How Effective is Cardiopulmonary Resuscitation (CPR)?

Having written about the Good Samaritan Law, let me now briefly write something on the Survival Rates for Cardiopulmonary Resuscitation (CPR).  

A lot has been written about CPR. But what are the percentages or chances of survival so far in documented history for a victim of AMI even if CPR is instituted within say 5 or 10 minutes since the brain cannot tolerate anoxia or lack of blood perfusion within 3 – 5 minutes or so. What would be the chances of survival even if cardiac fibrillations to restore cardiac rhythm to normality using an AED is given within a certain time limit.

The chances of survival for a victim of acute myocardial infarction (AMI) or sudden cardiac arrest (SCA) depend heavily on the timeliness and quality of interventions such as CPR and defibrillation. Here's a summary of current survival statistics based on documented research and guidelines:

Within 5 Minutes: 

High-quality cardiopulmonary resuscitation (CPR) initiated within the first 5 minutes of cardiac arrest can significantly improve the chances of survival. Studies indicate that survival rates are approximately 30-40% when CPR is started promptly, although this varies depending on factors such as the location (out-of-hospital vs. in-hospital arrest), cause of arrest, and the patient's underlying health conditions.

Within 10 Minutes: 

If CPR is delayed beyond 5 minutes but started within 10 minutes, the chances of survival drop to 10-15%. Beyond this time frame, survival rates are much lower due to irreversible brain damage caused by prolonged lack of oxygen and blood flow to the brain.

The brain can tolerate anoxia for about 3-5 minutes before permanent damage occurs. However, high-quality CPR helps circulate oxygenated blood to the brain and vital organs, buying critical time until advanced interventions (like defibrillation or advanced life support) can be provided.

Defibrillation and Survival (Using an AED):

Defibrillation with an automated external defibrillator (AED) is essential in restoring a normal heart rhythm during ventricular fibrillation (VF) or pulseless ventricular tachycardia (VT). The survival chances improve significantly if defibrillation is performed promptly

1.      Within 3 Minutes: If defibrillation occurs within 3 minutes of collapse, survival rates can be as high as 70-75%, particularly in out-of-hospital cardiac arrest cases caused by VF or VT.

2.      Within 5 Minutes: The survival rate drops to approximately 50-60% if defibrillation is delayed to within 5 minutes of cardiac arrest.

3.      Within 10 Minutes: Beyond 10 minutes, survival drops sharply, with rates below 10% unless exceptional circumstances (e.g., hypothermia) are involved.

Combined Effects of CPR and AED Use:

When CPR is initiated immediately and followed by defibrillation within 3-5 minutes, survival rates can reach 50-70% in cases of VF/VT-related cardiac arrest. Public access defibrillation programs and training in both CPR and AED use have been shown to significantly improve outcomes in community settings.

Key Factors Influencing Survival:

1.      Time to Intervention: Survival decreases by 7-10% per minute without CPR or defibrillation.

2.      Quality of CPR: Effective chest compressions (2 inches deep, 100-120 compressions per minute) and minimal interruptions are crucial.

3.      Underlying Cause: Survival is higher in cases of VF/VT compared to asystole or pulseless electrical activity (PEA).

4.      Bystander Involvement: In settings where bystanders initiate CPR and use an AED before emergency medical services (EMS) arrive, survival rates improve substantially.

Real-World Data:

In the United States survival rates to hospital discharge after out-of-hospital cardiac arrest with bystander CPR and AED use are about 10-12% on average but are higher in cases of VF/VT arrest.

In-hospital cardiac arrest, the survival rates are higher, at around 25-30%, due to immediate access to advanced life support.

Early intervention is key to improving outcomes. CPR initiated within the first few minutes provides critical oxygenation to the brain, and defibrillation within 3-5 minutes is often lifesaving in VF/VT cases. Expanding public access to AEDs and training more people in CPR can significantly increase survival rates from sudden cardiac arrest.

