Overview
- Goals of critical care
- Restore adequate perfusion and circulating blood volume
- Restore normothermia
- Correct acidosis
- Correct electrolyte disorders
- Correct coagulopathy
- Organ support, including maintaining oxygenation and ventilation
Lethal Triad
Hypothermia, coagulopathy and acidosis are known as the “lethal triad” in trauma because each condition worsens the other if left untreated, resulting in irreversible progression towards death. ****It was first described in 1982 by Kashuk et al.
Hypothermia
Hypothermia (core body temperature < 36.5 C) is associated with increased mortality in trauma. Core body temperature < 32 degrees (severe hypothermia) is associated with 100% morality regardless of injury or resuscitation.
Temperature in trauma
| Degree of hypothermia | Definition in trauma | Classic definition |
|---|---|---|
| Mild | 36 – 34 | 35 – 32 |
| Moderate | 34 – 32 | 32 -28 |
| Severe | < 32 | 28 – 20 |
- Causes of hypothermia in trauma
- Prolonged extrication
- Shock
- Vasodilation from anaesthetic
- Environmental exposure
- Large volumes of intravenous fluids and blood
- Surgical exposure of body cavities
- Alcohol intoxication (impairs temperature regulation)
- Traumatic brain injury (impairs temperature regulation)
- Comorbidities e.g. diabetes and thyroid disorders
- Consequences of hypothermia
- Impairs coagulation (coagulation is a serios of enzymatic reactions) → coagulopathy
- Decreased cardiac output → reduced oxygen delivery to tissue → worsens acidosis
- Impaired response to catecholamines
Coagulopathy
Coagulopathy occurs in 25% of patients with trauma. Acute coagulopathy
- Causes of coagulopathy in trauma
- Loss of clotting factors due to hemorrhage
- Dilution of clotting factors due to intravenous fluid resuscitation
- Consumption of clotting factors during the coagulation process
- Impaired enzyme function from hypothermia
- Increased fibrinolysis (plasminogen and tPA release increases due increased thrombomodulin and endothelial and platelet dysfunction)
- Increased thrombomodulin-mediated anticoagulation
- Hypofibrinogenemia (due to blood loss, dilution, consumption and impaired funciton)
Acidosis
Acidosis decreases myocardial contractility and cardiac output.
- Causes of acidosis in trauma
- Lactic acidosis from poor perfusion
- Resuscitation with normal saline (hyperchloremic non-gap metabolic acidosis in large volume resuscitation)
- Respiratory acidosis (from respiratory depression associated with altered mental status)
Balanced Resuscitation
Balanced resuscitation involves permissive hypotension (SBP ~ 80 -90 mmHg) and early use of blood products in trauma patients to optimize oxygen delivery and limit coagulopathy, hypothermia, acidosis and organ dysfunction.
- Principles of balanced resuscitaiton
- Permissive hypotension: keep SBP ~80 – 90 mmHg to avoid dislodging clots and reduce bleeding until surgical control
- Blood products in a 1:1:1: ratio of pRBC, FFP and platelets, or whole blood as an alternative (type -O uncrossmatched blood – Rh+ can be used for men and post-menopausal women)
- Early administration of tranexamic acid (TXA) within 3 hours of injury to limit rebleeding and reduce mortality (CRASH-2 trial)
Damage control surgery (DCS)
After initial trauma evaluation and resuscation, critically ill patients may require damage control surgery (DCS) to rapidly control hemorrhage and contamination before further definitive operative repair is done once physiology is normalised and homeostasis is restored.
The goal is to operate for a total time of less than 60 – 90 minutes.
- Priorities of damage control surgery (DCS)
- Control hemorrrhage (hemostasis)
- Control contamination
- Temporary abdominal closure
Control of bleeding (Hemostasis)
Bleeding is the most rapidly lethal issue addressed in damage controled surgery. Techniques for controlling hemorrhage include abdominal packing e.g. four quadrant packing**, vascular sutures, ligations, shunting** and splenectomy.
Forms of bleeding
| Form of bleeding | Description |
|---|---|
| Surgical bleeding | Bleeding due to extensive trauma to an organ involving major vascular structures and large blood vessels. This may not be controlled by packing meaning that direct hemorrhage control should be performed e.g. splenectomy, nephrectomy, vascular ligation, rapid repair or shunting. |
| Non-surgical bleeding | Bleeding that is due to coagulopathy or small vessel damage. Can be controleld by packing. |
packing the liver
Control of contamination
Once bleeding is controlled the abdomen is thoroughly explored for bowel injury. It is inspected from the ligament of treitz to the rectum. Exploring the intraperitoneal portion is often sufficient in blunt trauma. Peritoneal reflection planes may need to be opened to assess retroperitoneal organs, especially in penetrating injury.
If spillage is found it can be temporarily controlled by clamping or suturing for small enterotomies. Resection can be performed if there a re more extensive or multiple areas of injury.
Anatomic zones of the peritoneum
| Zone | Extent | Management |
|---|---|---|
| Zone I (midline retroperitoneum) | Aortic hiatus to sacral promontory. Supramesocolic and inframesocolic zones | Surgical exploration for all injuries |
| Zone II (lateral retroperitoneum) | Renal hila to pericolic gutters. | Surgical exploration for penetrating trauma |
| Zone III (pelvic retroperioneum) | Inferior to sacral promontory | Surgical exploration for expanding hematoma in penetrating trauma |
Temporary abdominal closure (TAC)
The abdomen is temporarily closed since it takes shorter time, reduces the risk of abdominal compartment syndrome in patients requiring ongoing resuscitation, and for future reoperation.
Options for temporary abdominal closure
| Temporary abdominal closure | Description | Nota bene |
|---|---|---|
| Skin-only closure (towel clip closure) | Running suture for skin closure or towel clips placed along the incision length. | Skin sutures can cut through and tear the skin as the patient develops abdominal wall edema from fluid resuscitation |
| Bogota bag | Non-adherent material e.g. catheter drainage bag is sewn to skin or anterior abdominal wall fascia | |
| Vacuum-assisted closure (VAC) | Small holes are cut into the bogota bag which is placed over viscera and below the abdominal wall circumferentially. It is then covered with large gauzes and drains are placed ver the gauze. An adhesive dressing is placed and the drains are placed to suction to allows fluid to be removed from the abdomen. | |
| Mesh closure | Mesh sutured to the fascia like a bogota bag |
After hemostasis is restored the patient is taken back to theatre for re-exploration 24 – 48 hours after initial exploration.