Tactical Medicine News Blog | 1631 words | May 13, 2026

Shock Index in Trauma Triage (2026): The HR >= SBP Rule for Tactical and Austere Medicine

Written by
Dr. Marco R. Torres, MD, NRP
Founder & CEO, MED-TAC International Corp.

Marco R. Torres, MD, NRP is a physician and Nationally Registered Paramedic, founder of MED-TAC International Corp. — an SDVOSB-certified, clinician-founded provider of tactical medical equipment and education for law enforcement, military, and first-responder teams. Editorial standards: every claim is sourced from primary literature (PubMed, JTS, JSOM, CoTCCC, WMS, ILCOR, AHA) and reviewed against current guidelines before publication.

BOTTOM LINE: Shock Index (SI) is simple: HR ÷ SBP. In 2026, more EMS systems are using SI ≥ 1.0 (HR ≥ SBP) as a trauma triage trigger. Here’s how to use it in tactical and limited-resource medicine.

If you remember one thing from this article, make it this:

If the heart rate is equal to or higher than the systolic blood pressure (HR ≥ SBP), your patient is not fine.

That single comparison is Shock Index (SI) without the calculator.

In 2026–2027, more EMS systems are formalizing SI as a trauma triage trigger (often SI ≥ 1.0), because it catches the patient who is “still talking” right before they fall off the cliff. The County of San Diego’s 2026–2027 EMS updates explicitly add shock index ≥ 1.0 (HR ≥ SBP) as a new Trauma Decision Algorithm criterion and reference SI ≥ 1.0 in TXA guidance for trauma-associated hemorrhage. (County of San Diego EMS protocol updates presentation: https://www.sandiegocounty.gov/content/dam/sdc/ems/Policies_Protocols/2026/2026-2027%20Protocol%20and%20Policy%20Updates%20Presentation.pdf)

This is not a trendy “new metric.” It’s an old idea that’s finally getting operational respect.

What is Shock Index (SI)?

Shock Index (SI) = Heart Rate (HR) ÷ Systolic Blood Pressure (SBP).

  • Example: HR 120 and SBP 100 → SI = 1.2
  • Example: HR 110 and SBP 110 → SI = 1.0

Why SI works in the field

In early hemorrhage, the body can keep SBP “normal” for a while by clamping down blood vessels and speeding up the heart.

So the patient can look okay on paper while they are actively bleeding internally.

SI turns “HR and BP” into a quick picture of compensation.

The no-BS threshold: SI ≥ 1.0 (HR ≥ SBP)

Many systems use different cutoffs depending on age and context, but SI ≥ 1.0 is the simplest, most field-proof trigger.

It’s also easy to teach:

  • If HR < SBP: keep assessing, trend matters
  • If HR ≥ SBP: assume shock until proven otherwise

Infographic: Shock Index Quick Reference

Shock Index (SI) Quick Reference for Field Triage

Where SI fits in tactical and austere medicine

SI is not meant to replace:

  • a good trauma exam
  • bleeding control
  • mental status checks
  • skin signs
  • respiratory effort
  • mechanism of injury

SI is meant to answer a tactical question:

“Do we need to increase urgency right now?”

In patrol/tactical, remote/wilderness, maritime, and limited-resource settings, “increasing urgency” typically means:

  • shorten on-scene time
  • change transport decision (destination, mode, intercept)
  • upgrade the team’s posture (additional security, more hands, more gear)
  • anticipate airway/ventilation needs
  • treat hypothermia early

Why SBP alone misses patients

If you only react when SBP drops below a certain number (90–100 mmHg), you will miss a lot of compensated shock.

A patient can be:

  • bleeding
  • tachycardic
  • pale and sweaty
  • increasingly confused

…and still have SBP around 110.

Infographic: SBP vs Shock Index (three common “looks fine” vitals sets)

Why SI can flag deterioration before SBP crashes

The “HR ≥ SBP” rule (no calculator, no excuses)

Under stress, you do not need to divide numbers.

Just compare them.

Infographic: The HR ≥ SBP card

The “HR ≥ SBP” Rule: Shock Index Without a Calculator

A simple field workflow (MARCH + SI)

Use SI as an overlay on what you already do.

Step 1: Control hemorrhage first

If the patient is bleeding externally, stop it.

Practical priorities:

  • tourniquet for life-threatening extremity bleeding
  • hemostatic gauze + direct pressure for junctional wounds
  • pressure bandage to maintain compression
  • chest seals for suspected penetrating chest trauma

Relevant MED‑TAC gear (examples):

Step 2: Get the numbers (and trend them)

  • Take HR and SBP.
  • Recheck after interventions.
  • Recheck after movement.

SI is a trend tool. One value matters; the direction matters more.

Step 3: If SI is high, make the call early

If SI is climbing toward 1.0, or it’s already ≥ 1.0:

  • Treat as occult hemorrhage until proven otherwise.
  • Upgrade transport urgency.
  • Minimize delays.
  • Prevent hypothermia aggressively.

Common tactical mistakes SI helps prevent

Mistake 1: “BP is normal so we have time.”

Normal SBP does not equal stability.

A patient who is compensating can maintain SBP until they cannot.

SI gives you a structured reason to move faster.

Mistake 2: “We’ll fix everything on scene.”

In penetrating trauma and major blunt trauma, you rarely “fix” shock on scene.

You control hemorrhage, support airway/breathing as needed, prevent hypothermia, and evacuate.

Mistake 3: “Pain meds first, then reassess.”

Analgesia matters. But if the patient is in early shock, sedatives/analgesics can unmask hypotension.

If SI is high, be cautious, titrate, and reassess after every step.

