Acid-base Balance Flashcards

1
Q

What is an acid

A

A compund that DONATES and H+ ion

Has a low pH

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2
Q

The more ___ in a solution causes the pH to decrease

A

H+ ions

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3
Q

What is a base

A

A compund that BINDS to H+ ions

Has a higher pH

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4
Q

Increasing the levels of a ___ will increase the pH

A

Base

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5
Q

Why are acid and base levels controlled in the body

A

To maintain a normal pH range

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6
Q

What is the normal pH range for most domestic species

A

7.35 and 7.45

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7
Q

pH is determined by the

A

Level of H+ ions

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8
Q

How are pH ranges maintained

A

Buffering systems

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9
Q

What happens with a deviation from the normal pH range

A

Enzyme and cell function will be negatively affected

Can cause death

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10
Q

What is acidosis

A

When the animal’s pH is lower than the normal range

Increase of acid levels or loss of a base

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11
Q

What is alkalosis

A

When an animal’s pH is above the normal range

Excess base or loss of acid

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12
Q

What is buffering

A

The body’s way of balancing acid and base to maintain a constant pH

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13
Q

What are the 3 main categories of buffering systems in the body

A

Chemical buffering

Ion excretion in the urine

Adjustment of respiratory rate

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14
Q

What are the two metabolic buffering systems in the body

A

Chemical buffering

Ion excretion in the urine

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15
Q

What is the chemical buffering system

A

K+ and H+ ion exchange between intracellular and extracellular space

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16
Q

How does the ion excretion in the urine buffering system work

A

The kidenys control excretion and retention of bicarbonate and H+ to alter pH

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17
Q

How does adjustment of respiratory rate alter pH

A

By adjusting respiratory rate, carbon dioxide levels in the bloodstream are altered which affects pH

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18
Q

How long does it take for the two metabolic buffering systems to significantly alter pH?

A

3-5 days

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19
Q

True or false

Respiratory rate can quickly alter pH

A

True

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20
Q

In a blood gas analysis, whats are the normal ranges of arterial and venous pH

A

Arterial: 7.40

Venous: 7.35

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21
Q

In a blood gas analysis, whats are the normal ranges of arterial and venous pCO2

A

Arterial: 40

Venous: 45

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22
Q

In a blood gas analysis, whats are the normal ranges of arterial and venous HCO3

A

Arterial: 25

Venous: 24

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23
Q

In a blood gas analysis, whats are the normal ranges of arterial and venous base excess (BE)

A

Both are 0

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24
Q

In a blood gas analysis, whats are the normal ranges of arterial and venous pO2

A

Arterial: 95

Venous: 40

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25
Q

What is the biggest difference in arterial and venous blood on a blood gas analysis

A

The levels of oxygen (pO2)

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26
Q

Why is there such a large difference in pO2 levels in arterial and venous blood

A

Arterial blood has recently been oxygenated (coming from the heart/lungs)

In Venous blood, oxygen has been used up in the tissues so oxygen levels are lower

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27
Q

If the doctor is worried about pulmonary disease in a patient, which sample, venous or arterial, would be most useful in a blood gas analysis

A

Arterial

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28
Q

How does potassium (K+) work in a buffering system

A

K+ is in high concentration within cells

When there is a high level of H+ ions (acidosis), they can be exchanged for K+ (H+ shifts into cells and K+ shifts into extracellular space) and increase the pH

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29
Q

What is a risk of the potassium buffering system

A

Can cause hyperkalemia

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30
Q

What are the symptoms of hyperkalemia

A
Decreased/irregular heart rate 
Bradycardia: can slow until death 
Decreased blood pressure
Muscle weakness
Lethargy
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31
Q

CO2 + H2O <> H2CO3 <> H+ + HCO3-

What is this equation

A

The carbonic acid equilibrium equation

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32
Q

In the equation, if H+ increases then CO2____

A

Increases

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33
Q

True or false

In the equation, H+ has a stronger effect than HCO3- (bicarbonate)

A

True

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34
Q

Cells produce CO2 as a by product of

A

Cellular metabolism/respiration

35
Q

CO2 levels in the body are highly variable based on

A

Respiratory rate and depth

Pathology in the lungs

36
Q

CO2 levels will ___ if gas exchange in the lungs is impaired or if respiratory rate or depth decreases

A

Increase

37
Q

CO2 levels ____ if respiratory rate is increased (panting/hyperventilation)

A

Decrease

38
Q

CO2 reacts with water to form

A

Carbonic acid (H2CO3)

39
Q

Carbonic acid (H2CO3) is NOT stable, so it breaks down quickly to

A

Bicrbonate (HCO3-) and Hydrogen (H+)

