What is the appropriate evaluation and management of chest pain in a casualty?

Evaluation and Management of Chest Pain in a Casualty

In a casualty with chest pain, immediately assess vital signs, obtain a 12-lead ECG within 10 minutes, administer aspirin 160-325 mg (chewable if available), provide oxygen, give sublingual nitroglycerin if blood pressure permits, and prepare for immediate transport to hospital while treating life-threatening conditions on scene. 1, 2

Immediate On-Scene Assessment (First 5-10 Minutes)

Rapid Triage and Vital Signs

• Check consciousness, respiration, blood pressure, heart rate, and temperature immediately upon arrival 1
• Severe prolonged chest pain of acute onset requires immediate action regardless of cause—this includes myocardial infarction, aortic dissection, pulmonary embolism, pneumothorax, or other pulmonary emergencies 1
• Physical examination contributes almost nothing to diagnosing myocardial infarction unless shock is present 1

ECG Acquisition

• Record and interpret a 12-lead ECG within 5-10 minutes of first patient contact 1, 2
• Pre-hospital ECG use reduces in-hospital delay time and mortality among patients with acute chest pain 1
• ST-segment elevation ≥1 mV in contiguous leads indicates thrombotic coronary occlusion requiring immediate reperfusion 1
• New left bundle branch block with symptoms consistent with acute MI should be managed like ST-elevation 1

Immediate Medical Management

Aspirin Administration

• Give aspirin 160-325 mg orally (chewable or water-soluble preferred) as soon as possible 1
• Early aspirin administration (within 1.6 hours) improves survival at 7 days, 30 days, and one year compared to late administration 3
• Aspirin is rarely associated with adverse events in the pre-hospital setting 4
• Do not withhold aspirin if patient already took aspirin that day—this is a common error 5

Pain Relief

• Administer morphine intravenously as the preferred analgesic, titrated to pain severity 1
• Pain relief should begin even before ECG interpretation 1
• Pain causes anxiety, sympathetic activation, and increased blood pressure, worsening myocardial ischemia 1
• Consider anxiolytics in conjunction with morphine 1

Nitroglycerin Administration

• Give sublingual nitroglycerin unless systolic blood pressure <90 mmHg, heart rate <50 or >100 bpm 1, 6
• Use nitrates liberally to decrease ischemia and reduce cardiac filling pressures 1
• Critical caveat: Nitroglycerin response does NOT diagnose cardiac ischemia—esophageal spasm also responds 2
• Patients should sit when taking nitroglycerin to prevent falls from hypotension 6

Beta-Blocker Therapy

• Intravenous beta-blockers are efficient if myocardial ischemia is suspected, particularly with tachycardia and hypertension 1
• Administer according to local protocols for suspected acute coronary syndrome 1

Oxygen Therapy

• Provide oxygen by nasal prongs immediately 1
• Oxygen is mandatory equipment for pre-hospital cardiac emergencies 1

Establishing Monitoring and Access

Cardiac Monitoring

• Establish cardiac monitoring to facilitate rapid defibrillation of ventricular tachycardia/ventricular fibrillation 1
• The risk for ventricular fibrillation is greatest within 1 hour of symptom onset 1

Intravenous Access

• Establish an IV line whenever possible 1
• This enables administration of medications and fluids for hemodynamic support 1

Critical History Elements to Obtain

Pain Characteristics

• Exact location and radiation pattern (left arm, neck, jaw suggests ACS) 1, 2
• Quality: retrosternal discomfort building gradually over minutes suggests ACS 2
• Sudden tearing or ripping pain radiating to back suggests aortic dissection 2
• Sharp pleuritic pain with dyspnea suggests pulmonary embolism or pneumothorax 2

Associated Symptoms

• Nausea, sweating, dyspnea, and lightheadedness increase likelihood of myocardial infarction 1, 2
• Diaphoresis, tachypnea, tachycardia, hypotension suggest acute coronary syndrome 2

Risk Factors

• Age, male gender, prior cardiovascular disease are general predictors for infarction 1
• Diabetes, hypertension, hyperlipidemia, smoking, family history of premature coronary disease 2

Decision Points for Reperfusion Therapy

ST-Elevation Myocardial Infarction (STEMI)

