The assessment of esophageal pressure using different devices : a validation study

BACKGROUND: Although esophageal pressure measurement could help clinicians to improve the ventilatory management of acute respiratory distress syndrome (ARDS) patients, it has been mainly used in clinical research. Aim of this study was to compare the measurements of end-expiratory esophageal pressure, end-expiratory transpulmonary pressure and lung stress by three systems: a dedicated manual device, taken as gold standard, a new automatic system (Optivent) and a bedside equipment, consisting of a mechanical ventilator and a hemodynamic monitor. METHODS: In sedated and paralyzed mechanically ventilated ARDS patients the esophageal pressure was measured at three PEEP levels in random fashion (baseline level, 50% higher and 50% lower). RESULTS: Forty patients were enrolled (BMI 25 [23-28] kg/m2, PaO2/FiO2 187 [137-223] and PEEP 9±3 cmH2O). The mean esophageal pressure measured during an expiratory pause by the dedicated system, the bedside system and Optivent were 10.0±4.2, 10±4 and 9.9±4.0 cmH2O, respectively. The respective bias and limits of agreement between the dedicated system and Optivent and between the dedicated system and the bedside system were as follows: end-expiratory esophageal pressure, 0.2 cmH2O, (-0.4 to 0.9) and -0.1 cmH2O (-1.9 to 1.7); end-expiratory transpulmonary pressure, -0.6 cmH2O (-1.7 to 0.4) and -0.4 cmH2O, (-2.2 to 1.5); lung stress -0.9 cmH2O (-3.0 to 1.1) and -1.5 cmH2O (-4.4 to 1.4). CONCLUSIONS: Both Optivent and the bedside system showed clinically acceptability if compared to the gold standard device. The possibility to apply one of these systems could allow a wider use of esophageal pressure in clinical practice.