Objective:To investigate the effects of continuous blood purification (CBP) on mitochondrial function of peripheral blood mononuclear cells and clinical prognosis of patients with traumatic sepsis.Methods:A prospective cohort study was used to analyze the clinical data of 90 patients with traumatic sepsis admitted to the Intensive Care Unit of Shaoxing People′s Hospital from January 2023 to June 2024. Based on standard operating procedures (SOP), patients were divided into CBP group and non-CBP group according to whether they received CBP treatment. The mitochondrial DNA (mtDNA) copy number, activity of mitochondrial respiratory chain complex V, levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-6 and IL-10 in the mononuclear cells on ICU admission and at 12, 24 and 48 hours after treatment were compared between the two groups. Acute physiology and chronic health evaluation II (APACHE II) score and sequential organ failure assessment (SOFA) score on ICU admission and at 48 hours after treatment were detected in the two groups. The length of ICU stay, total length of hospital stay and 28-day mortality after ICU admission were compared between the two groups.Results:A total of 90 patients with traumatic sepsis were included, comprising 56 males and 34 females, aged 18-82 years [51.3(38.7, 70.6)years], with injury severity score (ISS) of 16-54 points [36.2(17.0, 53.6)points]. There were 52 patients in the CBP group and 38 in the non-CBP group. All the patients were followed up for 7-14 days [10.0(8.0, 12.0)days]. On ICU admission, the mtDNA copy number was 638.5±124.0 in the CBP group and 634.7±122.1 in the non-CBP group ( P>0.05). At 12, 24 and 48 hours after treatment, the mtDNA copy number in the CBP group was 564.2±105.6, 415.7±83.5 and 303.7±77.0 respectively, significantly lower than 622.9±120.2, 581.5±113.6, 530.7±97.8 in the non-CBP group ( P<0.05 or 0.01). At 12, 24 and 48 hours after treatment, the mtDNA copy number in both groups continued to decrease compared with that on ICU admission ( P<0.05). On ICU admission, the activity of mitochondrial respiratory chain complex Ⅴ was (74.0±26.0)pg/ml in the CBP group and (72.8±25.3)pg/ml in the non-CBP group ( P>0.05); at 12, 24 and 48 hours after treatment, it was (69.4±24.2)pg/ml, (78.3±26.8)pg/ml and (91.5±33.5)pg/ml respectively in the CBP group, significantly higher than (65.3±23.6)pg/ml, (60.7±19.4)pg/ml and (53.8±16.9)pg/ml in the non-CBP group ( P<0.05 or 0.01); at 12 hours after treatment, it was decreased in both groups compared with that on ICU admission ( P<0.05); at 24 and 48 hours after treatment, it was gradually increased in the CBP group compared with those on ICU admission and at 12 hours after treatment ( P<0.05), while in the non-CBP group, it continued to decrease ( P<0.05). The levels of TNF-α, IL-6 and IL-10 on ICU admission were (51.6±17.1)pg/ml, (174.1±57.3)pg/ml and (67.6±16.2)pg/ml respectively in the CBP group and (49.5±16.7)pg/ml, (177.8±58.7)pg/ml and (65.7±16.6)pg/ml respectively in the non-CBP group ( P>0.05). At 12, 24 and 48 hours after treatment, the levels of TNF-α in the CBP group were (43.6±15.6)pg/ml, (29.4±12.5)pg/ml and (26.2±10.6)pg/ml respectively, the IL-6 levels were (122.4±41.7)pg/ml, (90.6±33.1)pg/ml, (75.6±24.7)pg/ml respectively and the IL-10 levels were (72.6±18.1)pg/ml, (80.7±20.6)pg/ml, (86.2±22.9)pg/ml respectively, which were significantly lower than (48.8±16.2)pg/ml, (46.5±15.5)pg/ml, (40.0±14.2)pg/ml at 12 hours after treatment, (168.4±51.6)pg/ml, (131.5±42.7)pg/ml, (112.7±35.8)pg/ml at 24 hours after treatment, and (78.6±19.3)pg/ml, (91.1±23.8)pg/ml, (99.4±26.6)pg/ml at 48 hours after treatment in the non-CBP group ( P<0.05 or 0.01). At 12, 24 and 48 hours after treatment, the levels of TNF-α and IL-6 in both groups continued to decrease, while the levels of IL-10 continued to increase compared with those on ICU admission ( P<0.05). On ICU admission, the APACHE Ⅱ and SOFA scores were (20.6±10.5)points and (6.2±1.9)points in the CBP group and (21.2±11.2)points and (6.7±2.1)points in the non-CBP group ( P>0.05). At 48 hours after treatment, the APACHE Ⅱ and SOFA scores were (13.5±6.6)points and (2.7±0.6)points in the CBP group, which were significantly lower than (18.3±9.3)points and (5.3±1.5)points in the non-CBP group ( P<0.01). At 48 hours after treatment, the APACHE II and SOFA scores in both groups were significantly decreased compared with those on ICU admission ( P<0.05 or 0.01). The length of ICU stay, total length of hospital stay and 28-day mortality after ICU admission were (13.0±5.7)days, (20.4±8.6)days and 19.2% (10/52) respectively, which were significantly shorter and smaller than (17.6±6.6)days, (26.5±9.4)days and 31.6% (12/38) in the non-CBP group ( P<0.05 or 0.01). Conclusions:CBP treatment may reduce the release of mtDNA by alleviating the mitochondrial damage of the mononuclear cells in patients with traumatic sepsis so that the release of inflammatory factors and cellular apoptosis is reduced, and improve the state of cell energy metabolism and cellular immune function by increasing the activity of mitochondrial respiratory chain complex V in the mononuclear cells, and participate in the reconstruction of immune homeostasis of the body so the inflammatory state and clinical prognosis of the patients are improved.