Angiotensin axis blockade, hypotension, and acute kidney injury in elective major orthopedic surgery

BACKGROUND: Patients presenting for surgery with angiotensin axis blockade (AAB) from therapy with either angiotensin-converting enzyme inhibitors or angiotensin receptor blockers experience an increased incidence of perioperative hypotension. Acute kidney injury (AKI) in patients receiving preoperative AAB has been demonstrated after lung, vascular, and cardiac surgery. However, there is little literature evaluating the hypotensive and renal effects of preoperative AAB and major orthopedic surgery. METHODS: We performed a retrospective chart review of 1154 patients who underwent spinal fusion, total knee arthroplasty, or total hip arthroplasty during the 2010 calendar year in our academic medical center. RESULTS: A total of 922 patients met inclusion criteria, 343 (37%) received preoperative AAB. Postinduction hypotension (systolic blood pressure ≤80 mm Hg for 5 minutes) was significantly higher in patients receiving AAB when compared to those not so treated (12.2% vs 6.7%; odds ratio [OR]: 1.93, P=0.005). Of the 922 patients, 798 had documented measurements of both preoperative and postoperative creatinine. Postoperative AKI was significantly higher in patients receiving AAB therapy (8.3% vs 1.7%; OR: 5.40, P<0.001), remaining significant after adjusting for covariates including hypotension (OR: 2.60, P=0.042). Developing AKI resulted in a significantly higher mean length of stay (5.76 vs 3.28 days, P<0.001) but no difference in 2-year mortality. CONCLUSIONS: Patients undergoing major elective orthopedic surgery who receive preoperative AAB therapy,have an associated increased risk of postinduction hypotension and postoperative acute kidney injury resulting in a greater hospital length of stay. Journal of Hospital Medicine 2014;9:283-288.