1
Q
Equation for calculating Dosing Body Weight (DBW)
A
DBW = IBW + 0.4(wt - IBW)
2
Q
When is it appropriate to use Dosing Body Weight (DBW)?
A
if actual body weight (ABW) > 130% of IBW
3
Q
What do is DBW used to calculate dosing for?
A
certain drugs
4
Q
Equation for calculating Nutrition Body Weight (NBW)
A
NBW = IBW + 0.25(wt - IBW)
5
Q
When is it appropriate to use Nutrition Body Weight (nBW)?
A
if actual body weight (ABW) > 130% of IBW
6
Q
What do is DBW used to calculate dosing for?
A
applies for calculating fluid, electrolyte & nutrition (FEN) parameters
7
Q
What does MIVF stand for?
A
maintenance IV fluid
8
Q
Define MIVF
A
normal amount needed over 24 hours
9
Q
What is the clinical estimate of MIVF for adults?
A
30 - 40 mL/kg/day
10
Q
What is the most common MIVF?
A
D5W + ½ NS + 20 mEq KCl/L
11
Q
What is D5W + ½ NS + 20 mEq KCl/L used for?
A
to increase plasma oncotic pressure
12
Q
Why is D5W + ½ NS + 20 mEq KCl/L the most common MIVF?
A
it has a similar composition to urine
13
Q
What is the equation used to calculate serum osmolality?
A
Osm = (2xNa) + (BUN/2.8) + (Glucose/18)
14
Q
How close should the calculated serum Osm match the measured serum Osm?
A
within 5-10 mOsm/L
15
Q
What is a normal serum Osm?
A
275 - 290 mOsm
16
Q
What imbalances are typically seen when a patient has Isotonic / Pseudo Hyponatremia?
A
hypertriglyceridemia (lipid imbalance)
hyperproteinemia (protein imbalance)
17
Q
How can Isotonic / Pseudo Hyponatremia be identified when comparing calculated vs measured serum Osm?
A
Measured serum Osm is not significantly affected
Calculated serum Osm is low
→ Osm gap (OG)
18
Q
What Osm value indicates Hypertonic Hyponatremia?
A
> 290 mOsm
19
Q
What Osm value indicated Hypotonic Hyponatremia?
A
< 275 mOsm
20
Q
What imbalance is typically seen in patients with hypertonic hyponatremia
A
elevated blood glucose
21
Q
Explain the relationship between Na+ decrease & BG increase in patients with hypertonic hyponatremia
A
Serum Na+ falls by 1.6 mEq/L for each 100 mg/dL increase in BG > 100 mg/dL
22
Q
What is important to assess in patients with Hypotonic Hyponatremia?
A
VOLUME STATUS
23
Q
A patient with a Osm of 270 mOsm has…
A
hypotonic hyponatremia
24
Q
A patient with a Osm of 300 mOsm has…
A
hypertonic hyponatremia
25
A patient with a Osm of 280 mOsm has...
isotonic / pseudo hyponatremia
26
A patient with hypotonic hyponatremia & the following volume status has...
*Low TBW
*Very low Na+
Hypovolemic hypotonic hyponatremia
27
A patient with hypotonic hyponatremia & the following volume status has...
*High TBW
*Normal (or slightly elevated) Na+
Isovolemic hypotonic hyponatremia
28
A patient with hypotonic hyponatremia & the following volume status has...
*Very high TBW
*High Na+
Hypervolemic hypotonic hyponatremia
29
Define "osmolarity"
measure of solute concentration
30
What is the equation used to calculate osmolarity?
Total Osmolarity = osmolarity of IV solution + osmolarity of added electrolytes
31
What is the osmolarity of 0.9% NaCl?
308 mOsm/L
32
What is the osmolarity of 0.45% NaCl?
154 mOsm/L
33
What is the osmolarity of Normosol-R/Plasma-lyte?
295 mOsm/L
34
What is the osmolarity of Potassium Chloride?
2 mOsm/mEq
35
IV of hypOtonic and hypERtonic solutions can result in…
Hemolysis of RBCs
Renal failure
Death :(
36
What is the osmolarity range of isotonic fluids?
