Conservative Oxygen Therapy during Mechanical Ventilation in the ICU

Abstract

Background: Patients who are going thorugh mechanical ventilation in the intensive care unit (ICU) often receive a high fraction of inspired oxygen (Fio2 ) and have a high arterial oxygen tension. The conservative use of oxygen may reduce oxygen exposure, diminish lung and systemic oxidative injury, and thereby increase the number of ventilator-free days (days alive and free from mechanical ventilation). Methods: We randomly assigned 1000 adult patients who were anticipated to require mechanical ventilation beyond the day after recruitment in the ICU to receive conservative or usual oxygen therapy. In the two groups, the default lower limit for oxygen saturation as measured by pulse oximetry (Spo2 ) was 90%. In the conservativeoxygen group, the upper limit of the Spo2 alarm was set to sound when the level reached 97%, and the Fio2 was decreased to 0.21 if the Spo2 was above the acceptable lower limit. In the usual-oxygen group, there were no specific measures limiting the Fio2 or the Spo2 . The primary outcome was the number of ventilatorfree days from randomization until day 28. Results: The number of ventilator-free days did not differ significantly between the conservative-oxygen group and the usualoxygen group, with a median duration of 21.3 days (interquartile range, 0 to 26.3) and 22.1 days (interquartile range, 0 to 26.2), respectively, for an absolute difference of −0.3 days (95% confidence interval [CI], −2.1 to 1.6; P=0.80). The conservativeoxygen group spent more time in the ICU with an Fio2 of 0.21 than the usual-oxygen group, with a median duration of 29 hours (interquartile range, 5 to 78) and 1 hour (interquartile range, 0 to 17), respectively (absolute difference, 28 hours; 95% CI, 22 to 34); the conservative-oxygen group spent less time with an Spo2 exceeding 96%, with a duration of 27 hours (interquartile range, 11 to 63.5) and 49 hours (interquartile range, 22 to 112), respectively (absolute difference, 22 hours; 95% CI, 14 to 30). At 180 days, mortality was 35.7% in the conservative-oxygen group and 34.5% in the usual-oxygen group, for an unadjusted odds ratio of 1.05 (95% CI, 0.81 to 1.37). Conclusions: In adults undergoing mechanical ventilation in the ICU, the use of conservative oxygen therapy, as compared with usual oxygen therapy, did not significantly affect the number of ventilator-free days.

Implementing target range oxygen in critical care: A quality improvement pilot study

“…The results of the much larger ICU-ROX multi-centre study have been published very recently. 10 This study did not demonstrate any difference in the primary outcome measure (ventilator free days) or any significant difference in 180 day mortality between ventilated ICU patients randomised to conservative oxygen therapy (target saturation range 91-96%) compared with ''usual care'' (target range 591%). However, the mean PaO2 of these patients was not widely different (108mmHg / 14.4 kPa in the usual care group and 90 mmHg / 12.0 kPa in the conservative oxygen group).…”

Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome: insights from the LUNG SAFE study

“…In randomized trials, "induced" hyperoxia (using 100% oxygen) increased 28-day mortality in septic shock patients [23], while critically ill patients randomized to a target arterial oxygen tension (PaO 2 ) of 70-100 mmHg had lower mortality compared to patients with a "conventional" target of PaO 2 up to 150 mmHg [24] in a single-center study. While a recent large international multicenter trial demonstrated no effect of conservative oxygen therapy in a diverse cohort of critically ill patients [25], a subsequent sub-study raised the possibility of clinically important harm with conservative oxygen therapy in patients with sepsis [26].…”

Conservative oxygen therapy for mechanically ventilated adults with sepsis: a post hoc analysis of data from the intensive care unit randomized trial comparing two approaches to oxygen therapy (ICU-ROX)

“…We recently reported the findings of the intensive care unit randomized trial comparing two approaches to oxygen therapy (ICU-ROX) [9]. ICU-ROX compared conservative oxygen therapy with usual oxygen therapy in 1000 mechanically ventilated ICU patients.…”