A 77-year-old man is admitted to the intensive care unit (ICU) of a university hospital from the operating room after resection of the rectosigmoid colon with closure of the rectal stump and formation of an end colostomy for the treatment of fecal peritonitis caused by a perforated sigmoid colon. The patient’s medical history includes treated hypertension and hypercholesterolemia, previous heavy alcohol intake, and mild cognitive impairment. He has received a total of 4 liters of crystalloid in the operating room.
When the patient arrives in the ICU, the arterial blood pressure is 88/52 mm Hg (mean arterial pressure, 64 mm Hg), the heart rate is 120 beats per minute in sinus rhythm, and the central venous pressure is 6 mm Hg. The results of serum biochemical analyses are as follows: sodium, 142 mmol per liter; potassium, 4.4 mmol per liter; chloride, 109 mmol per liter; urea, 22.0 mg per deciliter (7.9 mmol per liter); albumin, 23 g per liter; and creatinine, 2.3 mg per deciliter (203 µmol per liter). He has now been in the ICU for an hour. He is still undergoing mechanical ventilation and has received 1 liter of Hartmann’s solution (consisting of sodium, 131 mmol per liter; potassium, 5.4 mmol per liter; chloride, 111 mmol per liter; lactate, 29 mmol per liter; and calcium, 2 mmol per liter, for a total osmolarity of 280.6 mOsm per liter) and 500 ml of 5% human albumin solution
The arterial blood pressure is now 85/50 mm Hg (mean arterial pressure, 62 mm Hg), the heart rate is 105 beats per minute in sinus rhythm, the central venous pressure is 9 mm Hg, the capillary refill time is estimated at 1 second, and the measured urine output for the past hour is 35 ml.