Positive fluid balance as an early biomarker for acute kidney injury: a prospective study in critically ill adult patients

OBJECTIVES: Positive fluid balance is frequent in critically ill patients and has been considered a potential biomarker for acute kidney injury (AKI). This study aimed to evaluate positive fluid balance as a biomarker for the early detection of AKI in critically ill patients. METHODS: This was a prospective cohort study. The sample was composed of patients ≥18 years old who stayed ≥3 days in an intensive care unit. Fluid balance, urinary output and serum creatinine were assessed daily. AKI was diagnosed by the Kidney Disease Improving Global Outcome criteria. RESULTS: The final cohort was composed of 233 patients. AKI occurred in 92 patients (40%) after a median of 3 (2-6) days following ICU admission. When fluid balance was assessed as a continuous variable, a 100-ml increase in fluid balance was independently associated with a 4% increase in the odds of AKI (OR 1.04; 95% CI 1.01-1.08). Positive fluid balance categorized using different thresholds was always significantly associated with subsequent detection of AKI. The mixed effects model showed that increased fluid balance preceded AKI by 4 to 6 days. CONCLUSION: These results suggest that a positive fluid balance might be an early biomarker for AKI development in critically ill patients.

Technical note and clinical instructions for Acute Kidney Injury (AKI) in patients with Covid-19: Brazilian Society of Nephrology and Brazilian Association of Intensive Care Medicine / Nota técnica e orientações clínicas sobre a Injúria Renal Aguda (IRA) em pacientes com Covid-19: Sociedade Brasileira de Nefrologia e Associação de Medicina Intensiva Brasileira

ABSTRACT We produced this document to bring pertinent information to the practice of nephrology, as regards to the renal involvement with COVID-19, the management of acute kidney injury cases, and practical guidance on the provision of dialysis support.As information on COVID-19 evolves at a pace never before seen in medical science, these recommendations, although based on recent scientific evidence, refer to the present moment. The guidelines may be updated when published data and other relevant information become available.

RESUMO Este documento foi desenvolvido para trazer informações pertinentes à prática nefrológica em relação ao conhecimento sobre o acometimento renal da COVID-19, conduta frente aos casos de injúria renal aguda e orientações práticas sobre a provisão do suporte dialítico.Como as informações sobre a COVID-19 evoluem a uma velocidade jamais vista na ciência médica, as orientações apresentadas, embora baseadas em evidências científicas recentes, referem-se ao momento presente. Essas orientaços poderão ser atualizadas à medida que dados publicados e outras informações relevantes venham a ser disponibilizadas.

Balanço hídrico, injúria renal aguda e mortalidade de pacientes em unidade de terapia intensiva / Water balance, acute kidney injury and mortality of intensive care unit patients

Injúria renal aguda (IRA) é uma síndrome de elevada incidência, associada a altas taxas de morbimortalidade. Sepse, grandes cirurgias e baixo débito cardíaco são as principais causas de IRA no mundo. Na maioria destas situações clínicas, a expansão volêmica é o elemento fundamental de prevenção e do manejo terapêutico da IRA, restaurando a perfusão periférica e atenuando a nefrotoxicidade de drogas. Ressuscitação volêmica precoce em pacientes sépticos está associada à prevenção de isquemia tecidual e à maior sobrevida. Contudo, a manutenção de estratégia liberal de infusão de fluidos após ressuscitação inicial pode causar balanços hídricos cumulativamente positivos, e este vem sendo associado a aumento de morbimortalidade em pacientes criticamente enfermos. Neste trabalho, revisamos os principais estudos que associam balanço hídrico positivo (BH+) e morbimortalidade em pacientes internados em Unidades de Terapia Intensiva (UTI). Sugerimos que BH+ (não apenas o volume urinário) possa ser utilizado como possível biomarcador precoce de IRA nestes pacientes.

Acute kidney injury (AKI) has a high hospital incidence and is associated to significant morbidity and mortality. Sepsis, major surgery and low cardiac output are the main cause of AKI worldwide. In the majority of these situations, volume expansion is part of both prevention and therapeutic management, restoring peripheral perfusion and attenuating drug nephrotoxicity. Early and aggressive volume resuscitation in septic patients halts tissue ischemia and is associated with higher survival. However, a liberal fluid infusion strategy after six hours can cause fluid overload. Fluid overload has been associated with morbidity and mortality increase in critically ill patients. Herein, we present a review of the main studies that assessed the effects of net fluid balance/fluid overload on the morbidity and mortality of critically ill patients. We suggest that positive water balance may be used as a potential early biomarker of AKI in these patients.

