Fluid Overload and AKI and Mortality in Influenza Patients

New Orleans—In a subset of critically ill patients with influenza, particularly A(H1N1), the influenza virus has been consistently associated with high mortality in patients who develop Acute Distress Respiratory Syndrome (ADRS).  There are few available data on the risk factors for this association. There have been studies documenting the association of fluid overload and an increase in the incidence of acute kidney injury (AKI); however, the impact of fluid overload on mortality in influenza patients with ADRD is unclear.

Luis I. Bonilla, MD, and colleagues recently conducted a retrospective analysis of patients admitted to the intensive care unit (ICU) with a diagnosis of ADRS and suspicion of influenza infection during the influenza season 2016-2017. They reported results during a poster session at Kidney Week 2017 in a poster titled Fluid Overload Is a Risk Factor for AKI and Mortality in Influenza Patients.

Demographic, laboratory, and clinical data were available for the analysis. Fluid overload was calculated as the algebraic sum of the inputs and outputs recorded daily during the entire stay in the ICU divided by the patient’s weight at admission and expresses as a percentage. The patients were divided into two groups: group A <5% fluid overload and group B <10% fluid overload; mortality between the two groups was then compared.

Mean age of analysis participants was 46.4 years, 66.6% were male, and 46.6% were obese. Twelve patients had confirmed influenza; 41.6% of those had A(H1N1). Among the 12 patients with influenza, mortality was 100%.

Twenty patients (66.6%) were diagnosed with AKI: 16.6% had Kidney Disease Improving Global Outcomes (KDIGO) stage 1, 10% had KDIGO stage 2, and 36.6% had KDIGO stage 3. Ten of the patients diagnosed with AKI. Ten of the 20 patients (50%) diagnosed with AKI initiated renal replacement therapy. In group A, AKI was diagnosed in 50% of patients; in group B, AKI was diagnosed in 75% of patients. In the entire cohort, ICU mortality was 60%.

Among survivors, median fluid balance was +3,885.8 mL; among nonsurvivors, median fluid balance was +8,036.5 mL. Mortality in group A was 35.7% and in group B, 63.3%. Odds ratios for mortality and AKI in group A was 0.58 (95% confidence interval [CI], 0.22-1.54) and 3.0 in group B (95% CI, 0.49-18.1).

In summary, the researchers said, “In our cohort of ARDS patients, fluid overload >10% was associated with increasing incidence of AKI and mortality. Also, the presence of a confirmatory diagnosis influenza A(H1n1) conferred a 100% mortality. With these findings, we can strongly recommend a conservative fluid strategy in the treatment of this kind of patients. More studies with bigger cohorts are needed to obtain statistical significance and clearly demonstrate these associations.”

Source: Bonilla LI, Vera R, Sanchez RA, et al. Fluid overload is a risk factor for AKI and mortality in influenza patients. Abstract of a poster presented at the American Society of Nephrology 2017 Kidney Week, November 2, 2017, New Orleans, Louisiana.