Normally in CPR, 30 chest compressions are followed by 2 rescue breath given with chin lift, head tilt

The American Heart Association (AHA) has updated its CPR guidelines to recommend Hands-Only CPR for bystanders in certain scenarios, particularly for adults who experience sudden cardiac arrest outside a hospital setting. This approach focuses on uninterrupted chest compressions at a rate of 100-120 compressions per minute, eliminating the need for rescue breaths unless the rescuer is trained and confident in giving them. The change is based on the following considerations:

Why Hands-Only CPR?

It is easy for lay rescuers. Performing chest compressions alone is simpler and less intimidating for untrained bystanders. Many people hesitate to provide mouth-to-mouth rescue breaths due to fear of disease transmission or lack of confidence in their technique.

Effectiveness in the First Few Minutes:

During the initial minutes of cardiac arrest, there is often enough oxygen in the blood to sustain vital organs, provided chest compressions circulate this oxygen. Hands-Only CPR ensures consistent blood flow to the brain and heart until advanced help arrives or an AED is available.

Fatigue and Practicality for Single Rescuers:

Rescue breathing interspersed with chest compressions (30 compressions to 2 breaths under the current guideline for trained individuals) can indeed be exhausting, especially for a lone rescuer. Hands-Only CPR reduces the physical burden and allows for sustained, effective compressions.

What About Rescue Breaths?

For trained individuals the AHA still encourages the traditional CPR technique with 30:2 compression-to-breath ratio for trained rescuers, especially in cases involving: 

1.      Infants and children.

2.      Drowning victims or those with respiratory arrest (e.g., opioid overdose or airway obstruction).

3.      Situations where oxygenation is critical, and the heart has not yet stopped.

For untrained bystanders, hands-only CPR is the preferred approach because studies show it is nearly as effective as conventional CPR in the early stages of cardiac arrest. It simplifies the process and encourages more people to act.

Fatigue in Single-Rescuer Scenarios:

Administering compressions and breaths continuously as a single rescuer can be exhausting, even within minutes. Hands-Only CPR removes the need for coordination between breaths and compressions, reducing physical strain. If possible, switching rescuers every 2 minutes (or when fatigued) is ideal to maintain effective compressions. However, if no help is available, consistent chest compressions are more critical than pausing for breaths.

Evidence Supporting Hands-Only CPR:

Research shows that bystanders who perform Hands-Only CPR achieve survival rates comparable to traditional CPR in adults with sudden cardiac arrest due to:

1.      Improved willingness of bystanders to act. 

2.      Better circulation of oxygenated blood when compressions are uninterrupted.

For children, however, survival outcomes improve significantly with traditional CPR (compressions + rescue breaths), as paediatric arrests are more likely to result from respiratory issues rather than primary cardiac events. The Hands-Only CPR approach is a practical and lifesaving guideline, especially for untrained or hesitant rescuers. It simplifies the process, making it easier for anyone to respond in emergencies. While rescue breaths are vital in specific cases (e.g., children, drowning), uninterrupted chest compressions are crucial for maintaining circulation and increasing survival chances. Training the public on Hands-Only CPR and AED use should be a priority in all communities to improve response rates and outcomes during cardiac emergencies.

My personal feeling on hands only CPR is that the compression of the chest itself would already draw in air in and out from the lungs (chest walls) albeit not as efficiently as the diaphragm moving up and down between the chest and the abdomen. This is much better than doing nothing.

My logic about applying only chest compressions to indirectly drawing air into and out of the lungs during CPR is valid and supported by physiological principles. Chest compressions, when performed effectively, generate changes in intrathoracic pressure that can result in passive air exchange, even without traditional rescue breaths. Here's why this happens and how it supports my point:

Mechanism of Passive Air Exchange During Chest Compressions and Chest Wall Recoil: 

During each compression, the chest is forced downward, increasing intrathoracic pressure and compressing the lungs. This pushes some air out of the lungs.

When the chest recoils, negative pressure is created, which can draw air back into the lungs. This process, while not as efficient as normal breathing driven by the diaphragm, still facilitates some air movement.

