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N928 - Basics of Anesthesia > Fluid Management & Blood Therapy > Flashcards

Fluid Management & Blood Therapy Flashcards

1
Q

hypovolemia

A
  • common in patients scheduled for surgery
  • NPO status, bowel prep, surgical trauma, evaporative losses, dry anesthetic gases
  • significant increase in morbidity and mortality –> PONV, organ dysfunction, prolonged hospital stays, delirium
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2
Q

goals of fluid therapy

A
  • avoid or correct hypovolemia
  • restore intravascular volume
  • maintain oxygen carrying capacity
  • maintain adequate tissue perfusion (inadequate = poor surgical outcomes)
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3
Q

total body water

A

60% lean body weight; but varies with age, gender and body habitus
*NOTE adipose tissue does not carry as much water (has decreased water content)

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4
Q

ICV

A

intracellular volume
40% of body weight
2/3 total body water

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5
Q

ECV

A 
extracellular volume 
20% of body weight 
1/3 total body water 
plasma = 4%
interstitial volume = 16%
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6
Q

%TBW for 70kg adult male

A

60% TBW

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7
Q

%TBW for 70kg adult female

A

55% TBW

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8
Q

%TBW for term infants

A

75% TBW

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9
Q

%TBW for premature infants

A

80-90% TBW

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10
Q

%TBW for elderly

A

50-55% TBW

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11
Q

plasma electrolyte composition

A
  • Na 142
  • K 4
  • Mg 2
  • Ca 5
  • Cl 103
  • HCO3 25
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12
Q

intracellular fluid electrolyte composition

A
  • Na 10
  • K 150
  • Mg 40
  • Ca 1
  • Cl 103
  • HCO3 7
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13
Q

extracellular fluid electrolyte composition

A
  • Na 140
  • K 4.5
  • Mg 2
  • Ca 5
  • Cl 117
  • HCO3 28
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14
Q

osmosis

A

water moves across a semi-permeable membrane from solution of low to high solute concentration

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15
Q

osmolality

A
  • number of osmotically active particles per kg of water
  • calculated
  • increased by blood urea, hyperglycemia, hypernatremia
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16
Q

osmolarity

A
  • refers to the number of osmotically active particles per liter of solution
  • just another way to express the concentration of a solution
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17
Q

tonicity

A

-measure of those particles which are capable of exerting an osmotic force

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18
Q

isotonic solution

A
  • two solutions with the same osmolarity

- no osmotic pressure is generated across cell membranes

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19
Q

hypotonic solution

A

-solution with a lower osmolarity than plasma

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20
Q

hypertonic solution

A

-solution with a higher osmolarity than plasma

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21
Q

exchange between fluid compartments

A
  • plasma communicates continually with interstitial fluid via capillary pores
  • osmotic forces and hydrostatic pressures dictate fluid movement
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22
Q

what is the most important oncotically active constituent of ECV?

A

albumin

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23
Q

colloid oncotic pressure

A
  • osmotic pressure exerted by the macromolecules (colloid molecules)
  • prevents fluid from leaving the plasma and exerts a pull from the interstitial space
  • plasma colloid oncotic pressure maintains plasma volume using –> proteins, albumin, gamma globulins
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24
Q

endothelial glycocalyx

A
  • gel layer in capillary epithelium that creates a physiologically active barrier within the vascular space
  • creates a barrier between vessel and blood
  • binds to circulating plasma albumin, preserving oncotic pressure and decreasing capillary permeability to water
  • contains inflammatory mediators, free radical scavenging, activation of anticoagulation factors
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25
Q

RAAS role

A

reabsorption of sodium and water

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26
Q

antidiuretic hormone role

A

reabsorption of water

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27
Q

atrial natriuretic peptide

A

stimulates kidney to release sodium and water, thereby reducing intravascular volume

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28
Q

assessing fluid volume status

A
  • skin turgor
  • mucous membranes
  • edema
  • lung sounds
  • vital signs
  • UOP
  • HCT (high = prob dehydrated)
  • urine specific gravity
  • BUN/Cr
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29
Q

crystalloid solutions

A
  • ideally use isotonic fluids with lyte composition similar to ECF
  • rapidly distribute throughout ECF, hence large volumes required to expand IVF
  • approximately 3-4L crystalloid required to expand IV compartment 1 L
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30
Q

Lactated ringers (LR)

A
  • crystalloid
  • saline with electrolytes (K+, Ca2+) and buffer (lactate)
  • slightly hypotonic (275), provides 100 cc free water per liter of solution, tends to lower Na+
  • lactate converted to bicarb
  • more physiologic than NS
  • avoid in ESRD bc contains K+
  • avoid mixing with PRBCs –> calcium binds to citrate and blood coagulates
  • avoid in TBI bc slightly hypotonic
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31
Q

LR composition

A
  • Na 130
  • K 4
  • Ca 3
  • Cl 110
  • Lactate 28
  • Glucose 0
  • pH 6.5
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32
Q

what can the lactate in LR breakdown into?

