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119 Cards in this Set
- Front
- Back
What is ICF?
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intracellular fluid, the volume of fluid inside all cells
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What is ECF?
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extracellular fluid; the volume of fluid outside cells: intravascular volume (plasma) and interstitial (space between capillaries and cells)
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What percentage of the total body weight is fluid in the ICF?
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40%
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What percentage of the total body weight is fluid in the ECF?
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20% (16 in interstitial, 4 in plasma)
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What is the pressure needed to prevent water from passing through a semi-permeable membrane?
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oncotic pressure
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What term describes when a solution has equal amounts of water on both sides of a membrane with the same total concentration of solute particles?
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isotonic
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What maintains intravascular osmotic pressure?
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Sodium
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What maintains intracellular osmotic pressure?
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Potassium
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What is the equation for calculating osmolality?
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2(plasma Na) + (glucose/18) + (BUN/2.8)
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What is normal blood osmolality?
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276-295 mOsm/kg
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What are the two conditions that effect fluid balance?
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Change in blood osmolality and change in blood volume
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What controls changes in blood osmolality or volume?
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hormones
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What are the steps to normalizing osmolality in a fluid volume decrease?
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1.When fluid volume decreases in the intravascular compartment, Na concentration (osmolality) increases.
2.Increased Na concentration causes Pituitary to release anti-diuretic hormone (ADH) 3.ADH stimulates kidney to re-absorb more water into intravascular compartment. 4.Blood volume and serum Na return to normal 5.Decreased osmolalityturns off ADH, kidneys excrete more water in urine. |
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What happens when blood volume decreases to reach normalization?
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1. Decreasedblood volume:
a.Turns on Renin-Angiotensin-Aldosteronesystem (RAAS) b.Angiotensinis a vasoconstrictor –increases blood pressure c.Aldosteroneincreases kidney re-absorption of Na and water to increase blood volume. |
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What happens when blood volume increases to reach normalization?
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2. Increasedblood volume:
Stimulates atrialnatriuretichormone which causes kidney to excrete more Na and water to decrease blood volume |
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What system does decreased blood volume turn on?
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Renin-Angiotensin-Aldosterone system (RAAS)
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What is angiotensin?
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vasoconstrictor - increases blood pressure
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What does aldosterone do?
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increases kidney reabsorption of Na and water to increase blood volume
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What does increased blood volume stimulate the production of?
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atrial natriuretic hormone
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What does atrial natriuretic hormone do?
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causes kidney to excrete more Na and water to decrease blood volume
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What are the sources of fluid intake?
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IV fluids, medications given via IV drip, water flushes given with crushed medications, water flushes to keep tubes patent (?), water contained in tube feedings or TPN, oral intake
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What are the sources of fluid output?
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urine/stool, nasogastric tube suction, chest tubes, percutaneous drains, wound drainage, ostomies, fistulas, insensible losses, accelerated insensible losses (burns, tracheostomies, fever)
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What are some common conditions that increase body volume?
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heart failure, renal failure, liver failure (due to decreased albumin), sepsis (due to capillary leak), excessive sodium intake
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What are some conditions that decrease body volume?
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diarrhea, vomiting, increased sweating, diuretic drugs
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What is the definition of hypernatremia?
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plasma Na above 145 mEq
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What is the definition of hyponatremia?
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plasma Na below 135 mEq
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What is the definition of hyperkalemia?
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plasma K above 5 mEq
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What is the definition of hypokalemia?
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plasma K below 3.5 mEq
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What values are included in a BMP?
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Na, K, Cl, CO2, Ca, BUN, Cr
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Are phosphorus and Magnesium included in a BMP?
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no, must be ordered separately
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What does a BUN to Cr ratio of > 20 suggest?
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dehydration
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What is the risk if total protein and albumin is low?
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risk for 3rd spacing of fluid is increased
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What are the normal lab values for Sodium?
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135-147 mEq/L
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What are the normal lab values for Potassium?
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3.5-5mEq/L
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What are the normal lab values for Chloride?
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95-107 mEq/L
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What are the normal lab values for Bicarb?
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22-26 mEq/L
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What are the normal lab values for Glucose?
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60-110mg/dL
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What are the normal lab values for BUN?
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7-21 mg/dL
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What are the normal lab values for Creatinine?
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0.5-1.4mg/dL
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What are the normal lab values for calcium?
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8.8-10.3 mg/dL
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What are the normal lab values for phosphorus?
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2.5-4.5 mg/dl
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What are the normal lab values for magnesium?
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1.6-2.4 mEq/L
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What are the treatment goals in choosing IV fluids?