275 - 290 mOsm/L
37
A fluid with an osmolarity of < 275 mOsm/L is considered what?
hypOtonic
38
A fluid with an osmolarity of > 290 mOsm/L is considered what?
hypERtonic
39
What tonicity can crystalloid fluids be?
isotonic, hypotonic, hypertonic
40
List examples of crystalloid fluids
- NS
- ½ NS
- D5W
- LR
- Balanced salt solutions
41
List the role(s) of crystalloid fluids in treatment
Provide water and/or sodium
Maintain osmotic gradient between intravascular & extravascular compartments
42
List use(s) for 0.9% NaCl (NS)
- Used for intravascular fluid replacement (resuscitation)
- Used for sodium and/or chloride replacement
43
How much free water does 0.9% NaCl (NS) contain?
0/L free water
44
How much Na+ & Cl- does 0.9% NaCl (NS) contain?
154 mEq/L Na+
154 mEq/L Cl-
45
List use(s) for 0.45% NaCl (1/2 NS)
Used for maintenance fluids (combination products)
46
List the use(s) for Lactated Ringers (LR)
- Used for replacement of blood loss
- Used for resuscitation (trauma, burn, etc.)
47
List the use(s) of D5W (dextrose 5%)
free water replacement
*NOT a resuscitative fluid
* NOT a MIVF by itself
48
Describe balanced salt solutions
Crystalloid solutions containing physiologic levels of chloride of buffer solutions
49
List examples of balanced salt solutions
LR, Normosol-R, Plasma-lyte
50
What is the tonicity of colloid fluids?
hypertonic
51
List examples of colloid fluids
Albumin (5% or 25%), Hetastarch, Tetrastarch, Blood, Plasmanate
52
List the role(s) of colloid fluids
- used to increase plasma oncotic pressure
- used to move fluid from the interstitial compartment to the intravascular (plasma) compartment
53
What fluid category is blood in?
Colloid Fluids
54
What is another name for colloid fluids?
plasma expanders
55
Explain why colloids have increased mortality & toxicities compared to crystalloids
they have increased intravascular retention time (1/2 tife)
56
List the use(s) for albumin
Use for supportive / symptomatic treatment
*unless* specifically replacing proteins (hypoproteinemia)
57
When should albumin 5% be used?
if more volume is needed
58
When should albumin 25% be used?
if more protein is needed (more concentrated)
59
List synthetic colloid fluids
hetastarch, tetrastarch
60
Why might a patient be put on synthetic colloids?
if they do not want human derived products
61
Why are synthetic colloids not preferred?
High MW and substitution ratio (SR) associated with increased mortality & toxicities - stays in the vasculature longer
**use with caution**
62
List the use(s) of blood
- Acute blood loss (30-40% of blood volume)
- Inadequate resuscitation from fluids alone
- Pre-operatively
- Low hemoglobin (usually ≤ 7-8 g/dL)
63
How many units of RBC would be used to raise hemoglobin from 7 g/dL -> 10 g/dL?
3 units of RBCs
*1 unit of RBCs increases hemoglobin by approx. 1 g/dL (rule of thumb)*
64
What is the approximate volume of 1 unit of RBCs?
230 mL - 350 mL
65
List factor(s) affecting fluid balance
- Daily weight
- Daily ins/outs (I/O)
- Volume status
- Urine output (UOP) → in mL/kg/hour
- Vitals (HR, BP, CVP, etc)
66
List potential signs of dehydration
- Physical exam
- Tachycardia & hypotension may mean “dry”
- Peripheral pulse weak
- Dark urine
- Decreased urine output → < 0.5 mL/kg/hr
- BUN/Scr ratio → > 20
67
What is the normal range for Na+ ?
135 - 145 mEq/L
68
List the role(s) of Na+
- Primary extracellular cation
- Needed to maintain cellular integrity
- Maintains osmolar gradient → regulates fluid homeostasis throughout the different compartments
69
What body system does Na+ imbalance typically affect?
CNS !!