• If STEMI is identified, door-to-needle time for thrombolysis must be <30 minutes or first medical contact to balloon time <90 minutes (preferred <120 minutes acceptable) 1
• Pre-hospital thrombolysis reduces mortality by 17%, with 23 lives saved per 1000 per hour of earlier treatment 1
• Thrombolytic therapy saves 35 lives per 1000 when given within first hour versus 16 lives per 1000 when given 7-12 hours after symptom onset 1
• If hospital cannot be reached within 30 minutes, local protocols for pre-hospital thrombolysis are necessary 1

Primary Percutaneous Coronary Intervention

• Primary coronary angioplasty achieves more favorable outcomes than thrombolytics for acute myocardial reperfusion 1
• Casualty personnel must know local availability of primary PCI programs 1
• Direct transfer to PCI-capable centers should be arranged when feasible 1

Non-ST-Elevation Presentations

NSTE-ACS Management

• Patients without ST-elevation should NOT receive thrombolytic therapy 1
• Administer aspirin, consider heparin (enoxaparin preferred over unfractionated heparin) 1
• If troponin T >0.1 μg/L, heparin improves prognosis 1
• Consider ticagrelor as P2Y12 inhibitor—the only one with adequate safety data in pre-hospital setting 1

Transport Decisions

When to Call Ambulance Immediately

• For suspected acute coronary syndrome, call ambulance rather than attempting office-based evaluation 1, 2
• The general practitioner should call for ambulance by telephone triage when heart attack is suspected 1
• Stay with the patient until ambulance arrives if heart attack is suspected 1
• Transport by EMS allows for intervention if complications occur en route 1

Optimal Transport Timing

• Field delay (EMS call to team on scene) should be <20 minutes 1
• Door-in door-out time at non-PCI centers should be ≤30 minutes 1
• Greatest benefit occurs when treatment begins within 6 hours of symptom onset, with definite benefit up to 12 hours 1

Differential Diagnosis Considerations

Life-Threatening Causes Requiring Hospital Care

• Myocardial infarction or unstable angina 1, 2
• Aortic aneurysm/dissection 1, 2
• Pulmonary embolism 1, 2
• Pneumothorax 1, 2
• Pericarditis 1

Clinical Clues Against Cardiac Ischemia

• Pain affected by palpation, breathing, turning, twisting, or bending 1
• Pain generated from multiple sites 1
• However, reproducible chest wall tenderness does NOT exclude ACS—approximately 7% of patients with reproducible pain still have ACS 7

Musculoskeletal Pain

• Most prevalent diagnosis in chest pain presentations 1
• Cardiac problems account for only 10-34% of all chest pain episodes 1
• Even with musculoskeletal features, ECG and troponin must still be obtained 7

Special Population Considerations

Women

• At risk for underdiagnosis of ACS 2
• Emphasize accompanying symptoms like nausea, fatigue, and dyspnea 2

Older Adults (≥75 years)

• May present with atypical symptoms: isolated dyspnea, syncope, acute delirium, or unexplained falls without classic chest pain 2
• ACS should be considered even without typical chest pain 2

Young Patients

• Do not assume young age excludes ACS—it can occur even in adolescents without risk factors 2, 8

Common Pitfalls to Avoid

• Never rely on nitroglycerin response as diagnostic for ACS 2
• Never delay transfer to ED for troponin testing in office settings when ACS is suspected 2
• Never assume sharp, pleuritic pain excludes ACS—pericarditis and atypical presentations occur 2
• Never withhold aspirin because patient "already took aspirin today"—this is a common error 5
• Never assume reproducible chest wall tenderness rules out cardiac disease—7% still have ACS 7
• The most common reason paramedics fail to give aspirin is incorrectly believing chest pain is not cardiac 5

Contraindications to Check

Aspirin Contraindications

• Known aspirin allergy 1
• Active gastrointestinal bleeding 1

Nitroglycerin Contraindications

• Systolic blood pressure <90 mmHg 1, 6
• Heart rate <50 or >100 bpm 1
• Recent use of phosphodiesterase-5 inhibitors (sildenafil, tadalafil) 6
• Suspected right ventricular infarction 6

Thrombolysis Contraindications

• Should be checked but few absolute contraindications exist 1
• Proper ECG-based diagnosis is mandatory before thrombolytic therapy 1