Understanding MARCH - The Role of Circulation - Colorado Cardiac CPR & First Aid

From the MARCH Mnemonic Series – Tactical Trauma Care for EMS Providers

After addressing massive hemorrhage, airway, and respiration, the next priority is Circulation: the body’s ability to deliver oxygenated blood to vital organs and tissues.

In trauma, the circulatory system can be compromised by shock, internal bleeding, or poor perfusion, even when obvious external hemorrhage has been controlled.

Within the tactical environment, circulation assessment focuses on recognizing and managing shock, maintaining perfusion, and preventing secondary injury. The goal is to identify subtle but deadly deterioration before it progresses beyond recovery.

This article – the forth in a five-part series – will focus on that next critical step:

C – Circulation

In tactical casualty care, circulation assessment differs slightly from the traditional EMS approach. The emphasis is on speed, simplicity, and practicality in resource-limited or high-threat conditions.

Blood pressure cuffs and monitors may not be available, so providers rely on physical signs and simple indicators to evaluate perfusion. The presence of a radial pulse and normal mental status are key field markers of adequate circulation.

Principles of Circulatory Assessment and Management

Check for Pulse and Perfusion
- Radial Pulse: Presence suggests a systolic blood pressure above roughly 80 mmHg, generally adequate for perfusion in tactical settings.
- Weak or Absent Pulse: May indicate hypovolemia or shock; assess for additional signs of poor perfusion such as pallor, clammy skin, or delayed capillary refill.
- Mental Status: A sudden change in consciousness (e.g., confusion, lethargy) is often an early sign of inadequate cerebral perfusion.
Remember: weak radial pulse + altered mental status = shock until proven otherwise.
Identify and Manage Non–Life-Threatening Bleeding

Once major bleeding has been controlled, systematically check for and address secondary bleeding sites that may have been overlooked during the initial MARCH sequence.

Apply direct pressure, pressure dressings, or hemostatic agents as needed.
Treat for Shock

Shock – a state of inadequate tissue perfusion – can occur from blood loss (hypovolemic), cardiac injury, or tension pneumothorax.

In tactical medicine, hemorrhagic shock is the most common.
- Lay the casualty supine, if tactical conditions allow.
- Keep the patient warm, hypothermia worsens coagulopathy and shock (addressed further in Part Five).
- Provide fluids only when indicated by TCCC or TECC guidelines
If in shock (weak/absent radial pulse or altered mental status):
- Administer whole blood if available; otherwise, use 1:1:1 blood component therapy (plasma, platelets, red cells).
- If blood products are unavailable, give Hextend or Lactated Ringer’s solution, titrating only to restore a palpable radial pulse or improved mental status (per TCCC guidance).
- If the casualty is not in shock and has a palpable radial pulse and normal mental status, no IV/IO fluids are indicated.
Avoid over-resuscitation, too much fluid can dislodge clots and worsen bleeding.
Establish IV/IO Access When Appropriate

In tactical field care, IV or intraosseous access is indicated for:
- Fluid resuscitation in shock
- Medication administration (e.g., analgesics, antibiotics, TXA).
If available, administer Tranexamic Acid (TXA) within three hours of injury for casualties at risk of significant hemorrhage. Early TXA administration has been shown to reduce mortality from bleeding.
Continuous Reassessment

Circulation is dynamic, especially in prolonged field care or delayed evacuation.

Regularly recheck:
- Pulse quality and rate
- Mental status
- Skin color, temperature, and moisture
- Wound sites for renewed bleeding
Document all findings and interventions clearly for handoff to the next echelon of care.

Key Takeaway for EMS and Tactical Providers

Circulation management is about detecting shock early, maintaining perfusion, and preventing deterioration.
In the tactical environment, sophisticated monitoring tools are often unavailable, but trained observation remains powerful.
The provider’s mindset should be: Feel for the pulse, read the patient, and keep the blood where it belongs.

Coming Next: Part Five – Hypothermia and Head Injury

The final step in the MARCH sequence focuses on protecting what you’ve fought to preserve, preventing hypothermia and managing head injuries to maintain survivability after initial stabilization.

In Part Five, we’ll discuss how temperature control, positioning, and neurologic assessment all play critical roles in keeping your casualty alive until evacuation and definitive care.

Because in tactical medicine, saving a life isn’t just about stopping the bleeding—it’s about keeping that life sustained.

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