Anesthesiology Perioperative Fluid Therapy & Acid/base Balance

Front 1

What are 3 reasons to administer fluids perioperatively?

Back 1

1) Anesthetics cause relative hypovolemia
2) Absolute volume deficits
3) Maintain venous access

Front 2

What are 4 causes of relative hypovolemia during anesthesia?

Back 2

1) Myocardial depression
2) Vasodilation
3) Blunted sympathetic nervous system responsiveness
4) Ongoing obligatory losses

Front 3

What are 4 causes of absolute volume deficits during surgery?

Back 3

1) Dehydration
2) Blood loss
3) Third space losses
-edema, effusions
4) Uncorrected abnormalities in emergent procedures

Front 4

What is the most common side effect of anesthesia encountered in small animals?

Back 4

Hypotension

Front 5

What % of total body weight is water in a dog?

Back 5

60%

Front 6

What % of total body weight makes up the ECF in a dog? ICF?

Back 6

ECF= 20% of total BW
ICF= 40% of total BW

Front 7

What are the 2 compartments that make up the ECF?

Back 7

Intravascular (plasma)
Interstitial

Front 8

What % of total BW is made up of plasma in a dog? Interstitial fluid volume?

Back 8

plasma: 5% BW
Interstitial fluid volume: 15% BW

Front 9

What % of total body weight is RBCs in a dog?

Back 9

3%

Front 10

What determines fluid distribution?

Back 10

Presence of membranes that restrict/ control movement of certain substances that can act as effective osmoles

Front 11

What are 2 membranes that restrict/control movement of certain substances that can act as effective osmoles?

Back 11

1) Cell membrane
2) Capillary endothelium

Front 12

What barrier separates the ECF from the ICF?

Back 12

Cell membrane

Front 13

____ is the effective extracellular osmole and _____ is the effective intracellular osmole, with ______ pump maintaining concentration gradient.

Back 13

Na+=ECF
K+=ICF
Na+/K+ pump

Front 14

What does the capillary endothelium separate? What is the effective osmole?

Back 14

Intravascular fluid from interstitial fluid, with macromolecules (albumin) as effective osmoles

Front 15

What is the definition of osmolarity?

Back 15

Measure of the number of osmoles/ liter of solution

Front 16

Is osmolarity a property that is independent or dependent on membranes?

Back 16

Independent

Front 17

What is the definition of tonicity? Is it dependent or independent of membranes?

Back 17

Measure of effective osmolarity dependent of a semipermeable membrane

Front 18

How is tonicity typically expressed?

Back 18

Relative to plasma tonicity
-Hypertonic
-Isotonic
-Hypotonic

Front 19

Osmoles move freely b/w _____ & _____ space. Movement is inhibited by cellular ______.

Back 19

Vascular & extravascular space
Membranes

Front 20

Colloid movement is limited by _____ and creates _____ pressure.

Back 20

Vascular walls
Creates oncotic pressure

Front 21

The overall osmolarity in the body of the ECF & ICF is ____ mOsm/L.

Back 21

290 mOsm/L

Front 22

The 'effective' osmoles responsible for tonicity in the ECF is _____ and _____ in the ICF.

Back 22

Na+=ECF
K+=ICF

Front 23

We have access to the _____ space for fluid administration.

Back 23

ECF
-not gonna put fluids in cells

Front 24

The ONLY safe, effective osmole for extracellular fluid administration is ______.

Back 24

Na+

Front 25

Describe the concentration of sodium in a hypotonic state.

Back 25

[Na+]=0 or < plasma [Na+]
Distributed throughout all fluid compartments

Front 26

Describe the sodium concentrations and distribution in an isotonic state.

Back 26

[Na+]= plasma [Na+]
Distributes to the extracellular space

Front 27

Describe the sodium concentrations and distribution in a hypertonic state.

Back 27

[Na+] > then plasma [Na+]
Transiently increases in intravascular space, redistributes throughout extracellular space, may then draw fluid from intracellular space

Front 28

What is a 'colloid'?

Back 28

Large macromolecules impermeable to capillary membrane

Front 29

What are 2 natural colloids?

Back 29

Albumin, globulin

Front 30

What are 3 exogenous colloids?

Back 30

Sugars, starches, proteins

Front 31

What is colloid oncotic pressure?

Back 31

Colloids are 'active' molecules that produce an effect by 'drawing' or 'pulling' water across a semipermeable membrane (e.g. capillary membranes)

Front 32

What happens without colloids? What happens with colloids?

Back 32

Without: water freely distributes out of vascular space
With: water is retained w/in vascular space

Front 33

The amount of vascular volume expansion depends on the _____ properties of the solution.

Back 33

Colloidal

Front 34

What is responsible for maintaining fluid balance b/w intravascular (plasma) and extravascular space?

Back 34

Colloid oncotic pressure

Front 35

Where are cystalloids distributed in the body?

Back 35

Contains ions or solutes that may redistribute to all fluid compartments w/in the body

Front 36

What are 3 methods used to classify crystalloids?

