Defibrillation: Understanding Its Importance in Emergency Situations

Defibrillation is a life-saving method that uses a defibrillator to give an electric shock to the heart. It's crucial during heart emergencies like ventricular fibrillation and pulseless ventricular tachycardia. This shock helps stabilize irregular heartbeats quickly, preventing sudden cardiac arrest and increasing the chances of survival. Having automated external defibrillators (AEDs) in public places stresses the importance of knowing about electrical cardioversion for emergency medical care. This article explains what defibrillation is its purpose, how it works, and why it's vital for saving lives during heart crises.

What is Defibrillation?

Defibrillation is a medical procedure that restores a normal heart rhythm in individuals experiencing cardiac arrhythmias. During these arrhythmias, the heart's electrical signals become disorganized, leading to ineffective pumping of blood.

During the procedure, a defibrillator is used to send a controlled electric shock to the heart. This shock briefly stops the chaotic electrical activity, giving the heart's natural pacemaker cells a chance to take over and restore a steady and effective rhythm.

The purpose of defibrillation is to stop abnormal heart rhythms, prevent sudden cardiac arrest, and improve the chances of successful resuscitation. It's a critical step in emergency medicine, especially during heart emergencies, where acting quickly is crucial for saving lives.

What are the 2 types of Defibrillation?

Biphasic waveform and Monophasic Waveform Shocks are two types of electric shocks used in defibrillation. In studies involving 552 individuals experiencing out-of-hospital cardiac arrest, researchers investigated the effectiveness of two types of electric shocks in restarting their hearts. The analysis included four studies, each varying in methodological rigor. Results indicated that the use of biphasic shocks did not significantly outperform monophasic shocks in successfully restarting the heart. Whether administered as the initial shock or following subsequent attempts, both types of shocks demonstrated similar rates of success. Additionally, there was no noticeable difference in the likelihood of survival before or after hospital admission between the two methods.

What are the basic principles behind defibrillation?

The basic principles of defibrillation involve applying a controlled electric shock to the heart to restore its normal rhythm. Here's a breakdown of these principles:

  1. Identifying Cardiac Arrhythmias: Defibrillator is used for specific life-threatening heart rhythm problems, where the heart's electrical activity becomes chaotic.
  2. Administering the Electric Shock: A defibrillator sends a controlled electric shock to the heart muscle through electrodes placed on the chest. This shock aims to temporarily stop the chaotic electrical activity.
  3. Depolarizing the Heart Muscle: The electric shock simultaneously depolarizes the entire heart muscle. This brief pause in electrical activity allows the heart's natural pacemaker cells to take charge and restore a coordinated rhythm.
  4. Stopping Abnormal Rhythms: The main goal is to stop abnormal heart rhythms, especially those that leads to sudden cardiac arrest, and restore a regular pumping rhythm.
  5. Importance of Timing: The chances of success decrease rapidly with each passing minute during a cardiac emergency, so prompt defibrillation is crucial for survival.
  6. Different Types of Defibrillators: There are two main types of defibrillators—automated external defibrillators (AEDs) and manual defibrillators. AEDs are designed for use by non-professionals and provide automated prompts for ease, while manual defibrillators are used by trained healthcare pros, offering more control and flexibility.

Types of Defibrillators

There are two main types of defibrillators: automated external defibrillators (AEDs) and manual defibrillators. Each type serves a specific purpose and is used in different settings:


Automated External Defibrillators (AEDs)

AEDs are user-friendly devices designed for quick deployment in public spaces. They are accessible to individuals with minimal or no medical training. Equipped with voice prompts, AEDs automate the defibrillation process, analyzing the heart rhythm and guiding users through the necessary steps. The purpose of AEDs is to provide rapid and automated intervention in the early stages of cardiac emergencies.


Manual Defibrillators

Manual defibrillators are used by trained healthcare professionals and offer advanced control and flexibility. These devices allow for manual assessment of the patient's cardiac rhythm using electrocardiogram monitoring. Healthcare professionals selects and adjust the energy level of the electric shock based on the patient's needs. Manual defibrillators are essential in clinical and pre-hospital settings where skilled operators can customize the treatment for more complex medical situations.


