Clinical question: Does a conservative oxygenation strategy improve clinical outcomes, compared with standard clinical practice among critically ill patients?
Background: Supraphysiologic levels of oxygen have been linked to direct cellular injury through generation of reactive oxygen species. Hyperoxia is known to cause airway injury, including diffuse alveolar damage and tracheobronchitis; it also is linked to worse clinical outcomes in various cardiac and surgical patients. ICU patients have not been studied.
Setting: Single-center, academic hospital in Italy.
Synopsis: Investigators randomized 480 adults admitted to the ICU for at least 72 hours to either standard practice (allowing PaO2 up to 150 mmHg, SpO2 97%-100%) or the conservative protocol (PaO2 70-100 mmHg or SpO2 94%-98%). Patients who were pregnant, readmitted, immunosuppressed, neutropenic, with decompensated COPD or acute respiratory distress syndrome were excluded. Outcomes included ICU mortality, hospital mortality, new-onset organ failure, or new infection.
Enrollment was slow, the authors noted, partially due to an earthquake that damaged the facility, and the trial was stopped short of the planned 660 patient sample size.
In an intent-to-treat analysis, there was a statistically significant decrease in ICU and hospital mortality, shock, liver failure, and bacteremia among the conservative group.
Limitations included possible confounding from higher illness severity in the standard practice group, as well as the single-center focus that terminated early due to enrollment challenges.
Bottom line: A conservative oxygen strategy had a statistically significant decrease in ICU and hospital mortality, shock, liver failure, and bacteremia.
Citation: Girardis M, Busani S, Damiani E, et al. Effect of conservative vs conventional oxygen therapy on mortality among patients in an intensive care unit..
Dr. Marr is a clinical instructor at the University of Utah School of Medicine and an academic hospitalist at the University of Utah Hospital.