NREMT Cardiology and Resuscitation: Core Principles
Anatomy and Physiology of the Cardiovascular System
The NREMT expects candidates to understand the heart as a mechanical pump driven by an electrical conduction system. The flow of blood through the four chambers—right atrium, right ventricle, left atrium, and left ventricle—must be unimpeded. Oxygen-poor blood enters the right atrium via the vena cava, moves through the tricuspid valve to the right ventricle, and is pumped to the lungs. Oxygenated blood returns to the left atrium, passes the mitral valve into the left ventricle, and is ejected through the aortic valve. A critical concept for the exam is Preload, the amount of blood returning to the heart, and Afterload, the resistance the left ventricle must overcome to eject blood. Understanding the electrical pathway—starting at the Sinoatrial (SA) Node, moving to the Atrioventricular (AV) Node, and through the Bundle of His and Purkinje fibers—is vital for recognizing how arrhythmias disrupt mechanical output. Any failure in this system leads to hypoperfusion, or shock, which is the underlying driver of most cardiovascular emergencies.
The Chain of Survival
The Chain of Survival is a series of time-critical actions that increase the likelihood of survival from cardiac arrest. For the NREMT, you must differentiate between the in-hospital and out-of-hospital chains. The out-of-hospital chain consists of: early recognition and activation of the emergency response system, immediate high-quality CPR, rapid defibrillation, basic and advanced emergency medical services, and post-cardiac arrest care. The exam often tests your ability to prioritize these links. For example, if you witness a collapse, the priority is immediate activation of EMS and retrieving an AED. If you encounter an unwitnessed arrest, beginning CPR while preparing the AED is the standard. The NREMT cardiac arrest algorithm emphasizes that for every minute defibrillation is delayed, the chance of survival drops by approximately 7% to 10%. This makes the "rapid defibrillation" link the most critical intervention for shockable rhythms like Ventricular Fibrillation.
Adult Cardiopulmonary Resuscitation (CPR) Protocol
Assessing Responsiveness, Breathing, and Pulse
Assessment begins with ensuring scene safety followed by checking for a response using the "tap and shout" method. On the NREMT, the assessment of breathing and pulse must occur simultaneously to minimize delays in starting chest compressions. This check should take at least five seconds but no more than ten seconds. The pulse is checked at the Carotid Artery in adults and children. If the patient is unresponsive, not breathing (or only gasping/agonal respirations), and has no pulse, the candidate must immediately begin chest compressions. It is important to note that agonal gasps are not effective breathing and should be treated as a sign of cardiac arrest. The NREMT often uses scenarios where a patient has a pulse but is not breathing; in these cases, rescue breathing is indicated (1 breath every 6 seconds for adults) rather than full CPR. Correctly identifying the need for NREMT CPR guidelines application versus rescue breathing is a common point of evaluation.
High-Quality Chest Compressions: Depth, Rate, and Recoil
High-quality CPR is the cornerstone of resuscitation because it maintains a Coronary Perfusion Pressure (CPP) sufficient to keep the myocardium viable. For adults, compressions must be at a depth of at least 2 inches (5 cm) but no more than 2.4 inches (6 cm). The rate must be between 100 and 120 compressions per minute. A frequent exam trap involves "incomplete recoil." You must allow the chest to return to its natural position between compressions to allow the heart to refill with blood; failing to do so reduces the effectiveness of the next compression. The NREMT monitors the compression-to-ventilation ratio, which for a single or two-rescuer adult CPR remains 30:2. Minimizing interruptions in compressions is paramount; pauses should never exceed 10 seconds, except for specific interventions like AED analysis or clearing the patient for a shock.
Effective Ventilations with a Bag-Valve-Mask
When providing ventilations during CPR, the goal is to provide adequate oxygenation without causing gastric distention or reducing venous return. Using a Bag-Valve-Mask (BVM) with a reservoir and 15 liters per minute (LPM) of oxygen is the standard. Each breath should be delivered over 1 second and should result in visible chest rise. Over-ventilation (too much volume or too fast a rate) increases intrathoracic pressure, which prevents blood from returning to the heart, effectively neutralizing the benefits of chest compressions. In a two-rescuer scenario, the person at the head uses the "E-C clamp" technique to maintain a seal while the second rescuer provides compressions. If an advanced airway is in place (such as an endotracheal tube or supraglottic device), compressions become continuous, and ventilations are delivered at a steady rate of 1 breath every 6 seconds (10 breaths per minute).
