Aortic Dissection: Field Suspicion
Objective: Suspect dissection, avoid the ACS reflex that drops preload, and choose a hospital that can actually fix an aorta.
Why This Is Hard
It feels like a STEMI and sometimes the 12-lead even shows one (if the root involved a coronary). Aspirin and nitro are the ACS habit. If this is dissection, you may be dropping the only blood pressure keeping the other true lumen open.
- Two-arm BPs and pulse check if the story is tearing or ripping, or if there is a neuro deficit with chest/back pain.
- Do not withhold oxygen for hypoxia. Do withhold the automatic nitro/aspirin reflex until the picture is ACS, not dissection — follow protocol/medical control.
- Destination: a hospital that can do aortic surgery / hybrid OR, not the closest clinic with a hallway.
Field Rules (Education)
- Clues: sudden tearing/ripping chest or back pain, pulse or BP difference, focal neuro, syncope, new AI murmur you will not diagnose on the truck, Marfan/family history.
- 12-lead: still get it. Inferior STE can be ACS or a right-coronary dissected. The story still matters.
- 2025 ACS guideline: aspirin is Class 1 in ACS. Dissection is the pause. When in doubt, medical control.
- Pain control per protocol without dropping the BP below your floor.
Field Pitfalls
- Nitro into a possible dissection because “chest pain gets nitro.”
- Closest hospital with no surgical backup.
- Skipping the 12-lead because you “already know.”
Practice
60-second drill
Partner: sudden tearing back pain, right radial weaker, BP 188/110. Aspirin? Nitro? Destination?
Sources & Further Study
Named guidelines for further study. They are not clinical orders and do not replace your protocol or medical direction.
- NASEMSO National Model EMS Clinical Guidelines (2022) — U.S. EMS model language; protocol still wins
- 2025 ACC/AHA ACS Guideline — do not treat every chest pain as ACS by reflex; dissection is a caution for antiplatelet/nitro
- 2022 ACC/AHA Aortic Disease Guideline — rapid recognition and a center that can repair the aorta
Education only. Apply learning within your protocols and medical direction. This is not clinical care guidance.
Check Your Understanding
Street decisions from this lesson only. After you check, the key is highlighted. Education practice — not a certification exam.