Calculation of mean airway pressure during mecanical ventilation in neonates

Mean airway pressure (Paw) calculated by 4 methods was compared with measured Paw, using 833 observations on 16 infants requiring constant-flow, pressure-limited mechanical ventilation. Measured Paw was most accurately predicted by determining a waveform constant for each infant every 12 h, and then using the waveform constant in a general Paw equation for the ensuing 12 h. However, this method is impractical for clinical use. A square-waveform equation more accurately predicted Paw than did triangular or sine-like waveform equations. Because there was considerable interindividual variation in the accuracy of all methods, due to different individual respiratory waveforms and waveform constants, Paw should be measured and not calculated.