The effect of dexmedetomidine on acute kidney injury after elective major abdominal surgery : a retrospective single-center propensity score matched study.

Background: Major abdominal surgery is a kind of high-risk surgery type for postoperative acute kidney injury (AKI) among non-cardiac surgeries. Despite dexmedetomidine exerts significant renal protective effects in cardiac surgeries and animal studies, whether it is associated with a lower incidence of AKI in major abdominal surgeries remains unclear.

Methods: From January 2019 to July 2021, patients undergoing elective major abdominal surgery in West China Hospital were enrolled. Participants were divided into two groups based on exposure to continuous intravenous dexmedetomidine: the Dex group (exposed) and the Control group (not exposed). The primary outcome was the incidence of AKI in the postoperative 7 days. Secondary outcomes included intraopertive average urine output, renal function on the first day after surgery, incidence of postoperative dialysis, postoperative intensive care unit (ICU) admission, in-hospital mortality, length of hospital stay, incidence of intraoperative hypotension and bradycardia, and intraoperative use of inotropes and vasopressors. Propensity score matching (PSM), based on participants' baseline and intraoperative characteristics, was performed to minimize potential bias. Furthermore, a subgroup analysis was conducted based on the infusion rate and the use of a loading dose to explore the effects of different methods of dexmedetomidine administration on AKI. The subgroups included: loading dose, non-loading dose, low-infusion rate (infusion rate ≤ 0.4 µg/kg/h), and high-infusion rate (infusion rate > 0.4 µg/kg/h).

Results: After PSM with a ratio of 1:1, a total of 8836 patients were successfully matched. Dexmedetomidine administration had no association with the incidence of postoperative AKI, serum creatinine (Scr) level on the first postoperative day, incidence of postoperative dialysis, postoperative ICU admission, in-hospital mortality, length of hospital stay, intraoperative hypotension, or the use of inotropes and vasopressors, but had association with increased intraoperative average urine output (122.95 (76.80, 189.27) vs. 104.65 (67.04, 161.07) ml/h, P < 0.001), higher value of estimated glomerular filtration rate (eGFR) (97.33 ± 15.95 vs. 96.13 ± 16.35 ml/min/1.73m², P < 0.001) on the first day after surgery and a higher incidence of intraoperative bradycardia (37.0% vs. 30.6%; P < 0.001). In the loading dose subgroup, dexmedetomidine use was significantly associated with a reduced incidence of postoperative AKI (odds ratio (OR): 0.44, 95% confidence interval (CI): 0.23-0.76, P = 0.006).The association between dexmedetomidine and postoperative AKI was absent in subgroups of high or low infusion rate and no loading dose use.

Conclusion: In this single-center retrospective propensity-matched study, we did not detect a significant overall difference in post-operative AKI rates between patients treated with or without dexmedetomidine during major abdominal surgery. However, though additional prospective data are needed, our study found that administering dexmedetomidine with a loading dose may be associated with lower rates of AKI, potentially indicating a renoprotective effect of loading-dose dexmedetomidine in this setting.