Lecture 5: Obstructive Shock

Introduction

• Presenter: Eddie Watson
• Focus: Obstructive Shock
• Previous Lessons: Cardiogenic Shock

Obstructive Shock

• Defined as obstruction impacting blood flow due to mechanical issues.
• End result similar to cardiogenic shock (pump failure).

Causes and Pathophysiology

1. Tension Pneumothorax

   • Occurs when the intrathoracic cavity is exposed to outside air.
   • Air fills the space, increasing pressure, leading to lung collapse.
   • Causes: Traumatic injury, positive pressure ventilation.
   • Effects: Pressure on vena cava, decreased blood return, reduced cardiac output.

   Signs and Symptoms

   • Deviated trachea away from tension side.
   • Hyper-expanded chest, percussion changes, absent breath sounds.
   • Tachypnea and hypoxia.

   Diagnosis and Treatment

   • Look for tracheal deviation and chest X-ray.
   • Treat with needle decompression or chest tube insertion.

2. Cardiac Tamponade

   • Fluid accumulation in pericardial sac restricting heart expansion.
   • Reduces chamber size and venous return, impacting cardiac output.

   Signs and Symptoms

   • Beck's triad: Muffled heart sounds, JVD, hypotension.
   • Narrowing pulse pressure.

   Diagnosis and Treatment

   • Diagnose with an echocardiogram/ultrasound.
   • Drain fluid via pericardial synthesis or drain adjustment.

3. Constrictive Pericarditis

   • Thickening/scarring of pericardial sac.
   • Reduces heart's ability to fill and contract.

   Treatment

   • NSAIDs, steroids, potential surgery (pericardectomy).

4. Aortic Stenosis

   • Calcium buildup on aortic valve, restricting blood flow.
   • Decreases cardiac output.

   Signs and Diagnosis

   • Positive murmur.
   • Diagnose with an echocardiogram.

   Treatment

   • Valvuloplasty or valve replacement (TAVR or surgery).

5. Pulmonary Embolus (PE)

   • Embolus blocks pulmonary circulation.
   • Types: DVT, fat embolus.

   Clinical Considerations

   • Saddle PE can cause sudden death.
   • Signs: Increased respirations, cyanosis.

   Diagnosis and Treatment

   • VQ scan or CT angiography.
   • Treatment: TPA, TNK, heparin, embolectomy.

Conclusion

• All causes lead to pump failure, similar to cardiogenic shock.
• Resolve the underlying cause for rapid recovery.

Next Steps

• Upcoming lesson on distributive shock, focusing on neurogenic and anaphylactic shock.
• Check out lessons on hemodynamics.

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