What is the recommended action if a casualty shows signs of shock?

The recommended action if a casualty shows signs of shock is to lie them down and elevate their legs. This position helps to improve blood flow to vital organs by promoting venous return, which is crucial in a state of shock where the body is struggling to maintain adequate circulation. Elevating the legs assists in increasing cardiac output and can help stabilize the casualty’s condition while medical assistance is on the way.

In cases of shock, particularly hypovolemic shock, the body's blood volume is compromised, leading to inadequate perfusion of organs. By positioning the casualty flat with elevated legs, you are effectively facilitating better blood flow to the heart and brain, which may be enough in some instances to improve the situation until further medical treatments can be administered.

Other options do not prioritize the need for enhancing circulation effectively. Keeping the casualty sitting up could worsen their condition by further reducing venous return. Providing fluids slowly may not address the urgent need for immediate stabilization if the shock is severe. Monitoring without intervention does not provide the necessary support that could prevent further deterioration. Thus, the correct action is to lie the casualty down and elevate their legs to optimize blood flow and support their recovery.