1 - Shock Management

The first step in managing shock is to recognize shock. The definition of shock is circulatory dysfunction resulting in hypoperfusion and tissue ischemia. This is a clinical and laboratory diagnosis.

Shock Pathophysiology

• Cardiac output = SV x HR
• SV is determined by preload, contractility, and afterload.
• Preload is determined by the balance between venous capacitance, volume status, and the difference between MAP and RAP.
• Initial responses to shock are compensatory and may only manifest as tachycardia.

Initial Patient Assessment

1. Recognize Shock - this is NOT just hypotension as patients can lose up to 30% of blood volume before there are measurable changes in SBP
   1. Pulse pressure, heart rate, pulse character, respiratory rate, skin perfusion, mental status
   2. Tachycardia: >160 in infants, >160 in pre-school children, >120 in school aged kids, and >100 in adults
   3. Massive blood loss will not produce an immediate large decrease in Hb/Hct
   4. Consider lactate trending/measurements
2. What is the cause of shock?
   1. In trauma patients this is usually related to the mechanism of injury.
   2. Hemorrhagic shock - most common in trauma, and you need to identify and treat the hemorrhage. Where is the patient bleeding?
   3. Non-hemorrhagic shock
      1. cardiogenic shock - blunt cardiac injury, cardiac tamponade, air embolism, acute myocardial infarction
      2. neurogenic shock - isolated intracranial injuries do not cause shock unless the brainstem is injured. Spinal injuries (cervical and upper thoracic) can lead to spinal shock w/o tachycardia or peripheral vasoconstriction (normal pulse pressure).
      3. septic shock - suspect in delayed presentation or if history suggests underlying infection
      4. tension PTX - Beck's triad + decreased breath sounds, hyperresonant percussion
   4. Consider also neurogenic/spinal shock, brainstem injury, sepsis, hypovolemia, cardiogenic, obstructive.