What are the prehospital treatments for ACS?

• A. MONA; morphine, oxygen, nitroglycerin (0.4 mg SL x3 prn), aspirin (325 mg)
• B. Immediate thrombolysis without evaluation
• C. Oxygen only
• D. Nitrates and beta blockers only

Answer: (A)

The key idea is that early prehospital care for suspected ACS focuses on rapid anti-ischemic and anti-platelet therapy to limit heart damage while the patient is en route to definitive care. The MONA bundle—morphine, oxygen, nitroglycerin, aspirin—is the standard prehospital approach because it combines several proven measures that can quickly relieve symptoms and reduce myocardial workload.

Aspirin 325 mg chewed promptly is essential because it inhibits platelet aggregation, which slows the growth of a clot and lowers mortality in ACS. Nitroglycerin 0.4 mg sublingually, given up to three times at five-minute intervals if the patient remains hemodynamically stable and has no contraindications (such as hypotension or recent phosphodiesterase inhibitor use), helps by dilating vessels, reducing preload, and decreasing myocardial oxygen demand, which can lessen chest pain and ischemia. Oxygen should be given only if the patient is hypoxic or in respiratory distress, because routine oxygen for all ACS patients isn’t beneficial and can even be harmful in some cases. Morphine is used for severe chest pain unrelieved by nitrates, or when pain is causing significant distress, but it requires careful monitoring due to potential hypotension and respiratory depression.

Immediate thrombolysis without evaluation isn’t appropriate in the prehospital setting because a proper STEMI diagnosis and patient-specific considerations (including contraindications and arrival at an appropriate facility) are needed. Options that include only nitrates and beta blockers or rely on oxygen alone fail to address the anti-platelet and analgesic components that improve outcomes in ACS.