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Flashcards in Fluids- electrolytes Deck (60)
1

Components of body fluid?

- ICF: 2/3 of total body fluid
-ECF: 1/3
ISF, plasma, and lymphatic fluid

2

Electrolytes in ECF and ICF?

- ECF: Na+ (142 mEq/L), Cl- (103 mEq/L), HCO3-
- ICF: K+ (140 mEq/L), Mg, phosphates

3

Water movement regulation?

- starling forces: hydrostatic pressures and osmotic pressures:
Capillary hydrostatic pressure: pressure in capillary pushing fluid out
Interstial fluid hydrostatic pressure: pushing fluid in from ISF
- Osmotic force due to plasma concentration (drawing fluid into capillaries)
- Osmotic force due to ISF protein concentration (drawing fluid out)

4

What is osmolality? What is most important factor?

- concentration of an osmotic soln when measured in osmols of solvent
plasma: 280-295 mOsm/kg
- Na+ is most impt plasma osmolality factor (water follows Na+)

5

Process of fluid and electrolyte replacement? IV solutions?

- assess ins and outs
- oral replacement preferred when tx dehydration
- IV:
saline equivalents: crystalloids - normal saline or LR
water equivalents: D5W
if 3% NS - have to do central line (will destroy peripheral veins)

6

What are the components of LRs?

- 250-273 mOsm/L
- Na+, Cl-, lactate, Ca+, K+

7

Parenteral colloids?

isotonic
- albumin: 290-31- mOsm/L
- blood products:
packed RBCs, fresh frozen plasma

8

Saline: 3%, 5%, D5W1/2NS adverse effects?

- ICF depletion
- fluid overload
- hypernatremia
- hyperchloremia

9

Albumin adverse effects?

- allergic reactions
- possible infection transmission (hepatitis)

10

Impt steps in assessing types of fluid loss?

- pt hx
- sxs
- vital signs and PE

11

What is hypervolemia?

- too much Na+
- expansion of effective arterial blood volume
- CHF, cirrhosis, aldosterone, renal disease

12

WHat is hypovolemia?

- too little Na+
- volume contraction
- dehydration: V/D, exercise, not drinking enough water

13

What is hyponatremia? Hypernatremia? Edema?

hyponatremia:
- too much water
- not enough Na+

hypernatremia:
- too little water (dehydration)
- excess Na+

edema: too much Na+ with water retention in the ISF (abdomen, lungs) - alcoholics, cirrhosis, metastatic cancers

14

Severity of edema?

- 1+ = 2 mm
- 2+ = 4 mm
- 3+ = 6 mm
- 4+ = 8 mm

15

How to tx mild dehydration?

- oral replacement:
fluids with electrolytes are preferred
- avoid fluids with high sugar concentration
- water and sports drink or in children pediolyte
- stop activities that create ongoing losses

16

Assessing degree of fluid loss for moderate hypovolemia?

- hx: any GI losses (V/D), excessive exercise, renal losses
- sx: easy fatiguability, thirst, muscle cramps, postural dizziness, abdominal pain, CP, lethargy, confusion, decreased urination
- clinical manifestations: decreased skin turgor, tachycardia, dry mucus membranes

17

How do electrolyte imbalances present? How do these imbalances occur?

- sxs: precipitate as CV, neuro, and neuromuscular abnormalities
- disruptions occur: via drugs, disease states, diarrhea, vomiting, infection, hormone imbalances, malignancies
- to tx these: need results of lab tests then start IV fluids

18

Etiologies of hyponatremia?

- hypovolemia: GI losses: vomiting, and diarrhea, dehydratioon
renal losses: (thiazide diuretics), ACEIs, mineralocorticoid deficiency
- normovolemia: SIADH, primary polydipsia/marathon runners, low dietary solute intake, psychogenic polydipsia
- hypervolemia: CHF, cirrhosis, nephrotic syndrome, advanced syndrome (rare)
- others: hypothyroidism, primary adrenal insufficiency, drugs

19

What lab values do you want to know for hyponatremia? lab value indications?

hyponatremia is less than 135 meq/L
- serum osmolality impt
- urine Na+
- assess severity:
less or equal to 120 meq/L panic value***
- 120-130: depends on sxs and situations
- greater than 130 is generally not tx

20

Clinical manifestations of chronic hyponatremia?

