Suspicion Of Sudden Cardiac Arrest

*To take the corresponding CDE quiz, visit the College of Emergency Dispatch.*

It’s common for an Emergency Medical Dispatcher (EMD) to hear of a patient’s “sudden collapse.” Perhaps the caller has observed a student who “just slumped over and fell out of her seat,” a player who is “out cold after going for a layup,” or a visiting neighbor who “fell and is just lying on the rug.”

Each of these cases could have a different medical cause and appropriate response. However, when addressing a sudden, unexplained collapse, the EMD should maintain a strong suspicion of cardiac arrest “until proven otherwise,” according to the Medical Priority Dispatch System^™ (MPDS^®) (Chief Complaint Selection Rule 1).

Sudden cardiac arrest
Also called “sudden death,” sudden cardiac arrest (SCA) is a rapid, unexpected medical event caused by an abnormality in the heart’s electrical system. It stops oxygenated blood from flowing to the brain, the heart, and the rest of the body, causing nearly instantaneous loss of consciousness and collapse.

Unlike myocardial infarction (heart attack), which is characterized by recognizable symptoms of a building blockage, a victim of SCA may have no symptoms preceding a sudden interruption of the heart’s rhythm, causing them to lose consciousness before even recognizing the event.

As a leading cause of death in the United States, SCA is a national public health crisis with a higher number of fatalities than colorectal cancer, breast cancer, prostate cancer, influenza, pneumonia, auto accidents, HIV, firearms, and house fires combined.¹ The American Heart Association (AHA) statistics cite that SCA affects 1,000 people each day, of which nearly 90% of out-of-hospital events are fatal.²

Sudden cardiac arrest can strike at any age, but the numbers are especially sobering among young athletes. Over 7,000 children die from SCA every year, with two-thirds of these events occurring during exercise or while playing sports.³

SCA also comprises a third of catastrophic injuries in professional sports.⁴ This may be in part due to athletes’ intense physical activity or direct trauma to the chest, though atypical SCA events may also include genetic/ congenital electrophysical or structural heart problems that have gone undetected all their lives.

Between 2002 and 2015, sports-related SCA accounted for 39% of SCAs among those under age 18, 13% among those ages 19–25, and 7% for those ages 25–34.⁵ These statistics were brought to the spotlight in January 2023 when Buffalo Bills’ Safety Damar Hamlin shocked concerned crowds when he collapsed on the field during an NFL game against the Cleveland Browns. A few months later in July 2023, Bronny James, the son of NBA star Lebron James, suffered an SCA during practice with his basketball team at the University of Southern California.⁶

Fortunately, both players survived due to receiving immediate lifesaving care, demonstrating the critical need for schools to be equipped with AEDs and provided with relevant training on how to use them, which is an ongoing effort.

Dr. Dermot Phelan, NFL and MLB cardiology consultant, said, “In the vast majority of SCA cases that happen at recreational facilities across the country, defibrillators are not used, even when they are available.”⁷ Frustratingly, statistics show that laypeople rarely use AEDs (5.8%) and even fewer provide a subsequent shock (1.3%).⁸

Not using these lifesaving efforts due to lack of access, panic, ineffective communication, or inadequate training has tragic outcomes. Research shows that every minute a cardiac arrest victim doesn’t receive a shock from an AED, their chances of survival are reduced by 7–10%. As average EMS response times in the U.S. are between 8 and 12 minutes, early bystander defibrillation is vital to saving the lives of SCA victims.⁹

In the MPDS, Brock’s Law, named after SCA victim 16-year-old Brock Ruether, reminds the EMD that “The presence of an AED does not ensure its use—the EMD does.”

Case Entry interrogation: clinical description 

A critical commonality among sudden collapse patients is their unconscious state, signaling a potentially life-threatening condition that requires quick assessment and appropriate intervention to improve patient outcomes.

The MPDS Case Entry Protocol’s clarifying questions build upon the caller’s observation of the event to collect a clinical description of the patient’s status. By asking “Is s/he awake (conscious)?” and “Is s/he breathing?” the EMD can evaluate the possibility of cardiac arrest.

If the patient is not awake and not effectively breathing, the Case Entry Protocol immediately sends an ECHO-level response and leads the EMD to provide essential CPR and AED instructions. (Notably, however, Fast Track and other ECHO-level responses are limited by safety factors and intervention viability.)

Brett Patterson, IAED™ Medical Council of Standards Chair, said, “The EMD’s primary focus should be differentiating the potential for medical cardiac arrest from other potential complaints, including seizures, ground-level falls, and fainting.” Misclassification often results from not knowing exactly what happened at Case Entry.

Seizures vs. SCA
The well-trained EMD must understand the underlying complexity in distinguishing between patients with sudden cardiac arrest vs. seizing patients, as both can be described as displaying “seizure-like activity.”

SCA: seizure-like hypoxia
In an SCA patient, “seizure-like activity” is due to hypoxia, a lack of oxygen to the brain, which presents as rigid spasms that are more like involuntary “posturing.”

For instance, decorticate posturing may display as a stiff body with straight legs, clenched fists, and arms close to the sides. Decerebrate posturing is where the arms are tensed and rotated toward the body’s center, with the back arched or stiff.¹⁰ These indications are generally associated with coma or brain trauma, a need for extreme medical intervention, and poor outcomes.

Callers will often describe these observations this way: “It kind of looks like he’s having a seizure.” This could mean that the patient is experiencing rigidity or stiffening in unnatural positions. Or the patient is presenting with seizure-like activity that the caller recognizes as similar to a typical seizure, but less conclusively identifiable. Callers may also report gasping (agonal breathing) and rapid deterioration or “life draining.” Interestingly, and relevant to the EMD’s goal of early recognition, patients who are gasping are more likely to survive an SCA event than those who are not, simply because agonal respirations are an early sign of SCA.

