ARDS Esophageal Balloon Pressure Changes With Positioning Study

The use of esophageal balloon catheters shows promise in improving outcomes of patients with severe ARDS. The estimation of pleural pressure (Ppl) has been validated in the upright position in humans with few studies commenting on the changes in supine positioning and almost none on prone positioning aside from radiographic analysis. An abstract presented at the annual American Thoracic Society meeting recently reported a series of 18 patients undergoing spinal surgery. In this population of patients without ARDS, esophageal pressure (Pes) decreased when shifting from supine to prone positioning. This suggests that transpleural pressure (PtmL) would be increased at a given airway pressure. The investigators hope to measure changes in PtmL in patients undergoing treatment with mechanical ventilation while switching from the supine, upright (head of bed \>30 degrees), and prone positions. The esophageal balloon catheter will be placed using standard techniques and secured with tape to the patients' nares during changes in positioning. The goal will be to measure the changes in chest wall and lung compliance in mechanically ventilated patients with changes in position.