Automated external defibrillators used in the critical first minutes after cardiac arrest can ensure a victim’s best chance for survival. However, emergency medical responders often are delayed past the window when early defibrillation is most effective. Training programs for physicians and laypersons on how to use public access defibrillators in public venues can save precious minutes.
What if you were at the gym or the mall and someone around you suddenly collapsed? Would you be the one to rush to the rescue? What resources would you need to help you save that person’s life? What would you do without the team of nurses and respiratory therapists who are usually there to help you in the hospital or at the office? What would you do without equipment or a code cart?
Fortunately, many public locations are equipped with automated external defibrillators (AEDs), but are you completely comfortable using them? A recent cross-sectional survey that included medical personnel showed that more than half of those surveyed could not even recognize an AED and that less than half would be willing to use one if given the opportunity. Reasons cited for discomfort included not knowing how to use the equipment, fear of harming the patient, and fear of litigation.1 Let’s allay some of those fears.
Automated external defibrillators, first described in 1979, are computerized, voice-prompted portable devices that reliably detect monomorphic and polymorphic ventricular tachycardia or ventricular fibrillation.2 Shocks are not advised on the basis of heart rate alone, but the devices, along with specific self-adhesive electrode pads, look for and analyze shockable heart rhythms. The data in children is encouraging, showing that pediatric-based devices can differentiate between shockable and nonshockable rhythms with a high degree of sensitivity and specificity. Therefore, AEDs are safe and effective for use in children.3-5
Older versions of AEDs delivered monophasic shocks, meaning that current was delivered in 1 direction. Newer versions deliver a biphasic shock, with current delivered in 2 directions. Although these biphasic shocks deliver less energy than the monophasic ones, studies show that they cause less myocardial damage and lead to a higher percentage of patients with return of spontaneous circulation.6,7
Many studies show that early defibrillation of ventricular fibrillation cardiac arrest saves lives; however, defibrillation must be performed within the first few minutes because the probability for successful defibrillation declines by 7% to 10% for each minute of cardiac arrest.8-10 We know that our emergency medical service (EMS) colleagues are able to successfully defibrillate patients, but EMS response times vary. Sometimes it can take 5 minutes for EMS to arrive on the scene, sometimes 20 minutes. Those are minutes that can’t be lost when early defibrillation is needed. The best way to deliver this early defibrillation is through proper, rapid, on-the-scene use of AEDs, because early defibrillation can improve ventricular fibrillation survival rates by up to 50%.11-15
The need for early AED use is highlighted in 2010 American Heart Association (AHA) guidelines.10 The AHA recommends that 3 actions must occur to ensure a victim’s best chance of survival from sudden cardiac arrest: activation of the EMS system, provision of cardiopulmonary resuscitation (CPR), and operation of an AED.
Children have a higher frequency of primary respiratory arrest and asystole, so proper ventilation and oxygenation have been mainstays of therapy in pediatric resuscitation algorithms.16 However, ventricular fibrillation also occurs. Previous estimates of pediatric ventricular fibrillation prevalence were likely underestimated because, in the past, AEDs were not routinely used in most pediatric out-of-hospital arrests and there was no ability to quantify rates of pediatric rhythm abnormalities, including ventricular fibrillation.17 One study reported that ventricular fibrillation was the initial rhythm in 19% of children aged 5 to 18 years who experienced out-of-hospital cardiac arrest.
A more recent retrospective review found ventricular fibrillation rates of 7.6% in children aged 1 to 7 years and 27.0% in children aged 8 to 18 years, with an overall incidence of 17.6%.18 This higher incidence of pediatric ventricular fibrillation is also seen in the inpatient setting.19-22 Timely recognition and treatment of shockable rhythms are therefore paramount.