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1.Hemodynamic stability
2.Optimal oxygen delivery 3.Fluid balance without edema 4.Correct electrolytes22 |
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What is the HR and BP in euvolemic?
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normal
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What IV fluid should be give in euvolemic condition?
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D5 1/2NS with KCL 20mEq/L; needs isotonic maintenance fluid that will distribute equally to all compartments at a rate the keeps intake=output
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What is the current weight in euvolemic?
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normal
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What is another term for dehydrated?
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hypovolemic
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What is the HR in hypovolemic?
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increased HR
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What is the BP in hypovolemic?
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decreased BP
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What fluid should be used in hypovolemic?
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isotonic fluid until euvolemic (eg 0.9% sodium chloride)
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What are the s/sx for hypovolemic/
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thirsty, dry mucus membranes, altered mental status
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What can cause volume depletion leading to hypovolemic condition?
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gi bleed, trauma, excessive diarrhea
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What is another name for fluid overloaded?
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hypervolemic
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What can cause hypervolemic condition?
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CHF, Pulmonary Edema, Cirrhosis
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What fluid should be given for hypervolemic condition?
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None; need to remove water from interstitial space, limit sodium, minimal maintenance fluid, may need to use diuretic to get Output > Input
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What are crystalloids?
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electrolyte containing IV fluids; sodium content determines into which compartment the fluid distributes
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What are colloids?
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blood products, albumin, plasma proteins, dextran; contain high molecular weight molecules, stay in intravascular compartment
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Which crystalloid has the same NA concentration and osmolality as plasma, has no movement of water across the cell membrane, and distributes to intravscular and interstitial space but not intracellular?
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isotonic - 0.9% NaCl
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Which crystalloid has less Na concentration and less osmolality than plasma, approximately 10% stays in the IV compartment and 90% distributes to interstitial and intracellular space, not good for resuscitationn but good for maintenance fluid?
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Hypotonic - 0.45% NaCl, D5 1/2NS
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Which crystalloid pulls water from interstitial and intracellular space into intravascular, primarily used for cerebral edema?
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hypertonic - 3% NaCl, mannitol
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What effect do colloids have on ECF/ICF fluid distribution?
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draw water from the interstitial space to expand the intravascular compartment; the amt of water pulled from the interstitial space is greater than the volume infused
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Where is the place in therapy for colloids?
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anaphylaxis, shock, Acute Respiratory Distress Syndrome (ARDS), multi-organ failure
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How much fluid should a pt receive per day?
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30-35 ml/kg
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What are the two categories of hyponatremia?
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Hypertonic hyponatremia (10%) and hypotonic hyponatermia (90%)
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What are the three types of hypotonic hyponatremia?
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hypervolemic hyponatremia, euvolemic hyponatremia, hypovolemic hyponatremia
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What is the condition in which Na and water are both increased but water more than Na so that Na appears low?
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Hypervolemic hyponatremia
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What are the medical conditions associated with Hypervolemic Hyponatremia?
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CHF, cirrhosis, acute or chronic renal failure
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If a pt is hypervolemic hyponatremia with a fluid restriction and npo what should be used for fluid?
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0.9% NaCl at rate of 1000 to 1500ml/d
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What is the condition in which pt has normal Na but increased total body water, so serum Na appears low?
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euvolemic hyponatremia
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What are the common causes of Euvolemic Hyponatremia?
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SIADH, hypothyroidism, surgery, some drugs (NSAIDS)
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What is the tx for Euvolemic Hyponatremia?
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fluid restrict to 250-500ml/d using 0.9% NaCl and add diuretic
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What is the condition in which the pt has decreased Na and decreased total body water but more Na than water has been lost?
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hypovolemic hyponatremia
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What are the common causes of hypovolemic hyponatremia?
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vomiting, diarrhea, hyperglycemia, thiazide diuretics
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What does pt require with hypovolemic hyponatremia?
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volume expansion and Na replacement; use 0.9% NaCl calculated by formula; be sure to monitor urine output as ECF fluid replacement may inhibit ADH resulting in significant diuresis that can increase serum Na too fast
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What is the formula for estimating change in plasma sodium?
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(IVna-Sna)/(BW+IVvol); IVna= Na conc of IV fluid, BW= body water, Sna=serum NA, IVvol= 1L; BW =0.6X weight for men and children < 70Kg, 0.5X weight for men >70kg and women <77kg, 0.45X weight for women ?70kg
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What are the rules for correcting hyponatremia?
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If serum Na > 120, correct at rate not > 12 meqin 24 hours until symptoms resolved; If serum Na < 120, correct more rapidly until 120 mEq; infusion rates of > 250 ml/h should be reserved for emergencies (pulmonary edema or CHF)
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What can happen when correcting serum Na faster than 12 mEq/24h?
