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41 Cards in this Set
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Electrolytes |
Chemicals that conduct electricity when dissolved in water. Ex: sodium, potassium, calcium, magnesium, acids & bases. |
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Nonelectrolytes |
Do not conduct electricity. Ex: glucose & urea. |
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Body Water % |
60% = young adults 50% = older adults 70%-80% = infants |
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Interstitial Fluid |
Water that surrounds the body's cells & includes lymph. |
Type of extracellular fluid |
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Intravascular Fluid (Blood Plasma) |
Fluid within arteries, veins and capillaries. Fluids & electrolytes move between the Interstitial fluid & Intravascular fluid. |
Type of extracellular fluid. |
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Transcellular Fluid |
Those in specific compartments of the body, such as cerebrospinal fluid, digestive juices & synovial fluid in joints. |
Type of extracellular fluid. |
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Diffusion (passive transport) |
Mvt of a substance from an area of higher concentration to lower concentration. Body mvts cause this to occur faster. |
Pouring cream into coffee & stirring it. |
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Filtration (passive transport) |
Mvt of both water & smaller molecules through a semipermeable membrane (like a screen that keeps larger substances on one side & permits only smaller molecules to filter in to the membrane). |
Promoted by hydrostatic pressure differences between areas. |
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Osmosis (passive transport) |
Mvt of water from an area of lower substance concentration to an area of higher concentration. The substances exert an osmotic pressure sometimes called water-pulling pressure. |
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Adenosine Triphosphate (ATP) (active transport) |
Sodium-Potassium pumps. Located in cell membranes, cause sodium to move out of the cells & potassium to move into the cells when needed. |
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Osmolarity |
Concentration of the substances in body fluids. Normal osmolarity of blood is 270-300 milliosmoles per liter (mOsm/L). |
Another term is tonicity. Such as isotonic, hypotonic or hypertonic. |
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Common Causes of Dehydration |
Cecostomy Diabetes insipidus Diarrhea Diuretic therapy Draining abscesses Fever Frequent enemas Gastrointestinal suction Hemorrhage Ileostomy Long-term (npo) status Profuse diaphoresis Severely draining wounds Systemic infection Vomiting |
Elevated (BUN) & elevated hematocrit |
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Hypovolemia |
Decreased blood volume. Occurs when the pt is hemorrhaging or when fluids from other parts of the body are lost. Can also occur when fluid from the intravascular space moves into the interstitial fluid space, a process called third-spacing. |
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Conditions Common w/ Third-Spacing |
Burns, liver cirrhosis, & extensive trauma. |
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Pt w/ dehydration lab values |
Pt usually has elevated BUN level & hematocrit. Both are increased because there is less water in proportion to solid substances being measured. Specific gravity of urine also increases due to the kidneys attempt to conserve water. |
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Pt w/ fluid overload lab values |
BUN & hematocrit values tend to decrease due to hemodilution. The plasma content of the blood is increased compared to solid substances. The specific gravity of the urine also diminishes as urinary output increases. |
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Sodium Imbalances |
Normal level of serum sodium is 135-145 mEq/L. Because sodium is the major cation in the blood it helps maintain serum osmolarity. Sodium is important for cell function especially in the CNS. SODIUM imbalances are often associated w/ fluid imbalances. |
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Hyponatremia |
When serum sodium level is <135 mEq/L. Can be either actual or relative. In actual pt has has inadequate intake of sodium or excessive sodium loss from body. In relative decrease sodium is not lost from the body but may leave intravscular space & move to interstitial tissues (third-spacing). Relative cause can also occur when plasma volume increases (fluid excess) causing a dilution effect. |
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Hypernatremia |
When serum sodium is >145 mEq/L. May be actual or relative. In actual pt receives too much sodium or is unable to excrete sodium as seen in renal failure. In relative the amount of sodium does not change but the amount of fluid in the intravascular space decreases. In mild Hypernatremia most excitable tissues (muscle & neurons of the brain) become more stimulated. Pt becomes irritable & has tremors. In severe cases these tissues fail to respond. |
