Medical Emergencies: Respiratory and Cardiac Complaints |...

SECTION 1

Historical Context & Motivation

The ability to recognize and intervene in respiratory and cardiac emergencies in the prehospital setting has undergone a dramatic transformation over the past two centuries. Before organized emergency medical services existed, individuals experiencing chest pain or acute dyspnea were largely dependent on bystanders to transport them — often by horse-drawn carriage — to the nearest physician, a journey that frequently proved fatal. The evolution from untrained first responders to credentialed Emergency Medical Technicians (EMTs) represents one of the most impactful developments in modern public health, reducing prehospital mortality from acute myocardial infarction and respiratory failure by an order of magnitude.

Understanding this history is not merely academic; it contextualizes why current protocols emphasize rapid assessment, early oxygen delivery, and swift transport decisions. Each milestone below contributed foundational knowledge that shapes the care algorithms you will use as an EMT when confronting a patient in respiratory distress or experiencing cardiac compromise in the field.

1960

Modern CPR Developed

Kouwenhoven, Jude, and Knickerbocker published their landmark paper on closed-chest cardiac massage, establishing the foundation of cardiopulmonary resuscitation (CPR) that remains central to EMT practice.

1966

"White Paper" on EMS

The National Academy of Sciences published "Accidental Death and Disability: The Neglected Disease of Modern Society," catalyzing the creation of a standardized prehospital emergency care system across the United States.

1970

National Registry of EMTs Founded

The NREMT was established to provide a uniform certification standard, ensuring EMTs nationwide could competently manage respiratory and cardiac emergencies.

2000

AHA Guidelines Emphasize Early Defibrillation

American Heart Association guidelines codified the chain of survival, placing early recognition, CPR, defibrillation, and advanced care at the center of cardiac arrest management.

2015–Present

Evidence-Based Prehospital Protocols

Continuous refinement of AHA and NAEMSP guidelines integrates capnography, high-performance CPR, and targeted ventilation strategies, empowering EMTs with increasingly sophisticated assessment and treatment tools.

The central question driving this lesson is both clinical and operational: How does an EMT rapidly differentiate between respiratory and cardiac etiologies, prioritize interventions within scope of practice, and make time-critical transport decisions? The answer lies in mastering systematic assessment, understanding pathophysiology at a functional level, and building pattern recognition through scenario-based learning.

SECTION 2

Core Principles of Respiratory & Cardiac Assessment

At the EMT level, managing respiratory and cardiac emergencies rests on a set of foundational principles that guide every patient encounter. These principles bridge anatomy, physiology, and clinical decision-making, allowing you to translate observable signs into appropriate interventions. Mastery of these core ideas ensures that whether you are confronting a patient with acute pulmonary edema or a suspected ST-elevation myocardial infarction, your approach remains structured and efficient.

Adequate vs. Inadequate Breathing

Assess respiratory rate, tidal volume, and effort. Adequate breathing shows a rate of 12–20 breaths/min in adults with good chest rise, while inadequate breathing presents with accessory muscle use, abnormal rates, and diminished tidal volume. Inadequate breathing demands assisted ventilation.

Oxygen–Perfusion Relationship

Respiration delivers O₂ to alveoli; the cardiovascular system perfuses tissues. Hypoxia can result from ventilatory failure, perfusion failure, or both. Recognizing which system is primarily failing guides oxygen delivery versus circulatory support decisions.

The Cardiac Chain of Survival

Early recognition, early CPR, early defibrillation, early advanced care, and integrated post-arrest care comprise the five links. EMTs are directly responsible for the first three links, making their role in cardiac arrest survival pivotal.

OPQRST and SAMPLE History

OPQRST (Onset, Provocation, Quality, Radiation, Severity, Time) characterizes pain complaints. SAMPLE (Signs/Symptoms, Allergies, Medications, Past history, Last oral intake, Events) provides essential contextual data for both respiratory and cardiac presentations.

Transport Decision Framework

Time-sensitive conditions such as STEMI, tension pneumothorax, and status asthmaticus require rapid transport to appropriate receiving facilities. The EMT must weigh on-scene treatment benefits against transport urgency, applying the principle of "treat and transport" rather than prolonged scene times.

✦ KEY TAKEAWAY

Think of the respiratory and cardiovascular systems as a tandem bicycle. The lungs are the front rider steering oxygen into the blood, while the heart is the rear rider providing the power to push that oxygenated blood to every tissue. If either rider stops pedaling, the whole system falters. As an EMT, your assessment must identify which rider has failed — is the problem ventilatory (front rider), circulatory (rear rider), or both — because the intervention differs accordingly: assist ventilations for respiratory failure, CPR and AED for cardiac arrest, and supplemental oxygen as a universal support.