The Critical Role of Defibrillation in Emergency Medicine

Restoring normal heart rhythm is crucial in emergency medicine, particularly during cardiac arrests. Its importance lies in its ability to quickly address life-threatening heart rhythm problems, preventing sudden cardiac arrest and improving the chances of successful resuscitation. The idea of the "chain of survival" outlines the steps needed to maximize survival in cardiac emergencies, with a defibrillatorbeing a key step in this process. 

Defibrillation's Role in the Chain of Survival

Defibrillation is a crucial step in the chain of survival, positioned as "early defibrillation." Acting quickly to apply a defibrillator is vital for stopping chaotic heart rhythms, which is key to preventing sudden cardiac arrest. Whether it's bystanders or healthcare pros using AEDs, timely restoration significantly boosts the chances of restoring a normal heart rhythm and improves overall survival rates. Recognizing and prioritizing defibrillation's role in this sequence is essential for effective emergency response and saving lives during heart emergencies.

Recent research highlights defibrillation's importance in boosting survival during cardiac arrests. When a cardiac arrest is witnessed, giving heart rhythom restoration as soon as possible improves survival rates. On the other hand, if it's not witnessed, delivering high-quality chest compressions for 90 seconds before defibrillation also help improve outcomes.

Defibrillation vs. Cardioversion

Defibrillation and cardioversion are medical interventions used to treat abnormal heart rhythms (arrhythmias), but they differ in their purpose, timing, and type of rhythm. Here are the main differences between defibrillation and cardioversion:

  • Timing: Defibrillation is used during cardiac arrest as an emergency intervention, while cardioversion is typically a planned, elective procedure for stable patients.
  • Patient Consciousness: Defibrillation is typically performed on unconscious patients in emergency situations. Cardioversion is usually performed on conscious patients, often with mild sedation.
  • Electrical Energy: Defibrillation involves high-energy shocks to stop chaotic electrical activity, while cardioversion uses lower-energy shocks to synchronize the heart's electrical activity.
  • Indications: Defibrillation is reserved for ventricular fibrillation or pulseless ventricular tachycardia during cardiac arrest. Cardioversion is used for stable patients with atrial fibrillation, atrial flutter, or certain supraventricular tachycardia.

What is Implantable Cardioverter Defibrillator ICD?

ICDs are devices implanted inside the body, specifically for individuals at high risk of cardiac arrest. Unlike AEDs, ICDs continuously monitor the heart's rhythm and deliver a shock automatically if a dangerous rhythm is detected. They offer long-term protection for those with known heart conditions that put them at risk of sudden cardiac arrest.


How to Use Defibrillator?

Using a defibrillator involves several steps:

  1. Assessment: Evaluate the patient's condition to determine if defibrillation is necessary, typically in cases of ventricular fibrillation or pulseless ventricular tachycardia during cardiac arrest.
  2. Prepare Equipment: Ensure that the defibrillator is ready for use, including checking electrode placement and ensuring a proper connection.
  3. Clear the Area: Communicate clearly to ensure everyone is clear of the patient, bed, or any conductive surfaces to prevent injury.
  4. Apply Electrodes: Place the defibrillator electrodes on the patient's chest following the recommended placement (typically anterior-posterior or anterior-lateral).
  5. Analyze Rhythm: The defibrillator will analyze the heart's rhythm and determine whether a shock is advised.
  6. Charge the Defibrillator: If a shock is advised, charge the defibrillator to the appropriate energy level measured in joules.
  7. Clear Again: Ensure everyone is clear of the patient, and then deliver the shock by pressing the defibrillator's shock button.
  8. Post-Shock Assessment: After the shock, reassess the patient's rhythm and vital signs. If needed, repeat the process.


Understanding the Joules

Defibrillators deliver electrical shocks in joules (J), representing the amount of energy discharged. Joules are units of energy used to quantify the strength of the electrical shock delivered during defibrillation. The energy level is crucial in achieving successful outcome. Common energy levels range from 120 J to 360 J, but there are several factors influencing the joule selection, including:

  • Type of Arrhythmia: The specific arrhythmia being treated influences the selection of joules. Higher energy levels is required for certain arrhythmias.
  • Patient Size: Larger patients requires higher energy levels to ensure effective penetration of the electrical impulse to the heart.
  • Electrode Placement: Proper electrode placement is essential for effective energy delivery. Ensure electrodes are appropriately positioned for optimal conduction.
  • Impedance: Impedance refers to the resistance encountered by the electrical current as it travels through the body. Monitoring impedance helps determine the energy needed for effective restoration.
  • Response to Previous Shocks: The patient's response to previous shocks influence the decision to increase or decrease the energy level in subsequent attempts.

