Perioperative Acute Kidney Injury

Sam D. Gumbert, M.D.; Felix Kork, M.D., M.Sc.; Maisie L. Jackson, M.D.; Naveen Vanga, M.D.; Semhar J. Ghebremichael, M.D.; Christy Y. Wang, M.D.; Holger K. Eltzschig, M.D., Ph.D.

Disclosures

Anesthesiology. 2019;132(1):180-204. 

In This Article

Epidemiology of Perioperative Acute Kidney Injury

The effect of acute kidney injury on individual outcomes and healthcare systems is remarkable. Acute kidney injury in industrialized countries costs an estimated $1 billion, claims 300,000 lives, and contributes to the development of 300,000 advanced chronic kidney disease cases annually.[19,20] Acute kidney injury correlates with elevated mortality rates, longer hospital stays, and increased treatment expenses, with the seriousness of acute kidney injury directly linked to patient-centered outcomes. Although multiple studies have since substantiated the impact of acute kidney injury, the prevalence of acute kidney injury is dependent upon the definition, criteria, and study population.

Kork et al.[5] retrospectively examined 39,369 surgical patients in a single-center study utilizing the Kidney Disease Improving Global Outcomes criteria. Acute kidney injury occurred in 6% of the study population. After adjusting for multiple variables including age, hospital length of stay, sex, preoperative creatinine, and hemoglobin, the authors determined that minor changes in creatinine levels (25 to 49% above baseline) increased the risk of death by twofold and increased the length of hospitalization by 2 days.[5] In 2017, O'Connor et al.[21] investigated the association between postoperative acute kidney injury using the Kidney Disease Improving Global Outcomes standards for a retrospective cohort study and found that 6.8% of investigated patients sustained acute kidney injury resulting in a 13.3% in-hospital mortality rate compared with 0.9% without acute kidney injury (P < 0.001). At 1 year, 26.6% of patients with acute kidney injury died compared with 6.1% of patients without acute kidney injury (P < 0.001), resulting in an adjusted hazard ratio for death of 2.96 (95% CI, 1.86 to 4.71; P < 0.001) for acute kidney injury.[21] Both studies concluded that in noncardiac surgery patients, the presence of even mild forms of acute kidney injury posed a significant risk of death and increased the length of hospital stay.[5,21] The frequency, risk factors, and outcomes after noncardiac surgery have not been well identified and could offer a multitude of possibilities for further analysis in postoperative acute kidney injury research.

Cardiac surgery–associated acute kidney injury is a frequent source of perioperative acute kidney injury. Recent meta-analysis found the incidence of acute kidney injury in cardiac surgery patients to be as significant as 25 to 30%.[22,23] In 2016, Hu et al.[22] analyzed the pooled incidence rates of acute kidney injury in 300,000 postcardiac surgery patients and determined the incidence to be 22.3% (95% CI, 19.8 to 25.1). Utilizing Kidney Disease Improving Global Outcomes criteria, pooled rates for the development were 13.6, 3.8, and 2.7% for stages 1, 2, and 3, respectively, with 2.3% requiring renal replacement therapy.[22] The development of acute kidney injury increased the monetary cost and length of hospitalization.[22] The connection between acute kidney injury and postcardiac surgery has pronounced short- and long-term morbidity outcomes. In a cohort study looking at more than 1,000 patients undertaking elective cardiac surgery, acute kidney injury patients had a 26% 5-year cumulative risk of death, more than double the cumulative risk in patients without acute kidney injury.[24] Although the role of acute kidney injury is well established in patients receiving cardiac surgery, less information is available regarding noncardiac surgery.

To determine whether the type of surgery influenced whether a patient develops acute kidney injury, Grams et al.[25] performed a retrospective study of 161,185 Veterans Health Administration patients in 2016. Cardiac surgery presented the greatest risk for postoperative acute kidney injury (relative risk, 1.22; 95% CI, 1.17 to 1.27), proceeded by general thoracic (relative risk, 0.92; 95% CI, 0.87 to 0.98), orthopedic (relative risk, 0.70; 95% CI, 0.67 to 0.73), vascular (relative risk, 0.68; 95% CI, 0.64 to 0.71), urologic (relative risk, 0.65; 95% CI, 0.61 to 0.69), and ear, nose, and throat (relative risk, 0.32; 95% CI, 0.28 to 0.37).[25] Although cardiac surgery posed the greatest postoperative risk, similar risk factors including advanced age, African American race, hypertension, diabetes mellitus, and a lower estimated glomerular filtration rate was observed across surgical types.[25] Further, acute kidney injury postoperative patients had longer hospitalization, higher rates of 30-day readmission, heightened risk for developing end-stage renal disease, and higher mortality rates (19% vs. 8%). These findings corroborated research from Kork et al.[5] and O'Connor et al.[21] that examined the occurrence of morbidity with acute kidney injury among the noncardiac perioperative population. Taken together, these data indicate that the acute kidney injury occurs more frequently than previously anticipated. Even smaller changes in kidney function are associated with higher degrees of morbidity and mortality. Therefore, clinicians should carefully consider clinical and laboratory signs of mild kidney injury to be prepared to manage potential clinical complications, such as organ injury, multiorgan failure, or sepsis.

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