In a method and breathing apparatus for prediction of fluid responsiveness of a subject connected to a breathing apparatus, at least one parameter is monitored that is indicative of a degree of carbon dioxide elimination of the subject, and a positive end expiratory pressure PEEP regulator of the breathing apparatus is operated to apply a PEEP maneuver in which a PEEP applied to the subject is changed from a first PEEP level to a second PEEP level. A processor predicts the fluid responsiveness of the subject based on a change in the monitored parameter, following the change in PEEP.
