What is the immediate priority for a patient with external bleeding and low blood pressure?

The immediate priority for a patient experiencing external bleeding and low blood pressure is to start IV fluid resuscitation. This approach is critical because low blood pressure often indicates inadequate blood volume and can lead to shock. Rapidly administering intravenous fluids helps to restore circulating volume, improve blood pressure, and stabilize the patient's condition.

While applying a tourniquet can be essential for controlling severe limb bleeding, it is typically reserved for cases of profound bleeding where direct compression or other methods fail. In the context of this question, where the focus is on restoring blood pressure and volume rather than managing the bleeding site directly, IV fluids take precedence.

Providing blood transfusion is also a relevant intervention but typically follows the initiation of fluid resuscitation. The body's immediate need is to address hypovolemia, and IV fluids can often be administered more rapidly than preparing for a transfusion.

Administering pain relief is important in managing the patient's comfort, but it does not address the critical issues of blood loss and low blood pressure. Therefore, stabilizing the patient through IV fluid resuscitation is the most urgent and appropriate response.