February 7, 2022
by Bryan Waxman, BHSc(Hon.), DDS, Dip. Anaes.
The primary function of an automated external defibrillator (AED) is to convert certain fatal non-perfusing heart rhythms back into perfusing heart rhythms (producing a pulse that can provide oxygen to vital organs). They are now a required component of the Basic Life Support (BLS) training courses for healthcare providers such as dentists and dental personnel. So, why is it not mandatory to have these devices in dental offices across Canada? The only province where AEDs are mandated in dental offices is Québec.
Approximately 40,000 cardiac arrests occur each year in Canada (one cardiac arrest every 12 minutes). AEDs can be found in airports, casinos, theme parks, shopping malls and schools, and the list goes on. The one thing in common among these venues is they are stressful and/or airway-risk places that have at-risk populations (i.e. very young and elderly people). Take the examples of losing financial savings on black in a game of roulette or a fear of flying or a fear of roller coasters: Are these fears and stresses so different than going to the dentist for a procedure requiring local anesthesia and potentially even surgery? What follows is a brief review of AEDs and a discussion on their benefits versus the cost of mandating AEDs as a component of the dental office medical emergency kit.
How do AEDs work?
The Technology Explained
An AED’s most basic function is to analyze the electrical activity of the heart. Newer models have more added functions, such as measuring the depth and rate of chest compressions (with additional equipment) including voice prompts to improve some of these interventions. Additionally, they now measure the number of cycles of CPR given and store the information for any future inquests or for information for advanced healthcare providers in-hospital. AEDs can recognize two pulseless heart dysrhythmias where electricity (a “shock”) provides a cure. If these rhythms are recognized, the AED then advises for and enables defibrillation. One “shockable” rhythm is called (pulseless) ventricular tachycardia (V-Tach or pVT). Typically, the AED will recommend a shock when the ventricular rate is above 150 beats per minute in VT. The other shockable rhythm is called ventricular fibrillation (V-Fib or VF). The key factor is that an AED is only going to allow the electrical discharge if the victim is in one of these rhythms.
The AED has a microprocessor chip that interprets whether a shock is advised or not advised. These little micro-computers have greater than 90% sensitivity (delivering a shock when in fact it is necessary) and over 95% specificity (not delivering a shock when it is not necessary) for identifying the fatal rhythms described above.
Fortunately, AEDs are extremely user friendly. When they are to be used, the process is very simple and reliable. Just turning the machine on allows it to verbally guide the rescue efforts. The steps include placing the appropriate size pads (adult or pediatric) where indicated. Once the unit is on and the pads are attached, the computer within the machine instructs the rescuer(s) on the next steps. Initially the device will analyze the patient’s heart rhythm. If a shock is advised, it will ask the rescuer to charge the pads. Then it will ask all rescuers and bystanders to CLEAR the patient. Some AEDs deliver shocks on their own, while others activate a button that must be pushed to provide a shock.
As mentioned earlier, some newer AED models also verbally direct your manual efforts. They can tell you when to resume CPR and can count the 30:2 cycles before allowing the machine to analyze the rhythm again. It also records the time the event started and how many cycles have been completed so that if there is an investigation or review, the data is there.
The Importance of BLS
High quality CPR and EARLY defibrillation with an AED are the cornerstones for saving the lives of patients in cardiac arrest outside of a hospital setting. Dentists and their staff (as primary healthcare providers) should be able to recognize that a patient is not breathing and does not have a pulse and should be able to appropriately place defibrillator pads as part of their BLS training and medical emergency protocols. Ventricular fibrillation is the most likely rhythm to present in a patient in new-onset cardiac arrest. The goal of restoring spontaneous circulation is most likely achieved by using electrical conversion as quickly as possible.