(ex. effects: brain injury, seizure, death)
70
Name the most common electrolyte disturbance in hospitalized patients
Hyponatremia (low Na+)
71
What does Na+ < 135 mEq/L indicate?
hyponatremia
72
Patient presents with:
- Na+ = 100 mEq/L
- Osmolality = 240 mOsm
hypotonic hyponatremia
73
Patient presents with:
- Na+ = 100 mEq/L
- Osmolality = 285 mOsm
isotonic ("pseudo") hyponatremia
74
Patient presents with:
- Na+ = 100 mEq/L
- Osmolality = 320 mOsm
hypertonic hyponatremia
75
Patient presents with:
- Na+ = 100 mEq/L
- Osmolality = 240 mOsm
- TBW = low
hypovolemic hypotonic hyponatremia
76
Patient presents with:
- Na+ = 100 mEq/L
- Osmolality = 240 mOsm
- TBW = high
isovolemic hypotonic hyponatremia
77
Patient presents with:
- Na+ = 100 mEq/L
- Osmolality = 240 mOsm
- TBW = VERY high
hypervolemic hypotonic hyponatremia
78
What is the equation to calculate for corrected serum Na+ to account for elevated blood glucose in a patient with hypertonic hyponatremia?
corrected Na+ = serum Na+ + 1.6[(BG - 100)/100]
79
List renal causes for hypovolemic hypotonic hyponatremia
- Diuretics / excessive diuresis
- Adrenal insufficiency
- Salt losing nephropathy
- Cerebral salt wasting
80
Explain how to identify if the cause of hypovolemic hypotonic hyponatremia is renal or non-renal
Renal: urine Na > 20 mEq/L
Non-Renal: urine Na < 20 mEq/L
81
List non-renal causes for hypovolemic hypotonic hyponatremia
- Blood loss / hemorrhage
- Skin loss (burns sweat, wounds)
- GI losses (vomiting, diarrhea, suction)
82
List causes for isovolemic hypotonic hyponatremia
Adrenal insufficiency
Hypothyroidism
Psychogenic polydipsia
**SIADH → syndrome of inappropriate anti-diuretic hormone release (DRUGS)**
83
List common drugs that cause SIADH
Antipsychotics
Carbamazepine
SSRIs (fluoxetine, sertraline)
84
What are the overall goals of therapy for electrolyte imbalance treatment?
- Prevent & treat serious compilations
- Normalize serum concentration
- Identify & correct underlying cause(s)
- Avoid overcorrection
85
Name a severe result of acute symptomatic hyponatremia
cerebral edema
86
What time frame constitutes ACUTE hyponatremia
< 48 hours
87
Explain the treatment for acute symptomatic hyponatremia
Treat with 3% NaCl (hypertonic saline)
- Rule of 8's: replace ½ of Na deficit in 8 hrs, then remaining w/in 8-16 hrs
- Increase serum Na+ by 1-2 mEq/L/hr until symptoms resolved
*MAX increase of 8-12 mEq/L in the first 24 hours*
88
What is the consequence of correcting serum Na+ too rapidly?
diffuse demyelinating lesions
**central pontine myelinolysis**
89
List treatment options for drug-induced SIADH
1. stop the damn drug
2. first-line: free water restriction
90
What is the goal rate for raising serum Na+ in patients with hypotonic hyponatremia
In most cases the goal is to avoid rise in serum sodium > 0.5 mEq/L/hr or no more than (NMT) 8-12 mEq/L/day
91
What is the goal of treatment of hypovolemia?
to restore volume deficit
92
Explain how to treat symptomatic hypotonic hypovolemic hyponatremia
Hypertonic NaCl (3% NaCl)
93
Explain how to treat asymptomatic hypotonic hypovolemic hyponatremia
Isotonic NaCl (0.9% NaCl)
94
Explain how to treat symptomatic hypotonic isovolemic hyponatremia
Furosemide and 3% NaCl
95
Explain how to treat asymptomatic hypotonic isovolemic hyponatremia
0.9% NaCl & water restriction
96
Explain how to treat symptomatic hypotonic hypervolemic hyponatremia
Furosemide and judicious 3% NaCl
97
Explain how to treat asymptomatic hypotonic hypervolemic hyponatremia
Furosemide
98
What is the calculation for free water deficit?
