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Community responder use of automatic external defibrillators: Ease of training and retention of skills
ABSTRACTS
pothesis, epicardial and transmural activation was recorded in 11 open-chested dogs during electrically induced ventricular fibrillation (VF). Shocks of 1 to 30 joules (J) were delivered in 1-J increments through defibrillatory electrodes on the left ventricular apex and the right atrium. Simultaneous recordings were made from intramural, septal, and epicardial electrodes in various combinations. A total of 104 unsuccessful and 116 successful defibrillatory shocks were given. Immediately following all shocks, an isoelectric interval much longer than that observed during pre-shock VF occurred, during which no epicardial, septal, or intramural activations were observed. This isoelectric window was statistically significantly shorter (P < 0.02) following unsuccessful defibrillation (mean 2 SD = 64 2 22 msec) than following successful defibrillation (339 +- 292 msec). Earliest activation was recorded from the base of the ventricles following the isoelectric window of unsuccessful shocks, which was the area farthest from the apical defibrillatory electrode. After unsuccessful shocks, activation was synchronized for one or two cycles following which VF regenerated. Thus: a) an isoelectric window occurs during which no activation fronts are present after both successful and unsuccessful defibrillation with epicardial shocks of 21 J; b) this isoelectric window is shorter following unsuccessful than successful defibrillatory shocks; c) unsuccessful shocks synchronize activation transiently before fibrillation regenerates; d) following the isoelectric window for unsuccessful shocks, activation leading to the regeneration of VF originates in areas away from the defibrillatory electrodes. The presence of the isoelectric window does not support the hypothesis that defibrillation fails solely because activation fronts are not halted within a critical mass of myocardium. Rather, unsuccessful epicardial shocks of 21 J halt the activation fronts of VF, but give rise to new activation fronts that re-initiate VE Community Responder Use of Automatic External Detibrillators: Ease of Training and Retention of Skills. Richard 0. Cummins, Mickey S. Eisenberg, Thomas R. Hearne, Paul Litwin, Alfred P. Hallstrom, Jessica Schubach. King County Emergency Medical Services Division, and the University of Washington, Seattle, WA 98104. If individuals, unskilled beyond basic life support level, could be successful trained to operate the new technology of automatic external detibrillators (AEDs), the positive benefits of early defibrillation could be extended to many more cardiac arrest patients in ventricular fibrillation (VF). A new AED has been developed, designed specifically for layperson use. The purpose of this study was to determine ease of training and the degree to which adequate skills levels were retained by community responders trained to operate the device. Community responders from the following categories volunteered to participate in the study: security personnel, corporate administrative staff, caregivers for seniors, and flight attendants for a major international airline. A total of 138 community responders attended the two three-hour classes. They were trained to recognize a cardiac arrest, to activate the emergency medical system, to open and attach the semi-
FROM PERDUE CONFERENCE
ON CPR
automatic AED, and to follow the directions displayed on the LCD screen of the device. Demographic data were recorded, and each trainee was graded against both a stringent practical skills check sheet and for errors that would have prevented shock delivery to hypothetical patients in ventricular fibrillation. Skills retention was tested by unannounced spot checks performed at varying intervals after the initial training. Ability to learn to successfully operate the device did not vary by age, sex, or responder category. Retention of skills, however, deteriorated rapidly with time in all responder categories and was most severe in the older age categories. Errors occurred most often in either complete omission or incorrect sequencing of procedure steps. Errors that would have prevented delivery of a countershock to patients in VF increased with length of time from initial training, but they were extremely rare (< 1% of responders) and did not differ by demographics or responder category. The authors conclude that community responders can be successfully trained to operate AEDs, but long-term retention of adequate skills is a concern. Successful retraining gives a high assurance that proper use of the device will occur during an actual cardiac arrest. Frequency and best method of retraining remain to be determined. Future AED design must focus upon minimization of all operator errors that might prevent countershock delivery to patients in VE Development of a Database of Out-of-hospital Cardiac Arrest Arrhythmias to Test Automatic External Defibrillators: The Iowa-King County Tape Library. Richard 0. Cummins, Kenneth R. Stults, Bruce Haggar, Sherrie Schaeffer, Donald D. Brown, Richard E. Kerber. King County Emergency Medical Services Division, Seattle, WA; the University of Washington, Seattle, WA; the EMS Learning Resources Center, University of Iowa, Iowa City, IO; and the University of Iowa, Iowa City, IO. Automatic external defibrillators (AEDs) facilitate early defibrillation for larger numbers of cardiac arrest patients. Prior to widespread clinical use, the rhythm analysis system of these devices must be tested in vitro against arrhythmia databases. A non-proprietary and standardized database of rhythms obtained from cardiac arrest patients does not presently exists. Such a database would permit in vitro testing of the rhythm analysis system of AEDs prior to clinical field trials and would permit inter-device comparisons. The EMT-defibrillation programs in Iowa and in King County, Washington use defibrillators equipped with voice/ ECG tape recorders (calibrated to 10 mm/millivolt). From these tape recordings, the authors selected segments of ventricular fibrillation (VF) with minimal artifact and at least 7 seconds in duration (one segment per patient). For six seconds of each segment the average amplitude of the VF signal was calculated. This was done by dividing the sixsecond segments into 0.4 second periods and measuring the highest amplitude in each of these periods. Six seconds was selected because currently available AEDs are programmed to reach a treat/no treat decision within this period. Using the method of Stults et al, a total of 100 segments of VF were subcategorized as tine (1 to <3 mm), medium (3 to <7 mm), coarse (7 to 112 mm), and extra coarse (>12 mm). 417
