Angiotensin Axis Blockade, Hypotension, and Acute Kidney Injury in Elective Major Orthopedic Surgery

Background:

Recommendations regarding administering or withholding angiotensin axis blockade (AAB) prior to orthopedic surgery are not clearly defined in the current literature. Patients presenting for surgery with AAB with either angiotensin‐converting enzyme inhibitors (ACEIs) or angiotensin receptor blockers (ARBs) have an increased incidence of perioperative hypotension. The purpose of this study was to evaluate the effects of AAB on perioperative hypotension and acute kidney injury (AKI) in patients undergoing major orthopedic surgery.

Methods:

This was a retrospective chart review for the year 2010 of patients > 21 years old in an academic medical center who underwent elective spine fusion or total hip or knee arthroplasty. Postinduction hypotension was defined as systolic blood pressure ≤ 80 mm Hg for ≥5 minutes within 30 minutes of general anesthesia induction. Intraoperative hypotension was defined as ≤ 80 mm Hg for ≥10 minutes during maintenance anesthesia. AKI was defined as an increase in serum creatinine ≥ 0.3 mg/dL or a 50% increase in creatinine concentration from preoperative values. In the multivariate logistic regression analysis, the following covariates were accounted for: age; body mass index; comorbid medical conditions, including diabetes mellitus, coronary artery disease, hypertension, and congestive heart failure; medications including diuretics, β‐blockers, and calcium channel blockers, general anesthesia‐induction agents, and vasopressors; estimated blood loss; blood transfusions; intravenous fluid; and preoperative creatinine and hematocrit values.

Results:

A total of 922 patients met inclusion criteria; 343 (37%) received AAB with either an ACEI or ARB on the morning of surgery. Postinduction hypotension was significantly higher in patients receiving AAB (12.2% vs. 6.7%; OR, 1.93; P = 0.005). The incidence of intraoperative hypotension did not significantly differt (AAB, 26.0% vs. 20.9%; OR, 1.33; P = 0.078). Of the 922 patients, 798 had documented preoperative and postoperative creatinine. AKI was significantly higher in patients receiving AAB therapy (8.3% vs. 1.7%; OR, 5.40; P < 0.001.) Multivariate analysis demonstrated that AKI was associated with intraoperative hypotension (OR, 2.65; P = 0.017) and with AAB therapy independent of hypotension (OR, 2.78; 95% CI, 1.08–7.19; P = 0.035).

Conclusions:

We demonstrated an increased incidence of postinduction hypotension and AKI in patients receiving AAB undergoing major orthopedic surgery. After eliminating the effect of hypotension, AAB therapy continued to have a statistically significant independent risk of developing AKI. This suggests that preoperative therapy with AAB in patients undergoing major orthopedic surgery results in an increased incidence of AKI not accounted for by the standard definition of systemic hypotension alone. Our findings support withholding AAB therapy the morning prior to major orthopedic surgery to prevent perioperative hypotension and AKI.