1 - Fluids and Electrolytes Flashcards
ex of sensible fluid losses
urination
defectation
wounds
ex of insensible fluid losses
skin
lungs
normal tonicity
275-290 mOsm/L
crystalloid fluids are __tonic
iso
hypo
hyper
colloid fluids are __tonic
hyper
ex of crystalloid fluids
NS, 1/2NS
D5W
LR
bal’d salt sln
ex of colloids
albumin (5 or 25%) hetastarch (Hespan) tetrastarch(Voluven) blood plasmanate
What is the place of NS in therapy
fluid replacement: resus, hypoTN, shock
Na/Cl replacement
What is the place of 1/2 NS in therapy?
maintenance fluids
What is the place of LR in therapy?
resuscitation
–replacement of blood loss, traums, burn
What is the place of D5W in therapy?
used for free water replacement if dehydrated
What are examples of balanced salt solution?
lactated ringers (LR)
normosol-R
plasma-lyte
How much sodium is in NS?
154 mEq/L
What is the place of colloids in therapy?
increase plasma oncotic pressure
volume expansion,
intravscular repletion in sympomatic pts
hemorrhagic shock
adverse effects of albumin therapy?
hypervolemia
azotemia
infused-relation rxn/anaphylaxis
Why are synthetic colloids falling out of favor?
ass’d w increased mortality and tox
What is the place in therapy of blood?
acute blood loss
inadeuate resus from fluids alone
pre-op
low hemoglobin (<7-8 g/dL)
1 U RBCs incr Hgb by approx 1 g/dL
What is the most common maintenance fluid?
D5W + 1/2 NS + 20 mEq KCl/L
Signs of dehydration
PE:
decr skin turgor
dry mucus membranes
delayed capillary refill
tachycardia, hypoTEN
periph pulses weak
decr UOP, dark urine
BUN/SCr >20
Signs of shock
heart-->tachycardia, hypoTN brain-->AMS kidneys-->decr UOP liver-->incr INR skin--> cool, cyanotic
shock resuscitation goals
CVP 8-12 mmHg
MAP >65 mmHg
UOP >0.5 mL/kg/hr
normal range of serum sodium
135-145 mEq/L
what is an osmol gap?
difference btw measured and calc’d osmolality is greater than 15
indicates prescence of unidentified particles (such as alcohol)
describe pseudohyponatremia
extreme levels of lipids and proteins incr total plasma volume
calc’s Osm is low –> OG
Describe hypertonic hyponatremia.
most fequently seen in elevated BG.
serum sodium falls in attempt to maintain serum Osm.
what are the causes of hypovolemic hyponatremia?
renal (urine Na >20 mEq/L): diuretics/excessive diuresis adrenal/mineralcorticoid deficiency salt losing nephropathy cerebral salt wasting
non-renal causes:
blood loss/hemorrhage
skin losses
GI losses
What are the causes of isovolemic hypotonic hyponatremia?
adrenal/glucocorticoid def
hypothyroidis
psychogenic polydipsia
SIADH
What is the cause of SIADH
tumors
CNS disorders
DRUGS
What are some drugs that cause SIADH?
antineoplastics antipsychotics carbamazepine SSRIs (fluoextine, sertraline) NSAIDs TCAs
How to treat SIADH
remove underlying cause if possible
first line: free H20 restriction
Vaptans if above fails
Causes of hypervolemic hypotonic hyponatremia
cirrhosis
HF
RF
nephrotic syndromes
What is the max rise in serum sodium allowed during hyponatremia therapy?
0.5 mEq/L/h or NMT 8-12 mEq/L/d
How to treat hypotonic hypontremia if symptomatic?
3% NaCl
furosemide if eu or hypervolemic
How to treat non-symptomatic hypotonic hyponatremia
hypovol: isotonic NaCl
isovol: isotonic and water restriction
hypervol: furosemide
How do you replace sodium?
“rules of 8s”
1/2, 1/4, 1/4
How to treat acute symptomatic hyponatremia?
coma, AMS, Sz
increase Na by 1-2 mEq/L/hr until Sx resolve.
goal=120 mEq/L
complete correction unnec
max incr of 8-12 mEq/L in the first 24 hrs
How do vaptans work?
promote excretion of free H2O
think of as aquaretics
What is the dosing of Conivaptan?
