Cardiac Index Calculation in Hypovolemic Shock

A 70-year-old female patient with a history of hypertension presents to the emergency department with chest pain and shortness of breath. Upon examination, her blood pressure is 90/60 mmHg, heart rate is 120 bpm, and respiratory rate is 28 breaths per minute. The physician suspects hypovolemic shock due to possible gastrointestinal bleeding. To assess the patient's hemodynamic status, the nurse should calculate the patient's _____________, which is crucial for evaluating cardiac function and tissue perfusion.