Back 36

1) Electrolyte composition
2) Tonicity
3) Acid-base effect (pH)

Front 37

Describe the electrolyte composition of fluids used for replacement.

Back 37

Electrolyte composition is similar to ECF or plasma

Front 38

Describe the electrolyte composition of fluids used for maintenance.

Back 38

Electrolyte composition is not the same as ECF, used to replace electrolytes and water that are normally lost continuallow
-Low Na+, high K+, often Glu

Front 39

Maintenance fluids are effectively _______ relative to [Na+].

Back 39

hypotonic

Front 40

What happens to dextrose that is administered in fluids?

Back 40

Short lived Iv, metabolized and then osmotic component is gone and left w/ water

Front 41

Tonicity is based on osmolarity relative to ____ & ______ fluid.

Back 41

Plasma and ECF

Front 42

What is an example of hypertonic fluids?

Back 42

7.5% NaCl (2,400 mOsm/L)
*most commonly used

Front 43

What is an example of isotonic fluids?

Back 43

Lactated ringer's solution (273 mOsm/L)

Front 44

What is an example of hypotonic fluids?

Back 44

0.45% NaCl (154 mOsm/L)

Front 45

What is an example of acidifying crystalloids? Why is it acidifying?

Back 45

0.9% NaCl
-produces a hyperchloremic metabolic acidosis

Front 46

Alkalinizing crystalloids are based on _____ composition and ______ precursors.

Back 46

Electrolyte composition
Bicarbonate precursors

Front 47

What are 3 types of molecules in alkalinizing crystalloids that are precursors of bicarbonate? How do each one result in an alkaline solution?

Back 47

1) Lactate
-Metabolized to HCO3- by liver (LRS)
2) Acetate
-Metabolized to HCO3- by muscle (normosol, plasmalyte)
3) Gluconate
-Metabolized to HCO3- by most cells (Normosol, plasmalyte)

Front 48

What are 5 routes of fluid administration to the extracellular space?

Back 48

1) Oral
2) Intraosseous
3) Intraperitoneal
4) Subcutaneous
5) Intravenous

Front 49

During anesthesia what are the only two routes of administration that effectively get fluid in the extracellular space?

Back 49

Intraosseous
Intravenous

Front 50

What are the 4 steps in treating hypotension?

Back 50

1) Normalize HR
2) Check and assess anesthetic depth
3) Where are you at with fluids? Do you need fluid bolus?
4) Ionotropes to chemically support vascular function

Front 51

K+ is _______ when potassium containing fluids are given at high rates.

Back 51

**cardiotoxic

Front 52

**What is the recommended max rate of potassium containing fluid administration?

Back 52

0.5 mEq/ kg/ hr

Front 53

Many ______ fluids have high [K+] and it is not uncommon in an ICU setting to supplement K+ levels up to 40 mEq/L.

Back 53

Maintenance fluids

Front 54

What are 3 albumin containing blood products that are natural colloids?

Back 54

1) Whole blood
2) Plasma
3) Packed RBCs
-only if resuspended in a colloid

Front 55

What are 2 types of synthetic colloids?

Back 55

1) Complex carbohydrate solutions
2) Oxyglobin

Front 56

What are 3 complex carbohydrate solutions that are given as synthetic colloids?

Back 56

Dextrans, hetastarch, pentastarch

Front 57

What is oxyglobin?

Back 57

Bovine hemoglobin glutamer

Front 58

What are 4 possible side effects of colloid administration?

Back 58

1) Coagulopathy
-interfere w/ platelet function
2) Renal failure
-eliminated by renal filtration
3) Congestive heart failure
-Volume overload
4) Anaphylaxis
-rare

Front 59

What are 6 types of blood products available to administer to patients?

Back 59

1) Whole blood
-fresh, stored
2) Packed RBCs (pRBCs)
3) Fresh frozen plasma (FFP)
4) Frozen or stored plasma
-lacks coagulation factors
5) Platelet concentrates
6) Oxyglobin

Front 60

What are 4 indications for use of blood products?

Back 60

1) Hypovolemia due to acute hemorrhage
2) Anemia, hemoglobinemia
-normovolemic, hypovolemic
3) Coagulation disorders
4) Hypoproteinemia

Front 61

What do you want to give a patient that has hypovolemia due to hemorrhage?

Back 61

-Whole blood
-pRBCs resuspended in plasma or colloid works too

Front 62

What do you want to give a patient that is anemic and hypovolemia? Normovolemic?

Back 62

Whole blood= hypovolemic
pRBCs= normovolemic, because might overwhelm patient

Front 63

What do you want to give a patient that has a coagulation disorder?

Back 63

Fresh frozen plasmas or platelet concentrates

Front 64

What do you want to give an animal for hypoproteinemia?

Back 64

Plasma- fresh frozen or frozen stored

Front 65

When giving an animal a blood transfusion, there can be reactions so we need to first perform _______.

