Fluid and Electrolyte Imbalances

• Fluids and electrolytes are responsible for maintaining the complex environment within the body, including fluid distribution, electrolyte concentrations, and acid-base balance.
• Body fluids, composed of water, electrolytes, minerals, and cells, travel throughout the body.

Major Factors Influencing Body's Environment

• Body water content is a major factor
• Capillary permeability is a major factor
• Lymphatic drainage is a major factor

Total Body Water (TBW)

• TBW accounts for approximately 60% of body weight.
• Intracellular water constitutes 40% of the total body water.
• Extracellular water makes up 20% of the total body water.
• Interstitial spaces contain 15% of the total body water.
• Intravascular compartment holds only 5% of the total body water.
• Lymph, synovial, intestinal, CSF, sweat, urine, pleural, peritoneal, pericardial, and intraocular fluids account for less than 1% of TBW.
• Infants have a TBW of about 75-80% at birth, which decreases to around 67% by age 1.
• Infants have higher metabolic rates, greater body surface area, and immature renal regulation.
• Males generally have greater body muscle mass.
• Females generally have greater body fat.
• Aging leads to decreased percent of total body water, increased adipose tissue, decreased muscle mass, renal decline, and diminished thirst perception.

Fluid Compartments

• Intracellular fluid (ICF) resides inside cells.
• Extracellular fluid (ECF) includes interstitial fluid, intravascular fluid, and other body fluids.
• Plasma, or serum, makes up 55% of whole blood, with cellular components comprising the remaining 45%.
• Plasma is 90% water and contains plasma proteins, hormones, nutrients, electrolytes, wastes, and gases.
• Plasma proteins include albumin (60%), clotting factors (4%), and immune globulins (36%).
• Drinking water adds to the ECF.
• ECF losses occur via the lungs, GI tract, kidneys, and perspiration.
• ICF can only change in response to changes in the ECF.

Capillary Permeability

• Capillary permeability involves the movement of fluid components between organs and cells.
• This movement relies on the cell membrane's ability to permit fluid components within the vascular system.
• Diffusion, osmosis, filtration, and active transport are four transport mechanisms.
• Diffusion is high concentrate to low concentrate in the blood
• Osmosis is solvent that moves from low concentrate to high concentrate
• Filtration is high pressure to low pressure
• Active transport needs APT energy

Water Movement

• Osmolality refers to the concentration of molecules per weight of water.
• Osmolarity indicates the concentration of molecules per volume of solution.
• Osmotic forces influence water movement.
• Aquaporins are water channel proteins and are involved in the movement process.
• Starling hypothesis states that net filtration equals forces favoring filtration minus forces opposing filtration.
• Solution is made up of solute (particles) and solvent (liquid)
• A concentration gradient is the difference in concentration of particles across a membrane.
• Tonicity refers to the effect of osmotic pressure of a solution on cells in that solution.

Osmolarity and Osmolality

• Osmolarity is the concentration of a solution expressed as the total number of solute particles per liter, that interacts with ADH to increase or decrease.
• Osmolality is the concentration of a solution expressed as the total number of solute particles per kilogram, interacting similarly with ADH; normal range is 272-295 mmol/KG.

Fluid Balance

• Thirst mechanism controls water intake via osmoreceptors in the hypothalamus.
• Antidiuretic hormone (Posterior Pituitary) promotes water resorption into blood from kidney tubules.
• Aldosterone (Adrenal glands) determines resorption of sodium ions and water.
• Atrial natriuretic peptide regulates fluid, sodium, and potassium levels.
• Net filtration is influenced by forces favoring filtration and reabsorption.
• Regulation of body fluids involves the skin, adrenal gland, lungs, GI tract, and liver.
• Antidiuretic Hormone (ADH) System responds to changes in plasma osmolality or circulating fluid volume
• Effects of ADH are the body acts on renal tubules, causes water reabsorption, results in water conversation, and serum osmolality decreases The Renin-Angiotensin-Aldosterone System increases reabsorption of sodium and water retention resulting in increase in blood pressure, vasoconstriction and decreased potassium

Net Filtration Forces

• Capillary hydrostatic pressure (blood pressure) is outward pressure on the capillary walls, higher on the arteriole side.
• Interstitial oncotic pressure (water-pulling) attracts water from the capillary into the interstitial space.
• Capillary oncotic pressure (water-pulling) attracts water from interstitial space back into capillary
• Interstitial hydrostatic pressure causes inward the movement of water from interstitial space into capillary

Fluid Deficit (Dehydration)

