The main difference between respiratory arrest and cardiac arrest is that respiratory arrest occurs when a person stops breathing while cardiac arrest occurs when a person’s heart stops beating (or only quivers ineffectively). In respiratory arrest, there is still blood flow and a pulse for the first few minutes. However, if left untreated, the condition can lead to cardiac arrest and death.
What Happens to the Body During Respiratory Arrest vs Cardiac Arrest
The primary goal of breathing is gas exchange: oxygen goes in and carbon dioxide comes out. When there is no gas exchange, oxygen levels in the body go down and high carbon dioxide levels lead to a build-up of carbonic acid. Without sufficient oxygenation, the vital organs begin to die.
In cardiac arrest (also known as cardiopulmonary arrest or circulatory arrest), the heart stops beating altogether due to an electrical malfunction. Rather than beating, the ventricles only quiver. Blood flow around the body stops and—as in respiratory arrest—a lack of oxygen causes the vital organs to die.
In Medical Terms…
In medical terms, a lack of oxygen in the brain is referred to as hypoxemia. A lack of oxygen in the body tissues is hypoxia. The medical term for the build-up of carbon dioxide in the blood is referred to as hypercarbia. No matter how you put it, the body can’t function without oxygen!
Key Differences Between Respiratory Arrest and Cardiac Arrest
In respiratory arrest, the patient’s heart is still beating (during the first few minutes) and blood is still circulating around the body. The patient still has a pulse even though he or she is not breathing and is unconscious from the lack of oxygen.
In cardiac arrest, there is no pulse or breathing, or the patient may be gasping sporadically. In both cases, the patient is unconscious due to insufficient oxygenation and needs to be treated immediately. If left untreated, respiratory arrest leads to cardiac arrest.
Causes of Respiratory Arrest vs Cardiac Arrest
There are many possible causes of respiratory arrest, including physical obstructions, severe inflammation of the respiratory tract, and failures or fatigue of any part of the respiratory system in general. Some of the most common causes include:
- Upper airway obstruction
- Lower airway obstruction
- External crushing of the chest
- Acute respiratory distress syndrome
- Respiratory muscle weakness
- Obstructive sleep apnea
- Opioid overdose
- Seizure disorders
In contrast, sudden cardiac arrest is most often the result of heart disease or lifestyle factors that are conducive to heart disease. Some of the most common risk factors for cardiac arrest include:
- Coronary artery disease
- Heart failure or congestive heart failure
- Heart valve disease
- Congenital heart defects
- Severe emotional stress
- A sudden drop in electrolytes
- Sedentary lifestyle
- Excessive alcohol consumption
- Cocaine or amphetamine use
- Excessive caffeine consumption (especially in non-coffee drinkers)
Warning Signs of Respiratory Arrest vs Cardiac Arrest
Signs of impending respiratory arrest include:
- Feeling weak or feeble
- Increased respiratory effort
- Gasping or wheezing
- Turning blue
- Pointing at their throat (in the case of choking)
Typically, the person first goes into respiratory distress (increased respiratory effort) and then respiratory failure (decreased respiratory effort or breathing that is inadequate for the body’s needs) before they finally stop breathing (respiratory arrest).
Some of the warning signs for cardiac arrest are similar to the warning signs for respiratory arrest (such as shortness of breath and collapse) but are usually far less obvious.
Warning signs of impending cardiac arrest include:
- Shortness of breath
- Chest pain
- Back pain
- Heart palpitations
- Nausea and vomiting
- Extreme fatigue
- Dizziness and fainting
Whereas respiratory arrest usually comes after respiratory distress and respiratory failure (insufficient breathing), cardiac arrest often happens without any warning signs at all. Because there is typically some warning before a respiratory arrest, it’s essential to call 9-1-1 as soon as you see someone choking or struggling to breathe.
Treatment of Respiratory Arrest vs Cardiac Arrest
Cardiac arrest and respiratory arrest require different methods of treatment. In either case, treatment should be administered immediately.
Treating Respiratory Arrest
Respiratory arrest can be treated effectively before the victim’s heart stops beating (cardiac arrest) but requires a professional with basic life support training, advanced cardiac life support training, or similar. If the victim has a spinal cord injury, special care needs to be taken to avoid tilting the head when opening the airway.
To treat respiratory arrest, it’s necessary to remove any airway obstruction that’s present, establish an alternative airway, if needed, and potentially provide positive pressure ventilation or manual ventilation with a bag-valve mask.
When someone goes into respiratory distress, respiratory failure, or respiratory arrest in an out-of-hospital setting, a lay rescuer can help by administering the Heimlich maneuver or upper abdomen thrusts (in cases of choking), calling 9-1-1, wiping out the person’s mouth with a clean finger, and keeping the victim alive with 30:2 CPR until more qualified help arrives. Once EMS personnel are on the scene, let them know that there was a respiratory cause so that they can provide oxygen and establish an alternative airway if needed.
Important: If you aren’t trained in 30:2 cardiopulmonary resuscitation, do not attempt to give rescue breaths. Push hard and fast on the victim’s chest as soon as you see them collapse and send someone to call 9-1-1. If a trained first aider arrives on the scene, they can take over and give rescue breaths using the correct technique.
Treating Cardiac Arrest
Cardiac arrest is—in some ways—easier to treat in an out-of-hospital setting because the victim’s airways are clear. What you need to do is:
- Call 9-1-1 and send someone to grab an automated external defibrillator such as the Philips HeartStart FRx or HeartSine Samaritan PAD 350P.
- Commence hands-only CPR immediately, pushing down firmly on the middle of the victim’s chest with one hand over the other to the beat of the hit song Stayin’ Alive (approximately 100 to 120 compressions per minute).
- Attach the electrode pads of the AED and follow the instructions for chest compressions and defibrillation.
- Leave the pads and AED attached for handover to EMS personnel.
When You’re Not Sure Whether It’s Respiratory Arrest or Cardiac Arrest
As both conditions can cause the victim to become unconscious and stop breathing, it’s important to know how to respond when you don’t know the cause of the arrest. If you see someone collapse and stop breathing (or only gasping) and don’t know the cause:
- Call 9-1-1.
- Call someone to fetch an AED.
- Sweep out the victim’s mouth with a clean (if possible, gloved) finger to remove any obstructions near the tongue.
- Commence chest compressions and give rescue breaths (only if trained) until the ambulance arrives. If you’re not trained, give chest compressions alone.
Should You Check for a Pulse?
The presence or absence of a pulse can tell you whether someone is suffering respiratory arrest or cardiac arrest. However, in an emergency, few untrained bystanders can feel for a pulse accurately, so the AHA no longer recommends a pulse check. Instead, presume cardiac arrest and commence chest compressions immediately.
If the victim is not breathing, chest compressions will keep blood circulating around their body until the ambulance arrives and you won’t make the problem worse by trying to act above your pay grade (such as poking an obstruction further down their airway or wasting precious time with ineffective rescue breaths).
Furthermore, an external defibrillator won’t deliver a shock if the heart doesn’t have a shockable rhythm, so you don’t need to worry about hurting someone with unnecessary defibrillation.
Respiratory Arrest vs Cardiac Arrest: Different, but Both Life-Threatening
In basic terms, respiratory arrest occurs when breathing is halted and cardiac arrest occurs when the heartbeat is halted. However, respiratory arrest can lead to cardiac arrest in minutes if not treated, and both lead to near-immediate death if nothing is done.
To be prepared for both of these kinds of emergencies, consider taking a first aid course, carry a CPR rescue mask with you at all times, and find out where your nearest AEDs are located. You never know when you’ll be called upon to save a life.