- cerebral adaption:
going to have fatigue, nausea, dizziness, confusion, lethargy, muscle cramps, gait disturbances and forgetfulness

21

Clinical manifestations of acute hyponatremia?

- acute hyponatremic encephalopathy: cerebral over hydration related to degree of hyponatremia
fatigue an malaise are usually the first sxs
- HA, lethargy, coma, seizures and eventually respiratory arrest
- acute hyponatremic encephalopathy may cause permanent neuro damage or death
- can be hyponatremic classified by ECF status: hypovolemic: GI losses, renal losses (thiazides), normovolemic: SIADH, low Na+ intake, hypervolemic: CHF, cirrhosis

22

How does osmotic demyelination happen?

- try to correct hyponatremia and then you overcorrect making ECF hypernatremic so H2O leaves brain too quickly and it shrinks

23

How can acute hypotonic hyponatremia occur? WHat are the sxs?

- can result in sxs of neuronal cell expansion and cerebral edema
- Nausea/HA, seizure, coma and death

24

Hyponatremia etiologies with inability to suppress ADH problem?

- true volume depletion (GI or renal losses - thiazide diuretics), decreased tissue perfusion (reduced CO or systemic vasodilation in cirrhosis for instance)
syndrome of inappropriate ADH secretion (SIADH)

25

Causes of hyponatremia with appropriate suppression of ADH secretion?

- primary polydipsia
- low dietary solute intake
- advanced renal failure

26

Causes of hypovolemic hyponatremia?

- GI or renal losses
- if serum Na+ hasn't dropped critically low quickly
- usually just volume replacement orally or IV if more severe

27

Tx for hypovolemic hyponatremia?

- NS/isotonic saline
- depending on pt status may do slow bolus
- then maintenance depending on ongoing losses

28

Causes of hypervolemic hyponatremia?

- CHF, cirrhosis, renal failure

29

Tx of hypervolemic hyponatremia?

- restrict fluids: 1000-1200 ml/day
- restrict sodium: 1000-1200 mg/day
- utilize loop diuretics to remove excess fluid, K+ replacement

30

What is SIADH? Causes? Tx?

- too much ADH. Either Eu/hypervolemic hypotonic hyponatremic presentation

can be:
drug induced: carbamazepine, SSRIs, haloperidol, and thorazine

disease induced: malignancies, CNS disorders, post-surgery, pulmonary infections

Tx: tx underlying cause, fluid restriction is mainstay!!!!! May use oral salt tablets, loop diuretics

31

What is the therapy for severe hyponatremia?

- this puts pt at risk for brain herniation
- tx: 3% hypertonic saline:
goal to increase Na+ by 4-6 meq/L in 24 hr period, measure serum Na+ q hr, and measure urine output

32

What risk is there if you correct severe hyponatremia too rapidly? What are the high risk populations?

- develop osmotic demyelination
High risk pops:
- women and children postop period
- pts with hyperacute hyponatremia - psychosis, marathons, ectasy, and those with intracranial pathology

33

hypernatremia: etiologies?

Unreplaced water loss:
- impairment in thirst or access to water
- insensible and sweat losses
- GI losses
- central or nephrogenic diabetes insipidus
- hypothalamic lesions impairing thirst or osmoreceptor fxn:
- primary hypodipsia
- reset osmostat in mineralorticoid excess

water loss into cells:
severe exercise or seizures

sodium overload:
intake or administration of hypertonic sodium solns

34

Acute hypernatremia manifestations?

- rapid decrease in brain volume can rupture cerebral veins leading to focal intracerebral or subarachnoid hemorrhage
- demyelinating brain lesions as seen with overly rapid correction of chronci hyponatremia

35

Chronic manifestations of hypernatremia?

- brain adapts (within a day) by pulling water from the CSF and increasing the uptake of solute by the cells which also increases the amt of water into the cells
- assessment is difficult because most affected adults already have neuro disease diminishing the thirst response

36

Etiology of hypernatremia (greater than 145 meq/L?

- loss of water
- addition of hypertonic soln
- sodium overload

37

Tx of hypernatremia?

