TABLE OF CONTENTS From time to time it is necessary to use devices or machines which are temporarily in contact with living tissue and blood, or other body fluids. The most commonly encountered, are catheters and drain tubes, angioplasty devices, dialysis machines, blood oxygenators (heart/lung machines), certain types of artificial hearts, other cardiac assist devices, and endotracheal and endobronchial tubes.
All of these will be expected to operate in a dynamic situation, where the nature and response of the body fluids is constantly changing, and where external factors, such as temperature, movement &c., may be expected to fluctuate. We therefore have an environment where there are two main forces in action:
The effect of the device on the body
The effect of the body on the device itself (see Chapter 3).
Many of the devices which I shall describe have, in their present form, evolved from the single-minded persistence of medical innovators, often with an engineering turn of mind, who were clear in their goals, and whose inventions helped to save many lives. It will thus, I think, be interesting to dwell a little on the history of the more significant developments, as well as on the present day state of the machines themselves.
The term "catheter" is sometimes used for both catheters and drain tubes alike. However, there are differences, and I shall try to define them separately, although inevitably there will be some areas of overlap. A catheter is a tubular, generally flexible, surgical instrument that is...
