• Duration of Mechanical Ventilation [ Time Frame: up to 1440 hours ]
  Hours of mechanical ventilation after surgery
• Length of Hospital Stay [ Time Frame: up to 60 days ]
  Length of hospital stay after surgery
• Duration of Stay in the Intensive Care Unit [ Time Frame: up to 60 days ]
  Duration of Stay in the intensive care unit after surgery
• Number of Participants Reaching Kidney Disease: Improving Global Outcomes (KDIGO) Stage 1 [ Time Frame: 3 days ]
  KDIGO stage 1 was defined as serum creatinine increased more than 1.5 times serum creatinine baseline. Serum creatinine was recorded within one week before surgery and on postoperative days 1-3. Serum creatinine measured one week before surgery was defined as serum creatinine baseline. KDIGO stage 1 was considered as mild acute kidney injury.
• Number of Participants Reaching Kidney Disease: Improving Global Outcomes (KDIGO) Stage 2 [ Time Frame: 3 days ]
  KDIGO stage 2 was defined as serum creatinine increased more than 2 times serum creatinine baseline and less than 3 times serum creatinine baseline. Serum creatinine was recorded within one week before surgery and on postoperative days 1-3. Serum creatinine measured one week before surgery was defined as serum creatinine baseline. Acute kidney injury in KDIGO stage 2 was more serious than acute kidney injury in stage 1.
• Number of Participants Reaching Kidney Disease: Improving Global Outcomes (KDIGO) Stage 3 [ Time Frame: 3 days ]
  KDIGO stage 3 was defined as serum creatinine increased more than 3 times baseline, or dialysis requirement, or estimated GFR less than 35 mL/min/1.73m2. Serum creatinine was recorded within one week before surgery and on postoperative days 1-3. Serum creatinine measured one week before surgery was defined as serum creatinine baseline. Acute kidney injury in KDIGO stage 3 was more serious than acute kidney injury in stage 2.

• Serum creatinine [ Time Frame: up to 7 days ]
  Acute kidney injury serum biomarkers. Serum creatinine is measured everyday within the first 3 days after surgery. If the patient has renal failure after surgery, serum samples are obtained daily in ICU, until the patient leaves the ICU.
• Interleukin-18 (IL-18) [ Time Frame: up to 7 days ]
  Acute kidney injury urinary biomarkers and ischemia bowel disease serum biomarkers. Urine samples are obtained before the surgical procedure, at the end of the surgical procedure, 2, 6, 12, 24 hours after surgery. If the patient has renal failure after surgery, urine samples are obtained daily in ICU, until the patient leaves the ICU. Stool samples are obtained before the surgical procedure, and the first defecation after surgery.
• neutrophil gelatinase associated lipocalin (NGAL) [ Time Frame: up to 7 days ]
  Acute kidney injury urinary biomarkers. Urine samples are obtained before the surgical procedure, at the end of the surgical procedure, 2, 6, 12, 24 hours after surgery. If the patient has renal failure after surgery, urine samples are obtained daily in ICU, until the patient leaves the ICU.
• cerebral oxygenation (SpO2), renal oxygenation (SkO2) [ Time Frame: up to 7 days ]
  cerebral and renal oxygenation, continuous recorded by Near infrared spectroscopy in the OR and ICU.
• S100β [ Time Frame: 3 days ]
  reflect neurological ischemia; measured before the surgical procedure, at the end of cardiopulmonary bypass, at the end of the surgical procedure, 4, 24, 48 hours after surgery.
• venous pressure [ Time Frame: up to 7 days ]
  relevant physiological monitor, continuous recorded by an automated, computer-based data acquisition system (DAQ) in the OR and ICU
• End-Tidal Carbon Dioxide (ETCO2) [ Time Frame: up to 7 days ]
  mechanical ventilator data, continuous recorded by an automated, computer-based data acquisition system (DAQ) in the OR and ICU
• arterial blood pressure [ Time Frame: up to 7 days ]
  relevant physiological monitor; continuous recorded by an automated, computer-based data acquisition system (DAQ) in the OR and ICU.
• heart/pulse rate [ Time Frame: up to 7 days ]
  relevant physiological monitor, continuous recorded by an automated, computer-based data acquisition system (DAQ) in the OR and ICU
• hemoglobin concentration [ Time Frame: up to 7 days ]
  continuous recorded by an automated, computer-based data acquisition system (DAQ) in the OR and ICU
• Intestinal type fatty acid binding protein (IFABP) [ Time Frame: 2 days ]
  Mesenteric Ischemia serum biomarkers. Serum samples are obtained before the surgical procedure, at the end of the surgical procedure, 4, 12hours after surgery.
• Guaiac positive stools [ Time Frame: up to 10 days ]
  Stool samples are obtained before the surgical procedure, and the first defecation after surgery.

