The primary assessment is rechecked because the components of the primary assessment reveal a great deal about how the patient is doing. You can tell how a patient is doing immediately by noticing their "ABC" (airway, circulation and breathing). If their airway is clear, they have good capillary refill and their breathing is uncomplicated, your patient is doing well. If any of the above are not, you know immediately that they are not doing well. This also goes with LOC (level of consciousness). You know that a normal person has a GCS of 15. If they are altered in anyway, you know you may have more problems to come. If you're addressing AVPU; anything other than "alert", you know there is some kind of problem happening. It's very important for someone in EMS to re-evaluate their primary assessment.