The International Liaison Committee on Resuscitation, the AHA, and the National Association of EMS Physicians all advocate early use of AEDs on children to analyze rhythms and provide defibrillation in cases of ventricular fibrillation cardiac arrest.10,23,24 When recognized early and rapidly treated, pediatric patients with ventricular fibrillation have a higher survival rate (31.3%) than those with other rhythms (10.7%).18
The AHA recommends that a pediatric dose-attenuating system be used in children aged younger than 8 years to reduce the dose delivered by the device.25 This may be through either a pediatric-specific pad-cable system or an AED with a key or switch to select a smaller dose. If a pediatric dose-attenuating system is not available, then a standard AED should be used. A manual defibrillator is preferred for infants aged younger than 1 year. If one is not available, then an AED with a dose attenuator may be used.
Once an AED is turned on, it offers guided prompts throughout the entire resuscitation process (See, "Using an Automated External Defibrillator"). Before 2010, AEDs “told” the user to check patient responsiveness, call for help, open the airway, and give 2 breaths. In 2010, AHA guidelines changed from the A-B-C (airway, breathing, circulation/chest compressions) model to a C-A-B (circulation/chest compressions, airway, breathing) model. This allows for the immediate initiation of effective compressions.26
The AED manufacturers are incorporating these 2010 guidelines into their devices. There is an emphasis on high-quality CPR, allowing for adequate chest recoil and at least 100 compressions per minute. Some manufacturers offer a software upgrade that may be downloaded into existing AEDs.
The initial energy dose varies per manufacturer. Most adult pads will deliver 200 J with the first shock and then 360 J. Some adult pads come as 2 separate pads; some come as 1 unit that gets placed on the patient’s anterior chest.
The optimal energy dose required for pediatric defibrillation is unknown. Guidelines state that an initial energy dose of 2 J/kg to 4 J/kg of either waveform (monophasic or biphasic) is reasonable when treating ventricular fibrillation or pulseless ventricular tachycardia in infants and children. Doses higher than 4 J/kg and up to 9 J/kg may also be safe and effective.10 Most pediatric-specific pads will deliver 50 J.
One study compared AED use by untrained sixth-grade students versus trained paramedics and emergency medical technicians (EMTs) in mock cardiac-arrest scenarios.27 Mean time to defibrillation from arrival to scene was 90 seconds for the sixth-grade students and 67 seconds for the trained paramedics and EMTs. More important, there was no significant difference between the 2 groups in proper pad placement or clearing the victim before defibrillation. This study showed that AEDs are easy to use and supported the theory that untrained bystanders could successfully use the AEDs just by following the device’s visual and audio prompts.
Another study looked at pediatric residents’ time to defibrillation using an AED versus a manual defibrillator during a mock pediatric cardiac arrest scenario.28 The residents were able to successfully defibrillate the mock pediatric patient using an AED in a median time of 60 seconds, whereas the median time to defibrillation for those using the manual defibrillator was 103 seconds.
On-scene bystander AED use can save lives. One study demonstrated that onsite AED use decreased defibrillation time from 11 minutes to 4.1 minutes and doubled neurologically intact survival rates.29 Although untrained bystanders may successfully use an AED by following the device’s visual and audio prompts, studies have shown that formal training is more effective because proper AED use in conjunction with proper CPR delivery results in even higher survival rates.30,31
Public access defibrillation (PAD) programs are structured to place AEDs in the hands of trained laypersons. These programs mandate proper training and use of equipment. In 2004, the Public Access Defibrillation Trial investigators published results of a prospective, community-based, multicenter study involving 19,000 lay volunteers trained in CPR alone or in CPR and the use of an AED from 993 communities across 24 North American regions.32 Investigators randomly assigned community units (shopping malls and apartment complexes) to a structured, monitored emergency-response system. The primary outcome was survival to hospital discharge.
The study showed a greater number of survivors to hospital discharge in units with volunteers trained in CPR plus the use of AEDs (30 survivors among 128 arrests) than there were in the units with volunteers trained only in CPR. More important, the laypersons could use the AEDs safely and effectively in a variety of public locations.
