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Haemorrhagic shock in trauma and damage-control resuscitation
Shock in a trauma patient is bleeding until proven otherwise; modern resuscitation replaces large volumes of crystalloid with balanced blood products, accepts a controlled low blood pressure until bleeding stops, and controls the source as quickly as possible.
Why it matters in the exam
The exam first asks about assessment: how much blood a patient with a given heart rate, blood pressure and urine output has lost, that is, the four classes of haemorrhagic shock. Questions check that you remember blood pressure falls only in class III, after roughly 30%–40% of the blood volume is lost, and that the early signs are tachycardia, a narrow pulse pressure and slow capillary refill. Older patients, patients on beta-blockers and patients with pacemakers mask the tachycardia, and young athletes compensate for a long time.
Then resuscitation is tested: when to activate a massive transfusion protocol, the ratio of red cells, plasma and platelets, why many litres of crystalloid are avoided, and the blood pressure target before bleeding is controlled (and when low blood pressure is not accepted — head injury). Tranexamic acid is essential: its dose, the 3-hour window, and why it is harmful after that. Finally candidates are asked about the "lethal triad" — hypothermia, acidosis and coagulopathy — and about damage-control surgery, which aims to stop bleeding and contamination rather than repair everything at once.
Key points
- Four classes: blood pressure falls only from class III (about 30%–40% blood loss).
- Limited crystalloid, early blood products in a ratio of about 1:1:1.
- Tranexamic acid within 3 hours: 1 g bolus and 1 g over 8 hours.
- Systolic pressure of 80–90 until bleeding is controlled — but not in severe head injury.
- The lethal triad: hypothermia, acidosis and coagulopathy — damage-control surgery.
Summary table
| Class | Blood loss (of blood volume) | Heart rate and blood pressure | Treatment |
|---|---|---|---|
| I | Up to 15% | Normal heart rate, normal blood pressure | Minimal; fluids as needed |
| II | 15%–30% | Mildly raised heart rate, normal blood pressure, narrow pulse pressure | Moderate crystalloid; consider blood |
| III | 30%–40% | Tachycardia, falling blood pressure, reduced urine output, confusion | Blood products and haemorrhage control |
| IV | Over 40% | Severe tachycardia, very low blood pressure, no urine, depressed consciousness | Massive transfusion protocol and immediate haemorrhage control |
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Sources
- ATLS Advanced Trauma Life Support, Student Course Manual (American College of Surgeons), 10th edition (2018) — Shock
- European guideline on management of major bleeding and coagulopathy following trauma, 6th edition (2023) — Resuscitation, tranexamic acid and coagulation management
- CRASH-2 trial collaborators, The Lancet, 2010 — Tranexamic acid in bleeding trauma patients
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.