Fluid Volume Changes Flashcards

Fluid Volume Deficit (FVD)

A decrease in total body water due to fluid loss or inadequate intake; signs commonly include thirst, increased heart rate, low blood pressure, and reduced urine output.

Fluid Volume Overload (FVO)

Excess fluid in the body often caused by heart failure, liver cirrhosis, kidney failure, excessive sodium intake, corticosteroids, or severe physiologic stress.

Edema

Abnormal accumulation of fluid in the interstitial space; can be localized or generalized and may present as pitting edema.

Anasarca (Generalized Edema)

Severe generalized edema affecting the entire body, usually due to substantial fluid overload.

Dependent Edema

Edema in gravity-dependent areas (e.g., legs and feet) due to hydrostatic forces from standing or sitting.

Lymphedema

Edema caused by impaired lymphatic flow or removal of lymphatic vessels, often localized to limbs.

Third Spacing

Fluid shift from intravascular space into transcellular spaces (e.g., pericardial, pleural, peritoneal cavities), reducing circulating volume.

Capillary Hydrostatic Pressure

Pressure within capillaries from blood pressure and gravity that pushes fluid out into the interstitial space.

Oncotic (Osmotic) Pressure

Osmotic force from plasma proteins (especially albumin) that pulls water back into capillaries, helping maintain intravascular volume.

Albumin

Major plasma protein that remains largely in the vasculature and sustains colloid osmotic pressure.

Osmosis

Water movement across a semipermeable membrane from areas of higher water concentration to lower water concentration.

Diffusion

Movement of solutes from higher concentration to lower concentration across a membrane.

Passive Transport

Movement of substances across membranes without energy, driven by concentration or pressure gradients (e.g., osmosis and diffusion).

Active Transport

Energy-dependent movement of substances against their concentration gradient.

Isotonic IV Fluids

Fluids with osmolality similar to extracellular fluid; remain in the vascular space and are used for volume replacement.

Hypertonic IV Fluids

Fluids with higher osmolality than intracellular space; draw water from cells into the vascular space, potentially shrinking cells.

Hypotonic IV Fluids

Fluids with lower osmolality than intracellular space; water moves into cells, potentially causing swelling.

Serum Osmolality (FVD vs FVO)

In FVD, serum osmolality increases; in FVO, serum osmolality decreases due to dilution.

Hematocrit Changes (FVD vs FVO)

FVD causes hemoconcentration and increased hematocrit; FVO causes dilution and decreased hematocrit.

BUN Changes (FVD vs FVO)

FVD increases BUN due to reduced volume; FVO decreases BUN due to dilution.

Urine Specific Gravity Changes (FVD vs FVO)

FVD raises urine specific gravity (more concentrated urine); FVO lowers it due to dilution from increased urine output.

Crackles (Pulmonary Edema)

Adventitious lung sounds indicating fluid buildup in the lungs, often seen with fluid overload.

Pitting Edema

Edema that leaves a lasting indentation when pressed with a finger.

Thirst

Early clinical sign of fluid volume deficit due to body's need to increase intake.

Flat Neck Veins

Sign of hypovolemia where neck veins appear flat due to reduced circulating volume.

Distended Neck Veins (JVD)

Sign of fluid overload where neck veins appear full due to elevated venous pressure.

Orthostatic Hypotension

Drop in blood pressure on standing, often seen with fluid volume deficit.