Spuriously elevated intrinsic PEEP

Individual values of intrinsic PEEP (auto-PEEP) measured on esophageal tracings (PEEPi dyn) compared with values obtained after subtracting for the rise in gastric pressure resulting from expiratory muscle activity (PEEPi corrected). The difference shown represents the contribution of expiratory muscle activity to the measured auto-PEEP. The corrected auto-PEEPi would be that component of auto-PEEP expected to be responsive to the application of PEEP. Thus, the presence of expiratory muscle activity can lead to the erroneous impression of a higher level of auto-PEEP and to the application of PEEP in an amount which might result in worsened dynamic pulmonary hyperinflation.