A 23-year-old pregnant female is bleeding profusely from her vagina. All of the following actions are appropriate EXCEPT:

Placing a sanitary napkin in the vagina is not an appropriate action in the scenario of a pregnant female experiencing profuse vaginal bleeding. When dealing with significant bleeding in a pregnant patient, it's important to manage the situation in a way that does not introduce additional complications or risk infections. Using tampons or sanitary napkins can potentially absorb and retain blood where it could lead to confusion regarding the volume of blood loss, complicating emergency treatment.

In contrast, providing high-concentration oxygen, replacing pads as they become soaked to monitor the extent of bleeding, and ensuring rapid transport to a hospital are all critical actions. Oxygen can help address any potential hypoxia in the patient, while actively monitoring the pads allows for better assessment of bleeding severity without introducing foreign materials into the vaginal canal. Rapid transport is essential given the urgency of the situation, as the patient may require immediate medical intervention.