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Hypernatremia Complications |
May cause muscle twitches & unusual contractions later followed by skeletal muscle weakness that can lead to respiratory failure of it affects the diaphragm. Pt may become comatose or go into respiratory distress as skeletal muscles weaken. |
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Potassium Imbalances |
Most common electrolyte in the ICF compartment. Only a small amount 3.5-5 mEq/L is found in bloodstream. Important for cardiac muscle, skeletal muscle, & smooth muscle function. Hypokalemia is the most commonly occurring imbalance. |
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Hypokalemia |
Level <3.5 mEq/L. Inadequate intake of potassium or excessive loss of potassium through the kidneys. Most often occurs as a result of medications. Potassium may also be lost through the GI tract which is rich in potassium & other electrolytes. Vomiting, diarrhea & prolonged GI suction can cause Hypokalemia. |
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Hypokalemia Complications |
Pts. receiving Digitalis must be closely monitored. Muscle cramping or weakness can occur. Vital signs change, diminished skeletal muscle activity result in shallow ineffective respirations. Pulse is weak & thready & irregular which is a major danger due to dysrhythmia which can lead to cardiac arrest. Orthostatic hypotension may also be present. Nervous system is affected causing changes in mental status followed by lethargy. Motility of the GI is slowed causing nausea, vomiting, constipation & abdominal distention. |
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Dx Tests for Hypokalemia |
Serum potassium. ECG may show cardiac dysrhythmias associated with potassium deficit. Pt may also have an acid-base balance called metabolic alkalosis (serum pH of blood is >7.45). |
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Tips for pts taking oral potassium supplements |
°do not substitute one potassium supplement for another °dilute powders & liquids in juice or other desired liquid to avoid GI upset & improve taste °do not drink diluted solutions until mixed thoroughly °do not crush tablets such as slow-k or k-tab tablets. °take slow release tabs w/ 8oz of water to help dissolve °do not take potassium supplements of taking potassium sparing diuretics such as spironolactone & triamterene °do not use salt subs w/ potassium unless instructed by HCP °Take supplements w/ meals °report nausea, vomiting, diarrhea & abdominal cramping to HCP °have frequent lab testing of serum potassium levels as recommended by HCP |
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Hyperkalemia |
Serum potassium is >5 mEq/L. Rare in a person w/ healthy kidneys. May result from an actual increase in amt of total body potassium or from mvt of intracellular potassium into the blood. Can be caused from overuse of potassium based salt subs, excessive intake of oral or IV potassium supplements. Use of potassium sparing diuretics (spironolactone) may also contribute. Pts w/ renal failure are at risk because the kidneys can't excrete excess potassium. Mvt of potassium from the cells into the blood & other ECF is common in massive tissue trauma & metabolic acidosis (acid base imbalance commonly seen in pts w/ uncontrolled diabetes mellitus). |
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Complications of Hyperkalemia |
Most cases occur in pts who are hospitalized or undergoing therapeutic measures for a chronic condition. Muscle twitches, cramps, muscular weakness, increased GI motility (diarrhea), slow irregular HR, & decreased BP. Cardiac dysrhythmias & respiratory failure can occur & lead to death. |
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Dx of Hyperkalemia |
Elevated potassium level, irregular ECG, if the pt also has metabolic acidosis the serum pH falls below 7.35. For pts w/ renal problems a cation exchange resin such as sodium polystyrene sulfonate (kayexalate) is administered either orally or rectally. This drug releases sodium & absorbs potassium for excretion through the feces & out the body. Cases which cellular potassium has moved into the bloodstream administration of glucose & insulin can facilitate the mvt of potassium back into the cells. During tx of moderate to sever Hyperkalemia the pt should be hospitalized & on a cardiac monitor. |
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Calcium Imbalances |
Mineral that is primarily stored in bones & teeth. A small amount is found in ECF. Normal serum calcium is 9-11 mg/dL or 4.5-5.5 mEq/L. Calcium is needed for the proper function of excitable tissues, especially cardiac muscle. |
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Pts at risk for Hypocalcemia |
When serum calcium is <9 mg/dL or 4.5 mEq/L. Calcium deficits can be chronic or acute, most pts develop as a result of chronic disease or poor intake. The woman who is postmenopausal is most at risk. Immobility or decreased mobility contributes to bone loss. Hypocalcemia can result from inadequate absorption of calcium from the intestines as seen in pts w/ Chrons disease (chronic inflammatory bowel disease). Insufficient intake of Vit D prevents calcium absorption. Conditions that interfere w/ the production of parathyroid hormone (partial or complete surgical removal or thyroid or parathyroid) can also cause Hypocalcemia. Pts w/ hyperphosphatemia (usually those w/ renal failure) often experience Hypocalcemia. Calcium & phosphate have an inverse relationship (when one electrolyte increase the other decreases). |