Survival Rates and Defibrillation
Delivering a shock within the first minute of witnessed cardiac arrest has a success rate of up to 90%. Every minute a shock is delayed, the chance of survival decreases 7-10%. At five minutes, the survival rate is only 50%; the survival rate decreases to 30% at seven minutes. Emergency medical services, under ideal circumstances in a major city, usually would not arrive until after this seven-minute mark. AVERAGE AMBULANCE RESPONSE TIMES ARE UPWARDS OF 8-12 MINUTES. This is considerably longer than the above goal time for electrical therapy (i.e. under five minutes) and can significantly decrease the probability of saving lives.
American heart association Message to Healthcare Providers
“Healthcare providers with a duty to perform CPR should be trained, equipped, and authorized to attempt defibrillation (Class IIa).”1
Prevalence and Incidence of Cardiac Arrest in Dental Offices
In Europe, the incidence of cardiac arrest in dental offices is 0.003 annually, which is extremely low. In North America, the incidence is less than 0.002 annually in healthcare offices (including higher risk offices such as kidney dialysis centres). Cardiac arrest accounts for over 300,000 deaths in the United States alone each year.
Cost of AEDs
Generally, AEDs cost from $1300 (Phillips HeartStart) to $4000 (Zoll AED Pro) for the initial purchase.2 Accessories including pediatric pads cost approximately $100, and replacement adult pads cost around $150-$200.
It is imperative that the parts and batteries for your AED are checked for expiration and replaced accordingly. This should be done as per the manufacturer’s recommendations (usually every one to two years).
What about the Law?
There is encouragement from the provinces for bystanders to use an AED. Legally, rescuers will be protected under Good Samaritan acts. It’s important to note that each province is different and that all providers should check their provincial laws. The intent of such acts is to protect rescuers from liability based on the outcome of their intervention. All BLS courses provided for healthcare providers in Canada require education on the use of an AED. All dental providers and staff should have familiarity with the device and should have enough comfort to utilize the equipment if needed.
There is a clear tug-of-war for the justification to have all dentists purchase an AED and have it routinely serviced in their offices. The incidence of cardiac arrest in the dental office is very low. However, sicker patients are living longer and have multiple co-morbidities and medications. Furthermore, dentists routinely deliver drugs with vasoactive properties (e.g. epinephrine in local anaesthetic preparations) and many patients are apprehensive and stressed when they visit a dental office. Quéebec and numerous states in the USA have added AEDs as mandatory medical emergency equipment in dental offices.3,4
Dentists are trained to perform high-quality CPR and to use an AED effectively. All CPR recertification courses include detailed instruction on how to use the AED and these courses are mandatory for dental office personnel in all provinces. Additionally, the AED is a proven modality that saves lives for patients who require CPR.
Most cardiac arrests are in the elderly population and more infrequently in the paediatric population. Paediatric cardiac arrest is usually due to trauma, a congenital heart malformation or dysrhythmia (e.g. hypertrophic cardiomyopathy, long-QT syndrome) or from an acute respiratory event (which can happen with sedation providers working on paediatric patients). The cause of cardiac arrest in the elderly is often multifactorial. It can involve one predisposing factor but more commonly it is a combination of risk factors such as previous myocardial infarction, aortic stenosis, heart failure, severe kidney disease, electrolyte disturbances, or diabetes to name a few. More and more elderly patients are presenting to the dental office with these conditions. We also shouldn’t forget about our dental team members. They are also potential cardiac arrest victims.
More studies are needed on cardiac
arrests specifically in dental offices to help support the need for AEDs. However, considering the reasonable pricing as well as the AEDs crucial role in saving lives, they would seem to be an appropriate tool to have on hand in your practice. Here is a parting question: if your office has the misfortune of hosting a person in cardiac arrest, how prepared do you want to be knowing how critical AEDs are in saving that person’s life compared to CPR alone?
Oral Health welcomes this original article.
About the Author
Bryan Waxman is a Certified Dental Anaesthesia Specialist in private practice in Vaughan, Ontario. Dr. Waxman is a Diplomate of the American Dental Board of Anesthesia (ADBA) and a Past President of the Canadian Academy of Dental Anaesthesia (CADA) and served as a clinical instructor in Dental Anaesthesia Department at the University of Toronto in the Paediatric Surgicentre for over 10 years.