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Principles > Principles-Fluid, Electrolytes, and Acid-Base Management > Flashcards

Principles-Fluid, Electrolytes, and Acid-Base Management Flashcards

1
Q

What cation is most important for intracellualar volume regulation and determines osmolality

A

Potassium

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2
Q

What cation is most important for extracellular volume regulation determines osmolality

A

Sodium

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3
Q

What is the normal plasma osmolality

A

280-290 mOsm/kg

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4
Q

** What is the equation for calculating plasma osmolity

A

2XNa + Glucose/18 + BUN/2.8

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5
Q

Crystalloid solutions contain

A

Low-molecular-weight ions (salts)

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6
Q

Colloid solutions contain

A

High-molecular-weight ions (proteins, glucose)

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7
Q

Colloid solutions ——–plasma colloid oncotic pressure

A

maintain

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8
Q

Crystalloid solutions—–rapidly equilibrate with, and distributes throughout?

A

the intravascular and interstitial fluid space

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9
Q

True/False

crystalloids, if given in sufficient amounts, are just as effective as colloids in restoring intravascular volume

A

True

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10
Q

Replacing intravascular volume with crystalloids require how much more volume relative to colloid use

A

3-4 times

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11
Q

Generally, severe fluid deficits are corrected with

A

colloids

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12
Q

Rapid administration of large amounts of crystalloids > 4-5L is associated with

A

significant tissue edema

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13
Q

Solutions are chosen according to what type of fluid loss

A

Isotonic

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14
Q

Most intraoperative fluid losses are

A

isotonic, therefore, solutions are usually isotonic

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15
Q

What is the ratio of cyrstalloid replacement for blood loss

A

3 ml of crystalloid for every 1 ml of blood lost

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16
Q

True/False

Lactated Ringers is the most commonly used fluid in OR

A

True

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17
Q

Is LR considered Isotonic

A

Yes, although it is slightly hypontonic

*least effect on extracellular fluid composition, most closest to physiological solution

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18
Q

LR is less or more osmotic than saline

A

Less (273 vs. 308)

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19
Q

LR contains which electrolytes

A 
Tonicity- 273
Na-130 mEq
Cl-109 mEq
Potassium-4 mEq
Ca- 3 mE1
Lactate- 28 mEq/L
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20
Q

Infusion of 1L of LR will add approx. how much volume to plasma after 1 hr

A

150-185 mL

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21
Q

LR should be administered with caution in which type of patient

A

kidney failure due to potassium

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22
Q

NS contains which electrolytes

A

Tonicity-308
Na-154
Cl-154

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23
Q

When given in large amounts, NS can produce —-, why?

A

hyperchloremic Acidosis, due to higher cloride content

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24
Q

Infusion of 1L of NS will contribute to how much volume increase in the plasma after 1h