Balanço hídrico, injúria renal aguda e mortalidade de pacientes em unidade de terapia intensiva / Fluid balance, acute kidney injury and mortality of intensive care unit patients

Injúria renal aguda (IRA) é doença de elevada incidência, associada a altas taxas de morbimortalidade. Sepse, pós-operatório de grandes cirurgias e baixo débito cardíaco são as principais causas de IRA em todo o mundo. Na maioria destas situações, expansão volêmica é parte do manejo preventivo e terapêutico da IRA. Contudo, a manutenção de uma estratégia de infusão liberal de fluidos pode causar balanço hídrico positivo (BH+), que tem sido associado a desfechos desfavoráveis em pacientes criticamente enfermos. BH+ frequentemente ocorre nestes pacientes que recebem grandes infusões de volume, mesmo que apresentem volume urinário considerado satisfatório ou acima de 0,5ml/kg/h. Nesta situação, se não houver elevação da creatinina sérica, não será feito o diagnóstico de IRA pelos critérios do Kidney Disease Improving Global Outcome (KDIGO), ainda que haja claro déficit na eliminação da sobrecarga hidrossalina. Este estudo observacional prospectivo, com controle pareado por dias de exposição ao BH+ avaliou a associação entre BH+ e diagnóstico subsequente de IRA (pelos critérios do KDIGO) e mortalidade em 233 pacientes admitidos em uma unidade de terapia intensiva (UTI) geral. Observamos por análise de regressão logística que cada 100 ml de aumento no BH se associou a elevação de 4% na chance de desenvolver IRA (OR 1,04; IC 95% 1,01 a 1,08). Comparado ao primeiro quartil de BH médio, o quarto quartil de BH médio (BH > +1793 ml/dia) se associou a chance 3,12 vezes maior de desenvolver IRA (OR 3,12; IC 95% 1,13 a 8,65). Comparado ao BH de zero até +1500 ml/dia, o BH médio > +1500 ml/dia se associou a chance 3,4 vezes maior de desenvolver IRA, (OR 3,4; IC 95% 1,56 a 7,48). Um modelo de efeito fixo mostrou que BH+ estava presente pelo menos seis dias antes do diagnóstico de IRA pelos critérios do KDIGO. Para avaliar o desfecho óbito, consideramos o BH durante toda internação na UTI. Observamos que cada 100 ml de aumento no BH se associou...

Acute kidney injury (AKI) is a disease with high incidence, which is associated with high morbidity and mortality rates. Sepsis, major surgery and low cardiac output are the main causes of AKI worldwide. In the majority of these situations, volume expansion is part of both prevention and therapeutic management of AKI. However, maintaining liberal fluid infusion strategy can cause fluid overload and it is associated to poor outcomes in critically ill patients. Positive fluids balance (FB) frequently occurs in these patients receiving high volume infusion, even if the urinary output is adequate (above 0.5ml/kg/h). In this situation, if there is no serum creatinine (SCr) increase, AKI will not be diagnosed by current Kidney Disease Improving Global Outcome (KDIGO) criteria, even with a clear kidney inability to eliminate the body excess of fluid. This prospective, paired control, cohort study aimed to evaluate the association between positive FB and subsequent development of AKI by KDIGO criteria and mortality in 233 critically ill adults. By multiple logistic regression, we showed that each 100 ml increase in FB was independently associated to a 4% increase in the chances for developing subsequent AKI (OR 1.04; 95% CI 1.01 to 1.08). When compared to the first quartile, the fourth FB quartile (FB > +1793ml/day) was associated with a 3.12 times greater chance of developing AKI (OR 3.12; 95% CI 1.13 to 8.65). Compared to FB zero to 1,500ml/24h, the mean FB above +1,500 ml/24h was associated with an OR of 3.4 for AKI (OR 3.4; 95% CI 1.56 to 7.48). A mixed effect model demonstrated that a positive FB predicted AKI development defined by KDIGO criteria within 6 days. To assess the outcome mortality, we evaluated the mean FB during the whole ICU hospitalization. Each 100 ml increase in FB was associated to a 7% increase in the chances for death (OR 1.07; 95% CI 1.02 to 1.12). Compared to the first quartile, patients in the fourth FB quartile (FB > +1652 ml/day)...