Atelectasis and mechanical ventilation mode during conservative oxygen therapy: A before-and-after study.
OBJECTIVE
The purpose of the study is to assess the effect of a conservative oxygen therapy (COT) (target SpO2 of 90%-92%) on radiological atelectasis and mechanical ventilation modes.


METHODS
We conducted a secondary analysis of 105 intensive care unit patients from a pilot before-and-after study. The primary outcomes of this study were changes in atelectasis score (AS) of 555 chest radiographs assessed by radiologists blinded to treatment allocation and time to weaning from mandatory ventilation and first spontaneous ventilation trial (SVT).


RESULTS
There was a significant difference in overall AS between groups, and COT was associated with lower time-weighted average AS. In addition, in COT patients, change from mandatory to spontaneous ventilation or time to first SVT was shortened. After adjustment for baseline characteristics and interactions between oxygen therapy, radiological atelectasis, and mechanical ventilation management, patients in the COT group had significantly lower "best" AS (adjusted odds ratio, 0.28 [95% confidence interval {CI}, 0.12-0.66]; P=.003) and greater improvement in AS in the first 7 days (adjusted odds ratio, 0.42 [95% CI, 0.17-0.99]; P=.049). Moreover, COT was associated with significantly earlier successful weaning from a mandatory ventilation mode (adjusted hazard ratio, 2.96 [95% CI, 1.73-5.04]; P<.001) and with shorter time to first SVT (adjusted hazard ratio, 1.77 [95% CI, 1.13-2.78]; P=.013).


CONCLUSIONS
In mechanically ventilated intensive care unit patients, COT might be associated with decreased radiological evidence of atelectasis, earlier weaning from mandatory ventilation modes, and earlier first trial of spontaneous ventilation.
Department of Intensive Care, Austin Hospital, Heidelberg, Melbourne VIC, Australia.
Satoshi
S
Suzuki
Department of Intensive Care, Austin Hospital, Heidelberg, Melbourne VIC, Australia.
Glenn M
GM
Eastwood
Department of Radiology, Austin Hospital, Heidelberg, Melbourne, VIC, Australia.
Mark D
MD
Goodwin
Department of Radiology, Austin Hospital, Heidelberg, Melbourne, VIC, Australia.
Geertje D
GD
Noë
Department of Radiology, Austin Hospital, Heidelberg, Melbourne, VIC, Australia.
Paul E
PE
Smith
Department of Intensive Care, Austin Hospital, Heidelberg, Melbourne VIC, Australia.
Neil
N
Glassford
Department of Intensive Care, Austin Hospital, Heidelberg, Melbourne VIC, Australia.
Antoine G
AG
Schneider
Department of Intensive Care, Austin Hospital, Heidelberg, Melbourne VIC, Australia; Australian and New Zealand Intensive Care Research Centre, Melbourne, VIC, Australia. Electronic address: rinaldo.bellomo@austin.org.au.
Rinaldo
R
Bellomo
D000328:Adult; D000368:Aged; D065187:Controlled Before-After Studies; D005260:Female; D006801:Humans; D007362:Intensive Care Units / Q000706:statistics & numerical data; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D010865:Pilot Projects; D016016:Proportional Hazards Models; D001261:Pulmonary Atelectasis / Q000000981:diagnostic imaging / Q000628:therapy*; D011859:Radiography; D012121:Respiration, Artificial / Q000379:methods*; D015300:Ventilator Weaning / Q000706:statistics & numerical data
Atelectasis; Critical illness; Hyperoxia; Mechanical ventilation; Oxygen; Oxygen inhalation therapy