A 52-year-old man has undergone coronary artery bypass grafting and has returned to the critical care unit. During the last hour his parameters were as follows: O2 saturation 99, PaO2 with FiO2 0.4 184 mm Hg, Hemoglobin 12 gm/dL, Serum potassium 3.8 mEq/L, Urine output 100 mL/hr. Now the patient's venous oxygen saturation (SvO2) monitor shows a rapid decline from a reading of 75. The nurse would assess the patient for which of the following?
1) Decreased cardiac output
2) Internal hemorrhage
3) Hypermetabolism
4) Hypoxemia