Neurogenic & Obstructive Shock

Two shock types that break the rules: one gives you warm skin and bradycardia, the other kills by physically blocking blood from reaching the heart. Misidentifying either one is fatal.

Neurogenic shock is a form of distributive shock resulting from loss of sympathetic tone, most commonly after spinal cord injury at T6 or above. Without sympathetic input, vessels dilate massively and the heart loses its compensatory tachycardia. The signature triad is hypotension, bradycardia, and warm/dry skin below the level of injury — the opposite of every other shock type where you expect cool, clammy skin and tachycardia. Treatment targets the missing sympathetic response: vasopressors (phenylephrine or norepinephrine) to restore vascular tone and atropine for symptomatic bradycardia. Aggressive fluid resuscitation alone won't fix it because the problem is a dilated vascular bed, not volume loss. Note: neurogenic shock (hemodynamic instability) is distinct from spinal shock (temporary areflexia below the lesion). Obstructive shock occurs when blood physically cannot fill or leave the heart. The three classic causes are tension pneumothorax, cardiac tamponade, and massive pulmonary embolism. Each creates a mechanical barrier. In tension pneumothorax, look for tracheal deviation, absent breath sounds, and JVD. In cardiac tamponade, Beck's triad — hypotension, muffled heart sounds, and JVD. In massive PE, sudden dyspnea, hypoxia, and right heart strain. Obstructive shock is a surgical or procedural emergency: needle decompression, pericardiocentesis, or thrombolytics respectively. Fluids and vasopressors are temporizing — they cannot fix the obstruction.

Key Distinctions

Don't confuse neurogenic shock (bradycardia, warm skin) with hypovolemic or septic shock (tachycardia). Students assume all shock equals tachycardia — neurogenic is the exception. Don't confuse obstructive shock with cardiogenic shock: both show elevated CVP and JVD, but cardiogenic is a pump failure while obstructive is an external mechanical barrier requiring removal of the obstruction, not inotropes.

Clinical Pearl

Bradycardia plus warm skin after a spinal injury screams neurogenic — the sympathetic nervous system has left the building. Treat the tone, not just the volume.