Influence of duration of occlusion time on respiratory mechanics measured with the single-breath technique in infants.
To determine the effect of the length of end-inspiratory occlusion on the values of respiratory system compliance (Crs) and resistance (Rrs) calculated from the single-breath technique, 6 infants with cystic fibrosis were studied. End-inspiratory occlusions lasted between 0.3 and 1.2 seconds, and between 8 and 32 separate occlusions were made in each infant. Examination of the individual data showed a systematic tendency for Crs to decrease as the length of the airway occlusion increased, with statistical significance reached in two subjects. Using a random effects model, it was demonstrated that there was a decrease of 0.15 mL/cmH2O in Crs for each 0.1 s increase in occlusion time. The influence of length of plateau time for Crs was similar to that of total occlusion time. No such tendency was seen for Rrs. These data reinforce the current emphasis on greater standardization in the methodologies used for infant lung function testing and for more fully reporting methodological details.
Mallol
J
J
Division of Clinical Sciences, W.A. Research Institute for Child Health, Perth.
Willet
K
K
Burton
P
P
Sly
P D
PD
D000403:Airway Resistance; D003550:Cystic Fibrosis / Q000503:physiopathology*; D006801:Humans; D007223:Infant; D008170:Lung Compliance; D015233:Models, Statistical; D011897:Random Allocation; D012129:Respiratory Function Tests / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology*; D013995:Time