Medical Equipment Reliability
The earliest use of medical devices’ history may be traced back to ancient Etruscans and Egyptians using various types of dental devices . Nowadays, medical devices and equipment are widely used around the globe. In fact, in 1988, the production of medical equipment around the globe was estimated to be around $36 billion [ 1 ] and in 1997, the global market for medical devices was valued at approximately $120 billion .
In modern times, the beginning of the medical equipment or device reliability field may be traced back to the latter part of the 1960s, when a number of publications on the subject appeared [3-7]. These publications covered topics such as Safety and Reliability in Medical Electronics, Reliability of ECG Instrumentation, and Some Instrument Induced Errors in the Electrocardiogram [3-5]. In 1980, an article presented a comprehensive list of medical equipment reliability-related publications  and in 2000, a book entitled Medical Device Reliability and Associated Areas provided a comprehensive list of publications on the subject .
This chapter presents various important aspects of medical equipment reliability.
Medical Equipment Reliability-Related Facts and Figures
There are many, directly or indirectly, medical equipment reliability-related facts and figures. Some of these are as follows: •
In 1997, there were a total of 10,420 registered medical device manufacturers in the entire United States .
- • In 1969, the United States Department of Health, Education, and Welfare special committee reported that over a 10 year period, approximately 10,000 injuries were related to medical equipment/devices and 731 resulted in fatalities [11,12].
- • The Emergency Care Research Institute (ECRI) tested a sample of 15,000 products used in hospitals and discovered that approximately 4% to 6% of these products were sufficiently dangerous to warrant immediate correction .
- • In 1990, a study conducted by the US Food and Drug Administration (FDA) revealed that approximately 44% of the quality-associated problems that resulted in the voluntary recall of medical devices for the period October 1983 to September 1989, were due to errors/deficiencies that could have been prevented through effective design controls .
- • Due to faulty medical instrumentation, approximately 1,200 deaths per year occur in the United States [15,16].
- • A study reported that approximately 100,000 Americans die each year due to human errors, and their financial impact on the United States economy was estimated to be somewhere between $17 billion and $29 billion .
- • A study reported that over 50% of all technical-related medical equipment problems were directly or indirectly due to operator errors .
Medical Devices and Medical Equipment/Devices Categories
Nowadays, there are over 5,000 different types of medical devices being used in a modern hospital and they range from a simple tongue depressor to a complex pacemaker [1,9]. Thus, the criticality of these devices’ reliability varies from one device to another. Nonetheless, past experiences over the years clearly indicate that the failure of medical devices has been very costly in terms of dollars and cents, fatalities, injuries, etc. Needless to say, modern medical devices and equipment have become highly sophisticated and complex and are expected to function under stringent environments.
Electronic equipment/devices used in the health care system may be categorized under the following three classifications : 
fall under Classification I, because there is time for repair. Six examples of such devices/equipment are as follows:
- • Colorimeters
- • Spectrophotometers
- • Diathermy equipment
- • Gas analyzers
- • Ultrasound equipment
- • Electrocardiograph and electroencephalograph recorders and monitors
Finally, it is to be noted that there could be some overlap between the above three classifications of devices/equipment, particularly between classifications I and III. A typical example of such equipment/devices is an electrocardiograph recorder or monitor.
-  Classification I. This classification includes those medical equipment/devicesthat are immediately and directly responsible for the patient’s life or maybecome so under emergency situations. When such equipment/devices malfunction, there is seldom sufficient time for the repair action. Thus, this type ofequipment/devices must always function successfully at the moment of need.Four examples of such equipment/devices are as follows: • Cardiac defibrillators • Cardiac pacemakers • Respirators • Electrocardiographic monitors. • Classification II. This classification includes those medical devices/equipmentthat are not critical to a patient’s welfare or life but just serve as conveniencedevices/equipment. Some examples of such devices/equipment are as follows: • Wheelchairs • Bedside television sets • Electric beds. • Classification III. This classification includes those medical devices/equipment that are utilized for routine or semi-emergency diagnostic or therapeutic purposes. Failure of such devices/equipment is not as critical as those