Adaptive control of airway tone in sheep that have asthma-like responses

A model reference, direct adaptive control model has been identified and is able to track airway tone from sheep that have asthma-like responses. This closed loop control model uses the MIT adaptation rule to drive the controller gain that accounted for the decreases in lung conductance seen in allergen-challenged sheep. A single compartment viscoelastic closed loop model was used with the output being the tidal volume. Observations revealed that there are two distinct airway tone timescales: a slow time scale governing lung dynamic changes that was used to established the baseline; and a fast timescale related to the more transient response during allergen induced bronchoconstriction. The baseline provided the coefficients for the model and these were adjusted by the controller gains. The controller gains for saline-challenge sheep which were used as experimental controls, were within random error determined for spontaneous breathing. The experiments indicate that the dynamics of diseased lungs can be captured by an adaptively controlled model.