This section of our NREMT Study Guide will help you prep for the Resuscitation portion of the exam. Resuscitation & Cardiology account for 20%–24% of the exam. This section of our study guide covers cardiac arrest, how to identify when cardiopulmonary resuscitation (CPR) is required, how to perform CPR on infants, children, and adults, what an automated external defibrillator (AED) is, and how to use one.
After you study this material, there are five review questions to assess your comprehension and retention of the content.
Cardiac Arrest
Cardiac arrest occurs when the heart stops beating or is beating ineffectively and the blood in the body cannot circulate to the brain and other vital organs. When the heart stops beating, respirations will stop soon after, and the body’s organs will not receive the oxygen they need to survive. Without vital oxygen, brain damage will begin in four to six minutes. Within eight to ten minutes without oxygen, the damage is irreversible.
Sudden cardiac arrest happens without the typical warning signs seen in a heart attack. Sudden cardiac arrest is caused by chaotic electrical activity in the heart called arrhythmia. The most life-threatening arrhythmia is called ventricular fibrillation (V-fib). With a combination of cardiopulmonary resuscitation (CPR) and the use of an automated external defibrillator (AED), the patient has a chance of survival.
When infants and children are pulseless, apneic, and require CPR, it is generally not due to a cardiac event but is a result of respiratory arrest. When an infant or child goes into respiratory arrest, their heart rate decreases to the point that a pulse is not felt. CPR needs to be initiated any time there are absent pulses and respirations.
Many communities have encouraged their citizens to learn CPR and how to operate an automated external defibrillator (AED). Working as an EMT, you will come upon situations where laypeople have learned these skills and have put them to use before you arrive on the scene.
Some of the latest courses for laypeople teach “hands-only CPR,” so there is no bodily fluid exchange when doing mouth-to-mouth ventilation. In addition, studies have proven that compression-only CPR is more effective than traditional CPR when performed by bystanders with little or no training. People with less training tend to have longer intervals between compressions and ventilation, reducing the effectiveness of blood circulating to the patient’s organs.
Before Starting CPR
As with any patient interaction, always take standard precautions before assessing and treating your patient. Before starting CPR, determine whether the patient is unresponsive and without pulses or respirations.
For infant patients, tap their feet while saying their name to see if they respond. In children, tap their shoulders while saying their name to check for responsiveness. For the adult patient, gently tap or shake their shoulder if there are no signs of injury while saying their name and asking if they are okay.
If the patient is unresponsive, check the ABCs. Check the brachial pulse in infants and the carotid pulse (in the neck) in children and adults. If the patient is pulseless and apneic, begin CPR. If the patient has a pulse but is not breathing, provide artificial ventilation as you were taught.
When CPR is Not Indicated
There will be certain situations when CPR is not indicated even if the patient is pulseless and apneic, including:
- DNR orders. If the family, healthcare professional, or caregiver presents you with a “Do Not Resuscitate” (DNR) order signed by the patient and their doctor and it specifies “No CPR,” or “No lifesaving measures,” do not initiate CPR.
- Rigor mortis. Rigor mortis is a stiffening of the body and its extremities that starts to occur within two to twelve hours after death.
- Putrefaction. Putrefaction is a decomposition of body tissues, typically called “decomp.” Depending on the environmental temperatures, this occurs between 40 and 96 hours after death. Putrefaction can often be smelled from a distance before you even reach the patient.
- Mortal wounds. These will be obvious wounds, including decapitation, incineration, or a severed body. Mortal wounds also include injuries that are so severe that CPR cannot be performed effectively, such as severe crush injuries to the head, neck, or chest.
- Dependent lividity. When the blood settles to the lowest point of the body, it causes a discoloration of the skin, a mottled reddish-purple color, known as dependent lividity. For example, if a person is lying on their back, there will be dependent lividity to their back, buttocks, and the back of their legs and arms.
How to Perform CPR
The purpose of CPR is to circulate oxygen-rich blood to the patient’s vital organs during a cardiac arrest. CPR includes chest compressions, ventilation, and the use of an AED when available.
The compression to ventilation rate is the same in infants, children, and adults—30 compressions to 2 ventilations or 30:2 for one rescuer CPR. When two rescuers perform CPR, the rate changes to 15 compressions to 2 ventilations or 15:2, but only in infants and children. For adults, two-rescuer CPR remains the same at 30:2. The compression ratio ends up being approximately 100-120 compressions per minute. However, there is some difference in the depth of compressions and hand placement for different age groups.
When performing CPR on an infant, you will place two fingers in the middle of the sternum, just below the nipple line. You will then compress the sternum ⅓ of the chest, approximately 1.5 inches.
For children, the hand placement changes to the heel of one hand over the sternum in line with the nipples on smaller children, or two interlocking hands for larger children. Compress the sternum ⅓ of the chest, approximately 2 inches.
