Intraoperative Renal Regional Oxygen Desaturation Can Be a Predictor for Acute Kidney Injury after Cardiac Surgery

https://doi.org/10.1053/j.jvca.2013.12.005Get rights and content

Objective

To evaluate the usefulness of renal regional oxygen saturation (renal rSO2) in predicting the risk of acute kidney injury (AKI) after cardiac surgery.

Design

A prospective observational study.

Setting

Tertiary care university hospital.

Participants

One hundred patients undergoing cardiac surgery.

Interventions

Renal rSO2 was monitored continuously by near-infrared spectroscopy (NIRS) throughout the anesthetic period.

Measurements and Main Results

Postoperative AKI was defined using the Risk, Injury, Failure, Loss, and End-stage (RIFLE) criteria. Of 95 patients who were included in the final analysis, 34 patients developed AKI after surgery. Recorded renal rSO2 data were used to calculate the total duration of the time when renal rSO2 was below the threshold values of 70%, 65%, 60%, 55%, and 50%. The total periods when the renal rSO2 level was below each of the threshold values were significantly longer in patients with AKI than in those without AKI (p = 0.001 or p<0.001). Receiver operating characteristic (ROC) curve analysis was used to evaluate the predictive power of renal rSO2 for AKI. The ROC curve analysis showed that renal rSO2 could predict the risk of AKI with statistical significance and that a renal rSO2<55% had the best performance (area under the curve–ROC, 0.777; 95% CI, 0.669-0.885; p<0.001). Multivariate logistic regression analysis revealed that AKI significantly correlated with the duration of renal rSO2<55% (p = 0.002) and logistic EuroSCORE (p = 0.007).

Conclusions

Intraoperative renal regional oxygen desaturation can be a good predictor of AKI in adult patients undergoing cardiac surgery.

Section snippets

Methods

After approval by the Institutional Ethics Committee and obtaining written informed consent, a total of 100 adult patients who underwent elective cardiac surgery with cardiopulmonary bypass (CPB) were enrolled between October 2010 and August 2011. Exclusion criteria were off-pump coronary artery bypass surgery (OPCAB), aortic surgery (total arch replacement and/or descending aorta replacement surgery), emergency surgery, left ventricular ejection fraction (LVEF)<30%, body mass index (BMI)≥30

Results

Between October 2010 and August 2011, 153 patients admitted to this hospital met the inclusion criteria (Fig 2). Of these, 38 were excluded because both renal depths were≥40 mm. An additional 15 patients refused to enroll in the study. Of 100 patients who were enrolled in this study, 5 were excluded because of incomplete renal rSO2 data. Thus, 95 patients were included in the final analysis; 66 patients received bilateral renal rSO2 monitoring and 29 patients received unilateral monitoring.

Discussion

In the current analysis the authors have found that intraoperative renal regional oxygen desaturation is associated significantly with postoperative AKI and that use of NIRS for continuous monitoring of the intraoperative renal rSO2 can predict the risk of AKI in adult patients undergoing cardiac surgery with CPB.

Postoperative AKI is associated with increased morbidity and mortality in patients undergoing cardiac surgery.2, 3 Therefore, early detection of deterioration in renal function and

Conclusion

In conclusion, the current prospective observational study indicated a predictive ability of intraoperative renal rSO2 monitoring for postoperative AKI in adult patients undergoing cardiac surgery. However, the use of an NIRS sensor that can monitor tissue areas deeper below the skin surface is warranted to generalize the use of this method to all patients undergoing cardiac surgery. In addition, further studies are needed to evaluate effective interventions to correct renal regional oxygen

Acknowledgments

This study was partly supported by an unrestricted grant by E-Wha Biomedics Co., Seoul, Korea. The authors thank Seungbong Han, PhD, Statistician, Department of Clinical Epidemiology and Biostatistics, Asan Medical Center, Seoul, Korea, for valuable statistical advice and assistance.

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