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Special Considerations in Defibrillation

Defibrillation is a crucial intervention in managing life-threatening cardiac arrhythmias. Special considerations exist for pediatric defibrillation, advanced techniques like Dual Sequential Defibrillation, and various emergency scenarios.


Pediatric Defibrillation

For pediatric patients, different energy levels are recommended compared to adults. The American Heart Association (AHA) suggests using a dose of 2 J/kg for the first shock. If an AED with pediatric pads is available, it should be used. Pediatric pads attenuate the energy to an appropriate level for children.

If subsequent shocks are needed, the energy level is increased stepwise (4 J/kg and then 4–10 J/kg). For adolescents, adult energy levels is appropriate.


Dual Sequential Defibrillation

Dual Sequential Defibrillation involves using two defibrillators to deliver two simultaneous shocks to a patient in refractory ventricular fibrillation or pulseless ventricular tachycardia. This technique is not universally endorsed and is often based on local protocols and physician discretion. It typically involves placing two sets of pads on the patient and coordinating the delivery of shocks from two defibrillators.


Considerations for Different Emergency Scenarios

  • Traumatic Cardiac Arrest: Traumatic cardiac arrest requires modifications in approach and could involve addressing reversible causes related to trauma. Chest compressions and defibrillation are still crucial but must be integrated with trauma management.
  • Hypothermic Cardiac Arrest: In cases of hypothermic cardiac arrest, traditional guidelines recommend prolonged resuscitation efforts due to the potential for favorable outcomes. The threshold is lower in hypothermic patients.
  • Pregnancy: Special considerations apply to pregnant patients, such as manual displacement of the uterus to alleviate aortocaval compression during Cardiopulmonary Resuscitation. Standard defibrillation principles apply, with care taken to minimize interruptions in chest compressions.
  • Drug-Induced Arrhythmias: Some drug overdoses lead to life-threatening arrhythmias. Defibrillation is required in conjunction with antidote administration.

Can Defibrillation Be Performed Outside of a Hospital? 

Yes, defibrillation can be performed outside of a hospital setting. Automated External Defibrillators are equipped with easy-to-follow voice prompts and visual cues that guide users through delivering an electrical shock to the heart during sudden cardiac arrest. The prompt application of defibrillation is crucial in restoring a normal heart rhythm and improving the chances of survival. Many public places, such as airports, schools, and shopping centers, are equipped with AEDs to enhance the accessibility of this life-saving intervention in the community. Training in basic life support, including using AEDs, is recommended for individuals to respond to cardiac emergencies outside of a hospital setting effectively.

Who invented the Defibrillator?

Dr. Claude Beck invented the defibrillator in 1947, performing the first successful defibrillation on a human. However, the initial devices from this period were large, cumbersome, and necessitated open-chest procedures.

In the 1960s, Bernard Lown and William Kouwenhoven significantly advanced the field by developing the portable direct current (DC) defibrillator, which allowed for the external application of shocks. This marked a crucial step in improving accessibility. The 1970s witnessed the development of Automated External Defibrillators (AEDs), making them more user-friendly for non-medical personnel.

From the 1990s to the present, ongoing efforts have focused on miniaturization, resulting in more portable defibrillators applicable in various settings. Integrated monitoring capabilities and the incorporation of smart technologies further advanced the accuracy of rhythm analysis and the precise delivery of shocks.


What are the Recent Advancements in Defibrillation?

