Obstructive shock happens when something physically blocks blood flow into or out of the heart, even though the heart muscle and blood volume are normal. The main causes are tension pneumothorax, cardiac tamponade and massive pulmonary embolism, and each needs a specific fix within minutes.
Key symptoms
- Sudden shortness of breath
- Chest pain, sharp or pressure-like
- Lightheadedness, fainting or confusion
- Recent trauma, surgery, cancer or long travel
What you find on exam
- Low blood pressure, fast heart rate, distended neck veins
- Tension pneumothorax: absent breath sounds on one side, tracheal shift
- Tamponade: muffled heart sounds and pulsus paradoxus
- Pulmonary embolism: low oxygen and a swollen leg
Tests
- Bedside ultrasound: lung sliding, pericardial fluid, right ventricle size
- ECG: low voltage, electrical alternans or right heart strain
- CT pulmonary angiography if stable enough
- Lactate, troponin and blood gas
Treatment basics
- Tension pneumothorax: needle decompression, then chest tube
- Tamponade: pericardiocentesis
- Massive pulmonary embolism: heparin plus alteplase or embolectomy
- Careful fluids and a vasopressor such as norepinephrine as a bridge
Red flags
- Pulseless electrical activity or near arrest
- Worsening low oxygen despite high-flow oxygen
- Rising airway pressure on a ventilator with falling blood pressure
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Sources: NASEMSO National Model EMS Clinical Guidelines; NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations. Written by Making Synapses. Making Synapses is not affiliated with these organizations.