A high index of suspicion for developing shock should be maintained in the presence of any significant hemorrhage, both external and internal.

The natural response to decreased oxygen delivery is to try to increase the amount of oxygenated blood to the tissues, so early signs of shock will include tachycardia and tachypnea.

If those measures aren’t able to restore adequate oxygenation, signs and symptoms of hypoperfusion will develop. These can include:

- Mental confusion or altered mental status in the absence of a head injury
- Weak or absent radial pulses
- Tachycardia
- Tachypnea
- Excessive thirst
- Cyanosis with pale, grey, or blotchy blue skin
- Nausea and/or vomiting
- Diaphoresis with sweaty, cool, clammy skin

Those last two signs warrant additional discussion, as several of the other signs can also occur in non-shock situations on the battlefield. For example, the sweaty, cool skin may be a manifestation of physical exertion (sweat) that has just cooled, or the nausea and vomiting could be from the stress of an injury.