Electrolytes Flashcards
1
Q
what is the IBW for men?
A
IBW = 50kg + (2.3 x inches over 60’’)
2
Q
what is the IBW for women?
A
IBW = 45.5kg + (2.3 x inches over 60”)
3
Q
what is the equation for NBW?
A
NBW = IBW + 0.25 (wt-IBW)
4
Q
when do you use NBW and what does it apply to when doing calculations?
A
–> use NBW if ABW > 130%s of IBW
–> this applies to fluid, electrolytes, and nutrition (FEN) parameters
5
Q
what is the fluid distribution like in the body?
A
- intracellular –> 2/3 (40% of wt)
- extracellular –> 1/3 (20% of wt)
6
Q
what are the two types of extracellular fluid, what they are, and what percent of extracellular are they?
A
- interstitial – 3/4 – surrounding cell
- intravascular – 1/4 – plasma
7
Q
when balancing fluids what are the 3 key organs and how do we balance fluids?
A
- skin
- lungs
- kidneys
– fluid intake = fluid losses ( in=out)
8
Q
what is the body water composition for women, men, and neonates?
A
W – 45-55%
M – 50-60%
N – 75-90%
9
Q
what is the average fluid loss for sensible and what does that mean?
A
sensible – urination, poop, wounds
—– 1-1.5 L/day
10
Q
what is the average fluid loss for insensible and what does that mean?
A
insensible – skin and lungs
——- 1 L/day
11
Q
what is not counted toward the daily balance?
A
gastric, intestinal, pancreatic, and biliary secretions and almost completely reabsorbed
12
Q
what are some additional fluid losses we don’t think about that may or may not be measurable?
A
- NG output
- vomit
– diarrhea
– large wounds
– burns
– drains
– bleeding
13
Q
what is isotonic solutions range and meaning?
A
- same conc in as out
- between 275-290 mOsm/L
14
Q
what is hypotonic range and meaning?
A
- less conc in than out
- < 275 mOsm/L
15
Q
what is hypertonic range and meaning?
A
- more conc in than out
- > 290 mOsm/L
16
Q
why do we care about the osmolarity?
A
it can result in hemolysis of RBCs, renal failure, and even death
17
Q
how do you calculate osmolarity of IVs?
A
- total osmolarity = osmolarity of IV solution + osmolarity of added electrolytes
- in mOsm/ L
18
Q
How do you calculate MIVF and what are the amount needed?
A
– use 30-40 mL/kg x weight in kg = MIVF/ day
– for hourly rate use MIVF/ day and divide by 24 h to get mL/hr
19
Q
what is the tonicity of crystalloids?
A
isotonic, hypertonic, and hypotonic
19
Q
what is the tonicity of colloids?
A
hpertonic
20
Q
what do crystalloids solutions do?
A
- provide water and sodium
- maintain fluid between intravascular and extravascular space
21
Q
when is normal saline used (0.9%)?
A
- for fluid replacement
22
Q
when is 1/2 NS uses (0.45%)?
A
- for maintenance
23
Q
when do you use LRs?
A
- for resuscitation (trauma, burns, when they need blood)
24
when do you use dextrose 5%?
- for free water replacement
- NOT BY ITSELF & NOT RESUSCITATIVE FLUID
25
what are some examples of balanced salt solutions (buffer- solutions)?
- LRs
- Normosol-R
- Plasma-lyte
26
How much sodium is in 0.9% and 0.45%?
0.9% -- 154
0.45% -- 77
27
when are colloids used?
- to inc. plasma oncotic pressure
- move fluid into plasma
28
what are colloids place in therapy?
for volume expansion
- people who need blood
29
what is albumin used for and its adverse effects?
1. AEs
-- azotemia
-- hypervolemia
2. supportive/ symptomatic tx unless hypoproteinemia
30
when do you use 5% vs. 25% albumin
5%- when need volume
25%- when need protein
31
tell me about blood as a colloid?
- 1 unit RBC = 230-350mL
- low hemoglobin < equal to 7-8 g/dL
- 1 unit of blood increases Hb by 1 g/dL
32
what is the most common MIVF?
D5W + 1/2 NS + 20 mEq KCl/L
- similar to urine
33
what do we monitor for in fluid status?
1. volume status --> dehydration
2. OUP in mL/kg/hr
3. weight, vitals, ins/outs
34
what are possible signs of dehydrations?
- tachycardia and hypotension
- BUN/SCr > 20
- decreased urine output < 0.5 mL.kg.hr
35
what is the normal sodium range?
