Final answer:
The most appropriate initial intervention for an adult patient with symptoms indicative of possible vascular injury and hypovolemic shock following a vehicle accident is to stabilize ABCs, administer intravenous fluids, and prepare for a blood transfusion.
Step-by-step explanation:
An adult patient presenting with swelling and bruising to the right proximal thigh, weak pedal pulse, and skin that is pale, cool, and moist following a vehicle "roll-over" likely requires immediate medical intervention to address a possible vascular injury and to prevent hypovolemic shock.
Given these symptoms, the most appropriate initial intervention would be to stabilize the patient's condition by ensuring adequate airway, breathing, and circulation (ABCs). If there is a suspicion of internal bleeding or a vascular injury, starting intravenous fluids would be essential to increase volume and support blood pressure. Administering oxygen and preparing for blood transfusion, if necessary, are also crucial steps. Evaluating for further injuries and arranging for appropriate imaging studies would be subsequent steps after addressing any immediate life-threatening issues.