Updated: 7/9/2018

Obstructive Shock

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Snapshot
  • A 35-year-old woman presents to the emergency room with shortness of breath. She reports that she has had shortness of breath on exertion for a few weeks, which has progressively worsened. She also reports some chest pain. She has a history of breast cancer and is now post-chemotherapy and radiation therapy. Her blood pressure is 83/54 mmHg, pulse is 110/min, and respirations are 24/min. On physical exam, she has jugular venous distention, delayed capillary refill, and faint peripheral pulses. Her skin is cold and clammy. (Constrictive pericarditis)
Introduction
  • Clinical definition
    • shock secondary to extra-cardiac causes of pump failure
  • Etiology
    • pulmonary vascular
      • associated with right ventricular failure
      • pulmonary embolism
      • severe pulmonary hypertension
    • mechanical
      • tension pneumothorax
      • pericardial tamponade
      • constrictive pericarditis
      • restrictive cardiomyopathy
  • Pathogenesis
    • general concept
      • an underlying extra-cardiac event or process causes a cardiac outflow obstruction, resulting in ↓ cardiac output (CO)
      • ↓ CO results in compensatory ↑ systemic vascular resistance (SVR)
    • pulmonary vascular causes
      • ↑ pulmonary vascular resistance > right ventricular pressure
    • mechanical causes
      • ↓ preload and inadequate right ventricular filling
        • often presents like hypovolemic shock
Presentation
  • Symptoms
    • typically present with features of the underlying cause (e.g., pleuritic chest pain in pulmonary embolism)
  • Physical exam
    • hypotension
    • tachycardia
    • jugular venous distention
    • cold and clammy skin
Imaging
  • Echocardiography
    • indications
      • to detect underlying causes, such as pericardial tamponade
Studies
  • Pulmonary artery catheterization
    • findings
      • ↓ pulmonary capillary wedge pressure (PCWP < 15 mmHg) in most cases
      • ↑ PCWP in cardiac tamponade
      • normal or ↓ CO as severity progresses
      • ↑ SVR
  • Making the diagnosis
    • most cases are clinically diagnosed
Differential
 
Different Types of Shock
Shock Type Skin 

Wedge Pressure (PCWP) (Preload)

Systemic Vascular Resistance (SVR) (Afterload)
Cardiac Output
Hyovolemic Cold and clammy skin  ↓↓ 
Cardiogenic
Obstructive ↑ or ↓ ↔ or ↓
Distributive Warm or dry skin ↔ or ↓  ↓↓ ↓ or ↑
 
Treatment
  • Management approach
    • treat underlying cause
Complications
  • Death
  • Acute renal failure

 
 

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