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"hypovolemic shock" AND "damage control resuscitation"
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Here is a full, structured breakdown of everything on this page, cross-referenced with authoritative surgical textbooks.
Hypovolemic Shock - ATLS Classification
The ATLS (Advanced Trauma Life Support) system divides hemorrhagic shock into four classes based on estimated blood volume loss in a 70 kg adult (total blood volume ~5L, estimated at 7% of ideal body weight).
| Parameter | Class I | Class II (Mild) | Class III (Moderate) | Class IV (Severe) |
|---|---|---|---|---|
| Blood loss | <15% (<750 mL) | 15-30% (750-1500 mL) | 31-40% (1500-2000 mL) | >40% (>2000 mL) |
| Heart rate | Normal (↔) | Mildly raised (↑) | Raised (↑) | Markedly raised (↑↑) |
| Blood pressure | Normal (↔) | Normal (↔) | Decreased (↓) | Decreased (↓) |
| Pulse pressure | Normal (↔) | Narrowed (↓) | Narrowed (↓) | Narrowed/undetectable (↓) |
| Respiratory rate | Normal (↔) | Normal (↔) | Raised (↑) | Raised (↑) |
| Urine output | Normal (↔) | Normal/slightly ↓ (↔) | Decreased (↓) | Negligible (↓↓) |
| Glasgow Coma Scale | Normal (↔) | Anxious (↔) | Confused (↓) | Depressed (↓) |
| Base deficit | 0 to -2 mEq/L | -2 to -6 mEq/L | -6 to -10 mEq/L | <-10 mEq/L |
| Blood products | Monitor | Possible | Yes | Massive transfusion |
Key physiology by class:
- Class I: No clinical signs; the body compensates fully. Transcapillary refill restores volume within 24 hours.
- Class II: Pulse pressure narrows (diastolic rises due to adrenergic discharge/vasoconstriction). First class with mental status changes (anxiety).
- Class III: This is the smallest blood loss that consistently causes a drop in systolic BP. Confusion/combativeness appears.
- Class IV: Life-threatening. Diastolic may be unobtainable. Immediate surgery or angioembolization often needed.
Note: Individual response varies significantly with age, beta-blocker use, pregnancy, and baseline health. - Mulholland and Greenfield's Surgery, p. 531
ATLS Management of Hypovolemic Shock
The image lists the initial resuscitation protocol:
- Minimum cannula: 18G (large bore for rapid fluid delivery)
- Fluid type: 1L bolus of isotonic crystalloid - Normal Saline (NS) or Ringer's Lactate (RL)
- Fluid ratio: After the initial crystalloid bolus, transition to 1:1:1 ratio of:
- PRBC (Packed Red Blood Cells)
- FFP (Fresh Frozen Plasma)
- Plt (Platelets)
This 1:1:1 ratio constitutes the Massive Transfusion Protocol (MTP), which approximates whole blood and reduces dilutional coagulopathy.
Damage Control Resuscitation - CRASH-2 Trial
Tranexamic Acid (TXA): 1 gram IV over 10 minutes, given within 3 hours of injury.
TXA is an antifibrinolytic that blocks plasminogen activation, reducing hyperfibrinolysis - a key driver of trauma-induced coagulopathy. The CRASH-2 trial showed TXA reduces all-cause mortality and hemorrhage-related death in trauma patients when given early. Benefit diminishes rapidly after 3 hours and giving it late may actually increase mortality.
From Bailey and Love's: "Tranexamic acid should be given as soon as possible in almost all bleeding patients to stop hyperfibrinolysis."
Damage Control Surgery (DCS)
The Trauma Triad of Death
The three conditions that form a lethal positive-feedback cycle in major trauma:
- Hypothermia (<35°C) - impairs clotting enzymes and platelet function
- Coagulopathy - worsened by blood loss, dilution, hypothermia, and acidosis
- Metabolic Acidosis (pH <7.2) - from poor perfusion and lactate accumulation
Each worsens the others. DCS aims to break this cycle before it becomes irreversible.
DCS Stages
Stage I - Primary Emergency Surgery (Control damage, not reconstruct)
- Arrest hemorrhage (packing, vessel ligation, temporary shunts)
- Drain/control septic contamination
- Temporary abdominal closure - NOT definitive repair. Methods include:
- Bogota Bag - sterile IV bag sutured over the open abdomen
- Skin closure only
- Negative Pressure Wound Therapy (NPWT) covers
The core principle of DCS is borrowed from the military - keeping the ship operational (patient alive) takes priority over complete repairs.
Stage II - Resuscitation & ICU Care (24-48 hours)
- Correct the triad of death: rewarm the patient, correct coagulopathy, normalize acid-base
- Ongoing monitoring, ventilator support, reassessment of injuries
Stage III - Definitive Surgery
- Full gastrointestinal repair
- Resection and anastomosis
- Definitive abdominal closure (permanent fascial closure)
Stage IV - Abdominal Closure
- For patients in whom abdominal closure was not performed during Stage III
- Planned closure at a later date, once physiological stability is confirmed
DCS vs. Early Total Care (ETC)
DCS is preferred over ETC when the patient is in the "lethal diamond" - severe physiologic derangement (acidosis, hypothermia, coagulopathy, massive transfusion). ETC (performing definitive repair in one sitting) is appropriate for physiologically stable patients with isolated injuries.
From Bailey and Love's: "Damage control surgery: Arrest haemorrhage, Control sepsis, Protect from further injury - Nothing else." - Bailey and Love's Short Practice of Surgery, 28th Ed.
High-yield exam points to remember:
- Class III shock is the first class with consistent hypotension (BP drop)
- Class II shock: pulse pressure narrows BEFORE systolic BP drops
- TXA must be given within 3 hours (CRASH-2)
- The 1:1:1 ratio refers to PRBC:FFP:Platelets
- DCS Stage II is specifically 24-48 hours of ICU resuscitation
- The triad of death thresholds: Temp <35°C, pH <7.2, coagulopathy
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