Automated External Defibrillator (AED) Operation
Step-by-Step Application and Safety Procedures
NREMT AED use follows a strict sequence: power on the device, attach pads to a bare chest, clear the patient for rhythm analysis, and clear the patient if a shock is advised. Pads should be placed in the anterolateral position (one below the right clavicle, one to the left of the nipple line). Special considerations include removing the patient from standing water, drying a soaking wet chest, and avoiding placement directly over an implanted pacemaker or medication patch. If the patient has a very hairy chest that prevents pad adhesion, you must quickly shave the area or use a spare set of pads to "wax" the hair off. On the NREMT, the AED is the priority; if you are performing CPR and the AED arrives, you should stop compressions only long enough to apply the pads and analyze the rhythm. Safety is assessed by ensuring no one is touching the patient during the "clear" phase, as the electrical discharge can bridge to rescuers.
Understanding Shockable vs. Non-Shockable Rhythms
An AED is designed to treat specific electrical malfunctions. The two shockable rhythms are Ventricular Fibrillation (V-Fib), where the heart quivers chaotically, and Pulseless Ventricular Tachycardia (V-Tach), where the ventricles beat too fast to allow for filling. The AED will not advise a shock for "non-shockable" rhythms like Asystole (flatline) or Pulseless Electrical Activity (PEA). In PEA, the heart’s electrical system is firing, but the muscle is not responding with a mechanical contraction. Candidates must understand that the AED does not "restart" a dead heart; rather, it stops the chaotic electrical activity (defibrillation) in hopes that the heart's natural pacemaker (the SA node) can resume an organized rhythm. If the AED says "No Shock Advised," the provider must immediately resume CPR, starting with chest compressions, regardless of whether the patient shows signs of life, unless they are moving or breathing normally.
Post-Shock Protocol and Continuing CPR
Immediately after a shock is delivered, the rescuer must resume chest compressions without delay. Do not re-check the pulse or breathing at this point; the heart is often in a state of "stunning" post-shock and requires manual perfusion support. The AED will wait for two minutes (usually five cycles of 30:2) before prompting for another rhythm analysis. This cycle continues until the patient regains Return of Spontaneous Circulation (ROSC), the scene becomes unsafe, the rescuer is too exhausted to continue, or a higher level of care takes over. If ROSC is achieved, the patient should be placed in the recovery position (if no trauma is suspected) and oxygenation/ventilation must be closely monitored. Frequent reassessment of the pulse is required, as the patient can easily slip back into a shockable rhythm.
Managing Acute Coronary Syndromes
Recognizing Signs and Symptoms of a Heart Attack
NREMT acute coronary syndromes (ACS) encompass a range of conditions where the coronary arteries are suddenly blocked or narrowed, including unstable angina and Acute Myocardial Infarction (AMI). Classic signs include substernal chest pressure, often described as a "weight on the chest," which may radiate to the left arm, jaw, or epigastrium. Associated symptoms include Diaphoresis (profuse sweating), nausea, and dyspnea. However, the NREMT frequently tests "atypical" presentations. Women, elderly patients, and diabetics may not experience chest pain at all; instead, they may present with isolated shortness of breath, fatigue, or "silent" infarctions. Differentiating between Angina Pectoris and an AMI is also critical: Angina usually resolves with rest or nitroglycerin within 15 minutes, whereas an AMI does not. Regardless of the suspicion, any patient with symptoms suggestive of cardiac ischemia must be treated as an AMI until proven otherwise in a hospital setting.
Patient Positioning and Oxygen Administration
Management of ACS begins with placing the patient in a position of comfort, usually a semi-Fowler's position (sitting up), which eases the work of breathing. Oxygen administration is no longer automatic for all chest pain patients. According to current standards, oxygen should be administered only if the patient's oxygen saturation (SpO2) is below 94%, or if they show signs of respiratory distress, hypoxia, or heart failure. If oxygen is needed, start with a nasal cannula at 2-6 LPM. If the patient is in severe distress, a non-rebreather mask at 10-15 LPM is appropriate. High concentrations of oxygen in a stable patient can cause vasoconstriction of the coronary arteries, potentially worsening the infarct. Therefore, titrating oxygen to maintain an SpO2 of 94-99% is the preferred goal for the NREMT candidate.
