Sensitivity of Frequency Dependence of Lung Compliance in Detecting Uneven Time Constants

Praful V. Bhansali, J. A. Dempsey, L. Chosey, C. Iber, T. Musch, John G. Webster

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


We have evaluated the sensitivity of frequency dependence (spon-1.5 Hz) of dynamic compliance (Cdyn) and pulmonary resistance (RL) by introducing two bronchial catheters in dog’s lungs. We measured the differential bronchial pressure (Pbr) and defined the transfer ratio (H) as Pbr/P pleural at points of zero mouth flow. Calculations predict H to be more sensitive compared to Cdyn or RL. We infused 0.5 and 2.0 μg/(kg ∙ min) histamine to cause small airways constriction. With the larger dose, Cdyn, RL, and H all became frequency dependent with no change in RL(spon). With the smaller dose, H (spon) changed throughout the infusion and had different values from control at 30, 60, and 90 breaths/min. However, H was frequency dependent in control suggesting that it is sensitive to interlobal anatomical differences. We conclude that the frequency dependence of Cdyn is the most specific test for detecting small airways constriction.

Original languageEnglish (US)
Pages (from-to)625-630
Number of pages6
JournalIEEE Transactions on Biomedical Engineering
Issue number10
StatePublished - Oct 1983


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