Fluid Management in the Intensive Care Unit: Bioelectrical Impedance Vector Analysis as a Tool to Assess Hydration Status and Optimal Fluid Balance in Critically Ill Patients

F. Basso, G Berdin, G M  Virzì, G Mason, P Piccinni, S Day, D N Cruz, M Wjewodzka, A Giuliani, A Brendolan, C Ronco.  Blood Purif 2013;36:192–199  DOI: 10.1159/000356366 Published online: December 20, 2013

Fluid overload is a frequent condition in critically ill patient  and a significant predictor of mortality. Hydration status should be considered as an additional prognosticator in the clinical management of the critically ill patient. No. 280 BIVA  measurements on  64 patients were performed daily  during the 5 days following their ICU admission.We observed the evolution of the hydration status during the ICU stay in this population and analyzed the relationship between mean and maximum hydration reached and mortality. Logistic regression showed a strong and significant correlation between

mean/maximum hydration reached and mortality, both independently and correcting for severity of prognosis. On the day of ICU admittance, patients showed a marked tendency to overhydration (>70% of total). This tendency was more pronounced in patients on CRRT. Hyperhydration persisted during the ICU stay. Patients who underwent CRRT showed significantly higher hyperhydration from the 2nd day of hospitalization. Nonsurvivors showed worse hyperhydration patterns in comparison to survivors in logistic univariate analysis (p < 0.05). This relationship between hydration and mortality is confirmed even when controlling for the effect of a worse prognosis approximated by any of three ICU scoring systems (APACHE II, SAPS II and SOFA). Based on the current clinical-structural methods, measurement of the hydration status through BIVA can constitute an additional methodology to achieve correct monitoring of a patient’s fluid balance. It may also provide insight into the patient’s ideal weight, hence driving a more appropriate therapy management by ultrafiltration and diuretics in critically ill patients. This can ensure an adequate circulating blood volume and prevent complications during fluid removal.

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