• Insufficient body fluid can result from inadequate intake, excessive loss, or both.
• Weight change often measures fluid loss.
• Dehydration is more severe in infants and older adults.
• Water loss may be accompanied by loss of electrolytes and proteins (e.g., diarrhea).
• Average daily intake of water should be 2500mL.
• Water of Metabolism comes from 250 mL per day by 10%.
• Water in moist food comes from 750 mL per day by 30%
• Water in beverages comes from 1500 mL per day by 60%
• Average daily output of water should be 2500mL.
• Water loss is in sweat which is 150 mL per day or 6%
• Water loss is in feces which is 150 mL per day or 6%
• Water loss is through skin and lungs which is 700 mL per day or 28%
• Water loss is in urine which is 1500 mL per day or 60%
• ECF loss leads to mild dehydration, which is a decrease of 2% body weight and moderate (5% loss)..
• Severe dehydration is at 8% loss.
• Vomiting and diarrhea causes dehydration
• Excessive sweating with loss of sodium and water causes dehydration
• Diabetic ketoacidosis causes dehydration (Loss of fluid, electrolytes, and glucose in the urine)
• Insufficient water intake in older adults or unconscious persons causes dehydration
• Use of concentrated formula in infants causes dehydration Remember that water follows salt.

Manifestations of Dehydration

• Dry mucous membranes in the mouth
• Decreased skin turgor or elasticity
• Lower BP, weak pulse, and fatigue
• Decreased mental function, confusion, loss of consciousness (brain cells lose water, dec function)
• Weight loss, oliguria or anuria
• Concentrated urine
• Sunken eyes, sunken fontanelles in infants
• Increased temperature, cool extremities
• Weak, rapid pulse, hypotension
• Postural (orthostatic) hypotension
• Decreased capillary refill

Diagnostic Tests for Dehydration

• Increased hemoglobin & hematocrit (high and dry)
• Increased serum osmolality (more particles less fluid)
• Increased serum BUN, creatinine, Na
• Increase in urine specific gravity

Compensating for Fluid Loss

• Increasing thirst if thirst mechanism is intact
• Increasing heart rate (help with dec BP)
• Constriction of cutaneous blood vessels producing pale and cool skin
• Producing less urine that has amber color

Fluid Imbalances

• Fluid shifts out of the blood into a body cavity or tissue, where it cannot reenter the vascular compartment.
• Causes include high osmotic pressure of ISF, as in burns.
• Causes include Increased capillary permeability, as in some gram-negative infections

Fluid Excess (Edema)

• Excessive fluid is in the interstitial compartment with the effects of causing swelling or enlargement of tissue, being localized or throughout the body, possibly impairs tissue perfusion, and may trap drugs in ISF.
• Fluid retention; renal, liver, or heart failure; steroid therapy; hyperaldosteronism can cause edema
• Effects of edema include swelling, pitting edema, and an increase in body weight, as well functional impairment, pain restricted range of joint movement and impaired arterial circulation
• Edema causes reduces vital capacity
• Edema can cause headaches with cerebral edema.
• Edema can cause stretching of capsule in organs (kidney, liver)
• Tests show decreased serum osmolarity and sodium, decreased urine osmolarity, and increased output output

Electrolytes

• Electrolyte imbalances involve sodium (Na+), potassium (K+), chloride (Cl-), and calcium (Ca++).
• Sodium (Na+) 136-146 is the normal range
• Chloride (Cl-) 98 – 107 is the normal range
• Potassium (K+) 3.5 – 5.1 is the normal range
• Calcium (Ca++) 2.12 - 2.52 is the normal range
• Phosphate (PO4+) 0.81 - 1.58 is the normal range
• Magnesium (Mg++) 0.74 – 1.03 is the normal range
• Sodium (Na+), chloride (Cl-), potassium (K+), bicarbonate (HCO3-), and calcium (Ca+) are electrolytes.
• Glucose, albumin, and creatinine are non-electrolytes.

Sodium Imbalance

• Sodium is the primary cation in ECF.
• Transport happens into and out of cells by sodium-potassium pump
• Sodium exists in form of sodium chloride and sodium bicarbonate
• Sodium is ingested in food and beverages

Hyponatremia

• Causes are dilution of serum, inadequate intake, increased sodium excretion, and hormonal imbalances.
• Dilution of serum sodium occurs in excess of water, hyperglycemia, ingestion hypotonic fluids, cirrhosis, psychogenic polydipsia (water intoxication)
• Low salt diets causes inadequate sodium intake.
• Losses from excessive sweating, vomiting, diarrhea causes increased in sodium excretion.
• Use of certain diuretic drugs combined with low-salt diet cause increased sodium excretion.
• Insufficient aldosterone, adrenal insufficiency and Excess ADH secretion causes hormonal imbalance

Manifestations of Hyponatremia

• Low sodium levels cause fluid imbalance in compartments
• Fatigue, muscle cramps, abdominal discomfort or cramps, nausea, vomiting
• Decreased osmotic pressure in ECF compartment.
• Fluid shift into cells causing Hypovolemia and decreased blood pressure
• Cerebral edema causing confusion, headache, weakness, seizures

Hypernatremia

• Caused by an imbalance in sodium and water
• Insufficient ADH (diabetes insipidus), which has results in large volume of dilute urine
• Loss of the thirst mechanism
• Watery diarrhea
• Prolonged periods of rapid respiration
• Ingestion of large amounts of sodium without enough water

Manifestations of Hypernatremia

• Weakness, agitation
• Increased blood pressure
• Edema
• Dry, rough mucous membranes
• Increased thirst if thirst mechanism is functional.