- replace free water with D5W, add normal saline soln if hypovolemic - use a seond IV
- if replacing ongoing electrolyte losses (use 0.45% NS possibly with added K+)
- fast onset, less than 24 hrs, decrease by 1 meq/L/hr correction
- insidious is greater than 24 hrs, decrease in serum Na+ by no more than 10 mEq/24 hrs
- monitor serum Na+/K+ closely

38

What is central DI? what is the tx?

- not enough ADH production (tumors, or lesions on the brain)
- tx: desmopression: 10 mcg/day, ADH like activity
- titrate to 10 mcg/bid intranasally, and restrict fluid intake

39

What is nephrogenic DI? Tx?

- kidney resistant to ADH
- tx: thiazide diuretic to decrease ECF and Na+, Na+ restriction (2000 mg/day)

40

How do you tx hypernatremia?

- for hypernatremia from unreplaced water loss:
need to est water deficit
- need to replace ongoing losses, any ongoing GI losses and urine losses
- obligatory losses: sweat and stool
- determin safe rate plasma Na+ can be normalized:
usually less than 0.5 mEq/L/hr or about 10 mEq/day, usually use 0.45% NS with K+
- monitor lytes closely (q 4 hrs)
- overly rapid correction: can lead to cerebral edema

41

What percentage of Ca2+ is bound to albumin? Where is calcium normally found?

- 46%
- each 1 g/dL drop of albumin below 4.5g/dL, decreases serum calcium by 0.8 mg/Dl
- when you look at Ca2+ levels make sure you are looking at albumin levels too if Ca levels are off

- it is an extracellular electrolyte, and it is in an unbound/free fraction active form
- normal serum range (free): 8.5-10.5 mg/dL

42

Etiologies of hypercalcemia?

- greater than 10.5
- cancer and primary hyperparathyroidism (primary causes
- drugs: thiazide diuretics, calcium supplements, lithium

43

Sxs of hypercalcemia? What can occur if left untx?

EKG changes
N/V, anorexia, constipation
polyuria/dypsia
neuro/psych sxs

- if left untx:
metastatic calcification, nephroliathisis, renal failure

44

Outcome and tx of hypercalcemic crisis?

- outcome: oliguric renal failure, coma, v-arrhythmias, death
- tx: saline and loop diuretics: 2-3 mg/dL, drop in 24-48 hrs
bisphophonates: for malignant etiologies: zoledronic acid: 4 mg IV over 15 min
- osteoclast inhibitors: calcitonin
- dialysis

45

Etiologies of hypocalcemia? sxs?

- hypoparathyroidism, vit D deficiency, loop diuretics, and high or normal phosphates
- correct level for hypoalbuminemia
- hypomagnesemia assoc with refractory severe hypocalcemia
- sxs: tetany, paresthesias around mouth - hallmark sxs
- EKG: QT prolongation, decreased myocardial contractility

46

How do you tx acute sx HypoCa++?

- IV admin of calcium salts
- 100-300 mg elemental calcium IV over 5-10 min (less than 60 mg/min)
- continuous infusion: 0.5-2 mg/kg/hr for 2-4 hrs
- maintenance infusion 0.3-0.5 mg/kg/hr
- gluconate over chloride for peripheral admin because of less irritation
- Magnesium if hypomagnesaemia present

47

How do you tx chronic hypocalcemia?

- oral calcium supp (give Vit C with Ca, and Vit D if not responding)
- 1-3 grams elemental calcium/day: watch for -
constipation, GI upset, carbonate less expensive than gluconate/citrate , but citrate better absorption
- if not responding - add vit D: 1000 IU/day

48

Normal serum level of phosphorus? Hyperphosphatemia? Tx?

- 2-4.5 mg/dL
-hyperphosphatemia: decreased excretion due to low GFR (renal disease), chemo and rhabdomyolysis
- sxs due to Ca-phosphate interaction
- hypocalcemia results with chronic hyperphostphatemia
- tx: GI binders - IV Ca++ salts

49

Tx of hyperphosphatemia?

- emergency tx seldom necessary: this can be done with dialysis
- usually occurs in renal failure:
diet restriction, phosphate binding gel: selvelamer (decreases mortality), calcium supplements, avoid aluminum containing antacids - this can cause bone disease

50

What is hypophosphatemia? sxs? Tx?

