Fluids and Electrolytes Flashcards
major extracellular electrolytes
Sodium (142 mEq/L), Chloride (103 mEq/L), Calcium (2.4 mEq/L)
Bicarb (28 mEq/L)
major intracellular electrolytes
Potassium (140mEq/L), Magnesium (58 mEq/L), Phosphate (74 mEq/L)
% extracellular body water
1/3 (33%)
% intracellular body water
2/3 (67%)
% body water for an adult male
60%
% body water for an adult female
50%
% body water for an elderly male
50%
% body water for an elderly female
45%
what weight should be used to estimate total body water in obesity
ideal body weight
insensible water gains
water oxidation of metabolism (250mL)
total water gain in healthy adult
1.5-2.5 Liters
sensible water gains
oral fluid intake (800 mL to 1.5 L) and water from solid foods (500-700mL)
total water loss in healthy adult
1.5-2.5 liters
sensible water loss
urine output (800-1.5 L) and GI output (0-250mL)
insensible water loss
skin (600-900mL) and lungs
Where does fluid gain occur during digestion
saliva, food/drink, bile, pancreatic fluid, small bowel fluid, gastric fluid
how much water is reabsorbed total from digestion
6.5 Liters
how much fluid is created daily from saliva
1.5 Liters
how much water is gained total from digestion
8.5 liters
the stomach typically produces _____ L of fluid
2 liters
how much fluid is reabsorbed in the colon
1.9 liters (out of 2)
a patient has tented/dry skin, with dry mucous membranes, has increased heart beat (tachycardia), decreased blood pressure and urinary sodium above 20 they are likely
dehydrated
how to calculate fluid maintenance (adults and children over 5 years old)
4,2,1 or 100,50,20 method
calculate fluid maintenance for a 60 kg male (4,2,1 method)
4mL x 10 kg = 40mL/hr
2mL x10 kg = 20mL/hr
1mL x 40kg = 40mL/hr
Total 100mL/hr x 24 hours = 2.4 Liters
calculate fluid maintenance for a 60 kg male (100,50,20 method)
100mL x 10 kg = 1000mL
50mL x 10kg = 500 mL
20mL x 40 kg= 800 mL
Total = 2300mL/day
Fever, excessive sweating , hyperventilation and hyperthyroid _____ fluid needs
increase
abnormal shifts of fluid from the intravascular space (blood vessels) into the interstitial fluids (the tissues)
Edema
common causes of edema
decreased cardiac output, hypotension, decreased urine output
when you have edema, you are considered in a state of water
loss
conditions that can cause 3rd spacing
bowel obstruction, peritonitis, acute pancreatitis, ascites in liver/renal function, trauma
isotonic IV fluids
Normal Saline with Dextrose or balanced crystalloids (LR, plasmalyte)
should post op major abdominal surgical patients have liberal or restricted fluids in the 1st 24 hours post op
liberal fluids to prevent AKI
water deficit calculation
(Current Na - Desired Na / Desired Na) x %body water x body weight (kg)
Causes of primary hypervolemia
poor renal function leading to sodium retention and extracellular fluid expansion to preserve blood pressure
causes of secondary hypervolemia
CHF, cirrhosis, excessive IV administration
symptoms of hypervolemia
weight gain, edema, ascites, pulmonary effusion, rales, distended jugular veins
the primary extracellular cation is
sodium
the primary anion of the ECF is
chloride
the primary cation of the ICF is
potassium
the primary anion of the ECF is
phosphate
non-electrolyte components of body fluids that do not dissociate in solution are
glucose, urea and creatinine
when levels of cations and anions are in equal amounts is called
electroneutrality
electroneutrality is maintained by
buffering systems
a patient that has high loses via NG suction of about 2L a day would likely benefit from the replacement of ___ to maintain homeostasis
chloride
if a patient has high losses from diarrhea they would likely benefit from the replacement of ____ to maintain homeostasis
bicarb, alkaline solutions
the most common cause of hypernatremia
inappropriate/inadequate provision of fluids
increased blood glucose of hypertonic sodium free IV fluids can cause
hypertonic hyponatremia
when glucose is high, sodium will be artificially low because