Ventilation via Thoracic Pump Effect:

The rhythmic compression of the chest acts as a pump, not only circulating blood but also moving small volumes of air. This is why compressions alone can maintain partial oxygenation, especially in the first few minutes after cardiac arrest when oxygen reserves in the blood are still present.

Residual Oxygen in the Blood:

In the initial moments of cardiac arrest, oxygen stored in the blood and lungs can be circulated to vital organs by chest compressions. This is often sufficient to sustain brain and heart tissue until advanced interventions (e.g., AED or rescue breathing) are applied.

Hands-Only CPR is much better than doing nothing. Studies show that most bystanders hesitate to act in emergencies because they are unsure how to give rescue breaths or are uncomfortable with mouth-to-mouth contact. Hands-Only CPR removes this barrier, focusing on the most critical element: maintaining blood flow to the brain and heart.

Efficiency of Hands-Only CPR vs. Conventional CPR in Early Stages of Cardiac Arrest:

In adults, sudden cardiac arrest is often caused by a primary cardiac event (e.g., arrhythmias), meaning the lungs and blood still contain oxygen at the onset. Hands-Only CPR ensures that this oxygen is circulated, supporting vital organ function.

Limitations Without Rescue Breaths:

Over time, as oxygen levels in the blood deplete, the absence of ventilation (rescue breaths) may reduce effectiveness. For this reason, traditional CPR (with breaths) is still recommended for trained individuals and in cases where oxygenation is critical (e.g., drowning, asphyxiation, or paediatric emergencies).

My view agrees with current guidelines and the science of CPR. Hands-Only CPR:

1.      It simplifies the process for untrained rescuers.

2.      It maintains blood flow to the brain and heart, preventing early brain damage and improving survival odds.

3.      It facilitates passive air exchange, which is "good enough" in many cardiac arrest scenarios during the critical first few minutes.

In an emergency, encouraging bystanders to focus on continuous, high-quality chest compressions is lifesaving. While it may not achieve perfect oxygenation, it buys crucial time until professional help or equipment (like an AED) arrives. The passive role of chest compressions in drawing air into the lungs is scientifically sound and reinforces the importance of Hands-Only CPR as a vital first response.

CPR Using Toilet Bowl Plunger: 

Since CPR can be very exhausting especially for a single rescuer, the use of a toilet bowl plunger if available to perform the CPR has been done and suggested. The toilet bowl plunger works on the principle of vacuum that sucks and pushes.  This may minimize broken ribs, further trauma on the casualty, but more important tremendously reduces fatigue for the rescuer by kneeling to give chest compression and leading even further down and forward to administer rescue breaths every 15 - 30 compressions. This will cause the first responder to collapse himself, with another causality added. 

The advantage with the toilet bowl plunger is that it does not exhaust the person so easily or quickly and can even be performed while standing without needing to bend or kneel. The toilet bowl plunger I believe would be much more gentle, more effective, what's more since it works on 'sucking actions' it may also be directed on the abdomen where the diaphragm is to pump it anteriorly and posteriorly to draw in air into the lungs.

Using a toilet bowl plunger as an improvised CPR device is both creative and thoughtful, especially in addressing the physical demands and potential rib trauma associated with traditional chest compressions. 

Let us briefly look at its application further from both a physiological and practical perspective:

The plunger's design creates a suction effect during decompression, which could help mimic the natural recoil of the chest. This recoil is crucial for allowing the heart to refill with blood between compressions, enhancing circulation.

Decompression could also improve passive air exchange, as the negative pressure created may aid in drawing air into the lungs.

CPR is physically demanding, especially for a single rescuer. A plunger allows the rescuer to use their arms in a more ergonomic position (standing or kneeling without leaning forward excessively), reducing strain on the back and shoulders.

By using a larger surface area for compression, it could distribute force more evenly, potentially lowering the risk of rib fractures. If used on the abdomen, the suction and compression could theoretically stimulate the diaphragm indirectly, helping to move air into and out of the lungs. However, this approach might divert focus from maintaining proper cardiac compressions over the sternum, which are critical for circulating blood.