- less than 2.0
- sxs are rare until under 1 mg/dL
- long term: proximal muscle weakness and osteomalacia

- severe or sx hypophosphatemia:
IV phosphorus - give slowly, NaPO4, K+PO4
- oral phosphate replacement for mild to moderate:
neutra-phos
- neutra-phos K: 250 mg phosphate, GI upset

51

Causes of hypomagnasemia?

- reduced intake: dieting, unbalanced diet, depleted foods
- impaired absorption (malabsorption) - GI diseases -IBD - crohns, ulcerative colitis
- increased excretion: alcoholism, laxative abuse, tx with diuretics or digitalis

52

Clinical manifestations of hypomagnesemia? drugs that can cause this?

- occurs in nearly 12% of hospitalized pts
- manifestations: neuromuscular, muscle cramps, tetany, seizures, coma
abnormalities of Ca metabolism - hypocalcemia, CV: widened QRS, a fib, ventricular arrhythmias
- drugs that can cause this: diuretics, aminoglycosides, cisplatin, cyclosporine, and alcohol

53

When and what should you tx hypomagensemia with?

hypomag: is less than 1.4 mEq/L
- tx if less than 1 mEq/mL or sx
- Tx with:
IV MgSO4 if sx/severe:
bolus - can cause flushing, sweating
- a large amt is secreted in the urine so a continuous infusion is need after the bolus to raise the magesium level
- oral replacement if mild-mod:
sustained release preps preferred
otherwise usual dosing 800-1600 mg a day in divided dosing, often causes diarrhea

54

hypermagnesemia sxs?

- Mg 3-5 meq/L: N/V
- Mg 4-7 meq/L: sedation, decreased reflexes, weakness
- Mg 5-10 meq/L: hypotension, bradycardia, quadriplegia
- Mg 10-15 meq/L: no reflexes, respiratory paralysis, cardiac arrest

55

Tx of hypermagensemia?

- greater than 2 mEq/L
- IV calcium (100-200 mg elemental Ca++) to antagonize neuromuscular and CV effects of magnesium

- tx: renal failure: hemodialysis
if normal renal function: forced diuresis with fluid and loop diuretics

56

Hypokalemia? Etiologies? Sxs?

- less than 3.5 mEq/L
- etiologies: B-2 agonists, loop diuretics, ACEIs, thiazides, High dose PCNs, amphotericin B, insulin
medical: metabolic acidosis, vomiting, diarrhea
- sxs: low energy, muscle weakness, restlessness, cardiac sxs: EKG changes: U wave, cardiac arrhythmias
- danger in persons on digoxin

57

Hypokalemia tx?

- loop or thiazide deficit:
40-100 mEq K supp (BID or TID)
oral therapy is preferred: KCL (given in mEq not mg)
- without food to avoid GI upset

- severe or sx:
IV K in saline bag: dextrose stimulates insulin to further shift K into cells so don't give dextrose!!!
- 10-20 mEq KCL in 100 mL 0.9% saline over one hour
- more than 10 meq/hr monitor EKG
- limit 40-60 mEq/L peripheral line: phlebitis

58

Etiologies of hyperkalemia?

- greater than 5.5 mEq/L
- increased K+ intake
- decreasd excretion
- aldosterone resistance
- shift to ECF (in DKA)

59

Clinical manifestations of hyperkalemia?

- ascending muscle weakness
- usually doesn't affect respiratory muscles
- cardiac effects: EKG changes: initially peaked T waves and shortened QT interval, which progresses to prolonged QRS and QT interval and P waves may disappear, can can then lead to dysrhythmias

60

Tx of hyperkalemia?

- abnorm EKG: calcium gluconate IV (just tx cardiac effects)
- give D5W to create hyperglycemic state then insulin (make sure doesn't become to hyperglycemic)
- consider bicarb if acidotic: H+ exchanged for K+ in ICF to compensate for acidosis: bicarb reverses this
- renal failure: dialysis, K binders: Na polysterene sulfonate (kayexelate) exchanges Na for K in gut: constipation
- loop diuretics if not volume depleted or kidney disease