Recent studies highlight significant strides in public access defibrillation, showcasing its growing potential to enhance early intervention outcomes. Technological innovations enable the transportation of AEDs to locations experiencing cardiac arrests, whether in public or private settings. Additionally, emerging technologies have the capability to automatically identify and alert emergency medical services in cases of nonwitnessed out-of-hospital cardiac arrest (OHCA) that were previously untreated. Here are some recent advancements in defibrillation:

  1. Wearable Defibrillators: Advances in wearable technology have led to the development of wearable cardioverter defibrillators that continuously monitor heart rhythm. These devices automatically deliver a shock if a life-threatening arrhythmia is detected.
  2. Improved AED Technology: AEDs have become more intuitive with simplified interfaces, audio and visual prompts, and real-time feedback to guide users during resuscitation efforts. Some AEDs now offer pediatric pads and enhanced features for better adaptability.
  3. Dual Sequential Defibrillation: While not universally adopted, dual sequential defibrillation has been explored as an advanced technique for refractory cases. It involves using two defibrillators simultaneously to improve the chances of restoring a normal heart rhythm.
  4. Focused Ultrasound Defibrillation: Experimental research has been conducted using focused ultrasound, providing a potential non-invasive alternative to electrical shocks.
  5. Integration with Telemedicine: Defibrillators are being explored for integration with telemedicine platforms. This could allow for remote monitoring and guidance during emergencies, enhancing the reach and effectiveness of defibrillation.
  6. Personalized Therapy: There is a growing focus on tailoring defibrillation to individual patient characteristics. This involves considering age, comorbidities, and genetic predispositions to optimize treatment outcomes.
  7. Advanced Monitoring and Analytics: Continued advancements in monitoring technology, including artificial intelligence and machine learning, aim to enhance the accuracy of rhythm analysis and predict cardiac events more effectively.
  8. Nanotechnology and Biomedical Engineering: Ongoing research in nanotechnology and biomedical engineering leads to developing more efficient and targeted methods with reduced side effects.

Frequently Asked Questions

Here are the common questions about Defibrillator:

What's the difference between a defibrillator and a pacemaker?

A defibrillator and a pacemaker both help with heart problems, but they do different things. A defibrillator helps during emergencies by giving controlled electric shocks to fix dangerous heart rhythms. On the other hand, a pacemaker sends small electric signals to keep the heart beating regularly.

Can you have a heart attack with a pacemaker defibrillator?

Yes, even with a pacemaker or defibrillator, someone can still have a heart attack. These devices help with heart rhythm issues but don't stop heart attacks from happening.

What should you avoid when you have a defibrillator?

If you have a wearable defibrillator, avoid strong magnetic fields like those in MRI machines. Also, talk to your doctor about any sports or activities that might not be safe for you.

How much does a defibrillator cost?

On average, automated external defibrillators (AEDs) used in public places cost between $1,000 and $2,500. Implantable defibrillators, placed inside the body, typically range from $20,000 to $50,000. However, these costs vary depending on brand, features, and additional accessories.

What happens if you die with a defibrillator?

If someone dies with a defibrillator inside them, the device doesn't cause their death. It stays in the body and doesn't hurt anyone. Sometimes, doctors might check it during an exam to understand what happened.

Do you defibrillate asystole?

No, you don't defibrillate asystole. Defibrillation is for specific heart rhythm problems, not when the heart isn't beating.

Are there any risks or side effects associated with defibrillation?

Defibrillation is generally safe, but there are some potential risks and side effects. These include skin irritation or burns where the electrode pads are placed, muscle soreness, and, rarely, damage to the heart or surrounding tissues. However, the benefits of defibrillation in saving lives during cardiac emergencies usually outweigh these risks.

What should you do if a person doesn't respond to defibrillation?

If a person doesn't respond to defibrillation, it's crucial to continue CPR and follow emergency medical protocols. This includes performing high-quality chest compressions and ensuring proper airway management. Additionally, emergency medical services should be contacted immediately for further advanced care.

Can anyone use a defibrillator, or do you need special training?

While automated external defibrillators (AEDs) are designed to be user-friendly and used by individuals with minimal or no medical training, it's recommended to undergo basic training in CPR and AED use. Training helps you feel more confident and competent in using the device effectively during emergencies.


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Faddy SC, Jennings PA. Biphasic versus monophasic waveforms for transthoracic defibrillation in out-of-hospital cardiac arrest. Cochrane Database Syst Rev. 2016 Feb 10;2(2):CD006762. doi: 10.1002/14651858.CD006762.pub2. PMID: 26904970; PMCID: PMC8454037.