Association between Conventional Oxygen Therapy and Characteristics and Outcomes of Adult Patients in a Surgical Intensive Care Unit

Background: Oxygen therapy is often used in emergency departments and intensive care units. The prevention of hypoxia with associated complications remains the main target, but a high-concentrated usual oxygen therapy seems not to be the best strategy. We hypothesize that physiological pressure of arterial oxygen (paO 2 ) reduces mortality, onset of new infections and organ dysfunctions in critically ill patients compared with supraphysiological paO 2 . Methods: In this retrospective exploratory cohort study we included 112 critically ill adult patients treated in a surgical critical care unit. All patients were assigned to two groups defined a priori based on paO 2 mean values measured in the first 24 hours of mechanical ventilation: first group paO 2 75-100 mmHg (n=43), second group patients with paO 2 > 100mmHg (n=69). Primary outcome was the cumulative survival, defined from the day of admission in the intensive care unit (ICU) until death or end of the hospital stay. Secondary outcome was the incidence of infections and new organ dysfunctions in both groups. Results: The baseline characteristics like age, body mass index (BMI), lactate and severity of disease scores were similar in both groups. A total of 27 of 69 patients (39,1%) in the group paO 2 > 100mmHg and 12 of 43 patients (27,9%) in the group paO 2 75-100mmHg died during their ICU stay or further hospital stay ( p =0.54). There were no statistically significant differences in the incidence of new infections and new organ dysfunctions between the two groups. Positive end expiratory pressure (PEEP) and fraction of inspired oxygen (F i O 2 ) were in the group of patients with paO 2 > 100mmHg significantly lower 8,4 mbar vs. 9,5 mbar ( p =0.03). Conclusions: There was no significant increase in overall mortality or new onset of infections and organ dysfunctions in critically ill adult ICU patients requiring oxygen therapy with supraphysiological paO 2 (> 100 mmHg) compared to patients with physiological paO 2 (75-100 mmHg). Further studies are needed to define the optimal paO 2 parameter.