hyperglycemia is a hypertonic state intracellular water shifts out from inside the cell into the vascular space causing dilutional hyponatremia
for ever 100mg/dL increase in serum glucose from normal, serum Na decreases by
1.6 mEq/L
the most common cause of hyponatremia is
excess water provision
sodium is largely regulated by this organ _____ and this hormone_____
kidney, aldosterone (vasopressin)
aldosterone hormone causes ____ to be reabsorbed in the distal renal tubule in response to a change in sodium/volume status
sodium
serum ____ is essential to assess the cause and treatment of low sodium
osmolality
fatigue, weakness and muscle twitching are signs of symptomatic
hyponatremia
Normal Saline (IV) provides ____ sodium per liter
154 mEq/L
Hypernatremia is always associated with a __ state. Free water moves from the ICF to the ECF causing dehydration
hypertonic
dry mucous membranes, hypotension, oliguria, tachycardia and decreased skin turgor are symptoms of
dehydration
calculate the free water deficit of a 70 kg man with a serum sodium of 158
5.4 L (to 140mEq/L) 1.6 L (to 152 mEq/L)
Phosphorous is the primary ____ anion
intracellular
Phosphorous maintains the _____ cellular fluid, normal muscle/nervous function and important in metabolic pathways
intracellular
nervous system dysfunction, respiratory failure, decreased levels of 2,3-diphosphoglycerate and muscle weakness can be caused by
hypophosphatemia
reasons for elevated phosphorous
renal failure, metastatic calcification of soft tissue/blood vessels cellular destruction from trauma, cytotoxic medications, severe rhabdomyolysis
Optimal total serum phos and calcium should be a
55
the most common clinical manifestation of hyperphosphatemia is ___ caused by hypocalcemia d/t calcium phosphate precipitation
tetany
a patient with hypokalemia should also be assessed for what electrolyte
hypomagnesemia (magnesium regulates intracellular potassium)
when hypokalemia co-exists with hypokalemia and hypomagnesemia replete which first
magnesium
the following electrolyte disturbance can cause a deficit of hydrogen ions in the ECF precipitating in alkalosis
hypokalemia (potassium is on the inside of the cell normally, if low, protons will pump in potassium to correct causing a deficit of hydrogen ions into the ECF)
this electrolyte is integrating maintaining cell volume , hydrogen ion concertation, enzyme function, neuromuscular /cardiac function and cell growth
potassium
clinical manifestations of hypokalemia
cardiac arrhythmia, muscle weakness, ileus, EKG changes and paralysis
renal failure, rhabdomyolysis and acidosis can all cause
hyperkalemia
common causes of hypomagnesemia (3)
inadequate GI absorption, refeeding syndrome and DKA
DKA lowers serum hypomagnesemia because
- increased renal excretion during diuresis from high blood glucose
- shifting of magnesium into the cells by insulin
when maintained slightly above normal serum concentrations, which of the following electrolytes reduces the amount of potassium required in critically ill patients
magnesium
a patient getting a standard enteral feeding constantly has a magnesium level of 3.0 mEq/L. A prudent first step would to be
ensure that medications with supplemental magnesium have been held
causes of hypermagnesemia
renal failure ,excessive use of laxatives’ as they contain large amounts of magnesium (milk of magnesia)
low levels of serum calcium stimulates the release of this hormone which increases bone resorption, stimulates renal conservation of calcium and activates vitamin D (in turn increasing the absorption of calcium in the GIT)
parathyroid hormone
in response to elevated levels of serum calcium, the ____ releases ___ hormone which inhibits bone resorption
thyroid, calcitonin
Adjust the calcium for a patient with an albumin of 2.4 and calcium of 6.9
8.2
in the absence of excessive exogenous provision of calcium in a patient with normal renal function, the most common cause (s) of hypercalcemia are
hyperparathyroidism and bone cancer