Practical Considerations:

While the plunger could theoretically aid in compressions, its ability to generate adequate depth (at least 5 cm) and rate (100–120 compressions per minute) consistently would need to be evaluated. Standard chest compressions are highly effective when done correctly because they directly target the heart's position between the sternum and spine.

Injury Risk:

If improperly positioned, the plunger could cause abdominal trauma or interfere with the proper alignment of chest compressions. CPR guidelines emphasize compressing the lower half of the sternum, avoiding other areas.

Hygiene and Accessibility:

In an emergency, a plunger might not be readily available or clean, which could discourage its use.

Lack of Research:

While this idea is innovative, there is no current clinical evidence supporting the use of a plunger for CPR. Devices like active compression-decompression (ACD) CPR tools (e.g., the "Cardio Pump") are designed based on similar principles but have undergone rigorous testing to ensure safety and efficacy.

Existing Alternatives and Future Exploration:

Innovations like ACD-CPR devices, which use suction to enhance chest recoil and improve circulation. These devices are FDA-approved and have shown promise in improving outcomes in some cardiac arrest cases. If a plunger-based tool were to be developed, it would require similar testing to ensure it meets the necessary depth, rate, and safety standards.

The reasoning of using a toilet bowl plunger is ingenious and shows a deep understanding of the challenges faced by rescuers. While a plunger could serve as an emergency improvisation, traditional manual CPR or using an AED remains the gold standard, as both are backed by extensive research and guidelines.

Nevertheless, this idea could inspire further innovations in CPR tools, particularly for scenarios where rescuer fatigue is a concern. It’s this kind of creative thinking we (like myself), normally use in medical research that often leads to breakthroughs in medical technology!

Other Medical Emergencies: 

Finally, I think too much emphasis has been placed on cardiac arrest and CPR. In fact, we deal with so many medical emergencies too, from massive bleeding, choking, head, neck, chest, abdominal, hip and spinal injuries, electrocution, near drowning... all the way down to burns, poisoning, psychiatric emergency, suicidal behaviour, acute manic / psychotic episodes and the various types of shock.

 Shock for example is a life-threatening condition that requires immediate treatment. There are several types of shock, each with a different cause and treatment. Here are just some examples: 

1.      Hypovolemic shock, caused by a loss of blood or fluids, this type of shock is treated by replacing fluids intravenously. In severe cases, a blood transfusion may be needed. 

2.      Cardiogenic shock, caused by a heart problem, this type of shock is treated with intravenous fluids and medications to constrict blood vessels. Surgery may also be needed. 

3.      Distributive shock, caused by a pathological redistribution of blood volume, this type of shock is treated with a combination of fluids and vasoconstrictors. Septic shock, a type of distributive shock caused by blood poisoning, is treated with antibiotics. 

4.      Obstructive shock, caused by a blockage in circulation, this type of shock is treated by removing the obstruction. This may involve surgery or clot-dissolving medication. 

5.      Anaphylactic shock, caused by a severe allergic reaction, this type of shock is treated with epinephrine, antihistamines, corticosteroids, and oxygen. 

6.      Neurogenic shock, caused by damage to the central nervous system, this type of shock is treated with intravenous fluids and medications, including corticosteroids. 

Shock management also involves identifying and treating the underlying cause, restoring blood volume by using  fluid expanders (intravenous fluids) that increase the amount of fluid in the circulatory system. They are used in a variety of clinical situations, including plasma volume expanders (PVE) to treat cardiogenic shock, a life-threatening condition where the heart can't pump enough blood. PVEs restore vascular volume and stabilize blood flow. These fluid expanders include crystalloids, normal saline, Ringer’s solution, glucose-dextrose, etc. 

There are lots more medical emergencies we need to manage, not just acute myocardial infarctions and CPR. But we shall not go into them. I might as well write a textbook on emergency medicine for doctors instead of writing them here!