Patients in the ICU who undergo mechanical ventilation often receive a high fraction of inspired oxygen (FIO2) and have a high arterial oxygen tension. It is believed that conservative oxygen therapy could reduce oxygen exposure and diminish lung and systemic oxidative injury, thus increasing the number of ventilator-free days. 

A study was conducted with 1000 patients who were expected to receive mechanical ventilation beyond the day after recruitment in the ICU. Study patients were randomly assigned to receive conservative or usual oxygen therapy. The lower limit for oxygen saturation, measured by pulse oximetry (SpO2) was 90% in the two groups. The upper limit of SpO2 was 97% in the conservative-oxygen group, and the FIO2 was decreased to 0.21 if the SpO2 was above the lower limit. No specific measures limiting the FIO2 or SpO2 were specified for the usual-oxygen group. The primary outcome of the study was the number of ventilator-free days from randomisation to day 28. 

Findings from the study showed that the number of ventilator-free days did not differ significantly between the conservative-oxygen group and the usual-oxygen group (21.3 days versus 22.1 days, respectively). The absolute difference between the two was only -0.3 days. Patients in the conservative-oxygen group spent more time in the ICU with an FIO2 of 0.21 and less time with an SpO2 exceeding 96% compared to the usual-oxygen group. Mortality at 180 days was 35.7% in the conservative-oxygen group compared to 34.5% in the usual-oxygen group. 

The results show that in patients undergoing mechanical ventilation in the ICU, the use of conservative-oxygen therapy did not have a significant impact on the number of ventilator-free days compared to usual-oxygen therapy.

Source: NEJM
Image Credit: iStock

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References:

ICU-ROX Investigators and the Australian and New Zealand Intensive Care Society Clinical Trials Group, Mackle D et al. (2019) Conservative Oxygen Therapy during Mechanical Ventilation in the ICU. NEJM, doi: 10.1056/NEJMoa1903297



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ICU, mechanical ventilation, Critical Care, oxygen therapy, conservative oxygen therapy Findings show that the use of conservative oxygen therapy in critically ill patients undergoing mechanical ventilation does not have an impact on the number of ventilator-free days.