NL*TBW x [(serum Na/140) - 1]
99
Explain the treatment for acute isovolemic hypernatremia
SubQ/IV desmopressin
0.25 - 0.5 mL BID
-OR-
continuous vasopressin infusion titrated hourly to goal UOP
100
Explain the treatment for chronic isovolemic hypernatremia
Intranasal desmopressin
0.05 - 0.2 mL BID
101
Explain the treatment for hypervolemia hypernatremia
1. stop the cause
2. rapidly excrete
3. diuretic if needed
**match I/O**
102
What is the equation for corrected calcium?
Corrected Ca = Measured Ca2+ + [(4 - measured albumin) x 0.8)]
103
What calcium measurement is more accurate than the corrected calcium equation?
Ionized Ca
4.6 - 5.1 mg/dL (watch your units !!)
**represents the amount of calcium available for use in the body**
104
Explain the treatment of acute hypocalcemia
100-300mg elemental Ca IV over 5-10 minutes
- do not add bicarb or phos solution!!
- correct hypomagnesemia
105
Explain the difference between CaCl and calcium gluconate
270 grams elemental calcium:
* 1 gm CaCl
* 3 gm Ca gluconate
106
Explain the treatment for chronic hypocalcemia
PO calcium:
1-3 g/day elemental calcium
**CaCO3 650mg PO 4x/day = 1 gm elemental Ca2+ / day**
Vitamin D supplementation:
calcitriol 0.25 mcg PO QD / QOD
107
Explain the potential titration of vitamin d for the treatment of chronic hypocalcemia
May need to increase calcitriol dosage by 0.25 mcg q4-8weeks to 1 mcg PO QD
108
Explain the treatment for mild-moderate hypophosphatemia
ORAL phosphate:
- Phos-NaK (10 mMol phos/packet)
30-60 mMol/day in 2-3 divided doses
- Fleets Phospho-Soda (4.1 mMol/mL)
5mL diluted → 2-3 times per day
109
Explain the treatment for severe hypophosphatemia
IV phosphate:
- Use KPhos when K+ < 4 mEq/L
- Use NaPhos when K+ ≥ 4 mEq/L
110
Explain the mEq breakdown of the ingredients of NaPhos
1.33 mEq Na+
1.33 mEq Phos
111
Explain the mEq breakdown of the ingredients of KPhos
1.47 mEq K+
1.47 mEq Phos
112
Explain the rules for dosing phosphate
Give PO doses as divided doses
Infuse IV no faster than 7 mMol / hour !!
113
What is the equation for calculating free water deficit?
Free H2O deficit = NL TBW x [(serum Na/140) - 1]
114
Explain how to replace a free water deficit
Provide free water → D5W cont. infusion, enteral free H2O via feeding tube
115
What is the goal of treatment (levels to monitor) when replacing a free water deficit?
Goal: 0.5 mEq/L/hr decrease in serum Na
116
Explain the dosing intervals for the replacement of free water deficit
Give ½ of total deficit over 24 hours
Give remaining ½ over the next 24-48 hours
Adjust as needed
117
Explain the monitoring parameters for the replacement of free water deficit
Serum Na+ concentration & fluid status:
- Check q 3-6 hours over the first 24 hours
- After symptoms resolve & serum Na+ > 145 mEq/L → check q 6-12 hours
Check I/O q 8-12h (every shift)
Check overall fluid balance q 24 hours
118
Should hypokalemia be treated if the lab values are 3.5 - 4 mEq/L?
Generally - no therapy
119
Should hypokalemia be treated if the lab values are 3 - 3.4 mEq/L?
Treatment debatable
PO potassium for pts with cardiac conditions
120
Should hypokalemia be treated if the lab values are < 3 mEq/L?
ALWAYS treat
PO route is preferred in asymptomatic pts
IV for symptomatic pts or pts who cannot take PO
121
What other imbalance should be corrected in patients with hypokalemia?
