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


METHODS
Patients 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.


RESULTS
A 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).


CONCLUSIONS
Although 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.
Anna
A
Stein
Lucas Vieira
LV
de Souza
Cassian Rodrigues
CR
Belettini
Willian Roberto
WR
Menegazzo
Júlio Rosales
JR
Viégas
Edemar Manuel
EM
Costa Pereira
Renato
R
Eick
Lilian
L
Araújo
Fernanda
F
Consolim-Colombo
Maria Cláudia
MC
Irigoyen
D000368:Aged; D015415:Biomarkers / Q000097:blood; D006348:Cardiac Surgical Procedures / Q000401:mortality* / Q000639:trends*; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood*; D003422:Critical Care / Q000639:trends*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007362:Intensive Care Units / Q000639:trends*; D007902:Length of Stay / Q000639:trends*; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies
D015415:Biomarkers; D003404:Creatinine