- 135-145 mEq/L
36
what is hyponatremia and what classifies it?
- most common electrolyte disturbance
- Na < 135
37
how do we calculate serum osmolarity?
- Osm= (2 x Na) + (BUN/2.8) + (Glucose/18)
38
what is pseudohypontremia and when can we see this in patients?
- normal Osmserum
- can be seen with hypertriglyceridemia (TG > 1000) or hyperproteinemia
39
what is hypertonic hyponatremia and what population is it most seen with?
- high Osm >290
- in people with elevated BG
40
how do you calculate corrected serum sodium?
corrected Na = Naserum + (1.6 (BG-100)/100)
41
what is low osm for low sodium?
hypotonic hyponatremia
42
what makes a volume status of hypotonic hyponatremia HYPOVOLEMIC?
decrease in both TBW and Na+
43
what are the renal causes for HYPOvolemic ""?
urine >20
-- diuretics
-- salt losing nephropathy
- adrenal insufficiency
44
what are non-renal causes of HYPOvolemic ""?
- blood loss
- skin loss
- GI loss
45
what classifies hypotonic hyponatremia to "ISOvolemic"?
- increase in TBW and normal or slightly inc. Na+
46
what is a cause of ISOvolemic ""?
SIADH
47
what is SIADH and what is its main cause?
- syndrome of inappropriate AntiDiuretic Hormone release
- drugs are the main cause
48
what drugs specifically are the main cause?
- antipsychs
- carbamazepine
- SSRIs (prozac, zoloft)
49
how do you treat SIADH?
- remove underlying cause if possible
- first line: free H20 restriction
50
what makes it HYPERvolemic ""?
both TBW and Na+ increase
51
what are some clinical presentations of hypotonic hyponatremia for both hypo and hypervolemic?
- hypovolemic: dehydration
- hypervolemic: fluid overload
52
what are the goals in treatment of hypotonic hyponatremia?
- not to rise serum sodium > 0.5 mEq/L/hr or no more than NMT 8-12 mEq/L/day
53
what are the treatment options for hypovolemic hyponatremia (hypertonic and isotonic)?
- hypertonic NaCl 3% if symptomatic
- isotonic 0.9% if asymptomatic
54
what is the treatment for isovolemic hyponatremia?
- lasix and 3% NaCl if symptomatic
- 0.9% NaCl if asymptomatic and water restirction
55
how do you treat hypervolemic hyponatremia?
- lasix and judicious 3% if symptomatic
- lasix only if asymptomatic
56
what is acute hyponatremia?
- <48 hours
- very severe
--> canc ause AMS, seizures, cerebral edema
- need prompt treatment
57
how do you treat acute symptomatic hyponatremia?
1. increase serum Na+ by 1-2mEq/L/hr
- if too rapidly can cause central pontine myelinolysis
- max increase is 8-12 mEq/L in first 24 hours
58
what is the rule of 8s?
- replace half sodium deficit in 8 hours, then remaining deficit within 8-16hrs
59
how do you calculate TBW in M/F?
- M = 0.6 x wt (in kg)
- F = 0.5 x wt (in kg)
60
how do you calculate a sodium deficit?
TBW x Na goal - current Naserum)
61
what is hypernatremia and what must we access?
- - associated with hypertonicity
- must assess volume status
62
what classifies hypernatremia?
Na+ > 145 mEq/L
63
What classifies hypovolemic hypernatremia and where at?
- loss of water and sodium
- renal, GI, lungs, skin
63
what classifies hypervolemic hypernatremia?
- gain H20 and Na+
- sodium overload and mineralocorticoid excess
64
what classifies isovolemic hypernatremia?
- loss of H20 and na+ is normal or slightly high
- diabetes insipidus
- skin loss
65
how do you calculate free H20 deficit for hypovolemic hypernatremia?
Free H20 deficit =TBW x [(Naserum/140)-1]
66
how do you replace free water deficit?
- provide free water
- match I/O
- don't correct too quickly
- goal is 0.5 mEq/L/hr decrease in Naserum
67
what are the monitoring parameters for serum Na+ conc. and fluid status?
- check every 3-6hrs over the first 24 hours
- when sx resolve and Na+ < 145, then q 6-12hrs
- I/O q8-12hr
- overall fluid balance q24h
68
what is the treatment for ISOvolemic hypernatremia?
- desmopressin (DDAVP)
- vasopressin
69
tell me about hypervolemic hypernatremia and treatment?
