To help illustrate the importance of following signs and symptoms over time, it might be helpful to review the progression of symptoms you might encounter if someone were to experience ongoing blood losses without appropriate interventions to stop losses or replace them.

- Usually, up to 500 ml of blood loss is well-tolerated, often with no effects except perhaps a slight tachycardia.
- 1,000 ml of blood loss will usually produce tachycardia greater than 100, but otherwise, the casualty may appear normal.
- 1,500 ml of blood loss may be associated with changes in mental status, a weak radial pulse, persistent tachycardia, and tachypnea.
- 2,000 ml of blood loss is accompanied by confusion and lethargy, a weak radial pulse often greater than 120, and tachypnea greater than 35. This amount of blood loss is possibly fatal if not managed quickly.
- And 2,500 ml of blood loss will usually present with the casualty unconscious, no radial pulse, a carotid pulse greater than 140, and tachypnea greater than 35. This amount of blood loss will be fatal without immediate and rapid intervention.

So, you can see that by following the patient’s clinical status you may be able to detect persistent blood losses, even if there isn’t an obvious external loss.