Software compensation for lung volume in assessment of inspiratory muscle strength and endurance.
BACKGROUND
To increase the sensitivity of measurements of maximal inspiratory pressure (MIP) as a test of inspiratory muscle strength and endurance, software was developed to correct for variation in lung volume.


METHODS
Using a body plethysmograph to determine absolute lung volume during each manoeuvre, values for MIP were expressed as a percentage of the pressure "expected" from the unfatigued MIP/lung volume relation in each subject.


RESULTS
The method reduced the variance in peak and average pressure during a series of 18 MIP manoeuvres of 10 seconds duration separated by rest intervals of 10 seconds.


CONCLUSIONS
The correlation between average pressure and contraction number was improved significantly by the MIP/lung volume correction. This simple correction has many applications in measurements of the MIP.
McKenzie
D K
DK
Department of Respiratory Medicine, Prince of Wales Hospital, Sydney, Australia.
Gandevia
S C
SC
Gorman
R B
RB
Leeper
J B
JB
D000328:Adult; D005260:Female; D006801:Humans; D007320:Inspiratory Capacity / Q000502:physiology; D008176:Lung Volume Measurements; D008297:Male; D008451:Maximal Voluntary Ventilation / Q000502:physiology; D010993:Plethysmography, Whole Body; D015656:Respiratory Mechanics / Q000502:physiology*; D012132:Respiratory Muscles / Q000502:physiology*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D012984:Software