Determination of Dynamic Respiratory Mechanics with the Adaptive Slice Method

Respiratory system mechanics are nonlinear, i.e. may depend on volume, pressure and flow [1, 2]. A new multipoint method is presented for simultaneously determining dynamic compliance and resistance based on the equation of motion. The adaptive slice method (ASM) is derived from the slice method [4], which divides a breathing cycle into several fixed volume slices. For each slice, one compliance value and one resistance value are calculated by applying a least-squares-fit (LSF) method. Since compliance and resistance values are not constant, the calculated values will be changing if the width of the corresponding slice is changed. Therefore, instead of applying a fixed width, the width of each slice is determined according to a quality measure based on the confidence interval of the parameter estimation. The method was evaluated by using simulated and animal data obtained from former experiments. The comparison with other methods shows that the adaptive determination of slice bounds results in more consistent parameter values.