Fig. 6
From: Experimental validation of a portable tidal volume indicator for bag valve mask ventilation
a Flow sampling rate of the BENGI measured during multiple (n = 43) 1-s intervals. Error bars indicate mean ± standard deviation. b Flow measurement profile captured by the computer sensor (black line) of a single inspiratory cycle from a BVM delivered to a test lung (measured tinsp = 1.08 s and VT = 506 mL), and simulated flow measurement profiles captured at lower sampling rates (shown are sampling rates at 3, 10, 100, and 1000 samples of the full inspiratory time). c Log–Log plot of difference in calculated VT from the simulated measurement profiles (3 to 10 samples at 1-sample intervals, 10 to 100 samples at 10 sample intervals, and 100 to 2100 samples at 100 sample intervals) to VT calculated from the computer sensor versus the sampling rate (solid line indicates best-fit linear regression, R2 = 0.92). Red point indicates the predicted error between the BENGI VT and computer, given the measured mean sample rate for the BENGI (716 Hz) and assuming flow measurements were in exact agreement between the BENGI and computer sensor for all time points