SOFTWARE COMPENSATION FOR LUNG-VOLUME IN ASSESSMENT OF INSPIRATORY MUSCLE STRENGTH AND ENDURANCE

Background - To increase the sensitivity of measurements of maximal in spiratory pressure (MIP) as a test of inspiratory muscle strength and endurance, software was developed to correct for variation in lung vol ume. Methods - Using a body plethysmograph to determine absolute lung volume during each manoeuvre, values for MIP were expressed as a perce ntage of the pressure ((expected)) from the unfatigued MIP/lung volume relation in each subject. Results - The method reduced the variance i n peak and average pressure during a series of 18 MIP manoeuvres of 10 seconds duration separated by rest intervals of 10 seconds. Conclusio ns - The correlation between average pressure and contraction number w as improved significantly by the MIP/lung volume correction. This simp le correction has many applications in measurements of the MIP.