Mechanism of development and Allgöwer index
The pathogenesis of shock is triggered by pain and massive blood loss leading to critical hypovolemia. Not only the volume of blood lost is critical, but also the rate of bleeding. The situation is exacerbated by histamine release, activation of the kallikrein-kinin system, and the effects of toxins from destroyed tissues.
To rapidly assess hemodynamic status and estimate blood loss, the Allgöwer index is used — the ratio of heart rate (bpm) to systolic blood pressure (SBP, mmHg).
- 0.5 (Normal): e.g., heart rate 60, SBP 120.
- 1.0 (Transition to pronounced shock): heart rate 100, SBP 100. Corresponds to a loss of 20–30% of circulating blood volume.
- 1.5 and above (Developed shock): heart rate 120, SBP 80. Blood loss is 30–50% of circulating blood volume.
Phases of shock
The clinical presentation of traumatic shock is divided into two sequential phases:
- Erectile phase. Occurs immediately after trauma and is short-lived. Due to a sharp surge in the sympathoadrenal system, the patient is agitated, blood pressure is elevated, heart rate is rapid, and the skin is pale.
- Torpid phase. Replaces the erectile phase. It is characterized by general lethargy, a drop in blood pressure, and a weak, thready pulse. The severity of this phase directly correlates with the degree of hemodynamic impairment.
Severity degrees of the torpid phase
Depending on the severity of symptoms, four degrees of torpid shock are distinguished:
- Grade I (Mild). The patient is conscious, slightly lethargic. Skin is pale, muscle tremor is possible. SBP drops to 90 mmHg, heart rate is accelerated, capillary refill is slowed.
- Grade II (Moderate). Pronounced lethargy. Skin is pale, cold, covered with cold sweat, nail beds are cyanotic. SBP 90–70 mmHg, pulse of low volume (110–120 bpm), respiration is shallow.
- Grade III (Severe). Extremely critical condition. The patient is adynamic, gives one-word answers, and does not respond to pain. Skin has a cyanotic tint. SBP 70–50 mmHg, heart rate up to 140 bpm. Anuria develops.
- Grade IV (Preagonal). SBP below 50 mmHg, pulse is thready, consciousness is fading, respiration is rapid and shallow.
Prehospital care
The algorithm of actions at the scene is strictly regulated:
- Hemorrhage control. External bleeding is stopped using a tourniquet, pressure dressing, or digital pressure. In case of suspected internal bleeding — emergency hospitalization.
- Securing the airway. The patient is turned onto their side, the mouth is cleared, and if necessary, the jaw is displaced or an S-shaped airway is inserted to prevent aspiration of vomit or blood.
- Analgesia. Performed prior to splinting. Narcotic (morphine, trimeperidine) or non-narcotic (metamizole sodium) analgesics are used. Administered strictly intravenously, as absorption from muscles is halted due to vasoconstriction.
- Restoration of blood volume. Simultaneously with hemostasis, infusion of crystalloids, dextrans, or gelatin is initiated. If an IV drip is unavailable, the patient is placed in the Trendelenburg position (head down).
- Immobilization. Carried out using transport splints to prevent further trauma.
- Transportation. Conscious patients — on their back; unconscious patients — on their side; in case of facial bleeding — prone with the head turned to the side.
Briefly: answers to topical questions
Which laboratory blood parameters must be monitored to assess the severity of traumatic shock?
To assess the severity of traumatic shock and monitor the response to intensive care in patients with moderate and severe trauma, the following are monitored:
- acid-base balance (ABB);
- arterial blood gases.
The baseline laboratory panel for patients with pelvic trauma includes a complete clinical blood count, a general biochemical blood panel, and a coagulogram. However, hemoglobin and hematocrit levels lack sensitivity for the early assessment of the severity of traumatic shock.
Which specific crystalloid solutions are used for initial infusion therapy in shock?
To restore circulating blood volume in traumatic shock, the following are used:
- crystalloid solutions: Ringer's solution, isotonic sodium chloride solution;
- 5% dextrose solution.
Ringer-Locke solution is also used to treat shock and replace blood loss in combination with blood transfusions, plasma, and hemodynamic volume-substituting fluids.
Class and exam questions
In what position should an unconscious patient be transported?
An unconscious patient is transported on their side. This is necessary to prevent airway obstruction caused by the tongue falling back, blood, or vomit.
What is the purpose of a pneumatic antishock garment?
It is used for massive blood loss and pelvic or lower limb trauma. It compresses tissues to stop bleeding and redistributes blood, increasing effective circulating blood volume through centralization of circulation.
What else to study on this topic
- Features of infusion therapy: choice between crystalloids and dextrans.
- Indications and contraindications for narcotic analgesics (respiratory depression).
- Mechanism of kallikrein-kinin system activation in shock.
- Technique for applying the pneumatic antishock garment.
- Differential diagnosis of types of shock based on hemodynamic parameters.
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