Clinical question: Do patients receiving pre-operative angiotensin axis blockade (AAB) prior to elective major orthopedic surgery have an increased risk of peri-operative hypotension and acute kidney injury (AKI)?
Background: Patients with pre-operative AAB from angiotensin-converting enzyme inhibitors or angiotensin receptor blockers have an increased incidence of peri-operative hypotension. Patients undergoing cardiothoracic and vascular surgery with pre-operative AAB have increased incidence of post-operative AKI; however, there is scant literature evaluating the hypotensive and renal effects of pre-operative AAB prior to elective major orthopedic surgery.
Study design: Retrospective, cohort study.
Setting: Academic medical center.
Synopsis: Retrospective review of 922 patients undergoing spinal fusion, total knee arthroplasty, or total hip arthroplasty in one academic medical center in 2010 found that 37% received pre-operative AAB. Post-induction hypotension (systolic blood pressure ≤80 mm Hg for five minutes) was significantly higher in patients receiving AAB (12.2% vs. 6.7%; odds ratio [OR] 1.93, P=0.005). Post-operative AKI was significantly higher in patients receiving AAB (8.3% vs. 1.7%; OR 5.40, P<0.001), remaining significant after adjusting for intra-operative 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 two-year mortality.
The findings suggest an association exists between pre-operative angiotensin-converting enzyme inhibitors/ARB, hypotension, and AKI following major orthopedic surgeries but does not demonstrate causality. A prospective, multi-center, randomized trial is needed to confirm that holding pre-operative AAB would decrease the incidence of AKI in patients undergoing major orthopedic procedures under general anesthesia.
Bottom line: Patients who underwent elective major orthopedic surgery who received pre-operative AAB therapy had an associated increased risk of post-induction hypotension and post-operative AKI, resulting in a greater hospital length of stay.
Citation: Nielson E, Hennrikus E, Lehman E, Mets B. Angiotensin axis blockade, hypotension, and acute kidney injury in elective major orthopedic surgery. J Hosp Med. 2014;9(5):283-288.