Fluid and Electrolyte Balance Lecture Notes

Flashcards generated from lecture notes on fluid and electrolyte balance.

What is a solvent?

The fluid in which solutes are dissolved.

What are solutes?

Particles dissolved in a solvent.

What is interstitial space (third space)?

Space between cells. 3rd space

What are the functions of water in the body?

Transport waste products, necessary for metabolism, digestion, regulates body temperature, and maintains blood volume.

What is Filtration?

Moves by hydrostatic pressure from greater to lesser concentration; 'water-pushing' pressure.

What are Cankles?

Swollen ankles due to fluid pushed out of the vessel into the interstitial space.

What is Diffusion?

Movement of molecules from an area of higher concentration to one of lower concentration until equilibrium is reached.

What is clinical Example of Diffusion?

Smoke/Gas Exchange. Damage to alveoli in lungs causes decrease in diffusion.

What factors affect the rate of diffusion?

Concentration gradient and temperature.

What is facilitated diffusion?

Requires assistance to move molecules across a membrane. Example: Glucose needs insulin.

What is Osmosis?

Movement of water ONLY through a semipermeable membrane from an area of lesser solute concentration to an area of higher solute concentration.

What is an isotonic solution?

Stays equal on both sides of a membrane.

What is a hypertonic solution?

Too many solutes, so water is pulled in to dilute the space.

What is a hypotonic solution?

Less solutes, so water is pulled/pushed out to dilute.

What happens in ECF volume decrease?

Sweating leads to increased concentration of particles and fluid shifts from ICF to ECF, triggering cell shrinking and activating the thirst center.

What are sources of fluid intake?

Liquids, food, and catabolism.

What are sources of fluid loss?

Kidneys, skin, lungs, and GI tract.

What does Aldosterone do?

Reabsorbs sodium and water, preventing hypernatremia and hyperkalemia.

What is the function of Antidiuretic Hormone (ADH)?

Holds onto fluid and creates vasoconstriction to raise blood pressure.

What is the function of Natriuretic Peptides (ANP & BNP)?

Respond to increased blood volume and blood pressure by controlling sodium reabsorption.

What is Renin-Angiotensin-Aldosterone System (RAAS)?

Compensatory response initiated by the kidney when there is not enough fluid volume.

What is Hypovolemia (Dehydration)?

No Water. Intake or retention less that what's needed, resulting in fluid volume deficit.

What is Isotonic (Dehydration)?

Isotonic Fluids. Water & electrolytes lost equally. Most common type of fluid volume deficit (sweating).

how is Daily Weight used in Assessment of Dehydration?

1 L of water = 1 kg; change in body weight is best indicator of fluid loss/ retention

What are cardiovascular signs of dehydration?

Increased heart rate, 'thready' pulse, decreased blood pressure, orthostatic hypotension.

What are respiratory signs of dehydration?

Increased rate and depth of respiration, tachypnea, confusion, hypoxia.

What are integumentary signs of dehydration?

Dry, scaly skin; poor turgor; dry oral mucous membranes.

What are neurological signs of dehydration?

Lethargy, comatose state, mental status changes, fever.

What are renal signs of dehydration?

Decreased urine output and increased specific gravity.

What are lab assessment for Dehydration?

Hemoconcentration, elevated hemoglobin, hematocrit, serum osmolarity, glucose, BUN, electrolytes, urine specific gravity.

What is Fluid Overload (Overhydration)?

Also called 'hypervolemia.' Excess fluid in ECF.

What are some Causes of Overhydration?

Poor IV therapy control, decreased cardiac output, renal failure, long-term corticosteroid therapy, blood transfusions.

What are cardiovascular signs of overhydration?

Increased HR, bounding pulse, increased BP, distended neck veins, weight gain.

What are respiratory signs of overhydration?

Increased rate and shallow respirations, shortness of breath, hypoxia, moist crackles on auscultation.

What are skin and mucous membranes signs of overhydration?

Pitting edema, pale, cool, moist skin.

What are neuromuscular signs of overhydration?

Altered LOC, headache, visual disturbances, skeletal muscle weakness, paresthesia.

