Which symptom is most indicative of cardiac tamponade following CABG?

Hypotension is the symptom most indicative of cardiac tamponade following coronary artery bypass grafting (CABG) due to the accumulation of fluid in the pericardial space, which places pressure on the heart and prevents it from filling properly. This impaired filling leads to decreased cardiac output and, consequently, low blood pressure. Patients experiencing cardiac tamponade may exhibit signs of shock or feel faint due to this decrease in perfusion.

Increased respiratory rate can occur in many conditions, including anxiety and pulmonary issues, but it is not specific to cardiac tamponade. Fever higher than 100°F may signal infection or an inflammatory response, which could occur in the postoperative setting but is not a direct indication of tamponade. Increased urine output can sometimes be associated with improving renal perfusion but does not correlate with the presence of cardiac tamponade, as fluid overload due to reduced cardiac output typically leads to decreased urine output. Thus, hypotension stands out as the hallmark sign of cardiac tamponade in this context.