Fluid assessment and management in the emergency department

Evaluation of hydration state or water homeostasis is an important component in the assessment and treatment of critically ill patients in the emergency department (ED). The main purpose of ED physicians is to immediately distinguish between normal hydrated, dehydrated and hyperhydrated states. Fluid depletion may result from renal losses and extrarenal losses (from the GI tract, respiratory system, skin, fever, sepsis, third space accumulations). Total body fluid increase can result from heart failure, kidney disease, liver disease, malignant lymphoedema or thyroid disease. In patients with fluid overload due to acute heart failure, diuretics should be given when there is evidence of systemic volume overload, in a dose up-titrated according to renal function, systolic blood pressure, and history of chronic diuretic use. The bioelectrical impedance vector analysis (BIVA) is a noninvasive technique to estimate body mass and water composition by bioelectrical impedance measurements, resistance and reactance. In patients with hyperhydration state due to heart failure, some authors showed that reactance is strongly related to BNP values and the NYHA functional classes. Other authors found a correlation between impedance and central venous pressure in critically ill patients. We have been analyzing the hydration state at admission to the ED, 24, 72 h after admission and at discharge, and found a significant and indirectly proportional correlation between BIVA hydration and the Caval index at the time of presentation to the ED and 24 and 72 h after hospital admission. Moreover, at admission we found an inverse relationship between BIVA hydration and reduced urine output that became directly proportional at 72 h. This confirms the good response to diuretic therapy with the shift of fluids from interstitial spaces.