A
  • bicarbonate so cause cause a metabolic alkalosis in large amounts
  • also can cause gluconeogenesis in the liver, so caution with DM
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33
Q

normal saline (NS)

A
  • 0.9% NaCl in water
  • crystalloid
  • isotonic solution, osmolality 308
  • in large volumes produces high Cl- content, leads to a dilutional hyperchloremic metabolic acidosis
  • preferred solution for diluting PRBCs
  • also OK for use in ESRD because no K+
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34
Q

NS composition

A
  • Na 154
  • K 0
  • Ca 0
  • Cl 154
  • Lactate 0
  • Glucose 0
  • pH 6.0
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35
Q

normosol-R

A
  • most physiologic of the crystalloids
  • most expensive
  • used in trauma patients where a lot of volume is required
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36
Q

normosol-R composition

A
  • Na 140
  • K 5
  • Ca 0
  • Cl 98
  • Glucose 0
  • Mg 3
  • Acetate 27
  • Gluconate 23
  • pH 7.4
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37
Q

D5W

A
  • hypotonic solution, osm 260
  • has little place perioperatively
  • causes free water intoxication and hyponatremia
  • provides 170-200 calories/1000cc for energy
  • can cause hyperglycemia - except for DM receiving insulin or neonate
38
Q

3% or 5% NaCl

A
  • 3% has NaCl 513 mEq
  • 5% has NaCl 856 mEq
  • used for low volume resuscitation, burns, closed head trauma
  • principle role is treatment of hyponatremia
  • risk of hyperchloremia, hypernatremia, and cellular dehydration
39
Q

colloid solutions

A
  • osmotically active substances
  • have high molecular weight
  • administered in a volume equivalent to volume of fluid/blood lost from intravascular volume
  • half-life in circulation is 16 hrs but can be 2-3 hours (in pathophysiologic states)
40
Q

albumin

A
  • blood derived colloid solution
  • obtained from fractionated human plasma
  • does not contain coagulation factors or blood group antibodies
  • available as 5% or 25% solution
  • 5% solution common in OR
  • 5% oncotic pressure 20
  • expands IV volume up to 5x volume given by drawing fluid in from ISF
41
Q

dextran

A
  • water soluble glucose polymers
  • enzymatically degraded to glucose
  • dextran 70 used for volume expansion
  • dextran 40 used for improved blood flow in microcirculation & prevention of thrombosis
  • side effects –> highly antigenic (anaphylaxis), platelet inhibition, noncardiac pulmonary edema, interference with cross matching
42
Q

hydroxyetheyl starch (6%)

A
  • hespan - in 0.95% sodium chloride
  • hextend - in balanced electrolyte solution similar to LR
  • as effective as albumin for volume expansion, but less expensive than albumin
  • primarily excreted via kidneys
  • coagulopathy d/t dilutional thrombocytopenia
  • max dose - limited to <20 mL/kg/day
  • oncotic pressure 30
43
Q

why choose crystalloids?

A
  • effective for initial management of ECF losses
  • hemorrhagic shock, major surgery, or trauma
  • large volumes lead to hemodilution and decreased plasma colloidal oncotic pressure –> edema and transudates
  • continued fluid resuscitation should include colloids, attempting to minimize interstitial edema of vital organs (heart, lungs, brain)
44
Q

why choose colloids?

