Could chest ultrasound replace chest X-ray for the diagnosis of pneumothorax after pulmonary cryobiopsy?

Background: Transbronchial lung cryobiopsy (TBLC) has been established as a common and safe procedure in the diagnosis of diffuse interstitial lung diseases (ILD). The patient can be discharged after a few hours under observation, except if a complication is presented, mainly bleeding or pneumothorax (PTX). Chest X-ray (CXR) is the conventional examination performed to detect PTX, but sometimes the delay in carrying it out may lengthen the patient’s hospital stay. Chest ultrasound (US) is more sensitive in the detection of PTX. Objective: to assess if chest US could replace CXR to detect PTX. Methods: prospective study in patients with indication of TBLC for the study of ILD from April 2018 to February 2019. Chest US was performed 1 hour after the procedure in the recovery area and a CXR was performed 4 hours after the procedure in the Radiology department, except if the patient had symptoms or if the US showed PTX, performing CXR earlier. Results: 32 patients were included,57.3% males.94% of the biopsies were performed in lower lobes.24 patients did not present PTX on US and this was confirmed with CXR, except in one patient who presented late PTX on the CXR.4 patients presented PTX on US and it was also confirmed with CXR. US detected 1 PTX that was not visible in CXR. In 3 cases there were doubts in the US image due to a bad window, of which 1 had PTX and another 2 did not. About the patients who presented PTX (22%), only two (6.2%) required a chest tube. The rest were discharged after 24-72 hours of observation. Conclusions: Chest US can replace conventional CXR in a large number of patients, allowing early discharge, although the possibility of late PTX (3.1%) must be taken into account.