Driving Pressure and Lung Compliance Obtained by Electrical Bioimpedance: The Case of Smokers

Abstract

Survival in patients with mechanical ventilation depends on careful regulation of some critical parameters as the tidal volumes (VT), positive end expiratory pressure (PEEP), lower end inspiratory pressure (Plateau), the driving Pressure (DP=Plateau - PEEP), and respiratory system compliance (Crs= VT/DP) related with the functional lung size. These parameters are obtained from the flux signal in Pneumotachometer (PNT) technique. The present work studies the possibility of using the Electrical Bioimpedance (EBI) technique to obtain flux parameters as driving pressure and lung compliance in smokers, before and after tobacco consumption. Ventilatory pattern is obtained by initial comparison of EBI signal with a simultaneous measurement of integrated PNT signal. By differentiating in time EBI signal EBI flux pattern and then its corresponding flux parameters are obtained. Thirty-four young and healthy volunteers (17 men and 17 women) were evaluated. EBI flux parameters were compared with those obtained directly from PNT. By obtaining an initial personalized proportionality constant between the PNT signal and the electrical bioimpedance, it can be observed a good agreement between both techniques in the volumes estimation, in other stages of the experiment, flows and parameters derived from these such as driving pressure and compliance. An initial and personalized correlation between the PNT and bioelectrical impedance signals can be used to predict subsequent volumes, flows, driving pressure and lung compliance.