A

275 mL

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25
Which crystalloid is better for patient's with renal failure
Nacl
26
What is the intravascular half-life of crystalloids
20-30 minutes
27
What is the intravascular half-life of colloids
3-6 hours
28
Name two indications for colloid use
Severe intravascular fluid deficit where RBC not available Severe loss of protein (albumin)
29
Infectious transmission or anaphylactoid rxns are associated with which two colloids
Albumin (infection) Dextran (anaphlactic/anaphylactoid) -assoc. with renal failure
30
Hespan is a colloid that contains
Starch
31
Are there risks of transmitting infectious diseases, or anaphylactoid rxns with hespan
NO- synthetically made | -lowest risk of anaphylactoid
32
Large volume administration of hespan interferes with
blood clotting *Don't exceed 20 mL/kg
33
A unit of PRBC contains how much volume
250mL
34
A unit of PRBC has a hematocrit of
70%
35
How high will a unit of PRBC increase the Hgb/Hct
1 g/dL- hemoglobin 2-3%- hematocrit *if only given RBC
36
One unit of platelet will increase count by
10,000-20,000
37
What is the goal for introperative fluid requirements
maintain an adequate intravascular volume | end-organ perfusion and oxygenation
38
What four criteria are used when calculating intraoperative fluid requirements
maintaining baseline fluid requirements NPO deficit replacement intraoperative fluid shift replacement blood loss replacement
39
How is maintenance requirements calculated
4-2-1 Rule 1st 10 kg, give 4 mL/kg/hr next 10 kg, give 2 mL/kg/hr each kg above 20 kg, add 1 mL/kg/hr * Easiest way, add 40 kg to patient's wait
40
How is NPO deficit calculated
maintenance rate (IV) x number of hours NPO
41
How is NPO deficit replaced
in first hour, give 50% in second hour, give 25% in third hour, give 25%
42
Blood loss should be replaced with
crystalloids or colloids to maintain intravascular volume until anemia outweighs risk of transfusion
43
A healthy patient can tolerate a hgb as low as
7 g/dL
44
Elderly patients, or those with significant cardiac/pulmonary disease must have a hemoglobin level of at least
10 g/dL
45
How is hemoglobin calculated based on hematocrit
hgb=hct/3
46
What should the crystalloid to blood loss replacement ratio be
3: 1 | i. e. if patient lost 100 mL of blood, give 300 mL of crystalloid
47
What should the colloid-to-blood loss replacement ratio be
1:1
48
How low should the hemoglobin be to transfuse
depends on the patient
49
What is the Maximum Allowable Blood Loss (MABL)
A rough estimate of how much blood the patient can lose
50
When would the MABL not apply
hemodynamic instability or patient in need of oxygen carrying capacity
51
Describe how to calculate the MABL
1st- estimate patient's blood volume (EBV) 2nd- estimate red cell mass (preop hct x EBV) 3rd- estimate the lowest acceptable hct loss x EBV 4th- subtract 3 from ERCM at preop hct * this is the volume of rbc that would be lost if patient were to bleed to lowest acceptable hct 5th- multiply 4 by 2, then by 3 (this gives the range)- to account for plasma volume
52
What is the expected blood volume for a premature neonate
95 mL/kg
53
What is the expected blood volume for a full-term neonate
85 mL/kg
54
What is the expected blood volume for an infant
80 mL/kg
55
What is the expected blood volume for an adult male
75 mL/kg
56
What is the expected blood volume for an adult female
65 mL/kg
57
How is the Estimated Blood Volume determined (EBV)
multiplying patient's weight by their expected blood volume
58
What are the guidelines for replacing fluids for evaporation, and/or fluid shifts intravascularly
The degree of tissue trauma from procedure determines fluid requirements Minimal tissue trauma, give 1-2 mL/kg/hr Moderate tissue trauma, give 2-4 mL/kg/hr Severe tissue trauma, give 4-4 ml/kg/hr
59
Two causes of hyponatremia
sodium loss | free water excess
60
How is plasma osmolality affected by sodium deficits
decreased-hypoosmolality
61
Hypoosmolality r/t sodium deficit cause fluid to shift
into cells (swelling) and plasma volume to decrease leading to hypovolemia
62
HypoNatremia r/t free water excess cause
both ICF and ECF volume to increase leading to hypervolemia, water intoxication with cerebral and pulmonary edema
63
Sodium levels of > 125 mEq/L are
asymptomatic
64
Sodium levels of < 120 mEq/L causes
lethargy, confusion, seizures, coma
65
What is the treatment of choice for decreased total body sodium content
Isotonic Nacl
66
What is the treatment of choice for normal or increased total body sodium (water excess)
Water restriction
67
Rapid correction of hyponatremia can lead to what syndrome
Osmotic Demyelination Syndrome
68
What are the symptoms of Osmotic Demyelination Syndrome
transient behavioral disturbances seizures permanent demyelination and nerve damage *No cure
69
Osmotic Demyelinaton Syndrome can be prevented by
Correction < 2.5 mEq/L per hour
70
Never correct hypoNatremia any faster than
1.5 mEq/L per hour
71
Why would patient's with hypoNatremia be more sensitive to the myocardial depressant effects of anesthetics
Hyponatremia decreases the excitablilty of cells and may contribute to decreased myocardial contractility
72
What are the three anesthetic questions that must be asked on any electrolyte disturbance
