Fig. 5From: Current methodological and technical limitations of time and volumetric capnography in newbornsSchematic diagram of an ultrasonic flow meter (Exhalyzer D, Ecomedics, Dürnten, Switzerland). The flow rate V′(t) is directly proportional to the difference between transit times t1 and t2. The molar mass of the gas can be calculated from the sum of t1 and t2 Back to article page