A
  • effective plasma expanders
  • infusion of 500mL of albumin or hetastarch
  • 6% expand plasma volume by 500mL
  • colloids draw about 20 mL into plasma volume per gram of colloid given
45
Q

perioperative fluid goals

A
  • meet basal fluid requirements
  • replace losses
  • restore or maintain hemodynamic stability
  • enhance microvascular blood flow so that oxygen is delivered to tissues
  • maintain aerobic cellular metabolism
46
Q

sources of intraoperative fluid requirements

A
  • maintenance
  • fluid deficit
  • blood loss
  • evaporative loss (aka 3rd space loss)
47
Q

maintenance fluid components

A
  • water and electrolyte loss from urine and feces plus insensible loss from the respiratory tract and perspiration
  • average normothermic 70kg patient with normal BMR may lose 2500 mL water/day
48
Q

maintenance estimation

A
  • 4-2-1 rule
  • 4 mL/kg/hr for 1st 10 kg
  • 2 mL/kg/hr for 2nd 10 kg
  • 1 mL/kg/hr for each additional kg
49
Q

4-2-1 shortcut

A
  • any patient above 20 kg add 40 to weight to obtain MIVF

- example: 25 kg = 65 mL/hr

50
Q

fluid deficit

A
  • MIVF multiplied by hours patient was NPO

- if patient was receiving MIVF, there is no NPO deficit but consider other losses

51
Q

fluid deficit replacement strategy

A
  • 1/2 deficit replaced in 1st hour of surgery + MIVF
  • 1/4 deficit replaced in 2nd hour of surgery + MIVF
  • 1/4 deficit replaced in 3rd hour of surgery + MIVF
52
Q

evaporative loss/3rd space loss

A
  • evaporative loss related directly to surface area of surgical wound and duration of exposure
  • due to fluid shifts and intravascular volume deficit caused by redistribution of fluid (trauma, infection, burns, ascites)
53
Q

what do you need to know to calculate 3rd space loss?

A
  • type of procedure
  • degree of exposure
  • amount of surgical manipulation
  • replacement based on whether tissue trauma is minimal, moderate, or severe
  • guidelines only, will vary from patient to patient
54
Q

minimal tissue trauma

A

0-2 mL/kg/hr

eye cases, lap chole, hernia, knee scope

55
Q

moderate tissue trauma

A

3-5 mL/kg/hr

open chole, appe

56
Q

severe tissue trauma

A

6-9 mL/kg/hr

bowel surgery, THR

57
Q

emergency surgery tissue trauma

A

10-15 mL/kg/hr

gun shot, MVA

58
Q

estimating blood loss

A
  • vital task of anesthetist
  • 1g = 1 cc blood
  • visual estimation
59
Q

visual estimation of blood components

A
  • floor and surgical drapes
  • suction containers (minus irrigation fluid)
  • soaked gauze 4x4
  • ray-tech
  • soaked lap pads
  • wet sponges
60
Q

soaked 4x4 gauze

A

10 cc blood

61
Q

ray-tech

A

10-20 cc blood

62
Q

soaked laparotomy pads

A

100-150 cc blood

63
Q

wet sponges

A

20-30% of dry value

64
Q

what % of blood loss can most adults tolerate?

A

10%

measure hgb after 15-20%

65
Q

what is the normal transfusion threshold?

A
  • healthy patients tolerate hgb 6-7 g/dL (Hct 18-21%)
  • elderly/patients with significant CV, pulm, neurologic disease may require higher hgb of 10 g/dL and Hct 30%
  • if Hgb between 6-10, transfusion based on patient’s risk for complications and inadequate oxygenation
66
Q

blood loss crystalloid replacement

A

3:1, 3 mL crystalloid to 1 mL blood loss

67
Q

blood loss colloid replacement

A

1:1, 1 mL colloid to 1 mL blood loss

68
Q

blood loss blood replacement

A

1:2, 1 mL blood to 2 mL blood loss

69
Q

neonates EBV

A
  • premie = 95 mL/kg

- term = 85 mL/kg

70
Q

infants EBV

A

80 mL/kg

71
Q

children EBV

A

75 mL/kg

72
Q

adults EBV

A
  • males = 75 mL/kg

- females = 65 mL/kg

73
Q

elderly EBV

A
  • males = 65 mL/kg

- females = 60 mL/kg

74
Q

allowable blood loss (ABL)

A
  • determines how much blood you can lose to reach a particular Hct
  • helps anesthetist design appropriate plan and time to transfuse patient
75
Q

