Which of the following is NOT a treatment provided to external bleeding by a first responder?

Applying heat packs to the injury site is not a treatment for external bleeding. In managing external bleeding, the primary focus is on methods that promote clotting and minimize blood loss. Direct pressure is crucial as it helps to stop the bleeding by compressing the damaged blood vessels. Elevating the injured extremity can assist in reducing blood flow to the area, further aiding in controlling the bleeding. Using pressure points is another technique that can help manage severe bleeding by applying pressure to specific points on the body to slow down blood flow to the affected area.

On the other hand, applying heat to an injury can actually worsen bleeding, as heat causes blood vessels to dilate. This dilation can increase blood flow to the area, potentially exacerbating the blood loss rather than controlling it. Therefore, using heat packs is contraindicated in the treatment of external bleeding, making it the correct answer for the question.