SECTION 3

Visual Explanation: Respiratory vs. Cardiac Assessment Pathway

The following diagram illustrates the decision-making pathway an EMT follows when a patient presents with dyspnea, chest pain, or altered mental status — symptoms that may indicate a respiratory emergency, a cardiac emergency, or both. The flowchart begins with the primary assessment and branches based on key clinical findings, guiding you to the appropriate interventions within your scope of practice.

This flowchart traces the EMT's assessment and intervention pathway from initial scene arrival through the primary assessment, branching into respiratory and cardiac assessment tracks. Note that both pathways converge at the transport decision, reflecting the principle that definitive care occurs in the hospital.

As depicted above, the pathway begins with universal precautions and scene safety — steps that protect both the provider and the patient. The primary assessment determines airway patency, breathing adequacy, and circulatory status before the EMT narrows the focus to a specific system. Importantly, patients may present with overlapping respiratory and cardiac signs; for example, acute congestive heart failure produces both pulmonary crackles (a respiratory finding) and jugular venous distention (a cardiac finding). The skilled EMT recognizes these patterns and treats both systems concurrently while prioritizing rapid transport to definitive care.

SECTION 4

Pathophysiology: How Respiratory & Cardiac Emergencies Develop

Although EMTs do not diagnose, understanding the underlying pathophysiology of common respiratory and cardiac emergencies allows for more accurate pattern recognition and better clinical decision-making. The mechanisms described here directly inform why certain signs and symptoms cluster together, and why specific interventions are effective.

Respiratory Pathophysiology

Normal ventilation requires an intact airway, functional respiratory musculature, compliant lung tissue, and a functioning gas-exchange surface at the alveolar-capillary membrane. Respiratory emergencies arise when one or more of these components fail. In asthma, bronchospasm narrows the lower airways, increasing resistance to airflow and producing characteristic wheezing. In chronic obstructive pulmonary disease (COPD), chronic inflammation and loss of elastic recoil result in air trapping and a barrel-chest appearance. Pneumonia fills alveoli with infectious exudate, reducing the surface area available for gas exchange and producing crackles on auscultation. A tension pneumothorax represents a life-threatening mechanical disruption where air accumulates in the pleural space, collapsing the lung and shifting mediastinal structures, ultimately compromising venous return to the heart.

Cardiac Pathophysiology

The heart requires a continuous supply of oxygenated blood through its own coronary arteries to maintain effective pumping. Acute coronary syndrome (ACS) encompasses a spectrum of conditions — from unstable angina to ST-elevation myocardial infarction (STEMI) — that occur when atherosclerotic plaque ruptures and a thrombus occludes coronary blood flow. Myocardial cells deprived of oxygen begin to die within minutes, producing the substernal chest pressure, diaphoresis, and nausea that characterize the classic presentation. Congestive heart failure (CHF) develops when the heart can no longer maintain adequate cardiac output, causing fluid to back up into the pulmonary vasculature (left-sided failure) or systemic venous circulation (right-sided failure). Cardiac arrest represents the complete cessation of effective cardiac mechanical activity, most commonly from ventricular fibrillation or pulseless ventricular tachycardia, both of which are amenable to defibrillation — making the AED one of the EMT's most critical tools.

CARDIAC OUTPUT

CO = HR × SV

Where CO = Cardiac Output (L/min), HR = Heart Rate (beats/min), SV = Stroke Volume (mL/beat). This equation underpins EMT assessment: tachycardia often represents the body's attempt to compensate for decreased stroke volume.

BLOOD PRESSURE RELATIONSHIP

BP = CO × SVR

Where BP = Blood Pressure, CO = Cardiac Output, and SVR = Systemic Vascular Resistance. Hypotension in cardiac emergencies indicates either reduced CO (pump failure) or reduced SVR (vasodilation), guiding the EMT's assessment of shock etiology.

⚠️ Clinical Pearl

Nitroglycerin, which EMTs may assist patients in taking, works by reducing preload (venous return) and thus decreasing myocardial oxygen demand. However, it must never be administered if systolic blood pressure is below 100 mmHg or if the patient has taken a phosphodiesterase inhibitor (e.g., sildenafil) within 24–48 hours, as this combination can cause profound, refractory hypotension.

SECTION 5

Detailed Breakdown: Key Respiratory & Cardiac Conditions

EMTs encounter a finite set of respiratory and cardiac conditions with high frequency in the field. Recognizing the classic presentation of each condition — while remaining alert for atypical variants — is essential for making appropriate intervention and transport decisions. The table below organizes the most commonly tested conditions by system, key presentation features, and EMT-level interventions.

