Defibrillator maintenance policy.

Abstract

Sir, A defibrillator is a life support equipment used for the purpose of sustaining life and whose failure to perform its primary function will lead to patient death in the absence of immediate intervention. Though this equipment is not used regularly, it is important that the daily check must be carried out. The manufacturer recommends 30 J (Joules) self-test as the daily test procedure for Zoll M® series defibrillator.[1] For regular maintenance and to ensure patient safety, we follow the International Electro-technical Commission (IEC) 62353 hospital safety guidelines.[2] Typically, pre-installation safety check on defibrillators is done before using it in patient care areas. During this first maintenance, two unusual problems were identified in eight of the 45 Zoll M® series defibrillators in our institution. The unit passed pre-use check at 30 J and showed ‘TEST OK’. Whereas to assess the ability of machine at higher joules, we tested by connecting to fluke defibrillator analyser[3] (model-Impulse 6000DP). It was noticed that above 100 J the machine was unable to charge, took unusually longer time (more than 30 s) for charging and unit showed error ‘defib fault 78’ (high voltage module failure). In addition, three other defibrillators passed maximum energy discharge procedure but failed internal discharge tests. During this test, the unit was charged to higher joules, but was unable to hold the charge for 60 s followed by an error code ‘defib fault 108’. As per the manufacturer, both these error codes are related to the failure of the high voltage module/capacitor section. Both these faults require replacement for proper functioning of the unit. The checklist followed is shown in Table 1. Table 1 Bi-annual maintenance by Quality Cell, Biomedical Engg. Division The matter was reported to the manufacturer who responded by recommending 3 different test procedures. First, the daily test procedure 30 J self-test which will be a low energy test to check the charging circuits, the integrity of cables, along with other circuits that are not tested during the normal power-up self-test. This includes a capacitor, high voltage module, and the bridge resistor network used with the rectilinear biphasic waveform. Hence, this test ensures these circuits are working satisfactorily at low energy. Second, a weekly check is carried out to test at higher energy level using Zoll electrocardiography (ECG) simulator. Third, the detailed half-yearly test procedure should be performed by the biomedical department in a hospital [Table 1]. Since, manufacturer recommendation involves simulator in pre-use check which are not available to the end users, we modified the daily check procedure to be carried out by the end user without diluting weekly or bi-weekly test procedure in 3 simple steps: Step 1 - perform 30 J test procedure; Step 2 - charge the unit to maximum energy level; Step 3 - the unit should hold the charged energy for 60 s without any error code displayed and discharges internally on its own. The detailed checklist for daily low energy and weekly test procedure is shown in Table 2. Table 2 Daily low energy test The proposed check procedures were tested on the problematic defibrillators and error codes appeared during internal discharge test without using defibrillator analyser and ECG simulator. This conforms to manufacture recommendation and authenticated. The bi-annual check will be executed by biomedical engineers as shown in Table 1. In conclusion, we propose a simplified three steps ‘daily check procedure’ for end users like the paramedical staff and/or doctors who are acquainted with the use of defibrillators. In addition, charging the unit to a maximum energy level at regular intervals extends the lifespan of electrical components that are not included in normal power-up self-test.