Fig. 4

Example of NOWAPI^® detailed data in two typical patients. The device measures two pressure signals (upstream restriction and at the site of restriction, pink and blue curves, left y-axis). Variations in the difference between two pressures (differential pressure, yellow curve, right y-axis) indicate a flow rate is detected. Panel a shows detailed data in patient #20, with variation in differential pressure indicating detection of a flow rate in the patient circuit, i.e. a CPAP treatment. Panel b shows detailed data in patient #19. The two pressure signals are always superimposed, there is no variation in differential pressure. This finding is compatible only with two situations, either no flow rate in the patient circuit, either reverse connection