Correcting esophageal pressure measurements for patients undergoing mechanical ventilation

Abstract

Abstract During invasive mechanical ventilation, knowledge of the patient’s respiratory effort is valuable in guiding the clinical team to perform a personalized therapy. The same adjustment of the ventilator can produce excessive transpulmonary pressures for different patients, capable of generating or aggravating pre-existing lung injuries. The measurement of transpulmonary pressure (the difference between airway and pleural pressures) is not easily performed in practice. Although airway pressure measurement is available on most current mechanical ventilators, pleural pressure measurement is indirectly performed using an esophageal balloon. In many cases, esophageal pressure reading takes other phenomena into account and is not a reliable measure of pleural pressure. This work will study system identification techniques to obtain reliable pleural pressures based on esophageal pressure readings, aiming to provide the clinical team with information about the patient’s ventilatory therapy’s real status. By estimating transfer function models, autoregressive with external input (ARX) and output error (OE) polynomial models, waveforms were adjusted in two different patients’ occlusion maneuver data. Different metrics were used to assess the quality of the models obtained. The analysis results showed that the estimation methods used provided plausible representations of the underlying dynamic system. Therefore, there are indications that the system identification techniques presented in this work can be used in general, in a clinical environment, to provide reliable estimates of pleural pressure based on esophageal pressure measurements.