EMT · Patient Treatment and Transport · 7 min read
Acute Coronary Syndrome, Cardiac Arrest and AED Use
- Identify the signs, symptoms, and initial basic life support management for patients experiencing suspected acute coronary syndrome, including the administration of aspirin and assistance with nitroglycerin.
- Demonstrate the parameters of adult high-quality cardiopulmonary resuscitation, including proper compression depth, rate, chest recoil, minimization of pauses, and ventilation ratios.
- Explain the safe operation of an automated external defibrillator, special pad placement considerations, motion restrictions, and ongoing care following the return of spontaneous circulation.
Recognizing Acute Coronary Syndrome and Initial Management
Acute coronary syndrome refers to a broad spectrum of clinical conditions caused by a sudden, reduced blood flow through the coronary arteries. To understand this spectrum, consider the difference between stable cardiac disease and an acute crisis. Stable angina occurs when myocardial oxygen demand exceeds the available blood supply, which typically resolves within minutes with rest or prescribed nitroglycerin. However, when an individual experiences new, worsening, or persistent chest discomfort, this shift indicates that the patient may be developing acute coronary syndrome. Prolonged, sufficiently severe myocardial ischemia can cause an acute myocardial infarction with irreversible cardiac muscle injury; persistent symptoms alone do not establish that an infarction has occurred.
Recognizing acute coronary syndrome requires an EMT to identify both classic and atypical presentations. Classic symptoms include retrosternal chest pressure, diaphoresis, dyspnea, and nausea. Cardiac-related pain also frequently radiates away from the chest to the jaw, neck, left arm, back, or epigastric region. EMTs must be especially vigilant when assessing women, older adults, and people with diabetes. These patients may experience acute coronary syndrome without any classic chest pain at all, presenting instead with subtle signs such as dyspnea, nausea, unusual fatigue, or syncope.
Initial basic life support management focuses on comfort, sensible oxygenation, and rapid transport. A conscious patient experiencing acute chest pain should be placed into a position of comfort, which is typically a semi-Fowler or seated position to ease breathing and decrease cardiac strain. Supplemental oxygen must not be administered routinely to all patients; EMTs should avoid administering routine high-concentration oxygen to non-hypoxemic acute coronary syndrome patients to prevent hyperoxic vasoconstriction. Instead, administer supplemental oxygen only when indicated by hypoxemia, respiratory distress, or shock, and carefully titrate the oxygen according to local protocol while avoiding hyperoxia. Finally, ensure prompt transport to an appropriate hospital, selecting a PCI-capable hospital when indicated by local protocol.
Common mistakes
- Administering routine high-concentration oxygen to a non-hypoxemic patient with suspected acute coronary syndrome offers no established benefit and may cause hyperoxia; give oxygen when indicated by the patient's condition and local protocol.
- Failing to screen for recent phosphodiesterase-5 inhibitor use (such as sildenafil or vardenafil within 24 hours, or tadalafil within 48 hours) or omitting blood pressure checks before assisting with nitroglycerin.
- Interrupting chest compressions for longer than 10 seconds during pulse checks, AED pad application, or compressor rotations.
- Attempting to perform AED rhythm analysis or shock delivery while the ambulance is in motion rather than bringing the vehicle to a complete stop.
Key points
- Acute coronary syndrome includes unstable angina and acute myocardial infarction; stable angina is not an acute coronary syndrome.
- Women, older adults, and people with diabetes may have acute coronary syndrome without chest pain or with symptoms such as dyspnea, nausea, fatigue, or syncope, but chest discomfort remains a common ACS symptom in women.
- Aspirin (162 to 324 mg chewable) prevents clot expansion, while prescribed nitroglycerin (0.4 mg) reduces cardiac preload but requires strict screening for hypotension and recent phosphodiesterase-5 inhibitor use.
- High-quality adult CPR requires a compression rate of 100 to 120 per minute, a depth of 2 to 2.4 inches (5 to 6 cm), complete chest recoil, and a 30:2 ratio before an advanced airway is placed.
- The AED treats ventricular fibrillation and pulseless ventricular tachycardia; compressions must resume immediately after every shock or 'no shock' advisory.
- AED pads require good skin contact, dry wet pad sites, remove a transdermal patch if it is at a pad site, clear hair if it prevents adhesion, and place pads at least 1 inch from an implanted device.
- Following return of spontaneous circulation, leave the AED attached, ventilate inadequate breathing at one breath every 6 seconds, maintain normoxia, avoid hyperventilation, and transport promptly to an appropriate cardiac facility.
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