IV
load: 20 mg IV bolus over 30 min
continuous: 20 mg IV over 24 hr for 2-4 d
may incr dose to 40 mg IV over 24 hr based on sodium response
4 d max
What is the dosing of Tolvaptan?
PO–> for chronic SIADH pts
intital dose: 15 mg PO daily
may incr q24-60 mg max dose based on sodium respons
What is the place in therapy of vaptans?
Conivaptan: sev euvol and hypervol symptomatic hyponatremia
tolvaptan: asymp euvol, hypervol hyponatremia
What are contraindications for
hypovolemic
w/o sense of thirst
anuria
strong CYP3A4 inhibs
Acute symptomatic hyponatremia monitoring
heart lungs, neuro status several times over first 12 h
serum Na q2-4 hr until asymptomatic then q4-8hr until WNL
What is the cause of hypervolemic hypernatremia?
sodium overload (NaHCO3, hypertonic saline resus) mineralcorticoid excess
What is treatment for hypervolemic hypernatremia?
stop hypertonic fluids or cause
diuretic
What is the cause of hypovolemic hypernatremia?
renal GI adrenal lung skin
What is the treatment for hypovol hypernatremia?
restore hemodynamics first if needed: maybe NS
once volume resotred, replace free water def
How to provide free water?
D5W continuous inf
enteral
How quickly should free water be replaced?
1/2 of deficit over 24 hr
give remaining 1/2 over next 24-48 hr
What are the monitoring parameters for replacing free water?
check sodium and fluid status q3-6h for 1st 24 h
after symptoms resolve and Na<145 mEq/L then check q6=12 h
I/O q8-12 h
Overall fluid bal q24h (S/sx, UOP, CVP, wt, etc.)
What are the causes of isovolemic hypernatremia?
DIABETES INSIPIDUS skin loss latrogenic osmotic diuresis primary polydipsia
How should isovolemic hypernatremia be treated?
desmopression
vasopressin
The double check sodium eqn is for how much fluid?
1 L
What are the causes of hypokalemia?
diuretic loss beta-agonist meds NG drainage metabolic alkalosis diarrhea mag depletion (cofactor for Na/K ATPase)
How does hypokalemia present?
nonspecific and variable
arrhythmas
impared muscle contraction
When ?
<3mEq/L always
3-3.4 for cardiac pts
<4 in ICU
How should [K+]<3 mEq/L be treated?
asymp–po route
symp–IV
–correct Mg2+ also!
For every 10 mEq of K that is given to replete, can expect serum K to increase by
0.1 mEq/L
What are indications for IV potassium therapy?
<3 mEq/L
ECG changes
muscle spasms
can’t tolerate PO
**What is the dose of IV potassium to treat hypokalemia?
10-20 mEq in 100 mL of D5W
w/o cardiac monitoring: 10mEq/hr
w/ continuous cadiac moitoring 20 mEqh
How does hyperkalemia present?
peaked T wave
slow AP
VF or asystole
How is severe hyperkalemia treated? (what actions) K+>=7 mEq/L
- antagonize membrane actions
- decr EC K+ conc
- remove excess K from body
What is an example severe hyperkalemia treatement regimen?
1: 1 gm CaCl IVP
2: 10 U regular insulin IVP over 30 min + 50 mL D50W IVP over 30 min
(also consider NAHCO3, albuterol)
3. furosemide 20-40 mg IVP
Which hyperkalemia treatment option is for chronic patients?
patiromer (Veltassa)
binds K in GI trac and decr systemic absorption
What are the causes of hypomagnesemia?
diarrhea malabs malnutr DRUGS: amphotericin, aminoglycosides, diuretics, cyclosporine ALCOHOL
What is the clinical presentation of hypomag?
diff to isolate
oft ass’d w hypocal or hypokal
When is hypomagnesemia corrected with PO treatment?
asmptomatic pt w Mg>1 mg/dL
When in hypomagnesemia corrected w IV treatment?
symptomatic pts or cannot tolerate PO
What are PO hypomagnesemia treatment options?