When SI can mislead you (and how to stay smart)

SI is not magic. It can rise from causes other than hemorrhage:

  • stimulant use
  • severe pain/anxiety
  • hypoxia
  • dehydration
  • sepsis
  • heat illness

It can also look “better” in patients on beta blockers or in athletic patients.

Bottom line: SI is an early warning system, not a standalone diagnosis.

Operational takeaways (print this)

  1. SI = HR ÷ SBP.
  2. SI ≥ 1.0 (HR ≥ SBP) = treat as shock until proven otherwise.
  3. Use SI to upgrade urgency early: shorten on-scene time, prioritize evacuation, prevent hypothermia.
  4. SI is strongest when you trend it after interventions and movement.

Build your team’s “SI-ready” loadout

Shock kills by time and temperature as much as blood loss.

If you’re building a patrol/tactical, range, workplace, or expedition medical kit, prioritize:

  • proven hemorrhage control (tourniquets + hemostatics + pressure dressings)
  • chest seals
  • a reliable BP cuff (or validated monitor)
  • documentation tools (so the receiving team knows trends)

A solid starting point is a real IFAK (not a novelty pouch):

And if you’re the one carrying the heavier problem set:

BUILD YOUR KIT

MED-TAC International stocks CoTCCC-recommended tourniquets, hemostatic dressings, chest seals, airways, and complete trauma kits for LE, EMS, military, and prepared civilians.

Trauma Kits Tourniquets & Holders
— Versión en Español —

(Spanish Version)

Si solo recuerdas una cosa de este artículo, que sea esto:

Si la frecuencia cardiaca es igual o mayor que la presión arterial sistólica (FC ≥ PAS), tu paciente no está bien.

Esa comparación es el Índice de Choque (Shock Index, SI) sin calculadora.

En 2026–2027, más sistemas de EMS están formalizando el SI como disparador de triage (a menudo SI ≥ 1.0), porque detecta al paciente que “todavía habla” justo antes de colapsar. Las actualizaciones 2026–2027 del EMS del Condado de San Diego agregan explícitamente shock index ≥ 1.0 (FC ≥ PAS) como nuevo criterio del algoritmo de decisión de trauma y también mencionan SI ≥ 1.0 en la guía de TXA para hemorragia asociada a trauma. (Presentación de actualizaciones del EMS del Condado de San Diego: https://www.sandiegocounty.gov/content/dam/sdc/ems/Policies_Protocols/2026/2026-2027%20Protocol%20and%20Policy%20Updates%20Presentation.pdf)

Esto no es una “métrica nueva” de moda. Es una idea vieja que finalmente está recibiendo respeto operativo.

¿Qué es el Índice de Choque (SI)?

Índice de Choque (SI) = Frecuencia cardiaca (FC) ÷ Presión arterial sistólica (PAS).

  • Ejemplo: FC 120 y PAS 100 → SI = 1.2
  • Ejemplo: FC 110 y PAS 110 → SI = 1.0

El umbral sin vueltas: SI ≥ 1.0 (FC ≥ PAS)

Muchos sistemas usan diferentes puntos de corte según edad y contexto, pero SI ≥ 1.0 es el disparador más simple y aplicable en terreno.

También es fácil de enseñar:

  • Si FC < PAS: seguir evaluando; la tendencia importa
  • Si FC ≥ PAS: asumir choque hasta demostrar lo contrario

Dónde encaja el SI en medicina táctica y austera

El SI no reemplaza:

  • una buena evaluación de trauma
  • el control de hemorragia
  • el estado mental
  • los signos de piel
  • el esfuerzo respiratorio

El SI responde una pregunta táctica:

“¿Tenemos que aumentar la urgencia ahora mismo?”

En escenarios tácticos, remotos, marítimos y de recursos limitados, “aumentar la urgencia” suele significar:

  • acortar el tiempo en escena
  • cambiar decisión de transporte
  • anticipar necesidades de vía aérea/ventilación
  • prevenir hipotermia temprano

Por qué la PAS sola falla

Si reaccionas solo cuando la PAS baja de cierto número, vas a perder a muchos pacientes en choque compensado.

Un paciente puede estar:

  • sangrando
  • taquicárdico
  • pálido y sudoroso
  • cada vez más confundido

…y aun así tener PAS cerca de 110.

La regla “FC ≥ PAS” (sin calculadora)

Bajo estrés, no necesitas dividir números.

Solo compáralos.

Flujo simple en terreno (MARCH + SI)

Usa el SI como capa adicional sobre lo que ya haces.

Paso 1: Controlar hemorragia primero

  • torniquete para hemorragia masiva en extremidades
  • gasa hemostática + presión directa para heridas de unión (ingle/axila)
  • vendaje de presión para mantener compresión
  • sellos torácicos para trauma penetrante

Enlaces de equipo MED‑TAC (ejemplos):

Paso 2: Obtener números (y seguir tendencia)

  • medir FC y PAS
  • reevaluar después de intervenciones
  • reevaluar después de mover al paciente

El SI es una herramienta de tendencia. Un valor importa; la dirección importa más.

Paso 3: Si el SI está alto, decidir temprano

Si el SI sube hacia 1.0, o ya está ≥ 1.0:

  • asumir hemorragia oculta hasta demostrar lo contrario
  • aumentar urgencia de evacuación
  • minimizar demoras
  • prevenir hipotermia agresivamente

Conclusión

El Índice de Choque es simple, rápido y útil cuando el entorno está feo y el tiempo es corto.

FC ≥ PAS = actúa como si fuera choque.

Nota educativa: este artículo es para entrenamiento y preparación. Siempre sigue tus protocolos locales y la dirección médica.

Tag: austere medicine military shock index trauma triage
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