Fluid volume excess (FVE) refers to retention of extracellular fluid that is categorized as either isotonic or hypotonic, based on the proportion of water to (sodium) solute that is retained. Edema, excessive interstitial fluid that results is tissue swelling, is a major clinical manifestation of FVE, and has four primary causes. Edema associated with FVE is usually the greatest in dependent body areas such as the ankles and feet, or the sacrum in a bedbound person. It can be graded on a 4+ grading scale based on depth of indentation. Clinical manifestations of isotonic FVE can be divided into two categories, those due to increased interstitial fluids (edema) and those due to increased circulating fluid volume, such as sudden weight gain, distended neck veins, and possible pulmonary venous congestion or edema. Hypotonic FVE causes water to shift into the cells to equalize sodium concentrations, which results in cellular edema. Clinical manifestations of hypotonic FVE can be divided into two categories, those due to increased circulating fluid volume, which are the same as for isotonic FVE; and those due to cellular edema. Hypotonic FVE can result in cerebral edema, causing neurologic manifestations and lung edema, causing pulmonary manifestations. A focused fluid balance assessment is part of providing good nursing care. A fluid balance assessment should include a complete history, with further investigation of any indicators of fluid imbalance and viewing laboratory test findings. A focused assessment of fluid balance includes vital signs (especially pulse and blood pressure), intake and output, weight, edema, skin turgor, mucous membranes and lung sounds. Laboratory tests for fluid imbalance include tests of kidney function (BUN, creatinine), serum osmolality, blood cell tests (RBC, hemoglobin and hematocrit), and urinalysis (specific gravity and urine osmolality). A combination of clinical manifestations and correlation with related assessment findings can give the nurse an accurate picture of the patient’s fluid balance. Key Points The clinical manifestations of fluid volume deficit reflect decreases in circulating fluid volume and interstitial fluid. Hypertonic FVD also has associated neurological manifestations. Decreased circulating volume alters cardiac output, causing changes in vital signs, urine output, and other signs such as prolonged capillary refill and flat neck veins. Decreased interstitial fluid causes integumentary manifestations, such as decreased skin turgor and dry mucous membranes Fluid weight loss is present in both types of FVD and dehydration severity can be measured based on percentage of body weight lost. The patient with hypertonic FVD may present with the clinical manifestations of isotonic FVD relative to decreased circulating fluid volume and decreased interstitial fluid; however, neurological manifestations often predominate unless the FVD becomes more advanced. Fluid volume excess (FVE) refers to retention of extracellular fluid that is categorized as either isotonic or hypotonic, based on the proportion of water to (sodium) solute that is retained. Edema, excessive interstitial fluid that results is tissue swelling, is a major clinical manifestation of FVE, and has four primary causes. Edema associated with FVE is usually the greatest in dependent body areas such as the ankles and feet, or the sacrum in a bedbound person. It can be graded on a 4+ grading scale based on depth of indentation. Clinical manifestations of isotonic FVE can be divided into two categories, those due to increased interstitial fluids (edema) and those due to increased circulating fluid volume, such as sudden weight gain, distended neck veins, and possible pulmonary venous congestion or edema. Hypotonic FVE causes water to shift into the cells to equalize sodium concentrations, which results in cellular edema. Clinical manifestations of hypotonic FVE can be divided into two categories, those due to increased circulating fluid volume, which are the same as for isotonic FVE; and those due to cellular edema. Hypotonic FVE can result in cerebral edema, causing neurologic manifestations and lung edema, causing pulmonary manifestations. A focused fluid balance assessment is part of providing good nursing care. A fluid balance assessment should include a complete history, with further investigation of any indicators of fluid imbalance and viewing laboratory test findings. A focused assessment of fluid balance includes vital signs (especially pulse and blood pressure), intake and output, weight, edema, skin turgor, mucous membranes and lung sounds. Laboratory tests for fluid imbalance include tests of kidney function (BUN, creatinine), serum osmolality, blood cell tests (RBC, hemoglobin and hematocrit), and urinalysis (specific gravity and urine osmolality). A combination of clinical manifestations and correlation with related assessment findings can give the nurse an accurate picture of the patient’s fluid balance. Summary In this lesson, assessment of fluid imbalances has been presented. The subtypes of fluid imbalances share many of the same common manifestations, including: rapid weight changes and manifestations related to changes in circulating fluid volume and interstitial fluid. In addition, fluid volume imbalances that are either hypotonic or hypertonic also have associated neurological manifestations because of osmotic shifts of water, for example: Hypotonic FVE – water shifts into cells causing them to swell; of particular concern are cerebral edema and pulmonary congestion or edema Hypertonic FVD – water shifts out of cells causing them to shrink Edema is a common manifestation of fluid volume excess related to increased hydrostatic pressure. It is graded on a 4+ scale by depth of indentation. Edema associated with FVE is typically dependent (e.g., ankles and feet in an upright person). The severity of weight gain or loss is measured as a percentage of total body weight that is either gained or lost. Key assessments used for identifying actual or potential fluid imbalances include: vital signs, intake and output, weight, edema, skin turgor, mucous membranes, and lung sounds. Key laboratory assessments that the nurse may collect and interpret include: Renal tests (BUN and creatinine), serum osmolality, blood cell tests (RBCs, and hemoglobin and hematocrit) and urine tests (urine specific gravity and osmolality). Assessment data that has been collected should be considered as a whole to assure accurate identification of the fluid imbalance.
