Fluid and electrolytes

Fluid and Acid-Base Balance

— Is necessary

— There should be balance between fluid intake and fluid excreted

Body fluids

— These are liquids in the body like blood, sweat, and urine

Body water

— Water makes up most of our body and is needed for all body functions.

Homeostasis

— This means the body keeps everything balanced and stable, like temperature and fluids.

Intracellular fluid (ICF)

— vital to normal cell functioning. It contains solutes such as oxygen, electrolytes and glucose

extracellular fluid (ECF)

— is the fluid outside cells and includes intravascular fluid (in the blood) and interstitial fluid (between cells).

ECF

— (1/3 of body fluid)

ICF

— (2/3 of body fluid)

Electrolytes

— Compounds that forms or dissociates into ions when dissolved in water

> Promote neuromuscular irritability

> Maintain body fluid osmolarity

> Regulate acid-base balance

> Distribute body fluids

Cations

— are electrolytes with a positive charge that help with body functions like muscle movement and fluid balance.

Sodium (Na+) (Cations)

— is the most abundant cation in the ECF.

— Normal serum level is 135-145 mmol/L

— it control and regulates water balance.

Potassium (K+)(Cations)

— is the major cation in the ICF, with only a small amount found in the ECF.

— Normal serum levels 3.5 to 5.2 mmol/L

— is a vital electrolyte for skeletal, cardiac and smooth muscle activity.

Calcium (Ca2+)(Cations)

— vast majority of calcium in stored in the skeletal system, vital in regulating neuromuscular function.

— Normal values 2.1 -2.6 mmol/L

Magnesium (Cations)

— found primarily in skeleton and ICF, important for intracellular metabolism especially in the production and use of adenosine triphosphate (ATP).

— Normal serum level of 0.7-1.1 mmol/L

Anions

— are electrolytes with a negative charge that help keep fluid, acid-base, and electrical balance in the body.

Chloride (Cl-) (Anions)

— is the major anion in the ECF

— normal serum levels are 95-110 mmol/L

— functions with sodium to regulate serum osmolality and blood volume.

Phosphate (PO4) (Anions)

— is the major anion of ICF.

— Normal serum levels range from 0.75-1.5 mmol/L or mg/dL

— children and newborns have higher levels than adults.

— It is essential for functioning muscles, nerves and red blood cells.

— It also involved in the metabolism of protein, fat and carbohydrates.

Bicarbonate (HCO3) (Anions)

— is present in both ICF and ECF.

— Its primary function is regulating acid base balance

— Normal serum level range from 22-32 mmol/L

Sulfate (SO4) (Anions)

— helps in metabolism and detoxification (less common)

— Normal serum level range from 1 mmol/L or mg/dL

Diffusion

— Movement of particles

— Size of the molecule

— Concentration of molecules

— Temperature of solution (Eg. Gas exchange)

Osmosis

— Movement of solvent from an area of lower concentration to an area of higher concentration of solutes

— Net movement of water

— Semipermeability of the membrane

Active transport

— The sum of all the diffusion forces acting on the membrane from either a concentration gradient, electrical gradient, pressure gradient

— Requires ATP

Hydrostatic pressure

— The force of liquid that is exerted on the sides of a container

— Eg. Pressure against the blood vessel wall

Filtration

— The movement of fluid through a semipermeable membrane from an area with higher hydrostatic pressure to an area with lower hydrostatic pressure

Colloid osmotic pressure

— The movement of fluid between the intravascular and interstitial compartments based on the number of solute particles (colloids)

— Eg. Proteins, polysaccharides, drugs

Ingested liquids:

1500 mL

Water in foods:

700 mL

Water from oxidation:

200 mL

Skin

— 300-400 mL/day

— Loss occurs through perspiration

Lungs

— 300-400 mL/day

— Insensible loss

GIT

— 200 ml/day in feces

— Diarrhea can lead to fluid and electrolyte imbalances

Kidneys

— 1200-1500 mL/day \

— The excretion of water by healthy kidneys is proportional to the fluid ingested and the amount of waste or solutes excreted

— are the primary regulator of body fluids and electrolyte balance

— control the reabsorption of water from plasma filtrate and ultimately the amount excreted as urine.

Antidiuretic hormone (ADH, vasopressin)

: Secreted by the PP

Aldosterone

: Produced in the adrenal cortex of the kidneys

Renin

: Released form the juxtaglomerular cells of the kidneys

Hyponatremia

— Decreased concentration of Na in the ECF

— Can lead to edema (also cerebral edema)

Hypernatremia

— Excess Na in the ECF

— Can cause increase in the extracellular osmotic pressure

Sodium (Na) ter

— Primary determinant of ECF volume

— Unable to cross membrane easily

— It reabsorbs the Cl and wa

Potassium (K)

— The N range is narrow that any slightest decrease or increase can cause serious or life-threatening effects

— There is a reciprocal relationship between Na and K

Hypokalemia

— Decrease of K in the ECF

— Can cause metabolic alkalosis

— Can cause cardiac arrest (below 3 mmol/L, using digitalis)

Hyperkalemia

— Increase of K in the ECF level

— Causes include K-sparing diuretics, CNS agents (succinylcholine), oral and IV KCl replacements

— Do not administer more than 10 mmol/L per hour

— Never administer IV KCl undiluted

Calcium (Ca)

— 99% is in bone

— 1% is in the blood

Hypocalcemia

— Decrease Ca concentrations in the ECF

— Causes include rapid administration of citrated blood, metabolic alkalosis, increased levels of serum albumin

Hypercalcemia

> Increase Ca concentrations in ECF

Magnesium (Mg)

— Impt in metabolism of CHO and CHON

— Acts as mediator in neuromuscular activity

— Has a higher concentration in CSF than ECF

Hypomagnesemia

— Decrease Mg concentration in the ECF

— Occurs w/ hypokalemia and hypocalcemia

— Causes include digitalis, K-wasting diuretics, cortisone

Hypermagnesemia

— Increase Mg in the ECF

— Causes include overuse of high-Mg containing meds

Excess fluid volume (EFV)

— Increased interstitial and intravascular fluid retention and edema

> IV therapy, ↑ Na

> Chronic diarrhea, burns, kidney disease, malnutrition

> Kidney failure

> Impaired myocardial contractility

> Cancer, steroid excess, allergic reaction

Deficient fluid volume (DFV) r

— Vascular, interstitial or intracellular

Mild, marked, severe or fatal

Isotonic dehydration

— Loss of both fluid and particles

Hypertonic dehydration

— Greater loss of fluid than particles

Hypotonic dehydration

— Greater loss of particles than fluids