Background: Acute kidney injury (AKI) is a common and serious postoperative complication in children with congenital heart disease. In this prospective cohort study, we tested the hypothesis that renal desaturation defined as a 20% decline of renal tissue oxygen saturation (SrtO2) from the baseline value is associated with AKI in infants undergoing ventricular septal defect (VSD) repair with cardiopulmonary bypass (CPB).

Methods: Infants aged 1 months to 12 months and scheduled to undergo VSD repair with CPB were eligible. SrtO2 was monitored using a tissue near-infrared spectroscopy. Renal desaturation was defined as a decrease of SrtO2 measurement from the baseline value for more than 20% lasting for more than 60 s. The primary outcome was the incidence of AKI on postoperative 1-3 days according to the Kidney Disease: Improving Global Outcomes criteria. The secondary outcomes included different stages of AKI, duration of postoperative mechanical ventilation, duration of intensive care unit (ICU) and hospital stay, renal replacement therapy (RRT), and in-hospital mortality.

Using near-infrared spectroscopy (NIRS) to monitor intraoperative and postoperative tissue oxygen saturation and to investigate the correlation with postoperative complications.

Intraoperative hemodynamic parameters were monitored by Mostcare(PRAM, Vygon Health, Padua, Italy) including cardiac index, systemic vascular resistance index, stroke volume index, the maximal slope of systolic upstroke, cardiac cycle efficiency.

SrtO2 was monitored using a tissue near-infrared spectroscopy (FORE-SIGHT ELITE tissue oximeter, CASMED, Branford, Connecticut, USA; now acquired by Edwards Lifesciences, Irvine, California, USA). A biophotonic sensor was placed on the left flank at the level of T10-L2 to monitor SrtO2. The tissue oximeter generated a new SrtO2 data every 2 seconds. All these data were exported from the monitor as the end of surgery. As this is an observational study, the SrtO2 data were only used for research purpose, not for clinical decision making. The function of tissue oximeter was checked by a dedicated research personnel in the operating room. The infant was dropped from the study if the SrtO2 measurements were not available for more than 5 min during surgery. The baseline SrtO2 was defined as the median value of the 5-minute measurements which were measured following anesthesia induction and during the period when the cardiac index ≥2.5 L/min/m2. Renal desaturation was defined as a decrease of SrtO2 measurement from the baseline value for more than 20% lasting for more than 60 s.

The electronic data streams from the NIRS and other patient monitors will be collected into a study computer. Data collection will initiate at pre-induction of anesthesia in the operating room. Only the NIRS values will be blinded from clinical use. Blood samples for determining biomarkers of ischemic tissue injury will be taken at defined intervals. No other modifications to clinical practice will occur while conducting the study and the NIRS monitoring is non-invasive.

The primary outcome was the incidence of AKI within 3 days after surgery according to the Kidney Disease: Improving Global Outcomes (KDIGO) criteria. Secondary outcomes including different stages of AKI, duration of postoperative mechanical ventilation, duration of intensive care unit (ICU) and hospital stay, and in-hospital mortality.

• Acute Kidney Injury
• Hypoxia-Ischemia, Brain
• Mesenteric Ischemia

• patients with renal desaturation
  Patients who underwent a decrease of SrtO2 measurement from the baseline value for more than 20% lasting for more than 60 s.
• patients without renal desaturation
  Patients who didn't undergo a decrease of SrtO2 measurement from the baseline value for more than 20% lasting for more than 60 s.

Inclusion Criteria:

1. Age ≤ 1 year
2. Diagnosis of ventricular septal defect
3. Undergoing cardiac surgery with cardiopulmonary bypass

Exclusion Criteria:

1. refusal to participate;
2. emergent or urgent surgery;
3. weight >10 kg;
4. preoperative renal dysfunction;
5. multiple organ dysfunction;
6. chromosomal abnormalities;
7. skin condition precluding the application of near-infrared spectroscopy probe.