Adult patients require two interlocking hands over the middle of the sternum, compressing the sternum at least ⅓ of the chest, approximately 2.5 inches.
Compression and Ventilation Cycles
CPR is performed in cycles, always starting with compressions and followed by ventilation. One cycle is the required number of compressions (30 or 15, depending on one-rescuer or two-rescuer CPR) followed by two ventilations. Once compressions are complete, open the patient’s airway and give two ventilations. When you are finished giving ventilations, quickly reposition your hands and start another cycle of compressions.
After five cycles, reassess the patient’s pulse and breathing. Five cycles should take approximately two minutes to complete. If there is no pulse or respirations, continue CPR, starting with compressions.
If there are two rescuers, switch positions after five cycles. Performing compressions can be exhausting to the rescuer, and the quality of compressions can decrease.
When to Stop CPR
Once CPR has been initiated, you must continue until:
- Pulses return. Provide ventilation as needed and closely monitor the patient.
- Pulses and breathing return. Again, closely monitor the patient and be prepared to initiate CPR if needed.
- Another equally or higher trained healthcare professional takes over for you.
- You are too exhausted to continue.
- The base physician instructs you to stop.
Automated External Defibrillator (AED)
Automated external defibrillators are portable electronic devices that analyze the rhythm of the heart and deliver an electrical shock, known as defibrillation, when warranted. When a person has a “shockable” rhythm, and the AED delivers that shock, it helps the heart establish an effective rhythm.
AEDs are fully automated and monitor the heart’s electrical activity through two pads that are placed on the patient. The computer looks at the pattern, frequency, and size of the EKG waves to determine if a shock is needed. If the waves resemble a shockable rhythm, such as ventricular fibrillation (V-fib) or ventricular tachycardia (V-tach), the machine will notify the user that a shock is advised and will ready the charge.
Once the shock is delivered, it disrupts the irregular rhythm, which allows the heart to fire off electrical impulses that will hopefully cause the heart to beat effectively. If the rhythm is not corrected, all electrical activity will stop, which is called asystole, or flatline. Asystole cannot be corrected by defibrillation, so the AED will not deliver a shock.
You cannot tell if the patient has a heart rhythm by feeling for a pulse. Only a defibrillator can do that. By initiating CPR immediately and keeping circulation running through the body, it increases the chance that defibrillation will correct the arrhythmia. Use an AED only when all of the following are present:
- The patient is unresponsive
- There is no pulse detected
- The patient is not breathing
Using the AED
The AED should be used as soon as possible in a cardiac arrest. If CPR is in progress, do not interrupt chest compressions until the AED is turned on, the defibrillation pads are applied, and the AED is ready to analyze the rhythm. If the AED advises that a shock is needed, give one shock followed by two minutes of CPR.
There are many types of AEDs on the market, and while most deliver the same results, the instructions for each are slightly different. The general steps to operating an AED are as follows:
- Turn on the AED and follow the voice and visual prompts. Some units have a power button that must be pressed while others activate when the lid is opened.
- Expose the patient’s chest and wipe the chest dry if needed. The AED pads must be applied to bare, dry skin.
- Apply the pads to the patient’s chest, following the diagram on the pad. Some pads are pre-connected to the AED, while others require the user to plug them into the machine before analysis can begin. Use appropriate pads for the patient. Most machines have pediatric and adult pads, with lower energy levels given through the pediatric pads. Pediatric pads should not be used on an adult because enough energy will not be delivered. However, if pediatric pads are not available, adult pads can be used on infants and children.
- Most AEDs will automatically start analyzing after the pads are placed on the patient, while some have an analyze button that must be pushed. Listen for the voice prompts.
- When the unit is analyzing, be sure no one is touching the patient, as it can produce a false reading.
- Once the unit has completed analyzing the rhythm, the AED will advise if a shock is needed. If a shockable rhythm is detected, the AED will charge to deliver the defibrillation. Depending on the model, the AED will advise that a shock is being delivered or will advise to manually press the shock button. Be sure no one is touching the patient or is too close to them when a shock is being delivered, or they will also get shocked.
- After the shock is delivered, or if there is no shock advised, the machine allows a period of time (usually two minutes or five cycles) to continue CPR until the next rhythm analysis begins. Always start CPR after a rhythm analysis and shock (if advised) by beginning with compressions.
Infant Pad Placement
On an infant, you will apply one pad on the front of the chest and the other on the back, following the diagram on the pads.
Child and Adult Pad Placement
For children and adults, the pad placement will be the same. One pad is applied to the right of the sternum just below the clavicle, and the other is applied to the left lower chest area with the top of the pad two to three inches below the armpit. Again, follow the diagram on the pad for the AED you will be using.
If a child is small and the pads are too big for their chest and touch each other, place the pads as you would for an infant: one on the chest and one on the back. You must never cut or alter the AED pads as it could damage the pads and render them useless.