A method and system for detection of pulsus paradoxus are provided. In one embodiment, the method includes determining a power spectrum density for a plethysmographic waveform and identifying pulsus paradoxus based on the power spectrum density. The power spectrum density may include a first wave peak indicative of a respiratory rate and a second wave peak indicative of a heart rate. Pulsus paradoxus can be identified by comparing a height of the first wave peak and a height of the second wave peak.
Method and system for detection of respiratory variation in plethysmographic oximetry