the nurse is caring for a 100 kg patient being monitored with a pulmonary artery catheter. the nurse assesses a blood pressure of 90/60 mm hg, heart rate 110 beats/min, respirations 36/min, oxygen saturation of 89% on 3 l of oxygen via nasal cannula. bilateral crackles are audible upon auscultation. which hemodynamic value requires immediate action by the nurse?