Fluid Overload and Changes in Serum Creatinine after Cardiac Surgery: Predictors of Mortality and Longer Intensive Care Stay. A Prospective Cohort Study
ABSTRACT:
INTRODUCTION: 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.
