A few entries ago I introduced you to the Aura sealing sleeve from Evolution Liners. It worked very well for the one patient that we had a chance to try it on. But we just tried to order another one and Craig told us he had to take it off the market due to patent issues. Too bad, because it was unique and Craig put a lot of time into it, but hopefully the parties involved can reach an agreeable arrangment so that amputees will be able to benefit from this device, and at the same time everyone gets treated fairly.

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.

There was an excellent set of questions posted by a colleague on the O and P listserv. I will reprint  them here and comment with my initials on each question:

 1. What sleeves have you found to be the best? Obviously, the sleeves tend to be one of the weakest points of the system, and I'm wondering which sleeves have had the greatest durability in actual practice, rather than just theory. I've had patients using the OWW Alpha Flex sleeve, but they haven't lasted longer than their warranty period yet.

JB: For transfemoral, flexiblity is unimportant so resitance to wear, tear, and puncture is key. I have has good success with the Harmony sleeve or its equivalent.  For transtibial, the ALPS Easy Sleeve or its equivalent has worked well.

2. Which of the electronic pumps do you prefer, and why? I got disgusted with the harmony ePulse, due to my having to send nearly every one of them back, but I've heard it's been retooled. I've only used two limblogics, and I wonder how well they do, and how reliable they are.

JB: I have heard no complaints from any pump other than the ePulse, which did not work. I have not tried it lately either. DAW has a new one which looks promising and attaches around the pylon resulting in no added build height.

 3. What do you think of the Harmony mechanical pump in comparison to the electronic ones?

JB: The harmony is an excellent choice if there is suffient room for it with the desired componentry.  

4. Is there some other elevated vacuum suspension mechanism you may know of that you prefer?

JB: Evolution has recently released some exciting componentry. One is a distal attachment plate with a built in resevoir for vacuum, and the other is a sealing liner that allows the prosthetist to decide on the vertical location of the seal  on the liner. They also offer custom made liners fro elevated vacuum.

5. Does your answer differ between AK and BK patients, and why?

JB: Choice of suspension mechanism certainly depends on AK and BK, due to the often limited space available bewteen the AK distal socket and the knee. Almost any system can be used, but it is much less cumbersome if the pump fits between socket and knee.  

6. Especially regarding BK patients, how effective have you found it for them vs other types of suspension?

JB: Harmony offers the advantage of no chargin required, very simple to use, and the built in vertical shock absorber.

One attendee reported several interesting sound bytes or bites from the seminar. He recalled that Andy from OWW said they have had good results from Alpha Liners when used with the Limb Logic on transtibial residual limbs;  as for tranfemoral, he said they don't encourage using elevated vacuum for transfemoral. He also said the more vacuum the better unless there are unusual skin issues. He likes a minimum of 14 mm Hg for good results.

Since it is my blog, I get to be the first reponder.  As for transfemoral, if people are happy with thier less complicated sytems, I agree that there is no need to change to EV, but it is sure nice to have that tool when you need more stability, better suspension, less volumetic instability, and more hip range of motion.  

Mechanical hand vacuum pumps can be used to elevate the vacuum for testing purposes in the prosthetist's office as well as by patients for applying thier prosthesis (if the socket  was designed with that in mind).

We have tried a number of pumps and by far the best is the Craftsman all metal brake bleeding pump from Sears. It is much more durable than the plastic version. Inexpensive. and easy to find at Sears. It has a good guage, and it pumps up higher than any of the other pumps. And Craftsman has a good warrantee to boot.

It is the heaviest of the hand pumps so it  may not be appropriate for patients to carry around. But if a lighter pump is preferred, I would still recommend also having the all metal pump for use in the office or at home. It is so much better.

Elevated vacuum sockets use gel liners as a skin interface. One of the first decisions required when fitting elevated vacuum is which liner?   I have my answer and, as always, I invite others to share their experiences and opinions.  

I just recieved another call asking me to clarify the recommended height of trimlines on an elevated vacuum transfemoral socket. In the phone call the prosthetist said he asked a number of prosthetists and the responses were "all over the map".

I would like to first argue that it is incorrect to use the term "sub-ischial sockets" when referring to elevated vacuum transfemoral prostheses. One main difference between elevated vacuum and most other designs is that other designs such as the quad socket have specifically designed trimlines. In the case of elevated vacuum, the height is just as critical, but it depends on the individual patient and residual limb characterists. In one case the proper height is ischial level and in another it is 1" below the ischium.Keep in mind that trimlines affect stability, support, and suspension, but also affect comfort and range of motion. Too low, and the socket will not work; too high and there is unecssary restriction and discomfort.

There is no scientific way to determine the exact location, but in my experience there is no reason to go proximal to the ischium even on the short limbs.On short limbs the proximal brim helps to maintain a good seal between the inner gel liner and the sealing sleeve which is taped to the inner vacuum cap. 

On long residual limbs, I begin at ischial level and  then check for hip joint range of motion. If there is any restriction of range of motion even in the extreme limits, I lower the trimlines. Once the socket is comfortable with full range of motion, I do not lower the trimlines any further. I then fabricate the final socket with a flexible proximal brim.

I welcome other input from "the map".