[Assessment of positive end-expiratory pressure induced lung volume change by ultrasound in mechanically ventilated patients].

OBJECTIVE: To investigate the value of lung ultrasound for assessing positive end-expiratory pressure (PEEP) -induced lung volume change in mechanically ventilated patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) .

METHODS: Eighteen patients with ALI or ARDS were prospectively studied. P-V curves and lung ultrasound were performed at PEEP 12, 8, 4 and 0 cm H2O (1 cm H2O = 0.098 kPa). PEEP-induced lung volume change was measured using the P-V curve method and lung ultrasound.

RESULTS: Four lung ultrasound entities were defined: consolidation, multiple irregularly spaced B lines, multiple abutting B lines and normal aeration.For each of the 12 lung regions examined, PEEP-induced ultrasound changes were measured and an lung ultrasound score (LUS) was calculated. A highly significant correlation was found between PEEP-induced lung volume change measured by P-V curves and LUS change (r = 0.82, P < 0.01) . A statistically significant correlation was found between LUS change and PEEP-induced increase in PaO2 (r = 0.66, P < 0.01).

CONCLUSION: PEEP-induced lung volume change can be adequately estimated with bedside lung ultrasound. Since lung ultrasound cannot assess PEEP-induced lung hyperinflation, it should not be the sole method for PEEP titration.