Acute MI Interventions — MONA

The first 10 minutes of an acute MI determine myocardial survival. MONA isn't just a mnemonic — it's a sequenced intervention protocol where order and contraindications change the outcome.

MONA stands for Morphine, Oxygen, Nitroglycerin, and Aspirin, but the priority order is actually reversed: Aspirin first, then Nitroglycerin, then Oxygen (if indicated), then Morphine (used cautiously). Aspirin 162–325 mg chewed (not swallowed whole) is the single highest-impact first intervention — chewing accelerates platelet inhibition within minutes. Nitroglycerin 0.4 mg sublingual is given up to 3 doses, 5 minutes apart, while monitoring blood pressure; hold if systolic BP < 90 mmHg or if the client took a PDE5 inhibitor (sildenafil within 24 hours, tadalafil within 48 hours), as the combination can cause fatal hypotension. Oxygen is administered only if SpO2 falls below 94% — routine O2 for all MI clients is no longer recommended because hyperoxia may worsen ischemic injury. Morphine, once a standard, is now reserved for pain unrelieved by nitroglycerin because it can cause hypotension and respiratory depression, and some evidence links it to worse outcomes in NSTEMI. Throughout, you monitor vital signs continuously, establish IV access, obtain a 12-lead ECG, and keep the client on bedrest to reduce myocardial oxygen demand.

Key Distinctions

Don't confuse the mnemonic order (M-O-N-A) with the action order (A-N-O-M). Students assume oxygen is given to every MI client — current guidelines restrict it to SpO2 < 94%. Nitroglycerin is contraindicated with recent PDE5 inhibitor use AND with right ventricular infarction (these clients are preload-dependent); students often remember one but forget the other.

Clinical Pearl

Think 'A-N-O-M, not MONA': Aspirin chewed first, Nitro sublingual next, Oxygen only if sats drop, Morphine only as a last resort.