- generally this is uncommon
-- hypertonic saline resuscitation
- tx: diuretic if needed
- match I/O
70
how do you calculate the estimated change in sodium?
- Change in Naserum= (Nafluid-Naserum)/(TBW + 1L)
- estimates change per one liter
71
what is the normal range for potassium?
3.5-5
72
what factors affect potassium?
- Na/K ATPase pump
- kidneys
- arterial pH/ acid-base status
73
what are the causes of hypokalemia?
- magnesium depletion
--> co-factor for Na/K ATPase
74
what is the treatment for potassium of levels 3.5-4?
none
- if in ICU goal is 4 so may need to treat
75
what is the treatment for potassium at 3-3.4?
- debatable
- po potassium with cardiac outputs
76
what is the treatment for potassium <3?
- po route preferred if asymptomatic
- iv for symptomatic or patients who can't take PO
77
what do you do with any treatment of potassium?
attempt to correct magnesium deficit
78
what are some warnings/precautions with IV K+?
- arrhythmia or cardiac arrest if given too quickly
79
how do you administer IV K+?
- infusion rate WITHOUT cardiac monitor
-----> 10 mEq/hr
- infusion WITH cardiac monitoring
-----> 20 mEq/hr
80
what are the different stages of hyperkalemia?
- mild
-- 5.5-6
- moderate
-- 6.1-6.9
- severe
- > or equal to 7
81
what is a clinical presentation of hyperkalemia?
cardiac arrhythmias
-- peaked T waves
82
what are goals of therapy for hyperkalemia?
- antagonize AEs
- everse symptoms
- return K+ to normal
- correct underlying cause
83
how do you treat severe hyperkalemia (>7)?
1. antagonize membrane actions
2. decrease extracellular K+ concentrations
3. remove K+ from the body
84
how do we antagonize the membrane actions?
- calcium
85
how do we decrease extracellular K+ conc.?
1. albuterol
2. bicarb
3. insulin and glucose
86
how do we remove K+ from the body?
- lokelma
- diuretics
- renal unit for dialysis of patient
87
what is the normal range for magnesium?
1.5-2.5
88
what are some fun facts about magnesium?
- it is a co-factor for many enzymes in the body such as ATP and Alkaline phosphatase
- it is related to Ca2+ and K+ metabolism
89
what is a major drug cause of hypomagnesemia?
- diuretics (thiazide or loop)
90
what is the treatment for hypomagnesemia for asymptomatic patients?
- PO with Mg2+ > 1 mg/dL
---- MOM
---- Mag-Ox
91
what is the treatment for hypomagnesemia for symptomatic patients?
- goal in ICU is > equal to 2mg/dL
IV
-- mg 1-2 mg/dL : 0.5 mEg/kg
-- mg < 1: 1mEq/kg
---- 8mEq/1g= infuse 1 gm per hour
92
what is the normal range for calcium?
8.5-10.5
93
what are the etiologies for hypocalcemia?
- mag deficiency
- large volumes of blood products
- hypoalbuminemia (correct Ca2+)
94
how do you correct Calcium?
- measured Ca2+ +[(4-measured albumin) x 0.8]
95
what is the acute treatment for hypocalcemia?
- 100-300 ELEMENTAL Ca2+
----> 1 g Ca CHLORIDE = 3 g Ca GLUCONATE = 270 ELEMENTAL Ca
96
what is the rate for acute treatment for hypocalcemia and what else must you correct?
- admin at a rate of 1gm/hr
- correct hypomagnesemia
97
what is the chronic treatment for hypocalcemia?
- PO calcium
- 1-3g of ELEMENTAL/ day
- Vit D supplements
-- calcitriol
98
what is the normal range for phosphorus?
2.5-4.5
99
what is mild to moderate hypophosphatemia?
conc of 1-2
100
what is severe hypophosphatemia?
< 1
- icu goal is > or equal to 3
101
what are the etiologies of hypophosphatemia?
1. dec. intake
- impaired absorption
- intracellular shifts
102
how do you treat mild to hypophosphatemia?
ORAL
- Phos-NaK
- Fleets Phospho-Soda
103
how do you treat severe hypophosphatemia?
IV
- KPhos when K+ < 4
- NaPhos when K+ > or equal to 4
104
what is the phos replacement numbers for NaPhos ratio?
1 mMol = 1.33 Na & 1.33 Phos
105
what is the phos replacement numbers for KPhos ratio?
1 mMol = 1.47 K & 1.47 Phos
106
how do you administer IV phos replacements?
no faster than 7 mMol/hr
