Dépret F, et al. - In this prospective, monocentric study of 28 adult patients with acute circulatory failure, researchers examined if the effects of short respiratory holds on cardiac index, estimated by esophageal Doppler, predicts fluid responsiveness in patients under mechanical ventilation. Before and after infusing 500 mL of saline, they measured cardiac index before and during the last 5 seconds of successive 15-second end-inspiratory occlusion and end-expiratory occlusion, separated by 1 minute. “Fluid responders” were the patients in whom volume expansion increased cardiac index measured by transpulmonary thermodilution greater than or equal to 15%. They used cardiac index measured by the Pulse Contour Cardiac Output device (from pulse contour analysis or transpulmonary thermodilution) as the reference. They observed a likelihood of increased cardiac output with a 500 mL fluid infusion if the absolute sum of the percent change in cardiac index estimated by esophageal Doppler induced by two successive end-inspiratory occlusion and end-expiratory occlusion maneuvers is greater than 9%. This diagnostic threshold is higher than if only end-expiratory occlusion induced percent changes in cardiac index estimated by esophageal Doppler are taken into account.