What underlying disorder is present? Is the case elective or urgent? -must be > 130 for elective cases Is the patient hypovolemic or hypervolemic? - hypovolemic= more sensitive to volatile/IV anesthetics (decrease doses needed) - hypervolemic= pulmonary edema, alveolar edema, impaired gas exchange
73
Hypernatremia is always associated with what osmolality change
hyperosmolality * fluid shift from cells to interstitial space of brain leading to shrinkage with tearing of meningeal vessels, and intracranial hemorrhage
74
How to treat hypernatremia associated with hypovolemia
correct hypovolemia first with NS (restores intravascular volume) then, correct hypernatremia with hypotonic fluids (draws fluid into cells)
75
How to treat hypernatremia associated with hypervolemia
``` diuretics (enhances sodium removal) hypotonic solution (replaces water deficit) ```
76
Plasma sodium should not be decreased faster than
0.5 mEq/L/hr
77
Hypernatremia affects MAC how
increases
78
What is the normal plasma potassium
3.5-5 mEq/L
79
HypoKalemia is associated with
cardiac rhythm disturbances
80
True/False | Chronic hypoKalemia has fewer incidences of intraoperative dysrhythmias
True
81
What are six causes of hypokalemia
``` Intracellular movement of potassium Increased potassium losses Hypomagnesemia Diuretics Hypersecretion of aldosterone GI losses ```
82
What are the three ECG manifestations of hypokalemia
T-wave flattening and inversion Formation of a U wave ST depression
83
What effect does hypokalemia have on the excitablility of the heart
delayed ventricular depolorization-hyperpolarization decreased cardiac contractility
84
What are the four ECG manifestations of hyperkalemia
Peaked T waves Prolonged PR interval Progressive QRS widening to "sine wave" ST segment depression
85
Name three ways to treat hyperkalemia
Stabilization of membrane -calcium chloride ( decreases membrane excitability) Increase potassium movement intracellularly - hyperventilation - glucose + Insulin (50g glucose/10 Units of Insulin) - bicarbonate if acidotic - beta agonist- epinephrine Increase Potassium excretion - diuretics - hemodialyis - kayexelate
86
A 10mmHg decrease in PaC02 decreases serum potassium concentration by
0.5 mEq/L
87
What is the normal calcium concentration
8.5-10.5 md/L
88
What effect does calcium have on nerve tissue
hyperexcitable | -calcium stabilizes membrane of cells, so lack thereof would cause excessive excitability
89
What are classic signs of hypocalcemia
Chvostek's sign- tap jaw, excites facial mu Trousseaus's sign- carpal spasms when tourniquet applied Prolonged QT interval
90
What are classic signs of hypercalcemia
SHORTENED QT INTERVAL | lethargy, N/V, irritability
91
Which acid/base disorder should be avoided in hypercalcemia
acidosis * avoid alkalosis in hypocalcemia - alkalosis decreases ionized calcium
92
Hypophosphatemia has similar fluid shift behaviors as what electrolyte deficit
hypokalemia
93
Hyperphophatemia has what effect on calcium
lowers plasma levels via precipitation and deposition into bone/soft tissues
94
What is the normal magnesium concentration
1.7-2.1 mEq/L
95
Low levels of magnesium are directly proportional to what two electrolyte disturbances
hypocalcemia | hypokalemia
96
How does hypermagnesemia effect CNS, skeletal muscles, heart tissues, and respiratory system
sedation muscle weakness myocardial depression respiratory depression
97
How does hypermagnesemia effect NMB
potentiates it by antagonizing calcium at the pre-synaptic NM junction
98
Clinically, what is the cause of acidosis
low-perfusion lactic acidosis (metabolic acidosis) hypoventilation (respiratory acidosis)
99
Clinically, what is the cause of alkalosis
diuretic therapy (metabolic alkalosis) hyperventilation (respiratory alkalosis)
100
Alveoloar gas equation reflects
alveoloar oxygenation (PA02) *Always greater than Pa02
101
Define anion gap
the difference between the serum sodium and the sum of chloride and bicarbonate concentration normal=8-16
102
Define base excess
difference between the normal quanity of Total buffer base and the buffer base calculated from a blood sample Normal BE is -2 to +2 Elevation=increase in serum bicarbonate Reduction=reduced serum bicarbonate
103
Define compensation
alteration in bicarbonate or PaCO2 in direct response to a primary acid-base disturbance
104
Define hypocapnia
reduced PaC02 (<35 mmHg)
105
Define hypocarbia
reduced HCO3 ( < 22 mEq/L)
106
What is the normal oxygen saturation
95-98%
107
What effect does acidemia have on anesthetic agents
potentiates CNS and CV depressant effects of anesthesia
108
Lactated ringers has what effect of bicarbonate concentrations and pH
increases bicarb concentrations and pH | via metabolism of lactate to bicarbonate
109
Normal saline has what effect of bicarbonate concentrations and pH
decreases bicar concentrations and pH | -increased chloride ions leads to decreased bicarbonate leading to decrease in pH
110
If a patient's pH <7.2 and I have to administer sodium bicarbonate, how is the initial dose calculated
sodium bicarb= 0.3(24mEq/L - Actual HCO3)/2
111
What are the three negative effects of administering sodium bicarb for metabolic acidosis
increase sodium levels generates C02 decreases plasma potassium levels

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