Biomedical Engineering Reference
In-Depth Information
FIGURE 9-34
John Prestwich
using a cuirass
respirator.
2
(Courtesy of Maggie
Prestwich,
http://www
.johnprestwich
.btinternet.co.uk/
with permission.)
consists of an impermeable nylon jacket suspended by a rigid chest piece that fits over
the chest and abdomen, and the cuirass (or tortoise shell) ventilator, which consists of a
rigid plastic or metal dome over the chest and abdomen, as seen in Figure 9-34. These
chest and wrap ventilators are lightweight themselves, but both must be connected to
negative-pressure generators, which weigh 15 to 30 kg.
In 50 years, the ventilators that kept John Prestwich alive have taken more than
420 million breaths on his behalf. Should one have failed and not been repaired or replaced
for only 5 minutes during that time, John would have died. This speaks volumes for the
quality and reliability that is required from life-support hardware such as this.
Until fairly recently, paralyzed polio patients and quadriplegics relied almost entirely
on human support for every activity. However, the development of breath and sound
controlled interfaces has increased their independence considerably. In Prestwich's case a
series of whistles, similar to those used by shepherds to communicate with their dogs, are
picked up by a microphone and relayed to a computer to control peripheral devices. He
could control the TV, video, and hi-fi, open and close curtains, and control lighting and
heating as well as unlock the front door. The interface allowed him to make and receive
phone calls, while state-of-the-art software facilitated the use of his personal computer
(PC) for word processing, emailing, and playing games (Hill, 1996).
9.6.10 Other Uses for Negative-Pressure Ventilation
Though the iron lung is remembered most notably from the days of the polio epidemic, it
continued to receive occasional use after the development of the Salk and Sabin vaccines.
From the 1960s onward, most respiratory care patients were treated with new tech-
niques that used improved endotracheal or tracheostomy tubes, but some survivors of
2
Prestwich was paralyzed by polio at the age of 17 and spent more than 50 years using ventilators until
his death in 2006. His indefatigable spirit was an inspiration to all who knew him.
