Shock Types and Phases

Shock Types

• Hypovolemic shock is caused by loss of blood volume
  • Examples include hemorrhage, trauma, burns, dehydration, and athletic activity
• Cardiogenic shock is caused by failure of the heart to effectively pump blood
  • Most common causes are post myocardial infarction (MI), cardiac tamponade, pulmonary embolism (PE), septal rupture, and valvular heart disease.
• Distributive shock is caused by vasodilation and increased permeability of blood vessels
  • Types of distributive shock include anaphylactic, septic, and neurogenic

Shock Phases

• Phase 1: Decreased cardiac output, increased renin-angiotensin-aldosterone system (RAAS) activation
• Phase 2: Increased sympathetic nervous system (SNS) activation
• Phase 3: Initially increased heart rate and initially increased respiratory rate
• Phase 4: Lactic acidosis
• Phase 5: Vasodilation with increased permeability
• Phase 6: Hypotension, organ failure, death

Medical Management of Shock

• Goal: Improve tissue perfusion and preserve organ function
• Hypovolemic shock: Restore fluid volume
• Cardiogenic shock: Optimize cardiac output and preload
• Distributive shock: Fill the tank and optimize cardiac output

Hypovolemic Shock

• Cause: Loss of blood volume due to hemorrhage, trauma, burns, dehydration, or athletic activity
• Management:
  • Fluid resuscitation: Crystalloids (normal saline (0.9% NaCl), Plasmalyte A, Lactated Ringer's)
  • Colloids: Albumin
  • Blood products: Packed red blood cells, massive transfusion protocol (MTP)
• Key Points:
  • Replace what was lost
  • If the patient was bleeding, they will likely need blood products, not just intravenous fluids
  • Patients in shock may be hypotensive, tachycardic, have lactic acidosis, decreased urine output (acute kidney injury), and cool, clammy skin
  • Monitor urine output, passive leg raise, and hemodynamics to assess fluid responsiveness and guide treatment

Cardiogenic Shock

• Cause: Heart fails to effectively pump blood
• Manifestations:
  • Decreased systolic blood pressure (SBP)
  • Cool, pale, moist skin
  • Increased heart rate
  • Decreased urine output

### Hypovolemic Shock Management

• Fluid Resuscitation:
  • Use intravenous (IV) fluids if possible
  • Use oral (PO) fluids under certain circumstances, such as when the patient is vomiting, intubated, or PO intake is not feasible.
  • If the patient is vomiting and has been given Zofran, PO might be a better option
• Assessment of Volume Responsiveness:
  • Utilize Foley catheter to monitor urine output (no pee = no bueno). This can also be indicative of the need for extra volume expansion.
  • Perform passive leg raise, take the wait, then measure the change in mean arterial pressure (MAP)
  • If responding, increase fluids. If not responding, start hemodynamic monitoring.
• Hemodynamic Monitoring:
  • Use an arterial line and monitor stroke volume variation (SVV) and central venous pressure (CVP)
  • Monitor the patient for development of coagulopathy.

Hypovolemic Shock: Different Causes

• Dehydration: Replace the lost fluids, provide oral fluids if tolerated.
• Burns: Use the Parkland formula to calculate fluid resuscitation needs. Consider MTP for fluid resuscitation as well as other interventions like electrolytes, coagulation factors, etc.
• Hemorrhage: Provide blood products, utilize MTP if needed, and monitor for coagulopathy and possible complications.
  • Look at the patient's urine output for clues into adequacy of treatment.