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osmotic demyelination syndrome due to rapid shift of water from the brain
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What condition is characterized by a serum Na of > 145 mEq/L and increased osmolality?
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hypernatremia (rare)
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What are the common causes of hypernatremia?
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diabetes insipidus (lack of adh), fever with lack of water
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What pts is hypernatremia most common in?
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infants and elderly
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What is the treatment for hypernatremia?
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use 0.9% NaCl if BP is low, otherwise use 0.45% NaCl and correct 0.5 to 1 mEq/h
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What serum Na results in a 75% mortality rate?
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> 160 mEq/L
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When does serum K increase?
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with hyperglycemia and acidosis
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When does serum K decrease?
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with alkalosis and low magnesium
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How much KCl shoud be given to raise serum K by 0.1mEq?
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10 mEq KCl
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Which route of administration is preferred in K replacement?
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oral, given IV if patient is NPO, EKG changes, muscle weakness, Cardiac patient or on Digoxin
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What is the max infusion rate of K if not on monitor?
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10mEq/h
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What is the max infusion rate of K if on monitor?
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20 mEq/h
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What is the minimum volume KCl must be diluted in?
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50ml
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What is a K run?
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10mEq KCl in 50 ml D5W over 1 h
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What should be monitored during K replacement?
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magnesium, replace simultaneously if low
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When should serum K be rechecked?
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after 40mEq of K infusion
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What is the role of magesium in electrolyte balance?
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plays significant role in renal absorption of potassium
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Where is most Mg stored?
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bone
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What are common causes of hypomagnesemia?
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decreased absorption (malnutrition, alcohol, NG tube) and increased renal excretion (hypercalcemia, diuretics, Amphotericin B, aminoglycosides)
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If a patient is asymptomatic, what should the replacement of magnesium be?
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0.5 to 1 g/h
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If pt is symptomatic/seizures and has Magnesium < 1, what should the replacement be?
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2g in 6 ml NS over 1 min, then infusion of 0.5mEq/kg over 6 h
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If Mg is <1.4 how should the replacement be?
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2g over 4h x2
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If Mg is 1.5 to 1.7 how should the replacement be?
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2g over 4 h
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If Mg is 1.8 to 2 how should the replacement be?
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1g over 4 h
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What is pre-eclampsia?
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sever high B/P during pregnancy
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What is eclampsia?
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high B/P with seizures during pregnancy
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What is the treatment for eclampsia?
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magnesium 6g bolus then continuous infusion of 2g/h to prevent and treat seizures, also slows pre-term labor
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What is the purpose of phosphorus in the cell?
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Synthesis of ATP, modulates oxygen carrying capacity of hemoglobin, metabolism of carbohydrates, fat, and protein; critical element in cell membranes
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What is the tx if a patient has serum phosphorus of <1.5?
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stop dextrose solutions, 0.5mm/kg NaPhos in D5W 250ml over 4h
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What is the tx if a patient has serum phosphorus 1.5-2?
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0.25mm/kg NaPhos in D5W 250ml over 4h
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What is the tx if a patient has serum phosporus 2.1-2.4?
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0.15mm/kg NaPhos in D5W 250ml over 4 h
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When can KPhos be used instead of NaPhos?
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for phosphate replacement if K is also low; do not exceed 10 mEq K / h
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What is in 1 ml stock solution of NaPhos?
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3mm Phos, 4 mEq Na
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What is in 1 ml stock solution of KPhos?
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3mm Phos, 4.4 mEq K
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What does refeeding syndrome cause?
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hypophosphatemia; phosphate is taken up rapidly into cells with glucose when glucose is given to malnutritioned pts
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What are the problems with hypophosphatemia?
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limits oxygen unloading, immunocompromise, muscle weakness (leading to failure to wean from ventilator)
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What is the tx for hypophosphatemia?
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IV supplementation in emergent cases, PO supplementation routinely, keep (phos X calcium) product < 60, mag should be replenished simultaneously
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Where is calcium stored?
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bone
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What processes is calcium important for in the body?
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cardiac function, neuromuscular function, blood coagulation
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What is Ca level dependent on?
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parathyroid hormone, Vit D, calcitonin
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What is the corrected calcium equation?
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Corrected Ca= (4-Albserum)x0.8)+Caserum
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What is the replacement dose of calcium?
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1 to 2 g of calcium gluconate in D5W 50ml over 1 h
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What should be checked before replacing Ca?
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phosphate level as serum Ca X phos should not be > 60
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