Mg2+ deficit
122
List the criteria for administering IV K+
- severe cases of hypokalemia (K < 2.5 - 3 mEq/L)
- exhibiting signs/symptoms:
ECG changed
Muscle spasms
- patients unable to tolerate PO
123
List warnings / precautions for the use of IV K+
- Thrombophlebitis & pain at infusion site
- Higher risk of leading to hyperkalemia / overcorrection
- **Arrhythmia or cardiac arrest if given too quickly**
124
How should IV K+ be administered?
Generally each 10-20 mEq is diluted in 100mL of D5W
Infusion rate withOUT cardiac monitoring
10 mEq/hour
Infusion rate WITH cont. cardiac monitoring:
20 mEq/hr
40-60 mEq/hr if emergent w/ severe hypokalemia (ex. cardiac arrest)
125
What acronym can be used when treating hyperkalemia?
"C A BIG K DROP"
126
List the 3 steps for treating hyperkalemia
1. antagonize the membrane actions
2. decrease extracellular K+ concentrations
3. remove K+ from the body
127
What does "C A BIG K DROP" stand for?
**antagonize the membrane actions**
Calcium
**decrease extracellular K+ concentrations**
Albuterol
Bicarb
Insulin + Glucose
**Remove K+ from the body**
Kayexalate®/Lokelma
Diuretics (furosemide)
Renal unit for dialysis of patient
128
How should chronic hyperkalemia be treated?
Patiromer (Valtassa)
8.4 gm PO QD (oral suspension)
129
List the advantages of Calcium Gluconate
Lower percentage of elemental Ca2+
Less risk for extravasation (necrosis)
130
List the disadvantages of Calcium Gluconate
Less predictable increase in Ca2+ concentration
131
How should CaCl be administered?
IV push during code
132
How can calcium chloride be administered?
preferred for PIV administration
133
What other electrolyte imbalances is magnesium imbalance also associated with?
Hypocalcemia
Hypokalemia
134
List PO treatment options for hypomagnesemia
Asymptomatic patients with Mg2+ > 1 mg/dL
Milk of Mag (MOM) 5-10 mL PO QID
Mag-Ox 800 mg PO daily or 400 mg PO TID with meals
135
List IV treatment options for hypomagnesemia
Mg2+ 1-2 mg/dL: 0.5 mEq/kg
Mg2+ < 1 mg/dL: 1 mEq/kg
**8 mEq = 1 gm**
**Infuse 1 gm / hour**
136
When should KPhos be used for hypophosphatemia ?
when K+ < 4 mEq/L
137
When should NaPhos be used for hypophosphatemia ?
when K+ ≥ 4 mEq/L
138
What is the dosing for KPhos for patients with hypophosphatemia?
1 mMol KPhos
**1.47 mEq K+**
**1.47 mEq Pho**
139
What is the dosing for NaPhos for patients with hypophosphatemia?
1 mMol NaPhos
**1.33 mEq Na+**
**1.33 mEq Phos**
140
What is the infusion rate for KPhos?
Infusion rate w/o cardiac monitoring:
10 mEq/hr
Infusion rate w/ cardiac monitoring:
20 mEq/hr
141
List the potential etiologies for Hypophosphatemia
Decreased intake
Impaired absorption
Intracellular shifts
142
What concentration of PO4- indicates mild-moderate hypophosphatemia?
PO4 concentration → 1-2 mg/dL
143
What concentration of PO4- indicates severe hypophosphatemia?
PO4 < 1 mg/dL
144
List potential etiologies for hypocalcemia
Magnesium deficiency
Large volumes of blood volumes
Hypoalbuminemia
145
List body systems that hypocalcemia may affect (regarding clinical presentation)
neuromuscular
CNS
dermatologic
cardiac
146
What concentration of K+ indicates mild hyperkalemia?
5.5 - 6 mEq/L
147
What concentration of K+ indicates moderate hyperkalemia?
6.1 - 6.9 mEq/L
148
What concentration of K+ indicates severe hyperkalemia?
≥ 7 mEq/L
PHRM 802
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