In which situation would you apply a tourniquet without first using a pressure dressing?

Applying a tourniquet is a critical intervention in life-threatening situations where direct pressure and other methods to control bleeding have failed or are not appropriate. In the case of an amputation, especially one occurring four inches below the elbow, there is a significant risk of severe arterial bleeding due to the nature of the injury.

Tourniquets are specifically designed to occlude blood flow to prevent exsanguination and prolonged use of a pressure dressing in such a severe situation may not provide adequate or rapid control of the bleeding. The rapid application of a tourniquet can be lifesaving in an amputated limb scenario due to the potential for profuse bleeding from major arteries.

In contrast, other options like bleeding from a femoral artery might initially require pressure dressing, while minor lacerations and severe bruises do not warrant a tourniquet at all, as these situations can often be managed with less invasive methods. Thus, applying a tourniquet in the context of an amputation is both appropriate and often necessary to preserve life.