Don't Forget the Maintainer

Abstract

Todays' new technology would certainly appear to make our daily routine easier and use of tools more comfortable. However, with any change, there is the possibility of creating new problems.Let's take a look at what effects the progress of healthcare technology has had on the biomedical equipment technician (BMET). Veteran BMETs can tell you stories of troubleshooting devices to the component level, many times without the need for a technical manual. Earlier generations of medical devices were easier to troubleshoot because they were easier to understand. You could open up an electrocardiogram machine without using any special tools and be able to identify all the major cards on the main board. In today's market, medical devices are smaller, circuit functions are embedded on single integrated circuit cards, and it is challenging to understand what happens inside the device.Improvements in device design made possible by applying human factors engineering (HFE) principles come at some cost. As we make the device easier for the user, more intuitive on the front panel, we are also making the circuitry, programming, and overall layout of the device harder to follow. The device becomes less intuitive for the BMET; it turns into a black box. In some cases, medical devices are designed to keep the BMET entirely out of the process.I would argue that so long as the device can be evaluated by the BMET, then the user can effectively operate the device with confidence. However, by slowly removing or limiting what the BMET can do, we begin to remove or limit the confidence interval for the reliability of a particular device.Consider the following example. A BMET was issued a work order for a laboratory device. The device was supposed to act as a centrifuge for samples but it was not spinning. When the technician removed the front cover, a single potentiometer was noticed on a circuit with a connection to the tub that enclosed the heavy rotor. After a slight adjustment of that “pot,” the rotor began to spin. This technician performed a tachometer test on the unit and all rotational speeds were accurate, so the work order was closed.A month later, a doctor from the laboratory reported a problem. An engineer evaluated the device and found that the technician inadvertently increased the tolerance for vibrations caused by a warped rotor. The slightly increasing vibrations eventually caused severe damage to the device.This example points out several HFE considerations. First, designing for the human factor should not be limited to just the user. Because devices are increasingly complicated, it is now even more important to design for the maintainer as well. In this example, the expectations of the engineers and designers did not take into account the expectations of BMETs. Making slight adjustments to learn the behavior of a device is a self-training process BMETs use to learn more about the machine. But in this case, that process ultimately caused significant damage to the machine. Military standards require that designers consider the needs of equipment maintainers when designing devices. This recommendation is not made simply for the convenience of the maintainers, but rather to ensure safety.Second, the complexity of devices requires proper behaviors on the part of maintainers. Experimenting with adjustments or other aspects of maintenance invites risk.Third, adequate diagnostic and maintenance procedures should be provided by manufacturers/vendors for all aspects of shop maintenance. Where they are not provided, it can be advantageous for the BMET to develop them as best they are able.Finally, the importance of verifying proper device operation after maintenance becomes evident.While it is increasingly common for device designers to carefully consider the thought process of end users, they must also carefully consider the thought process of a typical BMET during all stages of the design process.