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Fluid and Electrolytes. CSON Spring 2009 PREPARED BY CARLA HILTON, MSN, RN PRESENTED AND REVISED BY REBECCA POWERS, MSN, RN 15 questions from all of powers’ stuff…. Water Balance = Homeostasis. Water in the body is used to or for: Transporting nutrients & oxygen to cells
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Fluid and Electrolytes CSON Spring 2009 PREPARED BY CARLA HILTON, MSN, RN PRESENTED AND REVISED BY REBECCA POWERS, MSN, RN 15 questions from all of powers’ stuff…
Water Balance = Homeostasis • Water in the body is used to or for: • Transporting nutrients & oxygen to cells • Removing waste from cells • Provides medium in which electrolyte chemical reactions can occur • Regulation of body temperature • Lubricates joints and membranes • Provides medium for food digestion • liter of water weighs 2.2 lbs • The most accurate way to measure fluid status in a person is daily weights, not I&O!!!
Water Distribution • ICF: Intracellular fluid • ECF: Extracellular fluid (lymph system, interstitial fluid, intravascular fluid or plasma) • TCF: Transcellular fluid (cerebral spinal fluid, fluid in joints, GI tract, and peritoneal fluid) • Third spacing: (a condition where fluid accumulates in a pocket that isn’t really serving a purpose. Acieties (sp?)- where fluid hangs out in your abd. The fluid is coming from somewhere else.) • More fluid in intracellular than anywhere else in the body!
Osmolarity / Osmolality • Osmole: • the amount of substance that dissociates in solution to form one mole of osmotically active particles • Concentration of solution measured in osmoles
Osmolarity / Osmolality • Osmolality is measured in milliOsmols/Kg (mOsm/Kg) • Osmolarity is measured in milliOsmols/L (mOsm/L) • Evaluates serum and urine in clinical practice • Normal: serum osmolality 275 – 295 mOsm/K • Lality= total volume will equal 1 L plus the amount of volume taken up by the solids! The koolaid and water equal a L • Larity= volume is going to be less than 1 L. The koolaid minus the water.
Concentrations of Solutions • Isotonic: Same osmolarity as blood plasma…no osmotic “pull” • Hypotonic: Less concentration than blood plasma…lower osmotic pressure • Hypertonic: More concentration than blood plasma….higher osmotic pressure
Movement of Water • Intracellular & extracellular approximately same osmolality • Solvent (water) and solutes (electrolytes) move across selectively permeable membranes (compartments) in the body (the bigger the particle, the slower they move, and they may need a little boost…)
Review of Terms • Osmosis • Diffusion • Active transport • Passive transport • Filtration • Hydrostatic pressure
Osmosis Review • Movement of water only • Speed of movement affected by: • temperature of fluid • concentration of fluid • electrical charge of particles in solution • The higher the solute concentration, the greater the osmotic pressure is.
Other Mechanisms of Movement • Diffusion: Solute (or gas) moves from area of higher concentration to area of lower concentration • Facilitated diffusion: Solute moves against concentration gradient (passive transport) • Active transport: Solute moved against concentration gradient using ENERGY
Active Transport • Na+/K+ pump: Maintains the higher concentrations of extracellular Na+ and intracellular K+ • In the cell, K is King. i.e. K is the major cation of the cell, Na is outside the cell.
Continued • Filtration: solutes & solvent move together in response to fluid pressure; moves from area of high pressure (hydrostatic pressure) to area of low pressure • Hydrostatic pressure: The force within a fluid compartment (as in the vascular system) The pressure that forces the fluid out of your capillaries. • Colloidal Osmotic Pressure – pulls it back into the capillaries.
Regulation of Body Fluids • Intake: osmoreceptors senseosmolality of serum, signals the hypothalamus, stimulates thirst • Impact on intake: Age (decreases desire to drink), conciousness, ability to take in fluids • Output: kidneys, lungs, GI tract, skin • Sensible: measurable….urine output, excessive perspiration, diarrhea, vomiting • Insensible: immeasurable…normal perspiration, normal breathing • Output for adults should be one mL/kg (of body weight) an hour
Role of the Kidneys • Filter approx 180 Liters of blood per day; GFR (glomerular filtration rate) • Produces urine between 1-2 Liters/day • If loss of 1% to 2% of body water, will conserve water by reabsorbing more water from filtrate; urine will be more concentrated • If gain of excess body water, will excrete more water from filtrate; urine will be more diluted
Hormonal Control • Antidiuretic hormone (ADH): Prevents diuresis; “water saving” • Question: Osmoreceptors sensing a/an increase in osmolality will cause the release of ADH • ADH acts on kidneys via the renal tubules. Makes them more permeable to water. The water will move from the tubes back into your body.