Common Respiratory and Cardiac Conditions at the EMT Level

Condition	Classic Presentation	Key Lung Sounds	EMT Interventions
Asthma	Acute dyspnea, tripod position, prolonged expiratory phase, often with known trigger exposure	Diffuse expiratory wheezing; absent sounds indicate severe obstruction	O₂ via NRB, assist with prescribed MDI (albuterol), position of comfort
COPD (Emphysema/Chronic Bronchitis)	Barrel chest, pursed-lip breathing, chronic productive cough, cyanosis	Diminished bilaterally, possible rhonchi or wheezing	Low-flow O₂ initially; titrate to SpO₂ 88–92%; BVM if inadequate ventilation
Pulmonary Edema (CHF)	Orthopnea, paroxysmal nocturnal dyspnea, pink frothy sputum, JVD, pedal edema	Bilateral crackles (rales), especially at bases	High-flow O₂, sit upright, CPAP if available, assist NTG per protocol
Tension Pneumothorax	Sudden pleuritic chest pain, progressive dyspnea, tracheal deviation (late), hypotension	Absent or diminished on affected side	High-flow O₂, BVM, rapid transport; needle decompression is ALS
Acute Coronary Syndrome	Substernal pressure, radiation to arm/jaw/back, diaphoresis, nausea, sense of doom	Usually clear; crackles if concurrent CHF	O₂ if SpO₂ < 94%, aspirin 324 mg chewed, assist NTG, monitor, rapid transport
Cardiac Arrest	Unresponsive, apneic or agonal respirations, no palpable pulse	Absent	High-quality CPR, AED, BVM ventilation, rapid transport

Side-by-side comparison of assessment findings specific to respiratory emergencies (left panel) and cardiac emergencies (right panel). Red flag boxes at the bottom of each panel highlight findings that demand immediate, time-critical action.

💡 Atypical Presentations

Women, elderly patients, and individuals with diabetes frequently present with atypical ACS symptoms such as isolated dyspnea, fatigue, epigastric pain, or syncope rather than classic substernal chest pressure. Maintain a high index of suspicion in these populations and err on the side of treating as a cardiac event when uncertain.

SECTION 6

Worked Example: Field Management of a Cardiac-Respiratory Emergency

The following scenario walks through the assessment and management of a patient presenting with overlapping respiratory and cardiac complaints, demonstrating the systematic approach an EMT should employ from dispatch to transport.

Scenario: 68-Year-Old Male with Dyspnea and Chest Pressure

Step 1 — Scene Size-Up & General ImpressionYou are dispatched to a residence for a 68-year-old male reporting difficulty breathing. On arrival, the scene is safe. You find the patient sitting upright at the edge of his bed, leaning forward on his arms. He appears diaphoretic and anxious, speaking in 2–3 word sentences. General impression: acute distress, priority patient.

Priority: HIGH — initiate rapid assessment

Step 2 — Primary Assessment (ABCs)Airway: Patent, patient is speaking. Breathing: Rate 28/min, shallow, bilateral crackles auscultated at lung bases, SpO₂ 86% on room air. Circulation: Pulse 110 bpm, irregular, skin cool and diaphoretic, BP 158/94, pedal edema noted bilaterally. You immediately apply high-flow oxygen at 15 L/min via non-rebreather mask.

SpO₂ pre-O₂: 86% → apply NRB at 15 L/min

Step 3 — Focused History (SAMPLE / OPQRST)The patient reports that the dyspnea began approximately 2 hours ago and has progressively worsened. He also describes a dull chest pressure rated 6/10 that does not radiate. SAMPLE reveals: prescribed nitroglycerin and furosemide, past medical history of CHF and hypertension, no allergies, last ate 4 hours ago, and he ran out of his furosemide one week ago. This history strongly suggests acute CHF exacerbation with possible concurrent ACS.

Working impression: Acute decompensated heart failure with cardiac chest pain

Step 4 — InterventionsWith SBP at 158 mmHg (above 100 mmHg threshold) and no phosphodiesterase inhibitor use reported, you assist the patient with his prescribed nitroglycerin: one 0.4 mg tablet sublingually. You administer 324 mg aspirin (chewed) for the chest pain component. If your service carries CPAP, this patient meets criteria — bilateral crackles, adequate blood pressure, alert and cooperative — and you apply it at 5–10 cm H₂O. You position the patient fully upright to reduce preload and improve respiratory mechanics.

