Abstract
Aims and objectives: This study aims to distinguish regional airway opening from airway dilatation during mechanical lung ventilation, more particularly the effect of PEEP on these parameters, in patients with acute respiratory distress syndrome (ARDS).
Methods: End-expiratory breath hold CT scans were subsequently taken at four different PEEP levels, ranging from 0 cmH2O to 20 cmH2O. The 4 CT scans were executed from high to low PEEP levels with a 2min stabilization period in between. Patients were ventilated during the entire recruitment and scanning sequence. The resulting images were post-processed by means of functional respiratory imaging.
Results: The regional characteristics of PEEP-related airway opening and dilatation could be delineated in six patients with full-blown ARDS in the acute phase. Bronchial recruitment (BR) is found to be dependent on the PEEP level (p=0.031) and this dependency is different between upper and lower lung lobes (more recruitment in lower lobes, p=0.004). Bronchodilation (BD) is only dependent on the PEEP level (p=0.002), and equally present in the upper (UL) and lower lobes (LL). Both values are found to be very patient specific (random intercepts and slopes).
From the lowest to the highest PEEP, the (median) BR of the UL was 78.94% and the BD of the UL bronchi was 79.31%. The BR of the LL was 212.09% and the BD of the LL bronchi was 117.88%. The ratio of BD/BR of bronchi was higher in the upper lobes than in the lower lobes (2.45 vs 0.56).
Conclusions: This pilot study gives an innovative insight into the relationship between PEEP-related airway opening and dilatation in recent onset ARDS, facilitating individualized ventilation strategies in ARDS patients.
- Copyright ©ERS 2015
