Effects of high-flow nasal oxygen during prolonged deep sedation on postprocedural atelectasis

BACKGROUND Atelectasis is common in patients undergoing prolonged deep sedation outside the operating theatre. High-flow nasal oxygen (HFNO) produces positive airway pressure which, hypothetically, should improve lung atelectasis, but this has not been investigated. OBJECTIVE We investigated whether HFNO ameliorates postprocedural atelectasis and compared the influences of HFNO and facial oxygen by mask on postprocedural outcomes. DESIGN A single-blind, open-label single-institution randomised controlled trial. SETTING A single university hospital, from February 2017 to July 2019. PATIENTS A total of 59 patients undergoing computed tomography (CT)-guided hepatic tumour radiofrequency ablation were randomly allocated to two groups. INTERVENTION These patients randomly received HFNO (oxygen flow 10 l min −1 before sedation and 50 l min −1 during the procedure) or a conventional oxygen face mask (oxygen flow 10 l min −1 ) during the procedure. MAIN OUTCOME MEASURES Changes in the area of lung atelectasis calculated on the basis of chest CT images and also recovery profiles were compared between the two groups. RESULTS The two groups had comparable procedural profiles, but the HFNO group exhibited less postprocedural atelectasis than the face mask group (median [IQR] 7.4 [3.9 to 11.4%] vs. 10.5 [7.2 to 14.6%]; P = 0.0313). However, the numbers of patients requiring oxygen supplementation in the recovery room and during transport from the recovery room to the ward did not differ significantly between groups (24.1 vs. 50.0%; P = 0.0596). CONCLUSION Our results suggested that HFNO ameliorates lung atelectasis after prolonged deep sedation in patients receiving CT-guided hepatic tumour radiofrequency ablation. TRIAL REGISTRATION Clinicaltrials.gov Identifier: NCT03019354.