Body Fluid Homeostasis and Imbalances

Maintaining balance in body fluid characteristics (volume, concentration, composition, and acidity) for health.

About 55-60% of a healthy adult's body weight is fluid, decreasing to around 50-55% in older adults.

Body fluids move between compartments (intracellular and extracellular) using methods like diffusion, active transport, filtration, and osmosis to maintain balance.

Imbalances occur from too little or too much isotonic fluid, or from hypertonic/hypotonic fluid, leading to issues like hypernatremia and hyponatremia.

Body fluid is divided into intracellular (inside cells) and extracellular (outside cells), further subdivided into intravascular, interstitial, and transcellular fluids.

A lack of fluid in the body, caused by insufficient intake or excessive loss. It can be actual dehydration, where total body water decreases, or relative dehydration, where water shifts from plasma to interstitial space.

A decrease in circulating blood volume due to loss of both water and electrolytes. It's also known as isotonic dehydration and fluid volume deficit.

Excessive loss from GI tract (vomiting, diarrhea), skin (sweating), kidneys (diuretics, kidney disease), or third spacing (burns). It can also be caused by decreased intake due to anorexia, nausea, confusion, or NPO status.

Hyperventilation or excessive sweating without replacing fluids, prolonged fever, diabetic ketoacidosis, insufficient water intake (enteral feeding without water, decreased thirst, aphasia), diabetes insipidus, osmotic diuresis, and excessive salt intake.

Fluid shifts from the blood (plasma) to the spaces between cells (interstitial space) without a change in total body water.

Common signs of hypovolemia include low blood pressure (hypotension), rapid heart rate (tachycardia), weak pulse, difficulty breathing (tachypnea), dizziness, and confusion.

Other than vital signs, hypovolemia symptoms can include dry mouth, thirst, decreased urine output, fatigue, and weakness.

Fluid imbalance in older adults has a greater impact due to age-related changes like decreased kidney function and loss of skin elasticity.

Severe dehydration can be dangerous, leading to seizures and other serious complications. Always seek medical attention if you suspect severe dehydration.

Hematocrit (Hct) increases in hypovolemia due to decreased blood volume and a higher concentration of red blood cells.

Blood Urea Nitrogen (BUN) increases in hypovolemia because less water is available to flush out urea, resulting in hemoconcentration.

Urine specific gravity becomes higher than 1.030 in hypovolemia because the kidneys try to conserve water by producing concentrated urine.

Blood sodium levels increase above 145 mEq/L in dehydration due to the loss of more water than sodium.

Blood osmolality (concentration of dissolved particles) increases above 295 mOsm/kg in dehydration, indicating higher solute concentration.

A life-threatening condition caused by severe fluid loss, leading to decreased blood flow and oxygen delivery to tissues.

Signs include low blood pressure, fast heart rate, weak pulse, rapid breathing, dizziness, and confusion.

Administer oxygen, monitor vital signs frequently, replace fluids with crystalloids or colloids, and consider vasoconstrictors or medications to improve heart function.

Colloids like whole blood, packed red blood cells, plasma, and synthetic plasma expanders increase blood volume and pressure. Crystalloids like lactated Ringer's and normal saline provide electrolytes and fluids.

Oxygen saturation reflects the amount of oxygen in the blood. Low saturation (below 70%) indicates a medical emergency and requires immediate treatment.

Overhydration is a condition where the body has too much fluid. This can happen from drinking too much water or the body not being able to remove excess fluids.

Fluid overload refers to a situation where the body has an excess of fluid, often accompanied by water intoxication. This can lead to a decrease in the concentration of blood components.

Individuals with fluid overload are at a higher risk of developing pulmonary edema (fluid in the lungs) or congestive heart failure due to the increased pressure on the heart and lungs.

Older adults are more susceptible to fluid imbalances due to age-related changes, such as decreased kidney function.

Overhydration, compromised regulatory systems (heart failure, kidney disease, cirrhosis), fluid shifts after burns, prolonged corticosteroid use, and severe stress.

Syndrome of inappropriate antidiuretic hormone; the body retains too much water, leading to overhydration.

Solutions with a lower concentration of solutes than blood, which can cause fluid to shift into cells and lead to overhydration.

Fluid overload is when the body has too much fluid, causing increased blood volume and pressure. Symptoms include rapid heartbeat, high blood pressure, difficulty breathing, swelling, and weight gain.

Fluid overload can be caused by excessive fluid intake, medical conditions like heart failure or kidney disease, or fluid shifts after burns. It can also result from prolonged use of corticosteroid medications.

Excess fluid can lead to serious complications such as pulmonary edema (fluid in the lungs) and congestive heart failure, making the heart work harder to pump blood.

Fluid overload affects various body systems. It can cause swelling in the extremities (peripheral edema), increased pressure in the veins of the neck, and increased urine production.

Treatment involves reducing excess fluid intake, restricting sodium, using diuretics to help eliminate excess water, and addressing the underlying medical condition causing the fluid overload.

Low hematocrit (Hct) and hemoglobin (Hgb) indicate decreased blood volume, often a sign of fluid overload.

Lower than normal sodium levels in urine suggest that the kidneys are retaining sodium to compensate for fluid loss.

A chest x-ray can reveal evidence of fluid accumulation in the lungs, known as pulmonary congestion, indicating fluid volume excess.

Closely monitoring fluid intake and output helps determine the body's fluid balance. This is crucial for managing fluid imbalances.

Raising the head of the bed elevates the chest and facilitates easier breathing, especially helpful for patients with pulmonary congestion.

When oxygen management is needed, respiratory services are consulted to help manage the client's breathing and oxygen levels.

If fluid moves into the lungs (like in pulmonary edema), a pulmonologist is consulted to diagnose and treat the underlying cause.

To manage fluid volume excess, the client may need to adhere to a specific fluid restriction. The healthcare provider determines the daily allowance and how it should be divided throughout the day.

Clients with fluid volume excess should weigh themselves daily. A gain of 1-2 pounds in 24 hours or 3 pounds in a week should be reported to the provider.

Excessive sodium intake can contribute to fluid volume excess. Clients are advised to follow a low-sodium diet, read food labels, and track daily sodium intake.

Fluid accumulation in the lungs, often caused by fluid overload, leading to breathing difficulties.

Symptoms include anxiety, rapid heartbeat, neck and hand vein swelling, irregular heartbeat, shortness of breath even at rest, confusion, restlessness, lethargy, abnormal lung sounds, and coughing up frothy pink sputum.

Position the client upright, administer oxygen, consider mechanical ventilation, and use medications like morphine, nitrates, and diuretics as prescribed.

Morphine is used to reduce anxiety, decrease the workload on the heart, and relieve shortness of breath in patients with pulmonary edema.

Diuretics help eliminate excess fluid from the body, reducing pressure on the heart and lungs, which aids in breathing.