Interventions: NRB O₂ → NTG 0.4 mg SL → ASA 324 mg PO → CPAP → position upright

Step 5 — Transport Decision & ReassessmentGiven the time-sensitive nature of both ACS and acute CHF, you initiate rapid transport to the nearest facility with cardiac catheterization capability. En route, you reassess vitals every 5 minutes. After NTG and CPAP, SpO₂ improves to 92%, respiratory rate decreases to 22/min, and the patient reports chest pressure has decreased to 3/10. You provide a concise radio report to the receiving facility and prepare for transfer of care.

Post-intervention SpO₂: 92% (improving). Chest pain 6/10 → 3/10. Transport to cardiac center.

✦ KEY TAKEAWAY

This scenario demonstrates that respiratory and cardiac emergencies frequently overlap, and the EMT must address both simultaneously. Think of it like triaging two fires in the same building: you don't choose one to fight and ignore the other. Instead, you apply oxygen and ventilatory support for the respiratory component (hose on the left wing) while administering aspirin, nitroglycerin, and positioning for the cardiac component (hose on the right wing), all while moving rapidly toward the definitive resource — the hospital fire department.

SECTION 7

Strengths & Limitations of EMT-Level Interventions

Understanding both the power and the limitations of the interventions available at the EMT level is critical for effective patient care and for knowing when to prioritize rapid transport over extended on-scene treatment. The following table compares the major interventions EMTs employ for respiratory and cardiac emergencies, noting both their efficacy and their constraints.

EMT-Level Interventions: Strengths vs. Limitations

Intervention	Strengths	Limitations
Supplemental O₂ (NRB)	Delivers up to 90–100% FiO₂; rapidly corrects hypoxemia; simple to apply; minimal contraindications	Does not address underlying cause; potential CO₂ retention concern in COPD (titrate accordingly); mask may cause anxiety
BVM Ventilation	Provides positive-pressure ventilation for apneic or inadequately breathing patients; can be used with supplemental O₂ for near-100% FiO₂	Requires proper seal and technique; risk of gastric insufflation; single-rescuer BVM is less effective; does not secure the airway
Prescribed MDI Assist	Delivers bronchodilator directly to lower airways; rapid onset (minutes); targets the specific pathology in bronchospasm	Requires patient's own prescription; patient must be able to coordinate inhalation; limited to conditions with bronchospasm; tachycardia side effect
Aspirin Administration	Inhibits platelet aggregation within minutes; significantly reduces mortality in ACS; EMTs can administer without prescription in most protocols	Contraindicated in aspirin allergy; ineffective if patient already anticoagulated; does not lyse existing clot; GI upset
NTG Assist	Reduces preload and myocardial O₂ demand; rapid sublingual onset (1–3 min); effective for angina and CHF-related dyspnea	Requires patient's own prescription; SBP must be ≥ 100 mmHg; contraindicated with PDE-5 inhibitors; can cause hypotension and headache
AED / Defibrillation	Only definitive treatment for V-fib and pulseless V-tach; automated analysis reduces operator error; survival rates up to 70% if applied within 3 minutes	Ineffective for asystole and PEA; requires recognizable rhythm; must pause CPR for analysis; environmental hazards (water, metal)

✦ KEY TAKEAWAY

EMT-level interventions are powerful first-line measures that stabilize patients and buy time, but they are not definitive treatments. Think of EMT care as applying a tourniquet to stop the bleeding while racing to the surgical suite — it controls the immediate crisis without fixing the underlying injury. The aspirin slows clot growth but cannot reopen a blocked coronary artery; the BVM provides ventilation but cannot reverse the pneumonia filling the alveoli. This is precisely why transport decisions carry as much clinical weight as any medication you administer.

SECTION 8

Connection to Advanced Life Support & Hospital Care

An effective EMT understands not only their own scope of practice but also where that scope interfaces with Advanced Life Support (ALS) and definitive hospital care. This understanding informs transport destination selection, ALS intercept decisions, and the quality of handoff reports. The table below highlights how EMT-level assessment and intervention connects to the advanced treatments that follow.

