Phenotyping Breathing Patterns and Patient-Ventilator Dyssychrony in Acute Respiratory Distress Syndrome - a Reapplication of the Campbell Diagram

Abstract

Purpose: Although many forms of patient-ventilator dyssynchrony have been observed and reported, the nature of spontaneous patient efforts and the resulting ventilator response is an underexplored aspect of patient management and may have important clinical implications. Many breathing patterns are difficult to identify solely by inspection of standard ventilator waveforms or even with esophageal manometry time tracings. The Campbell diagram (pressure- volume loops of the chest wall plotting pleural/esophageal pressure and volume changes), may improve our ability to phenotype breathing patterns. Methods: A retrospective analysis was performed on 56 mechanically ventilated patients with ARDS. Subjects had an esophageal balloon placed, were placed on a control mode of ventilation. Volumes were calculated as the integral of the flow and esophageal pressures used as a surrogate for pleural and trans-chest wall pressures to create Campbell diagrams. Unique breathing patterns were identified using the Campbell Diagram and qualitatively described. Results: Unique breathing phenotypes and their characteristic Campbell Diagram appearances were defined. Waveform data consisted of an average of 6.8 minutes per patient for a total of 384.12 minutes and 10323 breaths. Passive breathing accounted for 65.3% of all breaths analyzed. Spontaneous patient efforts were common; active inspiratory efforts, active expiratory efforts, and entrainment represented 25.3%, 6.4%, and 16.4% of all breaths analyzed, respectively. Conclusions: The Campbell Diagram is a promising tool in the identification of breathing phenotypes. Systematically identifying and describing breathing phenotypes will set the foundation for future investigation of their individual and unique clinical importance. Continued application of esophageal manometry and the Campbell Diagram may allow for more accurate phenotyping at the bedside and thus result in increased personalization of ventilator management for patients with ARDS.