Ventilator-Assisted Living©

Spring 1993, Vol. 7, No. 1

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Portable Positive Pressure Ventilators:
A History

Jerry Daniel, Vancouver, Washington

Today's positive pressure ventilator, with its rugged portability, minimum size, and smooth 12V battery operation, is the end product of two entrepreneurial engineers working near Boulder, Colorado, in the late 1970s. Both Richard Apple and Tommy Thompson were designing and manufacturing volume ventilators based upon a small, general purpose motor used for car window mechanisms.

This highly efficient little motor is shaped like a flying saucer, but does not have coils of wire like traditional motors. The gearbox is built into the compact design. Apple chose a version with grease in the gearbox, while Thompson used an oil-filled gearbox.

The two engineers were able to build ventilators that were lighter and smaller than any of the positive pressure ventilators made up to that time. There was a profound need for a truly portable ventilator to mount on electric wheelchairs or to use for other mobility applications. Hospital ventilators were too large and cumbersome for home care needs.

Thompson had produced a series of ventilators, both negative and positive pressure, some large and some small. His Bantam for positive pressure use was housed in a small Samsonite overnight suitcase. The packaging was truly small and rugged, but battery operation was limited by its vacuum cleaner blower motor and unstable rate motor technology. His first negative pressure unit, the Maxivent, has the power and stable rate control to drive any of the negative pressure enclosures used today. Because of the motor power required, it operates only on AC and is tabletop size. The Maxivent is still marketed today, but by Puritan-Bennett.

With the new motor, Thompson turned his attention to piston-type volume ventilation and put this new design into the same Samsonite suitcase which had been so popular. Now he had a unit that was ruggedly portable, stable in rate, and a miser in 12V battery operation.

Apple had worked for several home ventilator manufacturers in Colorado and felt he could produce a better positive pressure ventilator. In 1976 he went into his machine shop basement and designed his version of a truly compact and stable volume ventilator. He made several models and kept improving the design, finally coming up with his first production model, the Life Products No. 3 or LP3.

Apple made contact with Craig Hospital in Engelwood, Colorado, and received feedback from both patients and pulmonary medical professionals. He promoted the LP3 himself; product manufacturing was paid for by product sales no venture capital. The first LP3s sold for $2,300. But Apple was up against stiff competition because Thompson's suitcase ventilators were popular.

The LP3 used the minimum amount of aluminum for strength and lightweight, and was similar to the Maxivent in performance and battery operation, but it had one feature that made it more user friendly. Apple designed a unique electromechanical system for changing the length of the piston stroke while the machine was operating, actuated by pressing on a toggle switch until the desired volume was seen on an indicator. The volume change on the Thompson units was done by holding down a spring tab while rotating a knob and had to be done with the machine off.

The competition between Thompson and Apple was going strong. There was a need to provide setup modes that were closer to the options on hospital units such as the MA-1. The LP3 and early Thompson units operated only in continuous cycle with a 1:1 inspiratory to expiratory ratio. Thompson and Apple found that they could offer mode setup options on their units with very few mechanical changes, using electronic control of motor speed and timed intermittent motor operation. This enabled setups of a short inspiratory time and longer expiratory time. Thompson's first suitcase unit to meet this requirement was the M25-B and Apple's LP3 was electronically enhanced to become the LP4. Some of these ventilators are still around today.

The early 1980s were a period of more advanced electronics in portable ventilators, with larger and more complex circuit boards. Thompson's Companion 2500 was the M25-B with more sophisticated electronics. He then came out with a completely new ventilator, the Companion 2800, with microprocessor control and the same motor, but with a tachometer. Apple used that motor in his LP5. The tachometer and microprocessor electronics gave split second rate and inspiratory time control. Apple then produced the LP6 with his own brushless motor design.

After this flurry of development, Tommy Thompson sold his company to Puritan-Bennett in Lenexa, Kansas, and Rich Apple sold his to Aequitron Medical in Minneapolis, Minnesota. Both engineers soon went into retirement in Boulder, Colorado.

LIFECARE's history is different. Jim Campbell, the founder of LIFECARE, is not an engineer, but a retired IBM business manager who formed his company in the late 1960s, purchasing a wide variety of negative and positive pressure ventilators from the National Foundation for Infantile Paralysis (later known as the March of Dimes). Campbell organized an excellent service operation, with district offices spread throughout the United States.

Many of the machines Campbell acquired from the National Foundation were large and heavy, and had poor or no battery operation. Parts became a problem. Campbell had to provide his large base of ventilator users with a state-of-the-art ventilator to compete with Thompson's and Apple's units. He entered into a legal agreement with Apple and Life Products for manufacturing rights to the LP3. He called his version the portable volume ventilator or PVV, and leased it to many positive pressure ventilator users. His engineers made only minor changes in design. Under the agreement with Life Products, he could only lease the ventilator.

In the early 1980s, Campbell had his engineers working on a portable ventilator to compete with the Companion 2800 and LP6. The PLV-100 came to market in 1984, and many of LIFECARE's PVV users were switched to the PIV100 under lease or purchase. Campbell then went a step further by coming out with the first portable positive pressure ventilator, the PLV-102, to integrate oxygen into the positive pressure breath with proportional control and calibration of 02.

Today, Aequitron Medical, Puritan-Bennett, and LIFECARE are companies of high integrity that compete strongly in the limited portable ventilator market. All three companies have had problems with the Food and Drug Administration (FDA). While agreeing with the need to correct problems, the manufacturers often disagree with FDA’s slow and bureaucratic methods. These manufacturers all listen to ventilator users and pulmonary health professionals to help them make a better product.

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