Fingerprinting tests are conducted for two reasons. First, compliance with hospital policy on acceptance testing requires that representative samples of all devices be tested prior to entering the clinical environment for the first time. Second, both theory and experience have demonstrated the need for device testing. A device that radiates unintentionally can victimize other devices. It may also be susceptible to victimization by ingress at their egress frequencies and modulation parameters. Those devices already in the environment are fingerprinted if there is reason to believe that they have the potential to be an EMI victim or a culprit. The procedure used to initiate and track an EMI investigation is shown in Figure 63-2. Members of the clinical staff are instructed to call the biomedical engineering department and television services group in any case of a device malfunction not attributable to a routine failure. In cases of a new device entering the clinical environment for the first time or a new application for an existing device, a request to test the device for compatibility is generated. This call is referred to the clinical engineer responsible for EMI investigations. When an incident might be attributable to EMI, the engineer visits the site as a part of the initial investigation. The possible victim device is viewed and tested to determine whether it might have been, or is being, affected by EMI. Interviews with the personnel responsible for the area and the operation of the device(s) must be conducted. Based on the results of this preliminary investigation, a decision is reached as to the desirability or feasibility of further investigation. The decision to continue the investigation is based on several factors: Is there a high probability of operator error? Is this a very rare occurrence? Is this either a very old device that might be reaching the end of its reliable life cycle or a new device experiencing infant mortality. As part of the preliminary investigation process, maintenance histories of the device are reviewed. Another component involves the review of equipment added to the environment that might have increased the overall RF hostility in the area enough to cause interference. Footprinting records of the area are reviewed as are fingerprints of the victim devices(s). The mode of device failure (table 63-2) is an important part of the evaluation. Is the victim device alarming? Is it operating erratically? Is it changing its operational parameters either temporarily or permanently? Is it shutting down? Is there a latching change that created the alarm? The answers to these questions can all point to the criminal device or devices. If the failure mode can be duplicated and if the failure appears to have been caused by an intentional or incidental radiator, the culprit device can usually be identified. If it is within the clinical environment, it is silenced or removed. Many times, no further investigation is required. An incident report is generated and filed. A copy is provided to the department initiating the service request. A copy, if deemed necessary, is given to the appropriate reporting agency, such as the Food and Drug Administration Center for Devices and Radiological Health (FDA, CDRH). If a complete testing procedure is required and a recent footprint of the area exists, a new set is acquired and compared to the older set. Changes in the area environment are noted and analyzed. This is also compared with any existing fingerprints of the victim device. If no fingerprints exist for a representative victim device, or when a device shows signs that its ability to resist ingress may be compromised, it will be fingerprinted. After a cursory footprint of the quiet area, to ensure that no significant changes have occurred in that environment, the victim device, if practical (size and weight can affect the test location), can be moved to this area for fingerprinting