Computed Tomography

The quantitative analysis of lung CT scan allows to obtain useful information about the lung tissue aeration and, when performed at different pressure levels, can assess the potential recruitability. Historically, the concept of lung recruitability and PEEP titration in ARDS was investigated by means of CT analysis [13] that represents the most informative tool to assess lung aeration. CT can be considered as the gold standard to estimate lung recruitability, but it has several pitfalls that hamper its clinical application: the patients have to move to the ICU to the CT facility, the acquisition involves a high exposure to ionizing radiations, and the image postprocessing is time-consuming. Several solutions are under investigation, including the possibility to assess visually images to avoid manual image segmentation [43], to extrapolate the information from a reduced number of CT slices [44], and to use low-dose protocols to reduce radiation exposure [45, 46]. While its role has been established to assess lung recruitability, CT cannot be used for the assessment of a single RM. Further studies are necessary to clarify whether RMs should be the included in the standard ventilatory approach to patients showing a high recruitabil- ity at the CT scan.

In conclusion, CT is fundamental for diagnosis, to evaluate the lung recruitabil- ity at the admission, to assess the best ventilatory settings, and to titrate the initial PEEP [47], but more versatile tools are warranted to assess reliably recruitability, possibly at the bedside [48, 49].