Atelectasis and mechanical ventilation mode during conservative oxygen therapy: a before-and-after study

Abstract

PURPOSE: 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. MATERIALS AND 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.