Back 65

Cross matching

Front 66

What are 3 examples of immunologic reactions to blood transfusions?

Back 66

1) RBC incompatibility reactions
2) Reaction to plasma proteins
3) REaction to WBCs or platelets

Front 67

What are 8 examples of non-immunologic reactions to blood transfusions?

Back 67

1) Anaphylaxis
2) Volume overload
3) Hypothermia
4) Citrate intoxication
5) Heparinization
6) Microbial contamination -sepsis
7) Pulmonary microemboli
8) Increased ammonia, increased K+, decreased P, acidosis

Front 68

What are 4 types of reactions to blood transfusions that can occur during anesthesia?

Back 68

1) Hypotension
2) HR, RR, temp, hematocrit, serum color (from hemolysis) ECG changes
3) Urticaria
4) Facial swelling

Front 69

What should you do if you detect a reaction to a blood transfusion?

Back 69

Stop the transfusion
steroids? can help..

Front 70

Colloids are typically administered at ~______ the rate of crystalloids.

Back 70

1/3 the rate

Front 71

Colloids should be administered for a maximum of ____ days.

Back 71

3

Front 72

What is a test dose when administering a blood transfusion?

Back 72

Want to give a small dose (.25 mls/kg) over 15 minutes and observe for any reaction

Front 73

What are 3 clinically important electrolytes that have direct effects & impact on patient management under anesthesia?

Back 73

1) Calcium
2) Potassium
3) Magnesium

Front 74

What are the 3 steps to the fluid plan (3 types of fluid administration)?

Back 74

1) Replacement
-deficits related to blood loss, dehydration etc.
2) Maintenance
-normal sensible & insensible losses
-related to normal metabolism (i.e. urination, defecation, respiratory evaporation)
3) Ongoing losses
-Continued blood loss, evaporative losses from body cavities etc.

Front 75

What are 3 ways to assess the amount/type of fluids that should be administered?

Back 75

1) History
2) Physical exam
3) Lab results

Front 76

What are 3 factors you should consider when trying to decide which fluid to use?

Back 76

1) Mimic fluids lost or required
2) Distribute to body compartment required
3) Cost

Front 77

What are 4 factors to consider when trying to figure out which fluids are going to distribute to the different body compartments required?

Back 77

1) Electrolyte composition (Na+)
-ICF VS ECF distribution
2) Tonicity
-hypotonic solutions provide free water
-Hypertonic solutions will move water from other compartments
3) Acid- base effects
-Acidifying VS alkalinizing
-treat underlying cause of acid/base imbalance
4) Intravascular or extravascular
-to remain intravascular must have colloid component

Front 78

Compare the cost of crystalloids, colloids and blood products.

Back 78

Cystalloids- cheap
Colloids- expensive
Blood products- more expensive

Front 79

Maximal rate of fluid administration is limited by ______.

Back 79

Vascular access

Front 80

Resistance of intravascular fluid administration is proportional to the _____.

Back 80

radius, bigger is better
-Better to place 2nd catheter before hypotensive crisis!!!!

Front 81

What 3 things does a blood gas machine MEASURE?

Back 81

pH
pCO2
pO2

Front 82

What 3 things does a blood gas machine CALCULATE?

Back 82

1) HCO3
2) Base excess
3) Hb saturation

Front 83

When evaluating blood gas information, what are the first 2 questions you should ask yourself?

Back 83

1) What is the pH
-Normal? acidic, alkaline?
2) if pH is abnormal, is it a primary respiratory problem or metabolic problem

Front 84

Respiratory acidosis is when the PaCO2> _____ and respiratory alkalosis is when PaCO2 < ____.

Back 84

PaCO2 > 45
PaCO2 < 35

Front 85

Metabolic acidosis is when the base excess < ______ and metabolic alkalosis is when the base excess > ____.

Back 85

<-4
>4

Front 86

What is the treatment for respiratory acidosis?

Back 86

Ventilate

Front 87

What is the treatment for metabolic acidosis?

Back 87

Bicarbonate therapy
-if BE< -10 OR
-pH< 7.2

Front 88

***What is the equation used to calculate how much bicarbonate to administer an animal?

Back 88

mEq HCO3-=BW(kg) x BE x0.3
-recheck blood gas after partial dose

Front 89

PaO2 should~ FiO2 x ____

Back 89

5
-room air FiO2=21%

Front 90

What is the most common cause of "relative hypoxemia" under anesthesia?

Back 90

Ventilation/perfusion mismatching

Front 91

If a horse is breathing 100% oxygen, what should the PaO2 equal? PCO2 (without ventilation/perfusion mismatch)?

Back 91

PaO2=500
PaCO2= 40 (same as blood)

Front 92

What are 2 examples of ventilation/ perfusion mismatch?

Back 92

-Good ventilation but no perfusion
-Obstruction so no ventilation but good perfusion (same thing w/ atelactic lung

Front 93

True or false. You have big issues when the PaO2= PaCO2.

Back 93

True