Postoperative acute kidney injury in adult non-cardiac surgery: joint consensus report of the Acute Disease Quality Initiative and PeriOperative Quality Initiative

Abstract

Postoperative acute kidney injury (PO-AKI) is a common complication of major surgery that is strongly associated with short-term surgical complications and long-term adverse outcomes, including increased risk of chronic kidney disease, cardiovascular events and death. Risk factors for PO-AKI include older age and comorbid diseases such as chronic kidney disease and diabetes mellitus. PO-AKI is best defined as AKI occurring within 7 days of an operative intervention using the Kidney Disease Improving Global Outcomes (KDIGO) definition of AKI; however, additional prognostic information may be gained from detailed clinical assessment and other diagnostic investigations in the form of a focused kidney health assessment (KHA). Prevention of PO-AKI is largely based on identification of high baseline risk, monitoring and reduction of nephrotoxic insults, whereas treatment involves the application of a bundle of interventions to avoid secondary kidney injury and mitigate the severity of AKI. As PO-AKI is strongly associated with long-term adverse outcomes, some form of follow-up KHA is essential; however, the form and location of this will be dictated by the nature and severity of the AKI. In this Consensus Statement, we provide graded recommendations for AKI after non-cardiac surgery and highlight priorities for future research.

Fig. 1. Pathophysiology of PO-AKI.

Similar to most other forms of acute kidney injury (AKI), postoperative AKI (PO-AKI) commonly has a multifactorial aetiology, which is mediated by common injury pathways that affect the kidney microcirculation, oxygen demand and inflammation. In most cases, a combination of preoperative risk factors, intraoperative events and postoperative events leads to the development of AKI. Baseline risk factors and the persistence and severity of injurious factors in the postoperative setting also determine the outcomes of AKI, acute kidney disease and eventually chronic kidney disease. Adapted from Acute Disease Quality Initiative 24, www.ADQI.org, CC BY 2.0 (https://creativecommons.org/licenses/by/2.0/).

Fig. 2. The role of the KHA in postoperative AKI.

Kidney health assessments (KHAs) can be used in the risk assessment, detection, management and follow-up of postoperative acute kidney injury (AKI). A series of context-specific KHAs involving integration of medical history and clinical context, potentially in combination with further investigations, such as analysis of specific kidney biomarkers or imaging, in higher-risk settings, can provide kidney prognostic information to guide further monitoring and treatment. AKD, acute kidney disease; CKD, chronic kidney disease. Adapted from Acute Disease Quality Initiative 24, www.ADQI.org, CC BY 2.0 (https://creativecommons.org/licenses/by/2.0/).

Fig. 3. Conceptual model of PO-AKI and PO-AKD.

Postoperative acute kidney injury (PO-AKI) occurs when the Kidney Disease Improving Global Outcomes (KDIGO) criteria for AKI are met within 7 days of an operative intervention. Postoperative acute kidney disease (PO-AKD) occurs when patients with PO-AKI continue to meet KDIGO AKI criteria ≥7 days after surgery or when patients whose serum creatinine levels began to rise following surgery meet KDIGO AKI criteria ≥7 days after surgery. A number of potential trajectories of serum creatinine are depicted with suggested application of the proposed nomenclature. PO-AKI might commence and resolve before postoperative day 7 or persist after postoperative day 7 and therefore be classed as PO-AKD. If PO-AKD continues after postoperative day 90 it will be classed as chronic kidney disease (CKD) (trajectory 1). PO-AKD also occurs when evidence of new kidney injury was present before postoperative day 7 but did not meet the criteria for PO-AKI until after postoperative day 7. This form of PO-AKD might also either recover before postoperative day 90 or continue after postoperative day 90 and be classed as CKD (trajectory 2). Stand-alone AKI or AKD (that is, AKI or AKD that is seemingly not related to the operative intervention) can also occur during the perioperative period. As these new events occur distant to the surgical insult they should not be referred to as PO-AKI or PO-AKD and should be considered in the context of their direct precipitants (trajectory 3). Subclinical kidney injury can occur before or after postoperative day 7 (trajectory 4). This subclinical injury does not meet current criteria for AKI or AKD, but may be identified by risk-based serial kidney health assessments (KHAs). Source: Adapted from Acute Disease Quality Initiative 24, www.ADQI.org, CC BY 2.0 (https://creativecommons.org/licenses/by/2.0/).

Fig. 4. Outcomes of PO-AKI and PO-AKD.

Postoperative acute kidney injury (PO-AKI) is associated with an increased risk of short-term adverse outcomes, including need for dialysis, cardiovascular events, lung injury, delirium and infection. These adverse effects can in turn lead to increased long-term morbidity and mortality. Adapted from Acute Disease Quality Initiative 24, www.ADQI.org, CC BY 2.0 (https://creativecommons.org/licenses/by/2.0/).

Fig. 5. Potential monitoring approach for patients who experience PO-AKI or PO-AKD.

Limited data are available to inform the timing and nature of monitoring for patients who experience postoperative acute kidney injury (PO-AKI) or postoperative acute kidney disease (PO-AKD). We suggest that these patients should have their kidney function checked within 1 month of hospital discharge to confirm the extent of recovery or progression of kidney disease. Those with persistent kidney dysfunction at 90 days should be formally assessed for the development or progression of chronic kidney disease (CKD). The degree of nephrology involvement in follow-up monitoring should increase with the duration and severity of AKI or AKD commensurate with the risk of developing CKD. Patients with less severe AKI or AKD can be monitored in primary care or by the base specialist and referred for nephrology care if needed according to CKD guidelines. Future research is needed to clarify the optimal timings and methods to provide post-AKI or AKD care. Adapted from Acute Disease Quality Initiative 24, www.ADQI.org, CC BY 2.0 (https://creativecommons.org/licenses/by/2.0/).