Milk of Mag 5-10 mL PO QID
Mag-Ox 800 mg PO daily or 400 mg PO TID w meals
What are IV hypomagnesemia treatment options?
If Mg 1-2 mg/dL use 0.5 mEq/kg, <1 mg/dL use 1 mEq/kg
8 mEq=1 g
infuse 1 g/hr
What are he causes of hypermag?
RF/insuff excessive intake (laxatives)
What is the treatment for hypermagnesemia?
CaCl 1-2 g IV and repeat prn for cardiac comp
if adequate renal func: IV hydration w NS or 1/2NS ~200 mL/hr + 1-2 g Ca OR IV furosemide
renal dysfxn: forced diruesis, HD
and suportive care prn: cardiac pacing, vasopressors, mech vent
What are the causes of hypocalcemia?
Mg def
large volumes of blood products (citrate)
hypoalbuminema
post-op hypoparathyroid
vit D def
thyroid surgery
meds
What is the treatment for acute hypocalcemia?
100-300 mg elemental Ca2+ IV over 5-10 min
1 g CaCl= 3 g Ca gluc = 250 mg elemental
- CaCl during code
- gluconate during PIV admin: lower % elemental, less risk for extravasation, but less predictable
–> usually admin 1 g cal/h
-correct hypomag
What is the treatment for chronic hypocalcemia?
PO: 1-3 g/d elemental Ca2+
-CaCO3 (TUMS) 650 mg PO QID = 1 gm elemental /d
vit D supp: calcitriol 0.25 mcg PO d or qod
What are the causes of hypercalcemia?
cancer and primary hyperparathyroidism:
incr bone resorption
incr GI abs
decr elmin
oft asymp
What are the treatment options for hypercalcemia?
volume expansion/loop duretics
calcitonin
bisphosphonates
glucocorticoids
How should volume expansion/loop diuretics be used to treat hypercalcemia?
NS 200-300 mL/hr
furosemide 40-80 mg IV q1-4h
use in pts with normal-mod imp’d renal fxn
symptomatic pts
How should calcitonin be used in treatment of hypercalcemia?
for pts w CHF, mod-sev renal dysfxn: fluid restriction
inhib bone resorp
reduces renal reabs
SQ or IM 4 U/kg q12h
How should bisphosphonates be used in treatment of hypercalcmia?
block bone resorp–decline ~2 d
pamidronate more eff than etidronate
pamidronate 30-90 mg IV over 2-24 hr
How should glucocorticoids be used to treat hypercalcemia?
ind: multiple myeloma, leukemia, lymphoma, sarcoidosis
decr GI abs
interfer w vit D metab: incr bone resorp, decr osteoblast prolif
(-) slow, risk for hyperglycemia, infx
What is the normal range for phsophate?
2.5-4.5 mg/dL
What is the normal rnage for serum potassium?
3.5-5 mEq/L
What is the normal rnage for serum magnesium?
1.5-2.5 mgdL
What is the normal range for serum calcium?
8.5-10.5 mg/dL
What are the causes of hypophosphatemia?
decr intake
imp’d abs
IC shift
How does hypophosphatemia present?
nonspecific
What is the treatment for hypophosphatemia?
if <1 mg/dL then IV phos (KPhos or NaPhos)
if 1-2 mg/dl then PO:
Phos-NaK –> 30-60 mMol/d in 2-3 divided doses
Fleet’s phospho soda 5 mL diluted –> 2-3 times per d
How should phosphate be dosed?
Phos
- 2.3-2.9 mg/dL: 0.32 mMol/kg
- 1.6-2.2 mg/dL: 0.64 mMol/kg
- <1.6 mg/dL: 1 mMol/kg
What are the equivalences for 1 mMol NaPhos or KPhos?
- 33 mEq Na + Phos
1. 47 mEq K + Phos
What is the max IV infusion rate for phos replacement?
NMT 7 mMol/hr
also check K rules!
What are the causes of hyperhosphatemia?
RF/insuff
hypoparathyroidism
excessive intake
How does hyperphosphatemia present?
soft tissue calcifications when Ca2+ x PO4- >60
concurrent ypocalcemia
What is the treatment for hyperhosphatemia?
IV calcium
decrease phosphate GI abs