Public access defibrillation programs and lay rescuer AED programs are successful if there is medical provider oversight, training of anticipated rescuers in CPR and proper use of the AED, coordination with the EMS system, appropriate device maintenance, and ongoing quality improvement (Table 1).33 This allows for a focus on planning for a coordinated response to life-threatening conditions in public places rather than focusing on a single piece of equipment. It is best to establish these programs in areas where the EMS call-to-shock time is more than 5 minutes. The AED should be well marked in a central, secure, easy-to-access location near a phone so that EMS may be notified.
There has also been an increasing emphasis on the need for PAD programs in schools. In addition to their guidelines for successful PAD and lay rescuer programs, the AHA also highlights specific core elements of school emergency medical response systems (Table 2).33 These include rapid, efficient, and effective communication within the school and with EMS. The AHA also recommends a coordinated and practiced response plan, risk reduction, and training and equipment for first aid and CPR. School-based programs have the potential to save lives of children, adolescents, and adults.34,35
Some potential AED users may have concerns about liability. Fortunately, all 50 states have passed legislation or regulations that extend Good Samaritan limited immunity to lay rescuers who, without specific compensation, use an AED in a good-faith effort to save a life.
Additionally, the Cardiac Arrest Survival Act of 2000 required that federal guidelines be established for AED placement and lay rescuer AED programs in federal buildings. The act provides limited immunity for anyone who attempts to use an AED for a victim of perceived medical emergency. It also provides limited immunity for persons who acquire the device for anticipated future use. In such instances, local emergency response personnel or other appropriate entities must be notified of the placement of the AED within a reasonable period of time, the device must be properly maintained and tested, and the acquiring entity must provide appropriate training in the use of the device to expected users.36
In 2006, the AHA recommended that states adopt a legislative approach to support PAD programs.37 However, a recent study looking at individual state laws found that these essential elements are not required in all states.38 Investigators conducting a document review of laws in 51 jurisdictions, the 50 states and District of Columbia, as of January 1, 2010, found that only 60% of all jurisdictions require AED maintenance, less than half require medical oversight of the program, and only 1 in 4 jurisdictions requires continuous quality-improvement planning.
Nonetheless, individual PAD programs should be vigilant and adhere to AHA guidelines, because quality improvement and continuing education are vital elements that optimize success of these programs.
Cardiopulmonary resuscitation and AED skills may decay rapidly if not routinely used.39 First responders therefore need frequent practice in order to optimize their proper response to emergencies.
Lay rescuer programs, including school-based programs, need continuous quality improvement that analyzes performance of their emergency response plan, their equipment, and their responders. Several recent studies looked at methods for enhancing responders’ performance through new technology. In 1 study, a reminder video clip on a mobile phone was used to increase CPR and AED retention skills in lay responders.40 Another study developed a “Mobile AED Map” that allowed participants to decrease travel distance to access AEDs.41 This emphasizes the importance of ongoing education, skill retention, and the need for ongoing assessment of existing programs’ proper performance and ease of access and communication.
Health care providers must also maintain resuscitative skills. The AHA’s Basic Life Support (BLS) training reinforces the importance of proper early CPR and defibrillation though use of an AED. Pediatric Advanced Life Support (PALS) courses provide more detail about basic rhythms, common arrhythmias, and skills to assess and stabilize at-risk patients, as well as AED use. Biennial certification in BLS and PALS is offered and recommended. More frequent education will help optimize resuscitative skills because studies have shown that these skills may diminish 3 to 6 months after training.42,43 Ongoing education through high-fidelity simulation training sessions can result in higher quality level of care during actual resuscitation events. Simulation gives providers increased familiarity with resuscitative equipment while improving team dynamics. This in conjunction with performance debriefing improves resuscitative efforts.43 Continuous quality improvement and ongoing education is therefore paramount at all levels from laypersons to trained health care providers.
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