Hemodynamic effects of volume expansion in patients with cardiac tamponade.

BACKGROUND Volume expansion has been proposed as an alternative treatment for cardiac tamponade; however, the scientific evidence for this recommendation is very poor. METHODS AND RESULTS Forty-nine unselected patients (23 males; age 55+/-16 years) with large pericardial effusion and hemodynamic tamponade underwent fluid overload with intravenous administration of 500 mL of normal saline over 10 minutes. Cardiac index and intrapericardial, left ventricular end-diastolic, right atrial, and right ventricular end-diastolic pressures were measured during basal state (tamponade), after fluid overload, and after pericardiocentesis. Twenty-eight patients (57%) had physical signs of tamponade, and 10 (20%) were hypotensive. Size of pericardial effusion was 31+/-13 mm. Initial mean arterial pressure was 88+/-21 mm Hg, and cardiac index was 2.46+/-0.80 L x min(-1) x m(-2). Intrapericardial pressure was 8.31+/-5.98 mm Hg. Volume expansion caused a significant increase in mean arterial pressure (from 88+/-21 to 94+/-23 mm Hg, P=0.003) and cardiac index (from 2.46+/-0.80 to 2.64+/-0.68 L x min(-1) x m(-2), P=0.013), as well as in intrapericardial pressure (from 8.31+/-5.98 to 11.02+/-6.27 mm Hg, P=0.0001), right atrial pressure (from 9.76+/-5.91 to 12.82+/-6.34 mm Hg, P=0.0001), and left ventricular end-diastolic pressure (from 14.21+/-5.97 to 19.48+/-6.19 mm Hg, P=0.0001). Cardiac index increased by >10% in 23 patients (47%), remained unchanged in 11 (22%), and decreased in 15 (31%). No patient developed clinical complications. Predictors of this favorable response were systolic blood pressure <100 mm Hg and low cardiac index. CONCLUSIONS Approximately one half of patients with cardiac tamponade develop a significant increase in cardiac output after volume overload. Low systolic blood pressure (<100 mm Hg) at baseline was the simplest clinical finding that was predictive of this favorable response.