Final answer:
The nurse should immediately notify the physician when an intracranial pressure reading is significantly higher than the normal range, as a reading of 66 mm Hg indicates a potentially life-threatening situation that requires urgent medical intervention.
Step-by-step explanation:
The nurse is caring for a client with a head injury who has an intracranial pressure monitor in place. An intracranial pressure (ICP) reading of 66 mm Hg is significantly higher than the normal range of 5 to 12 mm Hg. Given the urgency of this finding, the nurse's best action is to notify the physician immediately.
High ICP can lead to serious complications such as brain herniation and death and requires prompt medical intervention. While recording the reading is important, it is not the only action that should be taken. Placing the client supine or repositioning may not be appropriate without further medical evaluation due to the risk of exacerbating the client's condition.