Assisting with Prescribed Nitroglycerin and Aspirin
For a patient with suspected ACS, the EMT may assist with or administer specific medications based on local protocols. Aspirin (usually 324mg or four 81mg baby aspirins) is given to prevent further platelet aggregation; it should be chewed to speed absorption. Nitroglycerin (NTG) is a potent vasodilator that reduces preload and afterload, thereby decreasing myocardial oxygen demand. Before assisting with NTG, the EMT must ensure the patient's systolic blood pressure is above 100 mmHg. A major contraindication for NTG is the use of erectile dysfunction medications (such as sildenafil or tadalafil) within the last 24-48 hours, as this can lead to fatal hypotension. The EMT should also verify the "five rights" of medication administration: right patient, right medication, right dose, right route, and right time. After administering NTG sublingually, the blood pressure must be reassessed before giving a second or third dose.
Pediatric and Infant Resuscitation
Age-Specific Compression Techniques and Ratios
NREMT pediatric resuscitation guidelines differ significantly from adult protocols to account for smaller anatomy and different physiological needs. For an infant (0-1 year), the pulse is checked at the Brachial Artery. Compressions are performed using the two-finger technique for a single rescuer or the two-thumb-encircling-hands technique for two rescuers. For children (1 year to puberty), one or two hands are used on the lower half of the sternum. The depth for infants is 1.5 inches (4 cm), and for children, it is approximately 2 inches (5 cm). While the single rescuer ratio remains 30:2, the two-rescuer ratio for both infants and children changes to 15:2. This increased frequency of ventilations addresses the fact that pediatric cardiac arrest is usually secondary to respiratory failure, making oxygenation and ventilation more critical than in adult primary cardiac arrests.
Common Causes of Pediatric Cardiac Arrest
Unlike adults, who usually suffer from primary cardiac events like AMI or arrhythmias, children most often experience cardiac arrest as a result of Hypoxia. Respiratory distress, airway obstruction, drowning, or trauma lead to respiratory failure, which then progresses to bradycardia and eventually asystole. Because of this, the NREMT emphasizes that if you are alone and witness a pediatric collapse, you should call 911 immediately. However, if you find a pediatric patient in arrest (unwitnessed), you should perform 2 minutes of CPR before leaving the patient to activate the emergency response system. This "oxygen-first" approach is designed to reverse the likely respiratory cause before the heart becomes irreversibly damaged by lack of oxygen.
Special Considerations for the Newborn
Resuscitation of a newborn (neonate) in the first minutes of life follows the Neonatal Resuscitation Program (NRP) guidelines, which are distinct from standard pediatric CPR. The ratio for newborn CPR is 3:1 (90 compressions and 30 ventilations per minute), totaling 120 events per minute. The primary indicator of a newborn’s health is the heart rate. If the heart rate is below 100 beats per minute but above 60, the focus is on providing Positive Pressure Ventilation (PPV) with room air (or 21-30% oxygen). If the heart rate drops below 60 beats per minute despite adequate ventilation, chest compressions must begin. The NREMT tests the ability to recognize these specific thresholds and the importance of warmth, drying, and stimulation as the initial steps of neonatal care before moving to more invasive resuscitation measures.
Other Cardiovascular Emergencies
Recognizing and Supporting Cardiac Arrest Rhythms (PEA, Asystole)
While the AED manages V-Fib and V-Tach, the EMT must understand how to manage non-shockable rhythms like Asystole and Pulseless Electrical Activity (PEA). In Asystole, there is no electrical or mechanical activity in the heart. In PEA, the monitor might show a normal-looking rhythm, but the patient has no palpable pulse. For these patients, the treatment is high-quality CPR and identifying reversible causes (the "H's and T's" such as Hypovolemia, Hypoxia, or Tension Pneumothorax). On the NREMT, if the AED advises "No Shock," the priority is immediate resumption of compressions. The candidate must also be prepared to provide psychological support to bystanders or family members and understand the criteria for terminating resuscitation in the field, which usually requires a direct order from medical control after a period of unsuccessful ALS intervention.
Managing Acute Pulmonary Edema and CHF
Congestive Heart Failure (CHF) occurs when the heart cannot pump efficiently, leading to a backup of fluid. Left-sided heart failure often results in Pulmonary Edema, where fluid leaks into the alveoli, causing severe dyspnea and rales (crackles) upon auscultation. Patients may also present with paroxysmal nocturnal dyspnea (waking up gasping for air) and orthopnea (difficulty breathing when lying flat). Right-sided heart failure often manifests as Jugular Venous Distention (JVD) and peripheral edema (swelling in the ankles). Treatment for acute pulmonary edema on the NREMT involves high-flow oxygen and the use of Continuous Positive Airway Pressure (CPAP) if the patient is alert and can follow commands. CPAP works by increasing pressure in the airways, which helps push fluid out of the alveoli and back into the capillaries, significantly improving oxygenation and reducing the work of breathing for the failing heart.