Methods: Between January 2007 and July 2018, a total of 119 patients (38 males, 81 females; mean age 54.4±13.0 years; range, 24 to 74 years) who received extracorporeal membrane oxygenation support for postcardiotomy shock and survived at least 48 hours in our center were retrospectively analyzed. Pre- and postoperative neutrophil-to-lymphocyte ratios, demographic characteristics, renal function parameters, and extracorporeal membrane oxygenationrelated data of the patients were recorded. Occurrence and stages of renal injury was determined using the revised Acute Kidney Injury Network and Kidney Disease Improving Global Outcomes criteria.

Results: No significant relationship was found between preoperative neutrophil-to-lymphocyte ratio and renal injury (p>0.05). Postoperative neutrophil-to-lymphocyte ratio was higher in patients who developed renal injury, compared to patients without renal injury (8.68 [0.84-42.00] vs. 4.02 [1.04-21.21], respectively, p=0.004). When patients were grouped for renal injury stage according to the revised Acute Kidney Injury Network (p=0.015) and Kidney Disease Improving Global Outcomes (p=0.006) criteria, the patients with more severe renal injury had higher neutrophil-to-lymphocyte ratio. The receiver operating characteristics analysis revealed a cut-off value of 6.71 for the neutrophil-to-lymphocyte ratio for the detection of renal injury. Patients with a value above 6.71 had an odds ratio of 5.941 for occurrence of renal injury.

Conclusion: Postoperative, but not preoperative neutrophil-tolymphocyte ratio is associated with presence and severity of renal injury in patients under extracorporeal membrane oxygenation support for postcardiotomy shock. Neutrophil-to-lymphocyte ratio is a simple and inexpensive marker of inflammation in this patient population.