When is it appropriate to apply a tourniquet?

Applying a tourniquet is appropriate in situations where there is severe, life-threatening bleeding, particularly from an arterial source. The condition described as "bright, red squirting arterial blood on an extremity" indicates that there is a significant arterial bleed, which requires immediate intervention to control the hemorrhage. In this scenario, the use of a tourniquet can quickly compress the affected area, helping to prevent exsanguination, which can lead to severe complications or death.

While tourniquets can be effective for other types of bleeding, such as significant venous bleeding, they are most crucial when arterial bleeding is present. Other circumstances, such as minor bleeding or a patient experiencing shock without visible bleeding, typically do not call for a tourniquet. Instead, those situations would be managed with direct pressure or other methods more appropriate to the severity of the bleed.