When a caregiver or responder reaches for an automated external defibrillator (AED), they need the device to be functioning correctly. Someone’s life literally depends on it. Routine visual and operational checks can go a long way toward ensuring the safety and effectiveness of AEDs; and some newer models include features that facilitate this process. ECRI’s testing of AEDs reveals which device features and deployment practices can be most effective.
Stand-alone automated and semiautomated external defibrillators, often collectively referred to as AEDs, are used in emergency situations when a person suffers a cardiac arrest. AEDs analyze the person’s ECG and either deliver a shock automatically or prompt the user to do so if one is warranted. If a defibrillation shock is not appropriate, the AED will advise against a shock, and will guide the user to perform cardiopulmonary resuscitation (CPR) until medical assistance arrives.
The speed with which a defibrillator is deployed can be critical to a successful resuscitation attempt. Every minute that a patient goes without defibrillation decreases the likelihood of resuscitation. Every minute that a patient goes without adequate circulation increases the likelihood of tissue death, which can lead to poor neurological outcomes or damage to heart tissue. High-quality CPR can help provide some circulation and delay the onset of negative health effects, but it is insufficient on its own.
Reducing the time to the delivery of a defibrillation shock can greatly improve a patient’s chances of survival with a good outcome. For that reason, ECRI recommends paying careful attention to factors that can impact the time-to-shock when making AED purchasing and deployment decisions.
Areas of Use
AEDs are intended for use by individuals who have CPR training or basic life support (BLS) training, but who are not qualified to analyze a cardiac rhythm and recommend a shock. Typical users include medical professionals, targeted responders (like security guards, police officers, firefighters and designated volunteers) and bystanders who witness a cardiac arrest or other medical emergency and are able to locate an AED and respond. The core purpose of an AED is to speed the delivery of potentially life-saving therapy by making defibrillation easier for users who have not received advanced cardiac life support (ACLS) training.
AEDs are often used for public access defibrillation, and thus may be found in public spaces like schools, athletic facilities, shopping centers and conference centers. In hospitals and other health care settings, AEDs may be located in lobbies, parking areas, stand-alone sub-acute care facilities or other areas that may not be supported by a code team or that may be subject to long response times.
Key Performance Characteristics
Performance characteristics that affect the time-to-shock include the following:
- Accuracy of ECG analysis. AEDs should have a high sensitivity and specificity for determining when a patient requires a defibrillation shock. Delivering a shock inappropriately may cause pain to the patient and could trigger a lethal arrhythmia. Conversely, failure to deliver a shock when one is appropriate will increase the time to shock delivery and decrease the likelihood of resuscitation with a good outcome.
- Analysis time and charge time. Both the time required for the AED to analyze the patient’s ECG and the time required for the AED to charge to the desired energy level factor into the time-to-shock. Minimizing the total hands-off time between the pause of CPR (to allow the device to analyze the rhythm) and the delivery of the shock (when warranted) can improve the chances of a successful resuscitation. Some AEDs allow the charging process to be initiated while CPR or rhythm analysis is ongoing; this feature can help reduce the hands-off time.
- Ease of use. The AED must be easy for the intended user population to operate, with clear instructions and controls. The device should not contribute to delay of therapy due to user uncertainty. Many newer models even provide real-time CPR feedback and a metronome to improve adherence to CPR guidelines during the periods before and between shock delivery.
Device Accessibility and Readiness
For best results, AEDs must be rapidly accessible and operational at all times. “The best defibrillator in the world is useless if it can’t be located or isn’t ready for use when it’s needed,” explains Mairead Smith, a principal project engineer in ECRI’s Device Evaluation group. Issues related to how a device is deployed and maintained can have just as big an impact on the success of a resuscitation attempt.
AED placement. Ideally, an AED would be located so that most of the covered area will be within a 60- to 90-second walk for likely responders, including bystanders. Further, units should be placed in a central location where rescuers are likely to look, such as a lobby, a security desk, an elevator bank or near emergency phones. Additionally, a unit may be needed on each floor of the building: Rescuers are likely to search for an AED on their floor, without going up or down stairs or an elevator. Also, be sure to consider restrictions that could delay access to a patient or AED, such as locked doors that a rescuer may not be able to open.
Within a health care facility, AEDs should be considered for spaces that may not be easily covered by the code team. This might include outlying buildings and parking areas, for example.
AED maintenance. AEDs in the United States are equipped with automated self-tests, in which the AED assesses key functions like battery operation, electrical circuit status, ability to charge and, sometimes, the status of preconnected defibrillation electrodes. Notably, two of the three models included in ECRI’s August 2022 evaluation of AEDs can transmit readiness statuses from these checks via Wi-Fi. This capability allows program managers to monitor readiness remotely.
“Remote monitoring reduces the need for in-person device checks, which can be very convenient when a device manager is responsible for multiple AEDs, especially if they’re located in separate buildings” explains ECRI’s Smith. “But you should still go around once in a while to make sure everything looks good in person.” ECRI recommends that health care facilities inspect each AED on at least a monthly basis to confirm that the device has passed its self-tests and is otherwise in good condition. Downsides to keep in mind with Wi-Fi capabilities are that they can add to the cost of the unit and can shorten the battery life.
To Learn More . . .
Members of ECRI’s Capital Guide, Device Evaluation, and associated programs can access the following resources for making effective AED purchasing and deployment decisions: “Evaluation Background: Automated External Defibrillators (AEDs)“ (2022 Aug 11); “Placement of AEDs for Quick Access in Healthcare Environments” (2022 May 18); and “Sure to Shock: ECRI’s Defibrillator Checklists“ (2022 Feb 22). To learn more about membership, visit https://www.ecri.org/solutions/device-evaluations, or contact ECRI by telephone at (610) 825-6000, ext. 5891, or by e-mail at clientservices@ecri.org.