Fluids shifts with Sodium

• High water and low sodium causes hyponatremia
• Low water and high sodium causes hypernatremia

Chloride Imbalance

• Is a major extracellular anion.
• Chloride levels are related to sodium levels.
• Chloride and bicarbonate ions can shift in response to acid-base imbalances.
• Hypochloremia is associated with alkalosis, and early stages of vomiting-loss of hydrochloric acid.
• Hyperchloremia results from Excessive sodium chloride intake.

Potassium

• A 6 month old presents with 3 day history of fever, vomiting and diarrhea and they have dehydration and HyperKalemia (high potassium)
• Potassium is the major intracellular cation.
• Serum levels are low, with a narrow range
• Is ingested in foods
• Excreted primarily in urine
• Insulin promotes movement of potassium into cells
• Level influenced by acid-base balance
• Excess potassium ions in interstitial fluid may lead to hyperkalemia.
• Abnormal potassium levels cause changes in cardiac conduction and are life-threatening!

Hypokalemia

• Potassium is < 3.5 mEq/L
• Excessive losses which caused by diarrhea and diuresis associated with some diuretic drugs.
• Exessive aldosterone or glucocorticoids, Example is Cushing syndrome
• Decreased dietary intake, may occur with alcoholism, eating disorders, starvation causing Hypokalemia
• Treatment of diabetic ketoacidosis with insulin is also factor

Hypokalemia

• Cardiac dysrhythmias happens when they have impaired repolarization leading to cardiac arrest
• Interference with neuromuscular function, where muscles are less responsive to stimuli
• Causes Paresthesias-“pins and needles”
• Decreased digestive tract motility
• Severe hypokalemia:
• Shallow respirations
• Failure to concentrate urine-polyuria

Hyperkalemia

• Potassium is > 5 mEq/L
• Renal failure
• Deficit of aldosterone
• "Potassium-sparing" diuretics
• Leakage of intracellular potassium into extracellular fluids in patients with extensive tissue damage
• Displacement of potassium from cells by prolonged or severe acidosis.

Hyperkalemia

• Cardiac dysrhythmias that may progress to cardiac arrest
• Muscle weakness common which Progresses to paralysis
• Causes of hyper kale is also May cause respiratory arrest
• Impairs neuromuscular activity
• Fatigue, nausea, paresthesias

Calcium Imbalance

• Review of calcium Important extracellular cation Ingested in food Stored in bone Excreted in urine and feces Balance controlled by parathyroid hormone (PTH) and calcitonin Vitamin D promotes calcium absorption from intestine, Ingested or synthesized in skin in the presence of ultraviolet rays, activated in kidneys Provides structural strength for bones and teeth Maintenance of the stability of nerve membranes Required for muscle contractions Necessary for many metabolic processes Essential for blood clotting

Hypocalcemia

• Causes are hypoparathyroidism, malabsorption syndrome, deficient serum albumin, increased serum pH level, and renal failure
• Manifestations include increased permeability and nerve excitability, tetany, weak heart contracts with with delay conduction and arrhythmia’s

Hypercalcemia

Uncontrolled release of calcium ions from bones like Neoplasms-malignant bone tumors Hyperparathyroidism Demineralization caused by immobility (Decrease stress on bone) Increased calcium intake (Excessive vitamin D) Depressed neuromuscular activity ( Muscle weakness)

Phosphate Imbalances

Phosphate is Bone and tooth mineralization of phosphates

• Important in metabolism-ATP Phosphate buffer system-acid-base balance Integral part of the cell membrane Reciprocal relationship with serum calcium Hypophosphatemia Malabsorption syndromes, diarrhea, excessive antacids Hyperphosphatemia From renal failure

Magnesium Imbalances

Magnesium is Intracellular ion Hypomagnesemia that results from malabsorption or malnutrition; often associated with alcoholism or caused by use of diuretics, diabetic ketoacidosis, hyperthyroidism, hyperaldosteronism Hypermagnesemia Occurs with renal failure Depresses neuromuscular function Decreased reflexes