GENERALIZED seizures
Patients with true seizures often present ongoing convulsions rather than spasms. These symptoms are reliably recognized by callers and are the most common cause of sudden unconsciousness reported to dispatch.

Seizing patients typically recover without intervention within minutes, slowly resuming normal breathing on their own. A true seizing patient requires extra time to monitor and allow the seizure to pass so that serious causes can be ruled out and appropriate instructions can be provided. (The first Rule on Protocol 12: Convulsions/Seizures reminds the EMD that use of the Breathing Verification Diagnostic Tool is mandatory after the jerking/twitching has stopped.)

Furthermore, most patients experiencing a GENERALIZED seizure have a history of seizures, which the caller would report if known and applicable. In fact, a person’s chance of SCA with a complaint of “seizure” is decreased by 75% when the patient has a history of seizures.

When listening to calls known to be cardiac arrest versus GENERALIZED seizure, Patterson can clearly identify the differences in the caller’s complaint description and patient’s presentation. “We just need to better educate EMDs to more easily differentiate the conditions,” he said.

Chief Complaint Selection Rule 13 gives guidance to the EMD on this issue: “When the complaint description strongly suggests GENERALIZED seizure, go to Protocol 12 regardless of consciousness and breathing status. If the scenario is atypical of GENERALIZED seizure, and is more typical of sudden cardiac arrest, go to [Protocol 9: Cardiac or Respiratory Arrest/Death]."

Ground-level falls vs. SCA 
When the caller reports a patient who has suddenly “fallen” and is now unconscious, it’s difficult to determine if what the caller reported visually is the offending cause medically. In essence, did the fall cause the patient’s unconsciousness, or did the patient’s lapse in consciousness cause the fall?

With the exemption of external factors such as falling from an extreme height or suffering another severe trauma, the answer is usually in favor of sudden cardiac arrest. “Ground-level falls are very unlikely to cause sudden unconsciousness,” Patterson said. “That’s simply because they do not involve a mechanism of injury capable of that result.”

That’s why the first Rule on Protocol 17: Falls states, “Always consider that the patient’s fall may be the result of a medical problem (fainting, heart arrhythmia, stroke, etc.).” SCA cases are often reported as “falls” simply because the fall is what the caller sees.

This proves the importance of the EMD understanding exactly what happened (the event or scenario) while addressing the clinical finding (the patient’s unconsciousness). “A sudden collapse with no known cause resulting in unresponsiveness is highly suggestive of SCA,” Patterson said, “even when the complaint is a ground-level fall.”

Fainting/Unconsciousness vs. SCA
The EMD’s selection of Protocol 31: Unconscious/Fainting (Near) has long been known to catch inadvertent cardiac arrest outcomes (meant to be handled on Protocol 9: Cardiac or Respiratory Arrest/Death). This mistaken trajectory is primarily caused by the caller’s report of “effective breathing” for an unconscious patient during Case Entry.

According to Patterson, this initial misclassification is complicated by the known difficulties of the EMD differentiating AGONAL/INEFFECTIVE BREATHING from effective breathing based on the caller’s description.

For this reason, an immediate fail-safe was created within the Key Questions on Protocol 31: “Is her/his breathing completely normal?” If not, the EMD is required to use the Breathing Verification Diagnostic Tool to assess the unconscious patient.

As the first Rule on Protocol 31 states, “An unconscious person whose breathing cannot be verified by a 2nd party caller (with the patient) is considered to be in cardiac arrest until proven otherwise.” 

Although there are several potential causes of sudden unconsciousness unrelated to cardiac arrest (e.g., diabetic problems, irregular heart rhythm, respiratory insufficiency, STROKE), the EMD must keep in mind the importance of understanding the initial circumstances or presentation of the event in properly addressing the needs of the patient.

Conclusion
Ultimately, the EMD fulfills a crucial role in quickly recognizing and addressing SCA cases because providing critical CPR and AED instructions can significantly increase the patient’s chances of survival. Though GENERALIZED seizures, ground-level falls, and other causes of unconsciousness can mimic the initial symptoms of an SCA event, the experienced EMD can distinguish between these scenarios while trusting the protocol’s collection of data and unique pathways to guide each call.

Sources
1. “SCA Statistics.” Avive Solutions, Inc. 2024. avive.life/facts/#:~:text=SCAisaleadingcausetobeingoodhealth (accessed Oct. 21, 2024).
2. Newman, MM. “Latest Statistics,” Sudden Cardiac Arrest Foundation. sca-aware.org/about-sudden-cardiac-arrest/latest-statistics (accessed Oct. 21, 2024).
3. “Data Doesn’t Lie: AEDs in Schools are Proven to Save Lives.” Avive Solutions, Inc. 2024. avive.life/industry-guides/aed-school/school-defibrillator-facts (accessed Oct. 22, 2024).
4. “Damar Hamlin Injury Shocked the Nation: One Year Later.” Atrium Health and Sanger Heart & Vascular Institute. 2024; Jan. 9. atriumhealth.org/about-us/newsroom/news/2024/1-january/damar-hamlin-injury-shocked-the-nation-one-year-later (accessed Oct. 21, 2024).
5. See note 2.
6. See note 4.
7. See note 4.
8. See note 2.
9. See note 3.
10. Allen S, Biggers A. “Abnormal Posturing.” Healthline. 2021; Aug. 5. healthline.com/health/neurological-health/abnormal-posturing (accessed Oct. 7, 2024).