Hormonal Control • RAA (Renin-angiotensin-aldosterone):cascade initiated by decrease in renal perfusion or low Na+ • If extracellular volume is decreased renal perfusion decreases renin secreted by kidneys renin acts to produce angiotensin I which then converts to angiotensin II results in massive vasoconstriction increases renal arterial perfusion and causes increased thirst, a release of aldosterone (causes the retention of Na and Water)
Hormonal Control • Aldosterone: • Angiotensin II causes the adrenal gland to release aldosterone • Aldosterone causes the kidneys to retain Na+ and water • Volume regulator….released if Na+ is low and K+ is high; increases reabsorption of Na+ (where salt goes, water follows) and the excretion of K+
ANP • Atrial Natriuretic Peptide: (ANP): secreted from atrial cells of heart (in response to too much volume in the blood) • acts as diuretic • inhibits thirst mechanism • suppresses the RAA cascade
Thirst Mechanism • Regulated by the hypothalamus • Stimulates thirst: • increased osmolality of ECF • decreased ECF • dry mucous membranes • Causes: eating salty foods, inadequate intake, excessive water loss
Pressure Sensors Baroreceptors: Nerve receptors that sense pressure in blood vessels (think barometer measures pressure in the atmosphere, this measures pressure in the blood vessels) • Low pressure: sensors in the cardiac atria; stimulate SNS (sympathetic nervous system) & inhibits PSNS (parasympathetic nervous system) (sns will increase heart rate and BP) • High pressure: sensors in the aortic arch, carotid sinus, and the juxtaglomerular apparatus in the kidney; stimulates PSNS and inhibits the SNS (psns will decrease your heart rate and lower BP)
Pressure Sensors • Osmorecptors: Sense Na+ concentration • Positioned on surface of hypothalamus • Increase in Na+ concentration: stimulates release of ADH • Decrease in Na+ concentration: inhibits release of ADH
Electrolytes • Minerals and salts: electrolytes • Cations: Positively charged; sodium, potassium, calcium, magnesium • Major cation in ECF is sodium • Anions: Negatively charged; chloride, bicarbonate, sulfate • Major cation in ICF is potassium
HyponatremiaUsually loss of Na w/o loss of fluid • Causes • Salt wasting fr. Kidney • Adrenal insufficiency • GI losses • Profuse sweating • Diuretics • SIADH • Syndrome of inappropriate Anti-Diruetic Hormone • Inadequate Na intake • Physical Exam • Apprehension • Personality change • Postural hypotension • Tachycardia • Convulsions/coma • NV&D • Anorexia
Hyponatremia cont’d • Labs • Serum Na+below 135 mEq/L • Serum Osmolality below 280 mOsm/kg • Urine specific gravity below 1.010 • Treatment • Restrict water • Sodium replacement
Hypernatremia • Causes • ingestion of salt • Iatrogenic (we caused it) • aldosterone • Water deprivation • Signs & Sxms • Thirst, sticky tongue • Dry, flushed skin • Fever • Convulsions, irritability
Hypernatremia cont’d • Labs • Serum Na+above 145 mEq/L • Serum Osmolality above 295 mOsm/kg • Urine specific gravity above 1.030 • Treatment • Hypotonic IV solution • or D5W
Urine Na+ Studies • Urine Na+ • Assesses volume status • Aids in diagnosing hyponatremia & acute renal failure • Random normal range = 50 -130 mEq/L • 24 hour = 75-200 mEq/L
Hypokalemia • Causes • Diuretics that “waste” potassium • D, V, & gastric suction • aldosterone • Polyuria, sweating • Iatrogenic – K+ poor solutions • Signs & Sxms • Weakness, fatigue • muscle tone • Hypoactive bowel sounds and distention • Weak, irregular pulse • Paresthesias • SOMETHING ABOUT CARDIAC FUNCTION
Hypokalemia cont’d • Labs • K+below 3.5 mEq/L • ECG abnormalities • Treatment • Oral K+ or IV solution w/K+ • Increased dietary K+
