The nurse is responsible for preparing the child for diagnostic tests such as MRI or a CT scan and for assisting with procedures such as a ventricular tap, which is often performed to relieve excessive pressure and to obtain CSF during the preoperative period. Sedation is required because the child must remain absolutely still during diagnostic testing. A variety of drugs are available for sedation. (See Chapter 27 for preparing children for procedures.) If surgery is anticipated, IV infusions should not be placed in a scalp vein.