Fluid overload and changes in serum creatinine after cardiac surgery: predictors of mortality and longer intensive care stay. A prospective cohort study

Abstract

IntroductionFluid overload is a clinical problem frequently related to cardiac and renal dysfunction. The aim of this study was to evaluate fluid overload and changes in serum creatinine as predictors of cardiovascular mortality and morbidity after cardiac surgery.MethodsPatients submitted to heart surgery were prospectively enrolled in this study from September 2010 through August 2011. Clinical and laboratory data were collected from each patient at preoperative and trans-operative moments and fluid overload and creatinine levels were recorded daily after cardiac surgery during their ICU stay. Fluid overload was calculated according to the following formula: (Sum of daily fluid received (L) - total amount of fluid eliminated (L)/preoperative weight (kg) × 100). Preoperative demographic and risk indicators, intra-operative parameters and postoperative information were obtained from medical records. Patients were monitored from surgery until death or discharge from the ICU. We also evaluated the survival status at discharge from the ICU and the length of ICU stay (days) of each patient.ResultsA total of 502 patients were enrolled in this study. Both fluid overload and changes in serum creatinine correlated with mortality (odds ratio (OR) 1.59; confidence interval (CI): 95% 1.18 to 2.14, P = 0.002 and OR 2.91; CI: 95% 1.92 to 4.40, P <0.001, respectively). Fluid overload played a more important role in the length of intensive care stay than changes in serum creatinine. Fluid overload (%): b coefficient = 0.17; beta coefficient = 0.55, P <0.001); change in creatinine (mg/dL): b coefficient = 0.01; beta coefficient = 0.11, P = 0.003).ConclusionsAlthough both fluid overload and changes in serum creatinine are prognostic markers after cardiac surgery, it seems that progressive fluid overload may be an earlier and more sensitive marker of renal dysfunction affecting heart function and, as such, it would allow earlier intervention and more effective control in post cardiac surgery patients.

Prognostic Factors in Continuous Hemofiltration Therapy for Patients with Cardiorenal Syndrome

“…Reduced cardiac pump function caused lower blood pressure that could not tolerate dehydration, and uncleared excess fluid led to the deterioration of cardiac function and a vicious cycle in heart and kidney hemodynamics. This finding was also consistent with research conducted in recent years [16,17], which found that volume conditions pre- and posttreatment with CRRT affected the prognoses of patients with acute kidney injury and that hypervolemia also seemed to be associated with cardiac edema, resulting in myocyte injury and malignant ventricular tachyarrhythmia.…”

Minor Postoperative Increases of Creatinine Are Associated With Higher Mortality and Longer Hospital Length of Stay in Surgical Patients

“…These studies categorized patients by absolute creatinine increases, 21,34,36 by relative creatinine increase 32,37 or by AKI stages. 38,39 Although explicitly accounting for minor creatinine changes, the patients identified as "at risk" were either likely to be diagnosed as stage 1 AKI by current AKI definition or the study failed to identify all patients at risk. Our findings decisively contrast these studies by demonstrating for the first time in a large and broad surgical patient sample that even minor creatinine increases below the current AKI criteria-i.e., ΔCr 25 to 49% but not ≥ 0.3 mg/dl-are independently associated with a two-fold risk of in-hospital death and a longer hospital stay.…”

Effects of Serum Uric Acid on Estimated GFR in Cardiac Surgery Patients: A Pilot Study

“…SCr adjustments were performed for postoperative SCr values. Daily cumulative fluid balance was calculated using the formula: (sum of daily fluid received (l) -total amount of fluid eliminated (l)/preoperative weight (kg) × 100) [17] . KeGFR was then calculated using the equation by Chan [13] : KeGFR = (steady state plasma creatinine × Cr Cl/mean plasma creatinine) × (1 -(24 Δ plasma creatinine/Δ time (h) × max Δ plasma creatinine/ day)).…”