Lung resistance - but not compliance - impairs P0.1 and maximal inspiratory pressure measurements.

Abstract

Introduction: Bedside tools have been developed to assess inspiratory muscle function and inspiratory drive for patients under invasive mechanical ventilation. Occlusion maneuvers are currently considered but their pitfalls remain underexplored. We aimed to assess the impact of respiratory system compliance and resistance on P0.1 (addressing respiratory drive and inspiratory muscle function) and maximal inspiratory pressure (MIP, assessing global inspiratory muscle function) monitoring for fixed inspiratory muscle pressure (P_MUS) through an in-silico model.

Methods: The Active Servo Lung 5000 (ASL-5000) was used to reproduce respiratory conditions under fixed P_MUS of 5, 10 and 20 cmH₂O. From baseline, resistance and compliance challenges were performed. P0.1 and MIP were monitored on a ventilator (Dräger Evita Infinity V500).

Results: Resistance challenge impacted the monitoring of both P0.1 and MIP while compliance challenge barely modified P0.1 and MIP under all P_MUS settings. Statistical analysis confirmed significant correlations for increased Resistance and under-estimation of P0.1 and MIP (Spearman coefficient - 0.80, p-value < 0.01), while reduced compliance had inconsistent effect on occlusion maneuver values. We found expiratory (rather than inspiratory) resistances impacted pressure monitoring.

Discussion: Lung Resistance - but not Compliance - impairs P0.1 and Maximal Inspiratory Pressure Measurements. Further clinical studies are mandatory to define pitfalls and limits of occlusion maneuver monitoring.