Provided are systems and methods for processing a physiological signal in order to determine fluid responsiveness of a subject. In some embodiments, a respiration rate of the subject is received or determined, the signal is filtered based on the respiration rate to generate a filtered signal, and the filtered signal is processed to determine fluid responsiveness. In some embodiments, regular respiration is detected and fluid responsiveness is determined when regular respiration is detected. In some embodiments, the respiration of a subject is controlled, and fluid responsiveness is determined during controlled respiration.
