Recognizing shock before the pressure falls

Blood pressure is the last thing to go

A falling blood pressure is a late sign, and in a young adult or a child it can be very late indeed. By the time it falls, compensation has already been running for some time.

What comes first is the compensating: a rising heart rate, a rising respiratory rate, a narrowing pulse pressure, cool skin with delayed capillary refill, falling urine output, and restlessness or anxiety. Restlessness is a perfusion sign, and treating it as a personality is a recognized way to miss shock.

Telling the types apart

All four drop the blood pressure eventually. The skin and the heart rate separate them faster than the pressure does.

• Hypovolemic: cool clammy skin, fast heart, from blood or fluid lost. Treat with volume.
• Cardiogenic: cool skin, fast heart, but with pulmonary congestion — the pump has failed. Volume makes it worse.
• Distributive, including septic and anaphylactic: warm flushed skin early, fast heart, because the vessels have dilated. Volume and vasopressors, plus removing the cause.
• Neurogenic: warm dry skin and a SLOW heart, after a spinal cord injury above about T6. The sympathetic outflow itself has been cut, so nothing compensates.

Neurogenic shock is the one that looks wrong, and that is what makes it recognizable: a low pressure with a slow heart and warm skin, in someone with a cord injury.

Anaphylaxis

1. Stop whatever is being given.
2. Call for help and maintain the airway.
3. Expect intramuscular epinephrine — this is the treatment, and it precedes the antihistamine and the steroid.
4. Lay the client flat with the legs raised unless breathing is worse that way, and give fluid.

The order matters on the exam and at the bedside. Antihistamines and corticosteroids have their place and neither of them reverses the airway swelling that is happening now.