Hyperkalemia • Causes • Renal failure • Fluid vol. deficit • Massive cellular injury (trauma/burns) • Iatrogenic • Potassium “sparing” diuretics • Addison’s disease • Signs & Sxms • Anxiety • Dysrrhythmias • Paresthesia (numbness, pins & needles feeling) • Weakness • Diarrhea
Hyperkalemia cont’d • Labs • Serum K+above 5.0 mEq/L. • ECG abnormalities – can lead to arrest (if too high or too low) • Treatment • Kayexalate • IV Na+ bicarb • IV Ca+ gluconate • Regular insulin and hypertonic dextrose IV • Limit via diet • Possible dialysis
Hypocalcemia • Causes • Rapid admin of blood w citrate • Hypoalbuminemia • Hypoparathyroidism • Vit. D deficiency • Pancreatitis • Stuff that relates back to preexisting conditions • Signs & Sxms • Numbness, tingling of fingers & mouth • Hyperactive reflexes • Tetany- a muscle contraction that stays contracted • Muscle cramps • Pathological fractures
Hypocalcemia cont’d • Labs • Serum Ca++below 4.5 mEq/L • ECG abnormalities • Treatment • Increase dietary intake • IV calcium gluconate • Ca+ & vit D supplements
Hypercalcemia • Causes • Hyperparathyroidism • Osteometastasis • Paget’s disease • Osteoporosis • Prolonged immobilization • Signs & Sxms • Anorexia, N & V • Weakness, lethargy • Low back pain (stones) • Decreased LOC • Personality changes • Cardiac arrest
Hypercalcemia cont’d • Labs • Serum Ca++above 5.5 mEq/L • X-rays showing osteoporosis • Stones & BUN / creatinine fr. FVD or renal damage • Treatment • Lasix (diuretic) • Increased fluids
Hypomagnesemia • Causes • Inadequate intake • Alcohol, Malnutrition • Inadequate absorption • V&D, Gastric aspirate • Fistulas, Sm. Bowel • Loss fr. Diuretics • Polyuria • Signs & Sxms • Tremors • Hyperactive deep tendon reflexes • Confusion • Dysrhythmias
Hypomagnesemia cont’d • Labs • Serum Mg++below 1.5 mEq/L • Treatment • Mag sulfate IV • Oral replacement • Increase dietary intake
Hypermagnesemia • Causes • Renal failure • Excess intake of magnesium • Signs & Sxms • Most frequently seen in acute • Hypoactive deep tendon reflexes & drowsiness • Decreased depth and rate of resp. • Hypotension • flushing
Hypermagnesemia cont’d • Labs • Serum Mg++ levels above 2.5 mEq/L • Treatment • IV calcium gluconate • Loop diuretics • NS or LR IV solutions • Dialysis
Additional Lab Data • Hematocrit • Measures the volume % of RBC’s in whole blood • Normal: M = 40-50%; F = 37-47% • Increases with dehydration (hemoconcentration) • Decreases with overhydration (hemodilution)
Hematocrit & Fluid Volume StatusFrom “Fluids & Electrolytes Made Incredibly Easy” 4th ed. Fluids & Electrolytes Made Incredibly Easy
Lab Data (cont’d) • Blood urea nitrogen (BUN) • Measures kidney function • Normal range: 7-20mg/dL • Varies with protein intake, fever, dehydration, GI bleeding, liver failure, etc.
Lab Data (cont’d) • Creatinine • End product of muscle metabolism • Better indicator of renal function than BUN • Doesn’t vary w protein intake or metabolic state • Normal range: 0.7-1.5mg/dL in 24 hr urine collection • Serum: adult female: 0.5 to 1.1mg/dL adult male: 0.6 to 1.2mg/dL
Lab Data (cont’d) • Urine Specific Gravity • Measures ability of kidney to excrete or conserve water • Normal range = 1.010 - 1.025 • Increased S.G.= concentrated urine • Decreased S.G.= dilute urine
Lab Data (cont’d) • Serum Osmolarity • Most accurate for kidney function • Remember norm? • 280-295 mOsm/L • Measured directly through blood • Indirectly using Serum Osmolarity Formula
Fluid Imbalances • Isotonic • Deficit – water, electrolytes and solutes lost in equal proportions to body solutions • Excess – water, electrolytes and solutes gained in equal proportions to body solution • FVD - fluid volume deficit-HYPOVOLEMIA • FVE - fluid volume excess-HYPERVOLEMIA