Calibration of Esophageal Balloon Catheter in Spontaneous and Mandatory Mechanical Ventilation

Calibration of the esophageal balloon catheter (Pes catheter) is important for the right measurement of the esophageal pressure (Pes) and subsequent interpretation of the derived transpulmonary pressures during mechanical ventilation. Both relative changes and absolute values of Pes can be affected by inappropriate filling of the esophageal balloon and by the elastance of the esophagus wall. Therefore one should calibrate the balloon to determine the best filling pressure. Calibration of the Pes catheter has only been validated in mandatory ventilation but not in support modes in which the patient triggers the ventilator and is supported by the mechanical ventilator. Because the forces in the thoracic cage behave differently in comparison with a controlled mode, it is to be expected that the calibration process in a support mode yields different filling volumes in comparison with the calibration process in a controlled mode. This would lead to a more reliable filling volume in support mechanical ventilation and a more reliable derivation of transpulmonary pressure and therefore to a better treatment of patients.