Obstructive Shock

Overview

• Obstructive shock is similar to cardiogenic shock.
• In cardiogenic shock, the heart cannot pump blood forward efficiently.
• In obstructive shock, an obstruction either around the heart or in the blood vessels prevents blood from being pumped forward.
• Symptoms can be similar to cardiogenic shock:
  • Pulmonary edema (fluid in lungs causing coughing and difficulty breathing).
  • Cardiomegaly (enlarged heart due to fluid overload).
  • Jugular venous distention (JVD) as blood backs up into the neck.
  • Anasarca (global swelling due to severe fluid overload).
  • Tachycardia (increased heart rate) and hypotension (decreased blood pressure).

Causes of Obstructive Shock

1. Cardiac Tamponade

   • Accumulation of fluid or blood in the pericardial sac causing pressure around the heart.
   • Leads to pericardial effusion, preventing expansion of the heart.

2. Constrictive Pericarditis

   • Rigid pericardium due to infection or scarring puts pressure on the heart.
   • Prevents effective blood pumping.

3. Tension Pneumothorax

   • Air leaks into the pleural cavity, increasing pressure and constricting the heart.
   • Typically caused by a stab wound or trauma.
   • Causes organ shift and pressure on heart and lungs.

4. Pulmonary Embolism

   • Blockage of pulmonary arteries by a clot (embolus), often originating from a DVT.
   • Prevents efficient blood flow to the lungs and heart.

5. Aortic Stenosis

   • Narrowing of the aortic valve due to calcium deposits on the leaflets.
   • Limits blood flow through the heart.

Diagnosis

• Typical labs: Serum lactate and arterial blood gas (ABG) tests.
• Specific diagnostic tests:
  • Echocardiogram for cardiac tamponade and constrictive pericarditis.
  • X-ray for tension pneumothorax.
  • Clinical observations such as tracheal deviation for diagnosing pneumothorax.

Treatment

• General approach: Relieve the obstruction to stop the shock.
• Specific Treatments:
  • Tension pneumothorax: Needle thoracostomy to release trapped air.
  • Aortic stenosis: Valvuloplasty to replace the narrowed valve.
  • Pulmonary embolism: Dissolve or remove embolism using a catheter.
  • Cardiac tamponade: Aspirate fluid from the pericardial cavity.
• Immediate treatment is crucial to save lives.