The patient is admitted with acute pancreatitis. He is complaining of severe abdominal pain and nausea. He has hyperactive bowel sounds and abdominal distention. His temperature is 103 degrees F and his blood pressure is 86/40 mm Hg. His WBC count is over 20,000/mL. He is jaundiced and the nurse notes a bluish discoloration around the umbilical area. Which of the following is indicated first in managing this patient?