Carboxyhemoglobin as Potential Biomarker for Cardiac Surgery Associated Acute Kidney Injury

Area of Science:

• Nephrology
• Cardiology
• Critical Care Medicine

Background:

• Carboxyhemoglobin (CO-Hb) is a known marker of hemolysis and inflammation.
• Both hemolysis and inflammation are risk factors for cardiac surgery-associated acute kidney injury (CSA-AKI).
• The direct association between CO-Hb levels and CSA-AKI has not been previously established.

Purpose of the Study:

• To investigate the association between CO-Hb levels at intensive care unit (ICU) admission and the occurrence of CSA-AKI.
• To determine if CO-Hb can serve as a predictive biomarker for CSA-AKI.

Main Methods:

• Retrospective cohort study including 1,698 adult patients undergoing on-pump cardiac surgery.
• Patients were stratified into quartiles based on CO-Hb levels measured at ICU admission.
• Multivariable logistic regression analysis was used to assess the independent association between CO-Hb and CSA-AKI.

Main Results:

• Higher quartiles of CO-Hb at ICU admission were progressively associated with an increased risk of CSA-AKI.
• The highest quartile of CO-Hb (≥ 1.4%) was independently associated with CSA-AKI (OR 1.45, p=0.038).
• Patients with CO-Hb ≥ 1.4% had significantly higher postoperative creatinine, increased rates of RRT, and a shorter time to AKI or death.

Conclusions:

• CO-Hb levels ≥ 1.4% at ICU admission are an independent risk factor for CSA-AKI.
• CO-Hb is a readily available biomarker from routine arterial blood gas measurements.
• CO-Hb can be utilized for practical risk stratification and patient selection in CSA-AKI prevention trials.