How Much Vacuum is Enough? Is More Better?

by Jon Batzdorff on Tuesday, June 29, 2010 5:56 AM

Yes, in most cases, more vacuum is better.

Some prosthetists have reported that too much vacuum in an elevated vacuum socket causes discomfort and "pulling" and too little fails to provide linkage between the socket and the residual limb. The argument goes that there is a "sweet spot" at around 10"Hg. One set of pump instructions even recommends "only enough to suspend the socket".  This is not a good reference since actually the the socket can be suspended with no vaccum at all using just the sealing sleeve. The goal is to achieve the best possible linkage, which is achieved with maximum possible vacuum.

Experience suggests that, just as in traditional suction sockets, discomfort and pulling occurs when there is lack of total contact or a lack of even socket pressures. If the fit of the socket is correct, the vacuum can be much higher and the linkage much better. I suggest that, if there is pulling and discomfort, check the socket fit distally BEFORE simply having the patient use less vacuum. The exceptions would be with invaginated and severe scarring and adhesions where vacuum may intially have to be reduced.

Comments

I think Jon may have meant 10 in hg not 10 mm hg or 254 mm hg

by Craig Mackenzie on Thursday, July 01, 2010 4:53 AM #

It has been my personal experience with elevated vacuum that more is better.I think that the issue is reduction of shear forces or pressure positive or negative as well as suspension.All are addressed if we can freeze the tissue in place by external pressure as well as the bony structure.The amount of compression should be commensurate to the type of tissue,oft or toned.The amount of pressure should be enough to keep blood circulating threw the residual limb while under pressure.the socket must fit the contour of the limb perfectly to avoid tissue pulling even while sitting.This is also the secret to keeping a susp. sleeve last longer than a day.The socket has to keep from webbing the sleeve when seated and smooth when standing.I use more than one layer of material to achieve this and have had very good results.Obviously there is a lot more to it, but less mods to the shape nis better.Forget P.T.B.type sockets there are useless with this system that kind of thinking only gets you in trouble when they feel pressure and you heat it up and push it out.I wear two below knee prosthesis and only will wear elevated vacuum because its the best we have available today.Bla Bla BLA sometimes I don't know when to shut up...

by William Bley C.O. on Friday, July 16, 2010 1:35 PM #

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