Acute kidney injury and renal replacement therapy: terminology standardization

Abstract The Department of Acute Kidney Injury (IRA) of the Brazilian Society of Nephrology prepared this document for the purpose of standardizing AKI terminology and dialysis modalities in the Portuguese language for Brazil. Several terms with similar meanings have been used in AKI and its dialysis modalities, causing confusion and disparities among patients, nephrologists, health institutions, private care companies, insurance companies and government entities. These disparities can impact medical care, hospital organization and care, as well as the funding and reimbursement of AKI-related procedures. Thus, consensual nomenclature and definitions were developed, including the definitions of AKI, acute kidney disease (AKD) and chronic kidney disease (CKD). Additionally, we addressed all dialysis modalities and extracorporeal procedures related to AKI, currently approved and available in the country. The Brazilian Society of Nephrology hopes that this Consensus can standardize the terminology and provide technical support to all involved in AKI care in Brazil.


IntroductIon
Acute kidney injury (AKI) is a frequent complication in hospitalized patients, especially in ICUs, still causing high rates of morbidity and mortality. AKI can also occur in outpatients and in the community, often related to socioeconomic and cultural conditions. Several terms with similar meanings have been used in AKI and its dialysis modalities, causing confusion and disparities among patients, nephrologists, healthcare institutions, private care companies, insurance companies and government entities. These disparities can impact medical care, hospital organization and care, as well as the funding and reimbursement of AKI-related procedures. Thus, we worked on the terminology and consensual definitions, including the definitions of AKI, acute kidney disease (AKD) and chronic kidney disease (CKD). Additionally, all dialysis modalities and extracorporeal procedures related to AKI, currently approved and available in the country, were addressed in this document by the AKI Department of the Brazilian Society of Nephrology.

Acute KIdney Injury (AKI)
Preferably, use the term Acute Kidney Injury, in order to maintain the acronym AKI, which is well established and widespread in our country. In addition, the term was also approved in the Ibero-American Consensus on the Uniformity of Nomenclatures, observing the deliberations proposed by the Kidney Disease: Improving Global Outcomes (KDIGO) panel [1][2][3][4][5][6][7][8] . An additional advantage of using the term "injury" is that it encompasses initial cases with cellular and tissue functional alterations to cases of established anatomical lesions [9][10][11][12][13][14][15][16] . Therefore, it is suggested to avoid the term acute kidney lesion (AKL), which would be restricted to cases of anatomic kidney lesion.
We must also avoid the term "failure", as it denotes a more advanced stage of renal failure.

KIdney FAIlure (KF)
KF refers to a renal condition with a glomerular filtration rate lower than 15 mL/kg/1.73 m 2 or when dialysis is required (Table 1)

renAl replAcement therApy (rrt)
RRT refers to any therapy associated with the process of replacing native kidney function, such as hemodialysis, peritoneal dialysis and kidney transplantation.

stAge 3d Acute KIdney Injury
3D AKI is ARF requiring artificial renal support/ dialysis. It is recommended to use the term 3D stage AKI instead of dialysis-dependent AKI.

ArtIFIcIAl KIdney support (AKs)
AKS encompasses all methods of artificial clearance.
Artificial renal support therapies are based on their modality and frequency:

Frequency:
-Continuous: uninterrupted method of clearance, used with equipment with autonomy for uninterrupted operation of more than 24 hours. -Intermittent: clearance method lasting less than 12 consecutive hours. Intermittent therapies are subdivided into: -Conventional: lasting up to 6 hours.

Modalities:
The terminology in this text was based on the dialysis methods approved by ANVISA up to the date of document preparation.

conclusIons
The AKI Department of the Brazilian Society of Nephrology prepared this document in order to standardize the terminology and definitions related to AKI.
Terminology and consensual definitions were addressed, including definitions of AKI, acute kidney disease (AKI) and chronic kidney disease (CKD). All dialysis modalities and extracorporeal procedures related to AKI, currently approved and available in the country, were described. The Brazilian Society of Nephrology hopes that this Consensus can standardize