Association between muscular tissue desaturation and acute kidney injury in older patients undergoing major abdominal surgery: a prospective cohort study

<bold>Purpose </bold>Present study was designed to investigate the association between muscular tissue desaturation and acute kidney injury (AKI) in older patients undergoing major abdominal surgery. <bold>Method </bold>A total of 253 patients (>= 65 years old) who underwent abdominal surgery with expected duration >= 2 h were enrolled. Muscular tissue oxygen saturation (SmtO(2)) was monitored at quadriceps and bilateral flanks during surgery. Muscular desaturation was defined as SmtO(2) < 90% baseline lasting for > 60 s. The primary outcome was the incidence of AKI within postoperative 7 days. The association between muscular desaturation and AKI was analyzed by multivariable logistic regression model. The secondary outcomes indicated the other complications within postoperative 30 days. <bold>Results </bold>Among 236 patients, 44 (18.6%) of them developed AKI. The incidence of muscular desaturation at quadriceps was 28.8% (68/236). Patients with muscular desaturation had higher incidence of AKI than those without desaturation (27.9% [19/68], vs. 14.9% [25/168], P = 0.020). After adjustment of confounders, multivariable analysis showed that muscular desaturation at quadriceps was significantly associated with an increased risk of AKI (OR = 2.84, 95% CI 1.21-6.67, P = 0.016). Muscular desaturations at left and right flank were also associated with an increased risk of AKI (OR = 6.38, 95% CI 1.78-22.89, P = 0.004; OR = 8.90, 95% CI 1.42-45.63; P = 0.019, respectively). Furthermore, patients with muscular desaturation may have a higher risk of pulmonary complications, sepsis and stroke at 30-day follow-up. <bold>Conclusion </bold>Muscular desaturation was associated with postoperative AKI in older patients undergoing major abdominal surgery which may serve as a predictor of AKI.