Lung imaging for titration of mechanical ventilation.

PURPOSE OF REVIEW: Computed tomography (CT) has fostered pivotal advancements in the understanding of acute lung injury/acute respiratory distress syndrome and ventilator-induced lung injury. Apart from CT-based studies, the past years have seen fascinating work using positron emission tomography, electrical impedance tomography and lung ultrasound as diagnostic tools to optimize mechanical ventilation. This review aims to present the major findings of recent studies on lung imaging.

RECENT FINDINGS: Patients presenting with a focal loss of aeration on CT may not be suitable candidates for recruitment maneuvers and high levels of positive end-expiratory pressure (PEEP) in supine position. PET/CT has provided valuable insights into the inflammatory response of the lung. Electrical impedance tomography has been used to assess lung recruitability and to titrate PEEP. Finally, lung ultrasound has proven to be reliable diagnostic tool for assessing PEEP-induced recruitment.

SUMMARY: Whereas quantitative CT remains the gold standard to assess lung morphology, recruitment and hyperinflation of lung tissue at different inflation pressures, EIT and LUS have emerged as valuable, radiation-free, noninvasive bedside lung imaging tools that should be used together with global parameters like lung mechanics and gas exchange to acquire additional information on recruitability and ventilation distribution.