Shock

Definition:

  • Under perfusion of tissues 

Cardiogenic Shock:

  • When the heart is unable to generate CO sufficient to maintain tissue perfusion
  • Defined as: systolic BP <90, urine output <20 mL\hr, and adequate LV filling pressure

Causes:

  • After acute MI (MCC)
  • Cardiac tamponade, tension pneumothorax (compression of heart)
  • Arrhythmias
  • Massive PE -> RVF
  • Myocardial ds: cardiomyopathies, myocarditis
  • Mechanical abnormalities: valves, VSD

Treatment:

  • ABCs
  • Treat underlying cause
  • Give a trial of crystalloids (250 cc) and watch for clinical improvement?
  • Vasopressor \ inotropes: dopamine, NE, dobutamine
  • Intra-aortic balloon pump

 


Hypovolemic shock:

  • ↓ circulatory blood volume -> ↓ preload -> ↓ CO

Causes:

  • Hemorrhagic: trauma, GI bleed, retroperitoneal
  • Non-hemorrhagic: voluminous vomiting, severe diarrhea, severe dehydration, burns, third-spacing

Treatment:

  • Hemorrhagic:
    • Stop bleeding
    • Give whole blood: PRBC, FFP, PTT in 1:1:1 ratio
  • Non-hemorrhagic:
    • Give crystalloids: 1-2 L bolus initially until clinical response (peds 20 cc\kg)

Shock 1

 


Distributive; Septic Shock:

  • SIRS -> sepsis -> septic shock -> multiple organ dysfunction syndrome (MODS)
  • Hypotension induced by sepsis persisting despite adequate fluid resus
  • Severe decrease in SVR secondary to peripheral vasodilation
  • Might lead to sludging of blood -> RBC agglutination -> DIC

Causes:

  • MC organisms: E. coli and S. aureus
  • Pneumonia
  • Pyelonephritis
  • Meninigitis
  • Abcess
  • Cholangitis
  • Cellulitis
  • Peritonitis

Treatment:

  • Treat the infection: IV broad spectrum antibiotics or control source through surgery
  • IV fluids to maintain BP: at least 3 L of crystalloids
  • If persistent hypotension -> vasopressors (NE, dopamine)

Shock 2

 


Distributive; Anaphylactic Shock:

  • Generalized hypersensitivity type I: IgE event -> triggers massive release of immune response mediators -> widespread peripheral vasodilation, bronchial smooth muscle contraction
  • Involves 2 systems

Clinical features:

  • Altered MS, tachycardia, ↓ BP, tachypnea\wheezing, flushed warm skin\rash, swollen tongue\lips, -\↑ JVP

Treatment:

  • EPINEPHRINE: 0.3 mg IM
  • Maintain airways
  • Fluid resus w\ crystalloids
  • Steroids
  • Antihistamines

 


Distributive; Neurogenic Shock:

  • Vascular denervation: failure of sympathetic nervous system to maintain adequate vascular tone
  • Peripheral vasodilation + ↓ SVR

Causes:

  • Spinal cord injury
  • Severe head injury
  • Spinal anesthesia
  • Pharmacologic sympathetic blockade

Treatment:

Shock 3

  • IV fluids
  • Vasoconstrictors
  • Supine or Trendelenburg position

 


Obstructive Shock:

  • Obstruction in the circulation leading to hypoperfusion of organs

Causes:

  • Tension pneumothorax
  • Pericardial tamponade
  • Massive PE

Clinical features

  • Alterend MS, -\↓BP, tachycardia, cold clammy\cynotic skin, ↑JVP, distant heart sounds (peridacial temoponade), signs of DVT (in case of PE)

Treatment:

  • Cardiac tamponade: pericardiocentesis
  • Tension pneumothorax: chest tube
  • Massive PE: fibrinolysis

 


  Signs CO SVR JVP PCWP HR BP
Cardiogenic Pale and cool
Hypovolemic Pale and cool
Septic Warm and flushed
Neurogenic Warm and flushed

Shock 5

 


Download the PDF version: here


References:

  • Step up to medicine
  • Step up to USMLE step 2

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

w

Connecting to %s

%d bloggers like this:
search previous next tag category expand menu location phone mail time cart zoom edit close