A 36-year-old man is admitted to your unit 4 hours after a surgical reduction of a compound fracture of the femur. His other health problems include hypercholesterolemia, for which he takes atorvastatin (Lipitor) 80 mg once daily, and bipolar disorder for which he takes lithium (Eskalith) 600 mg once daily. He has an IV of dextrose 5% in 0.45% saline infusing at a rate of 150 mL/hr. His blood pressure is now 96/70, down from the last reading of 128/80 obtained in the postanesthesia recovery area. His pulse is 84 and regular, and his pulse oximetry is 99%. In assessing him for possible shock, you note that the catheter drainage bag contains 800 mL of pale urine. His last output, measured 1 hour ago, was 1100 mL. According to the operative record, his output during the 3-hour surgery was 1800 mL. His total IV intake for the surgical and postoperative period was 1500 mL. He is to have his IV and Foley catheter removed when stable.