The correlation study between post-surgery oxygen partial pressure level and prognosis of patients with sepsis during hospitalization
Authors: Wang Anqi , Chen Jieying , Gao JL 
Published: March 2024

Background
The high mortality and medical costs of sepsis have resulted in a significant consumption of medical resources, and improving the diagnosis and treatment strategies for the disease has always been a hot area. Studies have indicated that the clinical outcomes of sepsis patients with hyperoxaemia after surgery have improved, but they are still limited to observational studies with small samples. The aim of this study is to examine the suitable range of oxygen partial pressure for post-surgery sepsis patients and its correlation with prognosis.
Methods
We extracted clinical data from adult patients who met the diagnostic criteria for sepsis from the Medical Information Mart for Intensive Care (MIMIC)-IV database. By retrieving the patient's surgical information and time, we obtained data on patients who developed sepsis after undergoing surgery.Firstly, we categorized patients into a control group (PaO2 ≤ 100mmHg) and a hyperoxemia group (PaO2 > 100mmHg) based on their oxygen partial pressure levels. We preliminarily evaluated the clinical information, disease scores, and laboratory parameters of the two groups of patients. The primary clinical outcome set was the 90-day mortality rate after ICU admission, and secondary clinical outcomes included 1-year mortality rate, ICU length of stay, hospital length of stay, and the incidence and duration of invasive ventilation. Subsequently, we conducted a restricted cubic spline analysis based on the patients' 90-day mortality rate and re-categorized the patients' oxygen partial pressure levels 48 hours post-surgery into: normal group (PaO2 ≤ 128.7mmHg), mild hyperoxemia group (128.7mmHg < PaO2 < 162.1mmHg), and severe hyperoxemia group (PaO2 ≥ 162.1mmHg) based on the results of the restricted cubic spline analysis. We re-evaluated the patients' clinical information for this grouping, then conducted Kaplan-Meier analysis, and univariate and multivariate regression analysis based on the patients' 90-day mortality rate. Finally, we conducted subgroup analysis on meaningful variables and plotted a forest plot.
Results
A total of 1220 patients were included in the study. Compared to sepsis patients in the control group, hyperxemia patients were typically younger, had lower disease scores within 24 hours of admission, and received more aggressive treatment. The proportion of patients with hyperxemia undergoing high-flow oxygen therapy and tracheostomy is relatively low. Data, after grouping by restricted cubic spline based on the 90-day mortality rate of patients, showed similar results. Meanwhile, the proportion of hyperxemia patients with complications of acute respiratory failure and acute kidney injury was lower. In the final multivariate logistic regression model, the 90-day mortality rate of mild hyperxemia patients grouped by restricted cubic spline (OR:0.54, 95%CI 0.34–0.86, P = 0.010) was lower than that of normal group patients, but the patients in the severe hyperoxemia group did not show significant statistical value (OR:0.60, 95%CI 0.30–1.20, P = 0.147). After plotting the Kaplan-Meier survival curve based on the 28-day, 90-day, 180-day, and 365-day mortality rates, it was found that the long-term survival rate of patients with mild hyperoxemia was higher, which was statistically significant.
Conclusion
The occurrence of hyperoxemia in patients with post-surgical sepsis is associated with a reduction in 90-day mortality.