Book 00 · Page 4444 / 80

Shock: the four types

Four columns comparing hypovolemic, cardiogenic, distributive and obstructive shock by preload, afterload and cardiac output. — Fig 1.44 · pending clinical review

Shock is inadequate tissue perfusion. A closed circuit can fail in only four ways: the pump quits, the tank empties, the pipes dilate, or something blocks the flow. Name the break point and the intervention is already decided, which is why memorizing four unrelated syndromes is wasted effort.

	CARDIOGENIC	HYPOVOLEMIC	DISTRIBUTIVE	OBSTRUCTIVE
Break point	The pump	The tank	The pipes	The outflow
Cause	Infarction, cardiomyopathy, severe dysrhythmia	Hemorrhage, burns, vomiting, diarrhea, third spacing	Sepsis, anaphylaxis, spinal cord injury	Tamponade, tension pneumothorax, massive pulmonary embolism
Preload	Up	Down	Down	Down at the ventricle despite high venous pressure
Resistance	Up	Up	Down	Up
Skin	Cool, clammy	Cool, clammy	Warm and flushed early, cold late	Cool, often with distended neck veins
Is fluid the answer?	No, it worsens pulmonary edema	Yes	Yes, alongside the specific treatment	No, relieve the obstruction

The one that looks different

Distributive shock presents warm before it presents cold. Early sepsis shows a flushed patient with a widened pulse pressure and a bounding pulse, which reads as "not shocked" to an untrained eye. Neurogenic shock shows hypotension with bradycardia and warm, dry skin below the level of injury, the opposite of every other shock, because the sympathetic outflow that normally drives compensation has been cut.

Compensated is not stable

Blood pressure holds while heart rate rises, pulse pressure narrows, urine output falls, and mentation changes. The exam scores the candidate who acts in the compensated stage, not the one who waits for the systolic to fall.

Memory hookPump, Tank, Pipes, Block.

Margin notewarm and slow means spine, every time.

Watch outfluid boluses given to a patient in cardiogenic shock worsen pulmonary edema.

TakeawayFind the break point in the circuit and the first intervention follows without guessing.

→ BOOK 09 · P6 for full shock management · → BOOK 05 · P9 for the agents · → P40