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PHOENIX -- Targeting normoxemia in critically ill trauma patients appeared to increase supplemental oxygen-free days in a cluster randomized stepped-wedge trial that missed on statistical significance.

Through 28 days, patients in the post-implementation group who were targeted to normoxemia had a mean 20.3 supplemental oxygen-free days compared with 18.8 days for those in the pre-implementation group who received usual care, a non-significant adjusted mean difference of 1.13 days (95% CI -0.31 to 2.58), reported David Douin, MD, of the University of Colorado School of Medicine in Aurora.

At 90 days, the in-hospital mortality rate was numerically lower in the post-implementation group (8.7% vs 11.4%; adjusted HR 0.58, 95% CI 0.33-1.02), according to findings presented at the Society of Critical Care Medicine Critical Care Congress.

The majority of patients ultimately needed little to no supplemental oxygen during the course of the trial. Douin stressed that improving supplemental oxygen-free days and reducing the need for supplemental oxygen can make a huge difference for patients and facilities that have limited means to access that care.

"We overall reduced need for supplemental oxygen, which in resource-rich settings may not seem like a big deal, but in austere settings such as military operations or in any other resource-limited settings, it can be a big deal," he said.

Aanchal Kapoor, MD, of the Cleveland Clinic, told 番茄社区app in an email that "supra-physiological levels of oxygen have been identified as having deleterious effects not only on the lungs but also on multiple organs, including the brain and heart. The proposed mechanisms of injury encompass the formation of oxygen-free radicals, delayed vasospasm after traumatic injury, coronary vasoconstriction, and uncoupling of mitochondrial respiration."

"The results of this study are timely in emphasizing the importance of targeting normoxemia," she added. "Specifically, they highlight an increase in oxygen-free days with no significant difference in the rate of hypoxia between liberal and conservative oxygen therapy groups. It would be further beneficial to know if increased oxygen-free days are associated with less injury to other organs and an increase in survival."

Douin explained that a large part of the trial focused on what he described as a "culture change."

"Changing people's minds in the daily routine is really hard, in any field, in any practice. So, we spent a considerable effort at this trial focused on changing people's perceptions of oxygen," he told 番茄社区app.

Kapoor noted that, if this change occurs, it can improve patient care on multiple levels.

"Having well-defined target oxygen levels will allow physicians to create standardized protocols for oxygen therapy across different clinical scenarios," she said. "This consistency in approach will enable healthcare professionals to administer oxygen in a more precise and tailored manner based on the specific needs of each patient. This timely adjustment can contribute to earlier liberation from oxygen dependence, promoting a more efficient recovery process, active engagement in physical therapy by the patients, and earlier discharge from the ICU and hospital."

For this study, a team of 31 civilian and military experts were consulted to develop the targeted normoxemia strategy. The normoxemia definition consensus was an oxygen saturation (SpO₂) of 90-96%, an arterial partial pressure of oxygen (PaO₂) of 60-100 mm Hg, and a fraction of inspired oxygen for mechanical ventilation of 21%. These values were communicated with the clinical staff assigned to an admitted patient.

During the course of the trial, if a patient's SpO₂ rose above 96% or if their PaO₂ was found to be above 100 mm Hg, clinicians were provided with a digital warning and were encouraged to down-titrate the patient's oxygen within an hour. Once SpO₂ and PaO₂ levels returned to the acceptable intervention range, oxygen delivery was maintained at a constant level. Douin said that the intervention was considered non-binding, meaning that intervention measures could be overridden by a provider if it was in the best interest of the patient.

Eight Level 1 trauma centers throughout the U.S. were randomized from July 2020 to November 2022. Intervention strategies were implemented through the course of the trial, staggered from site to site -- switching from usual care measures, which acted as a placebo period, to intervention measures.

The analysis included 13,903 patients; mean age was 51-52, 24-28% were women, 42-56% were white, 27-41% had a traumatic brain injury, and 28-35% were on mechanical ventilation at baseline. Mean injury severity scores were 18.1 for pre-implementation patients and 17.2 for post-implementation patients.

Overall, hypoxemia was rare, and results were similar for mechanically ventilated patients and non-mechanically ventilated patients.

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