What are GI signs of overhydration?

Increased motility, enlarged liver, diarrhea, ascites.

What are some Interventions for overhydration?

Diuretics, fluid restriction, and sodium restriction.

What is Sodium and its function?

Located outside the cell; responsible for water balance, maintains BP, supports network of nerves & muscles.

What is Hyponatremia?

<135 mEq/L. Low Sodium most common electrolyte imbalance. Slows cell depolarization, cellular swelling, impaired function.

What is HypERnatremia?

145 mEq/L. Initially causes irritability of excitable tissues, later causes cellular dehydration and decreased response.

What is Potassium and its function?

Major cation of ICF (located inside cells). Maintains action potential in cardiac tissue, regulates glucose use and storage & protein synthesis. Most dangerous electrolyte in the body when out of range

What is Hypokalemia?

<3.5 mEq/L. Decreases excitability of cells (cardiac especially).

What are some Musculoskeletal related Symptoms to assess with someone with Hypokalemia?

Difficulty standing, weakened hand grips, decrease DTR (hyporeflexia)

What is HypERkalemia?

5.0 mEq/L. Alters functions of ALL excitable membranes to some degree. Heart extremely sensitive to potassium increases.

What are Normal Arterial Values for Blood chemistry?

Arterial (pH)7.35-7.45(alkaline); (CO2)35-45; (Bicarbonate)22-26.

What are Normal Venous Values for Blood chemistry?

Venous (pH)7.31-7.41; (CO2)40-50; (Bicarbonate)24-29

What is the goal of Acid Base Chemistry?

Balance is achieved by removal or uptake of H+ ions. Goal to get back to homeostasis

What are buffers?

Useful in binding or releasing H+ into fluid. Can act as acid/base depending on what's needed. Regulates body pH.

What does ↑pH & ↓ Acidity do?

Increase Alkalinity & decrease Acidity

What are the Acid-Base Regulatory Mechanisms?

Buffers, respiratory system, and renal system.

What is Compensation?

Process of correcting changes in blood pH.

What is the role of Chemical buffers in Acid-Base balance?

1st line of defense against changes in amount of free H+ ions, they are fast acting to reduce or raise H+ ions to normal.

What is the role of Respiratory System in Acid-Base balance?

2nd line of defense; Resp. compensates for 1st line for metabolic origin bicarb need to be out of control.

What is the role of Renal System in Acid-Base balance?

3rd line defense.Three renal mechanisms --> Movement of bicarbonate-if kidneys work, Formation of acids & Formation of ammonium- to help w/ alkalinity, to get rid of H+ ion through urine, converts to ammonia

What are Acid-Base Imbalances?

Changes in blood H+ ion level or pH; pH controls systemic changes if not corrected.

If Acid-base imbalances NOT corrected & interfere w/ many normal physiologic functions.

Change shape of hormones or enzymes, changing distribution of electrolytes, altering response of excitable membranes and decreasing uptake, activity, & effectiveness of many hormones & drugs.

What is Acidosis?

Results from actual or relative increase in amount or strength of acids.

What is Metabolic acidosis?

Overproduction H+ ions- increase blood H+ ions (metabolic process)

What is Respiratory acidosis?

Due to impairment of respiratory function

What is Combined metabolic & resp. acidosis?

Combination of metabolic & resp. acidosis is more severe

What should you assess during Acidosis?

Nervous system changes- headache, drowsiness decreases alertness or attention span, N/V, muscle weakness

What is Alkalosis?

Alkalosis. Not enough H+ & pH ↑

What is Metabolic alkalosis (Increase of base)?

Excessive bicarbonate- (antacids) intake or other bases- such as oral antacids contains sodium bicarbonate or calcium

What is Respiratory alkalosis?

Excessive loss of carbon dioxide through hyperventilation (too much CO2/H+ ion)

What are Neuromuscular Manifestations to assess in someone showing symptoms of Alkalosis?

Chvostek's, Trousseau's, Hypocalcemia, nervous system activity → muscle cramps, twitches (charley horse), ↑reflexes, tetany, hypocalcemia (painful & continuous contracting→ indicate worsening condition)