be used to break up the bubbles of DCS?

Since the US patent was issued in 2002 I'm surprised it hasn't been commercialized if the medical science behind it is valid.

Charlie Allen

 

[DocVikingo]

Hi Charlie,

The totality of scientific support for the device adduced in that patient application is:

"10 living shrimps are placed in a compression chamber where a 40% pressure reduction with respect to the atmosphere is done in 5 minutes. The formation of gaseous bubbles under their shells is visible which, after sonication with a suitable apparatus, disappear." (Daniels S, Estaugh K C, Paton W D M, Smith E B, Micronuclei and bubbles formation: a quantitative study using the common shrimps, crangon cragnon. In Bachrach A J, Matzen M M: Underwaterphysiology VIII. Bethesda, Undersea Medical Society, 1984).

I am not aware of any research on this hypothesis using human subjects.

I suspect that Dr Deco will have something to add and I much doubt it will be encouraging.

Regards,

DocVikingo

 

[Dr Deco]

Hi readers:

I will return to this in a couple of hours. This device has more errors than an early Mets game.

MRP

 

[Thalassamania]

Interesting idea, if the clotting system was not involved and if you could see where a bubble was blocking or pressing it might work, and if "ifs" were nickels we'd all be rich.

 

[JahJahwarrior]

Yeah, the science behind this doesn't seem to be ultra-sound.

 

[MookieMoose]

Some more science may be on its way. I have a grant application pending at the moment to investigate high-power ultrasound in conjunction with some other therapies to treat severe DCS. Since I have a lot of money riding on this I can't really say any more at the moment.

Cam

 

[Charlie99]

Some more science may be on its way. I have a grant application pending at the moment to investigate high-power ultrasound in conjunction with some other therapies to treat severe DCS. <emphasis added>

Interesting. The patent read more as if the ultrasound treatment was targeted as minor joint bend sort of problems, in much the same way that surface O2 is used to treat and limit damage from DCS while transporting the diver to a hyperbaric chamber. Of course, there's no reason that ultrasound couldn't be used in conjuction with recompression .........

 

[Dr Deco]

Hello Charlie:

I have had more time to look this and it appears not to be as “weird” as I initially thought. I am doubtful if it can do what the applicants desire, however. Their description of the bubbles in the shrimp (mimicking an experiment of Steven Daniels et al.) is very sketchy - to say the least.

Bubble Breakup

The desire to “break bubbles” is predicated on studies with microencapsulated bubbles ( = micro eggshells containing gas). The destruction is not desired because stability is lost and lifetime decreased. This is true only in an under saturated fluid. [In some cases, encapsulate destruction is desired because it destroys undesired tissue - a different matter.]

Bubbles disrupted in a gas-supersaturated fluid will grow again. Together they might be somewhat smaller in total volume because of the Laplace pressure (somewhat like a miniature hyperbaric chamber.) This would not amount to a great deal.

I doubt that this method would be of great utility for pain-only DCS (‘bends”).

Restored Perfusion

If bubbles could be broken in a capillary, perfusion might be restored. Restoration of blood flow would be valuable, since any medications administered by the circulatory route do not reach areas of no perfusion. This includes oxygen (except by diffusion). Circulatory bubbles might be dislodged since “adhesion pressure” is proportional to the bubble length. Reperfusion naturally starts dissolved nitrogen washout.

This could be of utility in treating spinal cord DCS.

Rectified Diffusion

Generally, ultrasound is thought to “pump up” gas bubbles by the method of rectified diffusion. This was thought to involve different fluxes based on surface area but now is thought to involve stirring effects in the surrounding fluid. Methods to visualize bubbles used this rectification. (Rubissow GJ, Mackay RS. Ultrasonic imaging of in vivo bubbles in decompression sickness. Ultrasonics. 1971 Oct;9(4):225-34.)

Dr Deco :doctor:


The next class in Decompression Physiology for 2007 is August 18-19. :1book:
This class is at the USC campus in Los Angeles.
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[DocVikingo]

Hi Charlie, ...I suspect that Dr Deco will have something to add and I much doubt it will be encouraging.

Regards,

DocVikingo