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Preventing Hypocalcemia |
AI of calcium for adults 19-50 is 1000mg. AI for adults over 50 is 1200 mg. An inexpensive source of calcium for pts who do not require Vit D supplements is calcium carbonate (Tums) which provides 240 mg of elemental calcium in each tab. Vit D supplementation may be required in addition to calcium for pts whose sun exposure is limited. |
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Sx of Hypocalcemia |
Chronic Hypocalcemia is usually not diagnosed until the pt breaks a bone (usually a hip). Acute Hypocalcemia which can occur in pts w/ acute pancreatitis or pts who had surgery (increased & irregular HR, mental status changes,hyperactive deep tendon reflexes, increased GI motility including diarrhea & abdominal cramping). Two classic signs are Trousseaus sign & Chvosteks sign. |
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Complications of Hypocalcemia |
In severe cases neuromuscular irritability can lead to tetany (continuous muscle contraction). The pt may have a sudden laryngospasm (will stop air from entering lungs). Seizures, respiratory failure or cardiac failure can lead to death. |
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Dx of Hypocalcemia |
Lowered serum calcium, abnormal ECG, the parathyroid level may be increased (attempts to stimulate bone to release more calcium into blood). Calcium supplements should be give 1-2 hrs after meals to increase intestinal absorption. Check compatibility when administering calcium w/ other meds. Pts w/ acute or severe cases iv calcium gluconate or calcium chloride is given. Pts w/ hyperphosphatemia (renal failure) aluminum hydroxide is used to bind the excess phosphate for elimination via GI tract. |
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Hypercalemia |
When serium calcium is >11 mg/dL or 5.5 mEq/L. Chronic cases result from excessive intake of calcium or vit D, renal failure, hyperparathyroidism, cancers, & overuse or prolonged use of thiazide diuretics. Acute cases occur as an emergency in pts w/ invasive or metastatic cancers, especially cancers of the blood or bone. |
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Complications of Hypercalemia |
Pts w/ mild or slowly progressing cases may have no obvious signs or symptoms. Acute cases are associated w/ increased HR, increased bp, skeletal muscle weakness & decreased GI motility. In some cases pt may experience renal or urinary calculi (stones) resulting from buildup of calcium. In more severe cases pt may experience respiratory failure caused by profound muscle weakness or heart failure caused by dysrhythmias. |
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Tx for Hypercalcemia |
Pts w/ severe cases should be in hospital on cardiac monitor. Unless contraindicated the primary Tx is to give large amts of fluids (saline infusions) to promote diuresis. HCP also discontinues thiazide diuretics & prescribes diuretics that promote calcium excretion (lasix). Drugs that slow calcium mvt from bones to good may be used (aredia,zometa,calcitonin). If hypercalcemia is so severe that cardiac problems are present hemodialysis, peritoneal dialysis, or ultrafiltration may be necessary to cleanse the blood of calcium. |
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Magnesium Imbalances |
Magnesium and calcium work together for proper functioning of excitable cells such as cardiac & nerve cells. Normal serum value is 1.5-2.5 mEq/L. |
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Complications of Hypomagnesemia |
Results from either decreased intake or excessive loss of magnesium. Causes of inadequate intake are malnutrition, & starvation diets. Pts w/ severe diarrhea & chrons disease are unable to absorb magnesium in the intestines. One of the major causes is alcoholism which causes decreased intake & increases renal excretion of magnesium. Certain drugs (loop & osmotic diuretics, aminoglycosides & some anticancer agents) can increase renal excretion of magnesium. |
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Sx of Hypomagnesemia |
Similar to those of Hypocalcemia (including Trousseau & Chvosteks sign). Magnesium sulfate is administered iv. If calcium is also low calcium replacement is prescribed. Pt is on cardiac monitor because of magnesiums effect on heart. |
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Hypermagnesemia |
Most common cause is increased intake coupled w/ decreased renal excretion caused by renal failure. Sx are not apparant until levels >4 mEq/L. Then sx include bradycardia, & other dysrhythmias, hypotension, lethargy or drowsiness, & skeletal muscle weakness. If not treated coma, respiratory failure or cardiac failure result. When kidneys are functioning Lasix & iv fluids help excretion. Those w/ renal failure may only benefit from dialysis. |
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