Management of ECG Cables and Leadwires

Electrocardiography (ECG) is the non-invasive capture and display (either on a screen or as a hard copy, such as a strip recording or page printout) of cardiac electrical activity. ECG provides a quick and highly reliable estimate of a patient's cardiovascular health, making it one of the most common non-invasive medical applications. ECG is used for monitoring cardiac activity, for the purpose of diagnosis and therapy in clinics, and all areas of the hospital, including operating rooms and intensive care units (ICU).Physicians can use ECG to quickly measure heart rate and cardiac rhythm of a patient. The physician can also identify abnormalities in how electrical impulses propagate through the heart and detect evidence of coronary artery disease, prior heart attacks, and thickening of the cardiac muscle.1–4 For more detailed information about a patient's cardiac electrical activity, a physician may request longer-term ECG recordings through the use of a Holter monitor (an ambulatory ECG) or during intentionally “loading” of the heart with a stress test, such as having the patient exercise on a treadmill. Continuous ECG monitoring during anesthesia provides vital information regarding a patient's condition throughout a surgical procedure. Continuous ECG data acquisition using a bedside monitor provides real-time health information for a patient in an ICU. In some instances, pacemakers or defibrillators (external and internal) significantly alter the appearance of the body-surface ECG. Many medical activities, including life supporting or life saving ones, depend on efficient acquisition of ECG data.ECG has been used since Willem Einthoven invented the first practical ECG in 1903, receiving the Nobel Prize in Medicine in 1924 for his invention.5 ECG systems have evolved over many years. Now, ECG systems are built with similar building blocks, and all have similar external components. Electrical or mechanical failures occur infrequently for ECG devices themselves; however, malfunctions due to problems with ECG electrodes, leadwires, and ECG (patient) cables are common.6 This article reviews these problems and presents the results from a 2010 AAMI survey of biomedical equipment technicians (BMET)s and clinical engineers (CE)s. The article covers issues related to clinical management of the cables and leadwires, as well as potential improvements in the design of new medical devices to increase efficiency and reliability.ECG cables, leadwires, and electrodes are used to connect the human body to many different types of ECG devices. Hospitals usually have many medical devices that record and display ECG signals including Holter monitors, stress-testing equipment such as treadmills, patient monitors, telemetry units, defibrillators, and diagnostic electrocardiographs (often referred to as ECG or EKG carts). Large multi-specialty clinics may have treadmills and Holters, but these are generally run through a cardiology subspecialty group. (Smaller clinics and physicians' offices also use some of these devices, but patient monitors and telemetry units are typically not on site.)These facilities stock large numbers of ECG cables, leadwires, and electrodes needed to use these devices. Poor electrodes and worn-out leadwires or ECG cables routinely cause failures that clinical users may not be able to readily identify. ECG cables and leadwires should be tested by a BMET regularly—or whenever an ECG device seems to be malfunctioning—and replaced when necessary. Leadwires should only be used if they remain in good condition (i.e., intact insulation, unbroken, no visible signs of wear). If a BMET is not available, clinical users should be able to visually check the cables and leadwires, and recognize that noisy ECG signals and “no recording” conditions usually occur when broken or poor-quality cables and leadwires are used. Clinical users should be able to replace these suspected defective cables and leadwires with good ones, and send the replaced cables and leadwires for service.In 2010, AAMI, on behalf of the authors, asked BMETs about their experiences with ECG cables, leadwires, and electrodes. A random sample of 300 BMETs was emailed a seven-question survey about ECG cables. From this group, 67 BMETs representing a cross-section of different hospitals responded. Survey participants were asked to describe the type of the facility, the total number of hospital beds, how many devices with ECG cables participants were used at their facility, and the names of those devices.The survey participants were also asked to cite the most common ECG cable and wire problems they encountered, their frequency, other experiences they would like to share, and what simple things nurses could do to troubleshoot issues.The most common problems reported, as seen in Table 1, were bad electrode placement, poor connectivity between electrodes and patients, broken leadwires, and dry or old electrodes. These problems can be avoided if the devices are used carefully. Clinical users of ECG devices are expected to know how to prepare the patient's skin and place the electrodes to obtain good electrical conduction. They should be able to determine whether the electrodes are too old or too dry or are still in good condition.Other reported problems were broken leadwires, broken clips, broken connectors, and broken pins in the ECG cable's connector to the device, A few responders mentioned noise problems, low signal/noise ratio, weak strain-relief of these parts, intermittent or lost connections during exercise, worn leadwires that have intermittent loss of continuity or high impedance problems, and leadwires breaking at the termination point. A less common problem was the tightness of the connection of the leadwire to the electrode. Fixing this group of problems is usually a job for a biomed.For most of these problems, the best solution is to replace the faulty ECG cable or leadwire with a new one. A well-trained clinical user can easily detect most of the aforementioned problems. Active involvement of clinical users in management of medical equipment can increase the department's efficiency and help it provide uninterrupted service. Potentially faulty material can still be tested and, if possible, fixed or replaced by a biomed. When the ECG cables and leadwires are tested, a biomed may check their impedance with an ohmmeter. An intact lead or cable wire will read a low impedance or resistance value. A continuity tester with audio feedback is probably a better tool than an ohmmeter. Another test that can be performed is to connect the leadwires to a patient simulator and observe signals on the screen. Biomeds can also flex all the ends where the wire meets the connector through various angles to look for an intermittent break. Either testing may provide insight into conductivity and hence the quality of the ECG cable and the leadwires. However, this may not be enough to eliminate problems if the electrodes used with them are too dry.Of the 67 responses received, 24 (36%) stated that these problems occur every day or several times a week; 10 (15%) stated they occur occasionally. This difference probably relates to how frequently a hospital replaces patient cables and leadwires. There may also be many other variables, such as how often nurses will report the problem as opposed to replacing the cables themselves. Cables and leadwires that are used for a long time are more likely to have these problems.Several responders wrote that patient cables and leadwires usually have problems after about 12 months of usage. In practice, leadwires may need to be replaced after anywhere from six to 24 months of use. This variability may seem suspicious, but several factors affect this.In many hospitals, a BMET or CE maintains and troubleshoots ECG devices, including their cables and leadwires. These devices are routinely used by a wide range of clinicians, from physicians and nurses to the care specialists, such as cardiology technicians and medical assistants. Clinical users usually try to address a noisy signal, generally by repositioning the leads and assuring good contact. This kind of troubleshooting may not be as thorough as that of a biomed, but a clinician's primary focus has to be on patient safety, not medical device repair.However, keeping ECG devices working properly all the time benefits everyone. Poor management of the available technology results in inefficient use of these medical devices, loss of time and resources, and, most importantly, loss of their availability to support patient care. Think about how frustrating it is if a monitor fails to provide vital information at a crucial time, especially when the root cause turns out to be an easily recognized broken ECG cable or leadwire. Education of the clinical user, collaboration between clinical users and biomeds, use of good quality equipment, good maintenance, and availability of spare ECG cables and leadwires can all contribute to change for the better.The survey responses also provided some clues on how new devices can be designed better. Here are some ideas:These suggestions can lead to more reliable ECG devices and their more efficient use. This paper presented many practical problems related to these external components. This study is based primarily on feedback from biomeds who are deeply involved in maintenance and repair of ECG devices. It proposes some solutions to eliminate or reduce the problems and to design better ECG devices. It should be beneficial for clinical users, BMETs and CEs, and designers of ECG devices. The authors appreciate the contributions of everyone who responded to the survey.