Objective Near Infra-Red Spectroscopy (NIRS), can be used to monitor renal tissue oxygenation (SrO2), as well as thenar muscle oxygenation (SmO2). In this study, we have examined the ability of SrO2 and SmO2 in predicting cardiac surgery related change in serum creatinine level (ΔsCr) and explored any correlation between these two parameters.

Methods This study included 55 adult patients (18 to 60 years), who were scheduled for elective cardiac surgery with cardiopulmonary bypass (CPB), having no pre-existing renal impairment, with skin-to-kidney depth ofSmO2, preoperatively. ΔsCr was investigated at 24, 48 and 72 hours post-operatively. Relative thresholds of SrO2 and SmO2 were quantified using the area-under curve; expressed in %min.

Results Area under the receiver-operating characteristic curve (AUROC) analyses showed SrO2 decrease >20% from baseline can significantly predict (AUROC 0.921; p=0.001) post-operative ΔsCr. SmO2 decreased 15% from baseline (AUROC 0.843; p=0.001) is a better predictor of ΔsCr than its fall >20% from baseline (AUROC 0.749; p=0.002). Correlation analysis revealed that the 15% and >20% decrease of SmO2 below baseline (Spearman’s rho 0.593 and 0.606 respectively) had significant (p=0.01) positive correlation with decrease of SrO2 >20% from baseline.

Conclusion

SrO2 and SmO2 have significant predictive values for post-cardiac surgery rise in serum creatinine, and there is strong positive correlation between them.