decreased vitamin D, decreased PTH activity after thyroidectomy/parathyroidectomy, massive soft tissue damage 2/2 trauma ,infection , or multiple blood transfusions 2/2 citrate binding of this element causes _____
calcium, hypocalcemia
in the setting of critical illness or injury, a patient has decreased UOP, hypotension, tachycardia, high urinary specific gravity, high osmolality, elevated Cr, poor skin turgor with minimal if any changes in body wt. The clinician should consider this change in body fluid
third spacing
Third spacing and critical illness/trauma
traumatic injury results in redistribution of intravascular fluid into the area of injury, therefore decreasing intravascular fluid volume, Sepsis produces generalized capillary leak, causing larger molecules such as proteins to readily pass through membranes, precipitating a disruption of oncotic pressure allowing the ICF to leak out of the cells
what are therapies used for standard care to treat third spacing
IV LR/normal saline, blood transfusion, correction of underlying cause
the most appropriate enteral formula for a patient with SIADH is
a concentrated formula (low in water)
the syndrome of inappropriate antidiuretics hormone (SIADH) is likely to present as
hyponatremia
hallmark signs of SIADH
low sodium, increased urine sodium and increased osmolarity
Euvolemic body with total body water overload d/t inappropriate concentration of the urine
SIADH
elevated serum sodium, flat neck veins, dry mucous membranes are signs of
dehydration
the preferred oral rehydration solution should be/contain
isotonic, with sodium and glucose/carbohydrate
oral rehydration solutions decrease _____ in short bowel syndrome
dehydration
this type of fluid is readily absorbed from the jejunum
sodium chloride
saline water is not absorbed well from commercially available rehydration solutions because they are hypotonic true or false
true
optimal sodium level (in mmol/L) of sodium in oral rehydration solutions
90mmol/L
____ in oral rehydration solutions is an important component because it promotes sodium/water absorption by acting as a transporter
glucose
this disorder is represented by hypernatremia with high urine output from 4-12L /day
Diabetes Insipidus
electrolyte abnormalities after feeding after starvation is called
refeeding syndrome
in the early phase of refeeding syndrome excessive sodium and fluid intake causing
fluid overload, pulmonary edema, cardiac decompensation
the three labs depleted in refeeding syndrome
hypomagnesemia, hypophosphatemia, hypokalemia
chronic starvation/alcoholism, anorexia/malabsorption, morbid obesity with weight loss and AIDS/Cancer patients are all at risk for
refeeding syndrome
A cachectic 42 year old F is re admitted 2 weeks s/p ex lap with post op SBO. She has lost an additional 8% of her body weight since her first admit to the hospital. She undergoes surgical repair of the obstruction and has a naso-enteric feeding tube placed in the OR. Upon initiation of nutrition support which of the following would be a major concern
refeeding syndrome
a patient getting normal saline at 75mL/hr with 20mEq KCl/L provides how many mE1 of sodium and _ mEq potassium chloride
154 mEq sodium (154 x 1.8)
36 mEq potassium (20 X 1.8 )
Lactated Ringers fluid is most similar to ____ fluid
jejunal fluid
Electrolytes of the GI tract Jejunum (Na, K, Cl, Bicarb)
Sodium: 95-120 mEq/L
Potassium: 5-15 mEq/L
Chloride: 80-130 mEq/L
Bicarb 10-20 mEq/L
Electrolytes of the GI tract Ileum (Na, K, Cl, Bicarb)
Sodium: 110-130 mEq/L
Potassium: 5-15 mEq/L
Chloride: 90-110 mEq/L
Bicarb: 20-30 mEq/L
Electrolyte Composition of Lactated Ringers
Na: 130 mEq/L Potassium: 4 mEq/L Chloride: 109 mEq/L Lactate: 28 mEq/L Calcium 2.7-7.7 mEq/L
1/2 Normal Saline (0.45%) provides ___ mEq of sodium and ___ mEq of chloride
77 mEq sodium
77 mEq chloride
Normal Saline (0.9%) provides __ mEq/L of sodium and __ mEq/L of chloride
154 mEq sdoium
154 mEq chlroide
D5W + 1/2 Normal Saline (0.45%) provides ___g/L dextrose, ___ mEq/L Sodium, and ___ mEq/L chloride
50 g/L dextrose
77mEq/L sodium
77mEq/L chloride
