Shock is the body’s failure to deliver adequate oxygen to its tissues. It is not a single event — it is a progressive deterioration that, untreated, ends in organ failure and death. It is also, in many cases, treatable in the field if recognized early and managed correctly. The problem is that shock often looks like other things in its early stages, and by the time it looks unmistakably like shock, it has progressed further than it needed to.
Know what shock looks like before it is obvious. That is when you can do something about it.
TYPES OF SHOCK
Hypovolemic / Hemorrhagic Shock — The most common in trauma. The body has lost blood or fluid volume to the point where the heart cannot maintain adequate circulation. Causes: bleeding (external or internal), severe burns causing fluid loss, severe dehydration, vomiting and diarrhea. This is the type most often encountered in field trauma and most directly treatable in the field.
Distributive Shock — Blood vessels dilate inappropriately, dropping blood pressure even with normal blood volume. Subtypes relevant to field medicine:
- Anaphylactic shock — Severe allergic reaction causing massive vasodilation and airway involvement. Covered in the Allergic Reaction & Anaphylaxis post.
- Septic shock — Systemic infection causing vasodilation and multi-organ involvement. The end stage of untreated infection. Covered in the Infection Management post.
- Neurogenic shock — Spinal cord injury disrupting the nervous system’s control of vascular tone.
Obstructive Shock — Physical obstruction preventing the heart from pumping effectively. Tension pneumothorax (collapsed lung with air trapping) and cardiac tamponade (fluid around the heart) are the primary causes. Requires specific interventions beyond basic field medicine.
Cardiogenic Shock — Heart failure. The pump itself is failing. Field treatment options are limited.
This post focuses primarily on hypovolemic shock because it is the type most frequently encountered in trauma and the type most amenable to field intervention.
STAGES OF SHOCK
Shock progresses through stages. Recognition at Stage 1 or 2 allows effective field intervention. Stage 3 and 4 require advanced care that may be unavailable.
Stage 1 — Compensated (up to 15% blood volume loss) The body is compensating effectively. Signs are subtle: slight anxiety or restlessness, skin that is slightly pale or cool, heart rate mildly elevated (above 90 in a healthy adult at rest). Blood pressure is maintained. Easy to miss. Easy to dismiss as anxiety or pain response.
Stage 2 — Mild (15-30% blood volume loss) Compensation is working but strained. Signs: heart rate elevated (100-120), increased respiratory rate, skin pale and cool, capillary refill slow (press a fingernail until white, release — normal refill is under 2 seconds; in early shock it is 2-4 seconds), anxiety or agitation, decreased urine output, thirst.
Stage 3 — Moderate (30-40% blood volume loss) Compensation failing. Signs: heart rate above 120, blood pressure dropping, significant pallor and cool clammy skin, capillary refill above 4 seconds, confusion or altered mental status, rapid shallow breathing, marked thirst.
Stage 4 — Severe (above 40% blood volume loss) Decompensated. Survival without immediate advanced intervention is unlikely. Signs: heart rate above 140 or dropping as the heart fails, blood pressure severely low or unmeasurable, skin mottled or ashen, unconsciousness or near-unconsciousness, no urine output, breathing very rapid and shallow or agonal.
FIELD ASSESSMENT
Assess for shock in every trauma patient, not just those with obvious bleeding. Internal bleeding (abdominal trauma, pelvic fracture, femur fracture) can cause hemorrhagic shock without visible blood loss.
Rapid assessment:
- Heart rate — elevated?
- Skin — pale, cool, clammy?
- Capillary refill — above 2 seconds?
- Mental status — appropriate for the situation, or confused and agitated?
- Thirst — severe thirst is a shock symptom, not just a discomfort
Any three of these positive should trigger shock management immediately. Do not wait for blood pressure to drop — blood pressure is one of the last things to fall as the body compensates, and by the time it drops the patient is in Stage 3 or worse.
FIELD MANAGEMENT — HYPOVOLEMIC SHOCK
Step 1 — Stop the bleeding. The cause of hemorrhagic shock is blood loss. Nothing else matters until the bleeding is controlled. Tourniquet, wound packing, direct pressure — use everything available. A patient in shock from active hemorrhage cannot be stabilized until the source is addressed. See Tourniquet and Wound Packing.
Step 2 — Position. Lay the patient flat. Elevate the legs 6-12 inches if no spinal injury is suspected — this is the modified Trendelenburg position, which shifts blood volume toward the core and vital organs. Do not put the patient in the traditional head-down Trendelenburg (body tilted, head lower than feet) — this impairs breathing and is no longer recommended. Flat with legs elevated is correct.
Step 3 — Keep warm. Hypothermia dramatically worsens shock — it impairs clotting, drops cardiac output, and accelerates deterioration. Cover the patient with blankets, sleeping bags, or any available insulation. This is not comfort care. It is direct treatment. The trauma triad of death is hypothermia, acidosis, and coagulopathy — cold patients bleed to death faster than warm ones.
Step 4 — Oral fluids (conscious patients only). If the patient is conscious, alert, and not at risk for surgery in the next hour, oral fluid replacement helps. Water with small amounts of salt and sugar — oral rehydration solution — is more effective than plain water for maintaining fluid balance. Do not give fluids to an unconscious patient, a patient with suspected abdominal injury, or a patient who may need anesthesia. Aspiration risk is real.
Step 5 — Reassess continuously. Shock is dynamic. A patient who appears stable can deteriorate rapidly. Check heart rate, skin condition, and mental status every few minutes during transport or while waiting for further care.
WHAT FIELD MEDICINE CANNOT DO
Hemorrhagic shock from massive blood loss cannot be definitively treated without blood transfusion or surgical control of the bleeding source. Field management buys time — it slows the deterioration and maintains the patient long enough to reach care. In a scenario where care is genuinely unavailable, field management is all there is. Know its limits.
Internal bleeding — abdominal, thoracic, or pelvic — cannot be controlled in the field. Position, warmth, and oral fluids are supportive only. A patient with suspected internal hemorrhage who is deteriorating despite field measures needs surgical care. If it is obtainable, make it the priority.
WHAT TO WATCH FOR — SHOCK MIMICS
Vasovagal syncope — Fainting from pain, emotional response, or prolonged standing. Heart rate typically drops (unlike shock, where it rises). The patient recovers quickly when lying flat. Differentiate from shock by the heart rate and rapid recovery.
Panic attack — Rapid heart rate, hyperventilation, feeling of doom. Skin is usually warm and flushed rather than pale and cold. Mental status is anxious but coherent. Differentiate from shock by skin presentation and lack of trauma history.
Hypoglycemia — Low blood sugar causes confusion, diaphoresis, and deterioration that can look like shock. Give glucose (juice, sugar, anything available) if hypoglycemia is possible and the patient can swallow safely.
WHAT TO STOCK
- Emergency blankets (mylar space blankets) — $1-2 each, pack multiple
- Oral rehydration salts (ORS packets — WHO formula or equivalent)
- Knowledge of pressure points and tourniquet application
- A pulse oximeter ($15-30) — reads heart rate and oxygen saturation, useful for early shock assessment
Cross-reference: Tourniquet | Wound Packing | Hypothermia | Allergic Reaction & Anaphylaxis | Infection Management