pothesis, epicardial and transmural activation was recorded in 11 open-chested dogs during electrically induced ventricular fibrillation (VF). Shocks of 1 to 30 joules (J) were delivered in 1-J increments through defibrillatory electrodes on the left ventricular apex and the right atrium. Simultaneous recordings were made from intramural, septal, and epicardial electrodes in various combinations. A total of 104 unsuccessful and 116 successful defibrillatory shocks were given. Immediately following all shocks, an isoelectric interval much longer than that observed during pre-shock VF occurred, during which no epicardial, septal, or intramural activations were observed. This isoelectric window was statistically significantly shorter (P < 0.02) following unsuccessful defibrillation (mean 2 SD = 64 2 22 msec) than following successful defibrillation (339 +- 292 msec). Earliest activation was recorded from the base of the ventricles following the isoelectric window of unsuccessful shocks, which was the area farthest from the apical defibrillatory electrode. After unsuccessful shocks, activation was synchronized for one or two cycles following which VF regenerated. Thus: a) an isoelectric window occurs during which no activation fronts are present after both successful and unsuccessful defibrillation with epicardial shocks of 21 J; b) this isoelectric window is shorter following unsuccessful than successful defibrillatory shocks; c) unsuccessful shocks synchronize activation transiently before fibrillation regenerates; d) following the isoelectric window for unsuccessful shocks, activation leading to the regeneration of VF originates in areas away from the defibrillatory electrodes. The presence of the isoelectric window does not support the hypothesis that defibrillation fails solely because activation fronts are not halted within a critical mass of myocardium. Rather, unsuccessful epicardial shocks of 21 J halt the activation fronts of VF, but give rise to new activation fronts that re-initiate VE Community Responder Use of Automatic External Detibrillators: Ease of Training and Retention of Skills. Richard 0. Cummins, Mickey S. Eisenberg, Thomas R. Hearne, Paul Litwin, Alfred P. Hallstrom, Jessica Schubach. King County Emergency Medical Services Division, and the University of Washington, Seattle, WA 98104. If individuals, unskilled beyond basic life support level, could be successful trained to operate the new technology of automatic external detibrillators (AEDs), the positive benefits of early defibrillation could be extended to many more cardiac arrest patients in ventricular fibrillation (VF). A new AED has been developed, designed specifically for layperson use. The purpose of this study was to determine ease of training and the degree to which adequate skills levels were retained by community responders trained to operate the device. Community responders from the following categories volunteered to participate in the study: security personnel, corporate administrative staff, caregivers for seniors, and flight attendants for a major international airline. A total of 138 community responders attended the two three-hour classes. They were trained to recognize a cardiac arrest, to activate the emergency medical system, to open and attach the semi-
FROM PERDUE CONFERENCE
ON CPR
automatic AED, and to follow the directions displayed on the LCD screen of the device. Demographic data were recorded, and each trainee was graded against both a stringent practical skills check sheet and for errors that would have prevented shock delivery to hypothetical patients in ventricular fibrillation. Skills retention was tested by unannounced spot checks performed at varying intervals after the initial training. Ability to learn to successfully operate the device did not vary by age, sex, or responder category. Retention of skills, however, deteriorated rapidly with time in all responder categories and was most severe in the older age categories. Errors occurred most often in either complete omission or incorrect sequencing of procedure steps. Errors that would have prevented delivery of a countershock to patients in VF increased with length of time from initial training, but they were extremely rare (< 1% of responders) and did not differ by demographics or responder category. The authors conclude that community responders can be successfully trained to operate AEDs, but long-term retention of adequate skills is a concern. Successful retraining gives a high assurance that proper use of the device will occur during an actual cardiac arrest. Frequency and best method of retraining remain to be determined. Future AED design must focus upon minimization of all operator errors that might prevent countershock delivery to patients in VE Development of a Database of Out-of-hospital Cardiac Arrest Arrhythmias to Test Automatic External Defibrillators: The Iowa-King County Tape Library. Richard 0. Cummins, Kenneth R. Stults, Bruce Haggar, Sherrie Schaeffer, Donald D. Brown, Richard E. Kerber. King County Emergency Medical Services Division, Seattle, WA; the University of Washington, Seattle, WA; the EMS Learning Resources Center, University of Iowa, Iowa City, IO; and the University of Iowa, Iowa City, IO. Automatic external defibrillators (AEDs) facilitate early defibrillation for larger numbers of cardiac arrest patients. Prior to widespread clinical use, the rhythm analysis system of these devices must be tested in vitro against arrhythmia databases. A non-proprietary and standardized database of rhythms obtained from cardiac arrest patients does not presently exists. Such a database would permit in vitro testing of the rhythm analysis system of AEDs prior to clinical field trials and would permit inter-device comparisons. The EMT-defibrillation programs in Iowa and in King County, Washington use defibrillators equipped with voice/ ECG tape recorders (calibrated to 10 mm/millivolt). From these tape recordings, the authors selected segments of ventricular fibrillation (VF) with minimal artifact and at least 7 seconds in duration (one segment per patient). For six seconds of each segment the average amplitude of the VF signal was calculated. This was done by dividing the sixsecond segments into 0.4 second periods and measuring the highest amplitude in each of these periods. Six seconds was selected because currently available AEDs are programmed to reach a treat/no treat decision within this period. Using the method of Stults et al, a total of 100 segments of VF were subcategorized as tine (1 to <3 mm), medium (3 to <7 mm), coarse (7 to 112 mm), and extra coarse (>12 mm). 417