The influence of airway resistance in the dynamic elastance model

Abstract

The selection of optimal positive end-expiratory pressure (PEEP) levels during ventilation therapy of patients with ARDS (acute respiratory distress syndrome) remains a problem for clinicians. A particular mooted strategy states that minimizing the energy transferred to the lung during mechanical ventilation could potentially be used to determine the optimal, patient-specific PEEP levels. The dynamic elastance model of pulmonary mechanics could potentially be used to minimize the energy by localization of the patients’ minimum dynamic elastance range. The sensitivity of the dynamic elastance model to variance in the airway resistance was analyzed. Subsequently, the airway resistance was determined using two alternate identification methods and was compared to the constant resistance obtained using the dynamic elastance model. Both identification methods showed similar decreasing trends of the resistance during inspiration. This declining trend is an apparent exponential decrease. Results showed that the constant airway resistance, presumed by the dynamic elastance model, has to be rechecked and investigated.