ABL formula

A

[EBV x (starting Hct - allowable Hct)]/starting Hct

76
Q

blood components

A
  • PRBC
  • platelets
  • fresh frozen plasma
  • cryoprecipitate
77
Q

type specific compatibility testing

A
  • ABO-Rh typing only

- 98.9% compatible

78
Q

type & screen compatibility testing

A
  • ABO-Rh type and screen for specific antibodies commonly associated with non-ABO hemolytic reactions
  • 99.94% compatible
79
Q

type & crossmatch compatibility testing

A
  • confirms ABO-Rh typing (done in <5 min)
  • detect antibodies to other blood groups
  • detects antibodies in low titers (may take up to 45 min)
80
Q

massive transfusion

A
  • replacement of patient’s total blood volume in <24 hrs
  • acute administration of > 1/2 the patient’s estimated blood volume in 3 hours or less
  • transfusion of 10 units of RBCs in 24 hours
81
Q

risks of blood product administration

A
  • infections - hep b or c, HIV, bacterial sepsis
  • allergic reaction/febrile reaction
  • TRALI - lung injury or noncardiogenic pulmonary edema
  • hemolytic reactions
  • acute hypotensive transfusion reaction
  • metabolic complications - decreased pH, increased potassium
  • coagulopathy - usually occurs after MTP
  • dilutional thrombocytopenia - responds well to plts
  • low factors V and VIII - stored blood factors may be 15-20% of normal
  • DIC - activation of clotting cascade –> microvascular fibrin deposition –> activation of fibrinolysis
82
Q

citrate toxicity

A
  • citrate preservative may bind to and chelate calcium
  • empiric admin of calcium is not warranted unless iCal low
  • clinically significant hypocalcemia resulting in cardiac depression does not occur in most normal patients unless the transfusion rate exceeds 1 unit q5min
83
Q

PRBCs (packed red blood cells)

A
  • type specific ABO and Rh factor alone is sufficient in 98.9% of patients
  • further testing if antibodies present or patient had numerous blood products
  • HCT of one unit of PRBCs is 70%
  • reconstituted with 0.9% NS
  • calcium in LR may cause blood to clot by reversing anticoagulant effect of citrate
84
Q

how much will 1 unit PRBCs raise Hgb and Hct?

A
  • hgb 1 g/dL

- hct 2-3%

85
Q

how much will a 10mL/g transfusion of PRBCs increase Hgb and Hct?

A
  • hgb 3 g/dL

- hct 10%

86
Q

transfusion alternatives

A
  • autologous blood
  • cell saver
  • acute normovolemic hemodilution
87
Q

autologous blood

A
  • unit of packed red blood cells from the patient themselves
  • not used anymore
  • complications include - anemia, pre-op myocardial ischemia, admin of wrong unit, need for more frequent blood transfusion, febrile/allergic rxn
88
Q

cell-saver

A
  • salvage of blood from the surgical site
  • blood processed, washed and separated
  • red cells transfused back
  • contraindications - surgery with wounds contaminated with bacteria, amniotic fluid, malignant cells, sepsis, chemical contaminants
89
Q

acute normovolemic hemodilution

A
  • remove blood from patient
  • replace blood volume lost with crystalloid or colloids
  • after surgical blood loss has slowed or stopped, patient’s blood transfused back to patient
90
Q

platelets

A
  • one unit obtained by centrifuging single unit
  • uses include - thrombocytopenia, dysfunctional plts, active bleeding, plt count <50,000
  • volume 200-400cc
  • one unit increases plt count 7000-10,000 one hr after transfusion
  • incidence of plt related sepsis is 1 in 12,000
  • bacterial contamination risk 1:2000
91
Q

FFP (fresh frozen plasma)

A
  • contains clotting factors and plasma proteins (no plts)
  • volume 200-250 cc
  • must be ABO compatible
  • uses - urgent warfarin reversal, known coagulation factor deficiencies, correction of microvascular bleeding in presence of increased PT or PTT, correction of microvascular bleeding in patient transfused with more than one blood volume when PT and PTT cannot be obtained in timely fashion
  • each unit increases each clotting factor level by 2-3%
  • FFP contraindicated for augmentation of plasma volume or albumin concentration
92
Q

cryoprecipitate

A
  • derived from precipitate remaining after FFP is thawed
  • contains - factor VIII, fibrinogen, vWF, XIII
  • used in treatment of von Willebrand’s disease, fibrinogen deficiency
  • ABO compatible
  • administer through a filter rapidly (200 mL/hr) and complete within 6 hrs

N928 - Basics of Anesthesia (17 decks)

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