Toxicosis often leads to multiple organ failure (MODS), with the kidney being the primary target organ due to its sensitivity to infection and ischemia. The kidney's vulnerability makes it a potential early indicator of organ failure, implying that further organ failure may occur later, thereby increasing the risk of patient mortality. Several studies conducted on sepsis patients in the Pediatric Intensive Care Unit (PICU) have revealed that 40.32% of sepsis patients experienced complications with acute kidney injury (AKI), and the case fatality rate could rise to 70% once AKI occurred. The Kidney Disease Improving Global Outcomes (KDIGO) scale is commonly used as a diagnostic criterion for AKI. However, the kidney's robust reserve function poses a challenge for early identification, diagnosis, and intervention of AKI since significant increases in creatinine levels and a sharp decrease in urine volume already indicate severe kidney damage. This situation calls for the development of alternative methods.

In our previous study, we discovered a strong correlation between urinary oxygen partial pressure and renal organ function impairment in children with sepsis. Building upon traditional biochemical indicators such as blood lactic acid levels, we will incorporate non-invasive tests like urine partial pressure of oxygen, renal ultrasound, and cardiac ultrasound, as well as novel markers like KIM-1, to establish a model for early recognition and assessment of kidney damage in children with sepsis. By utilizing commonly used biomarkers and the precise effects of urinary oxygen partial pressure, we aim to improve early identification and accurate intervention evaluation for pediatric sepsis kidney injury. This research will provide a crucial foundation for the development of early warning systems, diagnostic guidelines, and treatment protocols for pediatric sepsis kidney injury.

Inclusion Criteria:

• From May 2021 to December 2024, the study focused on patients admitted to the Pediatric Intensive Care Unit (PICU) for a duration exceeding three days. Specifically, patients with severe infection and those who underwent pediatric neurosurgery were diagnosed with sepsis according to the international standard for childhood sepsis established in 2005, the 2012 Surviving Sepsis Campaign guidelines for pediatric sepsis, and the 2015 expert consensus on sepsis criteria for Chinese children with septic shock. The age range of the patients included in the study spanned from 1 month to 16 years old.

Exclusion Criteria:

• Children who enter PICU 24 hours and die or exit PICU within 24 hours; Genetic metabolic diseases; Congenital immune deficiency; Can't sign an informed consent form.

Between the period of May 2021 to December 2024, the study focused on patients who were admitted to the Pediatric Intensive Care Unit (PICU) for a duration exceeding three days. Specifically, patients with a diagnosis of sepsis were selected based on the internationally recognized 2005 standard for childhood sepsis, the 2012 Surviving Sepsis Campaign guidelines for pediatric sepsis, and the 2015 expert consensus on sepsis criteria for Chinese children with septic shock. The age range of the patients included in the study spanned from 1 month to 16 years old