Device Safety and Errors

A medical device is expected to be not only reliable but also safe. This means that a given medical device must never function or malfunction in a manner that can be harmful to the user or the patient. The problem of safety in regard to humans is not new its history can be traced back to the ancient Babylonian ruler Hammurabi, who developed a code known as the Code of Hammurabi in 2000 b.c. [1-3]. The code contained clauses concerning injury and financial damages against those individuals who cause injury to other people. 

In modern times, in 1970 the U.S. Congress passed the Occupational Safety and Health Act (OSHA), which is considered an important milestone in regard to health and safety in the United States. Two subsequent milestones specifically concerned with medical devices in the United States are the Safe Medical Device Act of 1990 and the Medical Device Amendments in 1976. 

The occurrence of human errors in the area of medical devices has become an important issue, as operator errors account for over 50% of all technical medical equipment problems [4]. Furthermore, as per Refs. [5-7], human error is considered to contribute up to 90% of accidents both generally and in the area of medical devices. 

This chapter presents various important aspects of medical device safety and errors. 

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It is common on chemical plant to install safety devices such as trips and relief valves which protect the plant in the event of a malfunction of control systems or human error. Unfortunately, these devices can (and do) fail occasionally. The problem is that the failures cannot be seen until they are tested or until they are called upon to act (a plant may operate perfectly normally even though, say, a pressure relief valve is faulty, because under normal conditions the valve is never activated). It is thus necessary to test safety devices periodically to ensure they are functioning. 

Chapter 10 is devoted to medical device usability. It covers topics such as medical device users and use environments, medical device user interfaces, an approach to develop medical devices effective user interfaces, guidelines to reduce medical device user interface-related errors, guidelines for designing hand-operated devices with respect to cumulative trauma disorder, and useful documents for improving usability of medical devices. Chapter 11 presents three important topics relating to patient safety patient safety organizations, data sources, and mathematical models for performing probabilistic patient safety analysis. 

Another study by Hankin and colleagues evaluated 2009 IV-PCA-related reports filed with the FDA (MAUDE database) during a 2-year index period (2002-2003), the majority of which could be classified as possibly preventable (those classified as possible operator errors, patient-related events, or device safety events) [13]. Given that published accounts of IV-PCA problems have historically focused on operator error and patient tampering [14-16], the authors were surprised to find that device safety events (i.e. device malfunctions) were the suspected cause of nearly 80% of reported events (75% of these reportedly attributable to defective switches, display boards, or motors) (Table... 

It is easily understandable that the level of safety and thus the costs of a safety device should be adapted to the characteristics of the technical process. If e.g. the process is slow enough, the safety device may issue a faulty command if this error is detected in time. Quick processes call for error-free commands. 

It is a fact of experience that pressurized apparatus should be fitted with a control and monitoring unit to ensure an appropriate purging procedure and maintain the protective gas flow and pressure differential which guarantee the safe operation of the apparatus. Purely hand-operated purging procedures are susceptible to errors and slips, and a permanently man-operated flow or pressure control for the protective gas is too remote from all basic principles of economic efficiency. Besides, the standards for pressurization contain requirements for safety devices for zone 1 apparatus (EN 50016) and for type px, py and pz-apparatus (IEC 60079-2, see Table 6.7). So, a safety device, or better a control and monitoring unit, is an essential part of a p-apparatus especially for Group I application and for zone 1. It is by no means an imperative that the control unit forms an integral part of the apparatus or has been made by its manufacturer pressurized apparatus without a control unit shall be marked X and the description documents shall contain all necessary information required by the user to ensure conformity with the requirements of the p-standards. 

CA 31, 5631 (1937) (A device for detecting firedamp in mines) 6)R-Kattwinkel, Gliickauf 74, 482-84 (1938 CA 33, 3157 (1938) (New app for the study of firedamp) 7)F.Le-beter. Colliery Engrg 16, 245-48 (1939) CA 33, 9647 (I939) (Discussion of the Ringrose and McLuckie appliances and statement that detection of firedamp by means of a safety lamp is liable to many errors) 8)T D.Jones... 

Another remotely activated device has been described by Groning et al. (57). They demonstrated in a model the remote control of a device to delivery insulin (Fig. 7). This possibility of external programming and monitoring of insulin pumps is possible for continuous subcutaneous infusion. The use of SMS allows immediate transfer of commands to the pump. There are many pitfalls to overcome the ethics of taking control away from the patients and their carer is but one, and there are safety issues, should the GPS system fad, and presumably if in error the pump is activated by the physician or indeed by individuals accidentally. But there is no doubt that telepharmacy wiU impact on future medicine, whether personalized or not. The personal element could come simply as a result of automated reminders to patients to take their medications also discussed above, but the more sophisticated systems described by Groning et al. wiU also have their place. 

The worst nuclear power accident in the U.S. occurred at the Three Mile Island plant in Pennsylvania. In this accident no one was killed and no one was directly injured. The event at Three Mile Island occurred from faulty instrumentation that gave erroneous readings for the reactor vessel environment. A series of equipment failures and human errors along with inadequate instrumentation allowed the reactor core to be compromised and go into a partial melt. The radioactive water that was released from the core was confined within the containment building and very little radiation was released. In the Three Mile Island incident, the safety devices worked as planned and prevented any serious injury. This accident resulted in improved procedures, instrumentation, and safety systems being implemented. 

The minimum acceptable limit for the content of preservatives in a drug product should be demonstrated as microbiologically effective by performing a microbial challenge assay of the drug formulated with an amount of preservative less than the minimum amount specified as acceptable. This approach provides a margin of safety within the limit and a margin of error for the assays. In addition, compatibility of the preservative system with the container, closure, formulation, and devices (e.g., pumps,... 

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