by John D. Perry, Ph.D.
When I invented the first electromyographic (EMG) pelvic muscle sensor as a Psychology graduate student in 1975 I quickly focused on making it a quality medical device. The "perfect sensor", I reasoned, would have these characteristics: It should...
1. To last forever it had to be made of a tough, safe, impervious plastic that could be repeatedly sterilized without degradation. My dentist turned me on to acrylic denture material; expensive, but able to withstand temperature changes, moisture changes, blueberry stains, and long contact with human skin. Pure silver electrodes were used because traditional silver-chloride plating eventually wears off. The acrylic bonded to electrodes like false teeth in a denture.
2. To work accurately with every patient, I had to devise longitudinal electrode strips-because patient's pelvic muscles are located a varying depths from the orifice. I tried disk and ring electrodes but they did not give repeatable measures from week to week, so progress could not be charted. The dumb-bell shape was created to ensure that the electrodes were automatically positioned in the same relative location on each insertion.
3. To preserve the patient's dignity, the sensor had to be self-inserted. While patients will tolerate medical invasions of their privacy, such activity does not put them in the best frame of mind to learn about their internal muscles. The dumb-bell shape and incorporated third ("reference") electrode made it possible for all but the most disabled to insert and remove their own sensor, without embarrasment or discomfort.
In the late 1970's the "Electronic Perineometer(tm)" was finally perfected and ready for its first wide-scale testing at an NYU laboratory. But the very week the experiments were to begin, Time magazine ran a cover story about the new threat of Herpes, and all the subjects called up to cancel! Gradually, researchers discovered that cold sterilization (as used by dentists and colo-rectal surgeons) was effective against Herpes, and EMG perineometer useage began to spread around the world.
But only a few years later AIDS was invented, and a new wave of resistance set in. We had created "the perfect sensor" that would "last forever" - and AIDS changed the rules of the game. Now perfection had to include an new element: "perfectly safe". In 1984 I began working with William Benton to develop a "single-user" version of the sensor. Our target was a $19.95 product that everyone could afford. When the first batch of 5,000 sensors arrived, I eagerly began to test them - only to discover that 50% of the first 100 failed electrical tests. Eventually four large shipping crates of sensors had to be destroyed.
Within two years we did get a working single-user sensor in production, but the manufacturing costs were more than triple the projected selling price. They eventually sold for $125 to $165, nearly 9 times our target. There was significant resistance to that price, since for the price of less than four single-user sensors the the therapist could buy a "reuseable" sensor, which they continued to do. However, most therapists were reluctant to invest in more than two or three reuseable sensors, and they were providing only "in office" biofeedback training.
Many behavioral therapists were pleased with what they considered the high success rate of biofeedback incontinence treatments, which were at least as good as surgery. Typically, in what we call "The NIA Model", after three to five office visits for biofeedback and four to eight weeks of unassisted home practice, patients achieved a 75-85 percent reduction in symptoms ("accidents"). The patients were pleased, since this meant going from two to four "pads" a day they could get by with a single pad all day. Unfortunately only 29% got rid of all their incontinence (summary of NIA reserach published during 1982-86). Impressive, but not impressive enough, I reasoned. If we could tighten up the protocol [see The Perry Protocol in this library] we should be able to achieve nearly 100% reduction, or actual "cure" of most patients.
Like other psychologists specializing in biofeedback for stress-related diseases, I had been providing home training biofeedback devices to all my patients - except my pelvic muscle patients! I began to study the work of Arnold Kegel, who had invented an air-pressure biofeedback device in the 1940s. I learned that all of Dr. Kegel's patients practiced their "Kegel Exercises" at home with the help of his "perineometer" device. So William Farrall and I designed a simplified, inexpensive EMG device, the "Personal Perineometer", for patients to practice at home.
In 1986 Lesley and I got a NIH SBIR grant to create and validate a new computerized version of the home trainer. In a study we reported at the 1988 Biofeedback Society of America convention, we were able to show a 98 percent cure rate, in an average of just four weeks, when patients were required to practice daily at home with EMG biofeedback every day. Every patient had their own sensor and their own EMG instrument for the entire duration of treatment. They also received massive doses of attention and support from the staff. [See "The Patient Hot Line" in this forum library.]
The experiment was a great success; we had proven that an intensive program of biofeedback-assisted pelvic muscle exercise brought much higher improvement rates than the "office-only" model developed by the NIA. The only problem was that the sensors we used cost $500 each, and the instruments nearly $1,000 each. In our research, we had used eight permanent sensors and eight home trainers, which limited us to treating eight patients at any one time; a $12,000 equipment investment that covered only seeing patients on one day a week. A full-time clinic would have required a $60,000 investment -- clearly not practical. Besides, such a clinic could only treat 48 patients a year, hardly a dent in the problem.
Obviously there are two alternative solutions to this problem. The one taken by most therapists is to reduce the therapy time and instrumentation, at the cost of outcomes. This is the approach taken by Smith et al in New Jersey; how many patients can be treated reasonably well in how short a time? Each patient received a Personal Perineometer home trainer to use, but only for the first week or two of therapy. From the perspective of public health planning, it makes good sense. But from the perspective of professional practice standards, it borders on unethical behavior. And sooner or later someone is going to get sued for it.
The alternative is to bring down the cost of instrumentation so that all patients can get the full therapy and, therefore, have their incontinence cured. First we had to lower the price of the single-user sensors. Under Self Regulation Systems' management, new molds and production techniques, together with greatly increased volume of sales, has allowed a 64% reduction, to a $59.95 selling price (in Qty. 5). Since the AVERAGE incontinent person spends about $18 each week on adult diapers (1988 PHS figures), the new sensors now cost less than a month's supply of diapers.
The second cost-saving measure was the institution of the National PerryMeter Home Trainer Rental Program. This began as a result of Mayo Clinic requests; they couldn't afford the cash outlay, but they had many patients, so they asked to rent home trainers. The program was a great success, and was taken over in 1992 by my "son-in-law" JK Hullett and his wife Kim in Dallas. (You can reach them at 1-800-JD-PERRY). Since the average patient only needs the home trainer for two months, it is possible for each patient to have one for about $5 a day, with no capital investment.
Several manufacturers have now started to produce small portable EMG devices with a variety of features ranging from low cost to clever data storage and downloading. The only downside is that demand for single user sensors has increased much more rapidly than SRS's manufacturing capacity, so many hundreds of therapists have simply been unable to obtain enough sensors to use. Some have resorted to surface patch electrodes while others have simply cut back on their incontinence practice. Fortunately for all, SRS was recently bought out by Boston-based Fasstech, which infused new money for new tooling, and SRS is expected to "catch up" with purchase requests sometime in July, 1995. It is ironic that our very success with EMG pelvic muscle biofeedback has made it so difficult for us to continue and for others to enter the field.
Copyright 1995 by John D. Perry, PhD
10/95 note: Sensor production got caught up in July, and they are now "off the shelf".