EMT to ALS/Hospital Care Continuum

EMT-Level Action	ALS / Hospital Continuation
O₂ via NRB, BVM ventilation, CPAP	Endotracheal intubation, advanced airway (King/iGel), ventilator management, BiPAP, blood gas analysis
Assist MDI for bronchospasm	Nebulized albuterol/ipratropium, IV/IM epinephrine for severe bronchospasm, magnesium sulfate, IV corticosteroids
Aspirin 324 mg + NTG assist for ACS	12-lead ECG interpretation, IV heparin, clopidogrel, morphine, cardiac catheterization with PCI (stent placement), thrombolytics
AED defibrillation + high-quality CPR	IV/IO epinephrine and amiodarone, manual defibrillation, synchronized cardioversion, therapeutic hypothermia post-ROSC
Recognize tension pneumothorax, rapid transport	Needle decompression (ALS), followed by chest tube thoracostomy in the ED

Recognizing the ALS continuum is not merely academic — it directly shapes field decisions. When you encounter a patient with a STEMI-equivalent presentation, choosing a transport destination with percutaneous coronary intervention (PCI) capability rather than the closest community hospital can reduce door-to-balloon time and save myocardium. Similarly, requesting an ALS intercept for a deteriorating asthma patient ensures epinephrine and advanced airway management are available sooner. Your early recognition and accurate handoff report set the stage for every advanced intervention that follows.

📋 NREMT Exam Tip

The NREMT frequently tests the boundary between BLS and ALS scope. Remember: EMTs can assist with patient-prescribed medications (NTG, MDI, epinephrine auto-injector) but cannot independently administer most medications except aspirin and oral glucose (per most protocols). Needle decompression, intubation, and IV medications are ALS procedures. Knowing this distinction prevents scope-of-practice errors on the exam and in the field.

SECTION 9

Practice Problems

PROBLEM 1 — CONCEPTUAL

A 55-year-old patient with a history of COPD presents with increased dyspnea and an SpO₂ of 85%. Explain why high-flow oxygen at 15 L/min via non-rebreather mask is still the appropriate initial intervention, despite the traditional concern about suppressing hypoxic drive in COPD patients.

PROBLEM 2 — BASIC CALCULATION

A patient in acute CHF has a heart rate of 120 bpm. If a normal stroke volume is approximately 70 mL and this patient's stroke volume has decreased to 40 mL due to heart failure, calculate the patient's cardiac output. Compare this to the normal resting cardiac output and explain the clinical significance.

PROBLEM 3 — INTERMEDIATE

You respond to a 72-year-old female complaining of "indigestion" and fatigue that began 3 hours ago. She denies chest pain. Vitals: HR 96, BP 110/70, RR 20, SpO₂ 95%. She is diaphoretic with cool skin. Her medications include metformin and lisinopril. Should you suspect a cardiac etiology despite the absence of classic chest pain? Justify your assessment and describe your management plan.

PROBLEM 4 — APPLIED

You arrive on scene to find a 45-year-old male who collapsed during a basketball game. He is unresponsive, apneic, and pulseless. Bystander CPR has been in progress for approximately 2 minutes. Describe your complete management of this cardiac arrest, including CPR quality metrics, AED use, and any medications within your scope. Your AED advises a shock. After two cycles of CPR post-shock, the patient regains a pulse at 88 bpm but remains unresponsive with agonal respirations at 6 breaths/min. How do you manage the post-ROSC phase?

PROBLEM 5 — CRITICAL THINKING

You are managing a 58-year-old male with severe substernal chest pressure (9/10), diaphoresis, and an SpO₂ of 93%. His BP is 88/60. He has his own prescribed nitroglycerin and is begging you to give it to him because "it always helps." He also reports taking sildenafil (Viagra) yesterday afternoon. Analyze the multiple contraindications present, explain the physiological basis for each, and describe how you would communicate your decision to a distressed patient while maintaining rapport and providing alternative care.

SUMMARY

Lesson Summary

This lesson established the framework for managing respiratory and cardiac emergencies at the EMT level. The assessment pathway begins with scene size-up and primary assessment (ABCs), then differentiates between respiratory and cardiac etiologies using OPQRST, SAMPLE history, lung auscultation, and vital sign patterns. Key respiratory conditions include asthma, COPD, pulmonary edema, and tension pneumothorax, each with distinct auscultatory and clinical findings. Key cardiac conditions include acute coronary syndrome, congestive heart failure, and cardiac arrest. Physiologically, the relationship CO = HR × SV explains why tachycardia is a compensatory response to decreased stroke volume, and BP = CO × SVR explains the hemodynamic basis of hypotension in cardiac emergencies.

EMT-level interventions — supplemental oxygen, BVM ventilation, MDI assist, aspirin, nitroglycerin assist, CPAP, and AED defibrillation — are powerful stabilization tools but are not definitive treatments, making the transport decision equally critical. Key contraindications to remember include: no NTG with SBP < 100 mmHg or recent PDE-5 inhibitor use, and atypical ACS presentations in women, elderly, and diabetic patients. The EMT's role in the chain of survival — early recognition, high-quality CPR, and early defibrillation — remains the single most impactful determinant of cardiac arrest outcomes. Master these principles, and you become the critical link between a patient's emergency and their survival.