40
Q

What is the base in the carbonic acid equilibrium equation

A

Bicarbonate (HCO3-)

41
Q

What is the acid in the carbonic acid equilibrium equation

A

Hydrogen (H+)

42
Q

How does adding one molecule of base (bicarbonate) to extracellular fluid affect pH

A

There is LOTS of bicarbonate in extracellular fluid, so one molecule has a small affect on the concentration and therefore a small affect on the pH

43
Q

How does adding one molecule of acid (H+) to extracellular fluid affect pH

A

There are very few hydrogen ions in extracellular fluid, so adding H+ causes a significant change in pH

44
Q

If CO2 increases, H+ ____ and pH ____

A

H+ increases and pH decreases

45
Q

What are the 4 categories of acid base disturbances seen in the body

A

Metabolic acidosis

Respiratory acidosis

Metabolic alkalosis

Respiratory alkalosis

46
Q

What is metabolic acidosis

A

When the pH falls below 7.3

47
Q

What are the 2 causes metabolic acidosis

A

Loss of bicarbonate (normally through DIARRHEA)

gain in organic acids (ingestion of acid, increase in acid production, decreased excretion of acid)

48
Q

What are some examples of organic acids that could cause metabolic acidosis

A

Ketoacids

Uremic acids

Lactic acids

Ingested toxins

49
Q

What is Base excess

A

Used to measure the amount of a strong acid that would be needed to bring 1L of blood to a pH of 7.4

Can be positive or negative

50
Q

When used with a patient with metabolic alkalosis the base excess number will be

A

POSITIVE

Have to ADD an acid to bring it down

51
Q

When used with a patient with metabolic acidosis the base excess number will be

A

NEGATIVE

Essentially have to REMOVE the acid from the solution

52
Q

Clinical signs of metabolic acidosis include

A
Depression
Weakness
Recumbency 
Ataxia (drunken gait)
Alterations in cardiovascular system (hyperkalemia)
Death
53
Q

In metabolis acidosis, treatment for a mild-moderate case (pH of 7.2-7.35) includes

A

Addressing underlying issue as well as fluid therapy will often be enough (oral electrolytes, sodium bicarbonate via IV)

54
Q

In metabolis acidosis, treatment for a moderate to severe case (pH <7.2) includes

A

Treatment of the acidosis (addition of sodium bicarbonate to IV fluids)

55
Q

What is respiratory acidosis

A

The accumulation of CO2 (hypercapnia) causes an increase in production of H+ and a decrease in pH

56
Q

An increase in CO2 levels occurs when

A

Lung is diseased (asthma, pulmonary edema, neoplasia)

Anesthetized patients thats are too deep (too much anesthetic gas)

57
Q

Why does receiving too much anesthetic gas increase CO2 levels

A

Causes the respiratory center to become depressed and therefore the respiratory rate will decrease (wont be able to blow of CO2 efficiently)!

58
Q

Treatment of respiratory acidosis includes

A

Treatment of any underlying causes

If anesthetized, gas levels should be decreased if needed

Increases resp rate if manually bagging

Check if they are on correct breathing system (not an excessive amount of dead space)

59
Q

What is metabolic alkalosis

A

When pH exceeeds 7.45

60
Q

What are the 2 causes of metabolic alkalosis

A

Excess bicarbonate (can be iatrogenic)

Loss of H+ (VOMITTING or upper GI obstruction)

61
Q

Treatment of metabolic alkalosis includes

A

Aggressive fluid therapy with 0.9% NaCl saline
(Fluids will dilute the bicarbonate in the blood, and extra Cl- in fluids will increase excretion of bicarbonate in the urine)

62
Q

What is respiratory alkalosis

A

A decrease in CO2 results in an elevated pH

Decrease in CO2 results in a decrease in H+ which causes an increase in pH

63
Q

CO2 levels will be decreased with

A

Hyperventilation (anxious/stressed animals)

aggressive manual ventilation during anesthesia

64
Q

A slow resp rate can result in

A

Increase on CO2 levels

65
Q

A fast resp rate can result in a

A

Decrease in CO2 levels

66
Q

Treatment of respiratory alkalosis includes

A

Addressing underlying issues

Decreased resp rate with manual bagging

Try and calm anxious animals down

67
Q

A blood gas analysis is useful for evaluating

A

pH abnormalities

Whether the body has employed its buffering systems to try and normalize the pH

68
Q

What 5 things should you consider when looking through a blood gas analysis and determining the pH abnormality

A

Look at pH (high or low?)

Look at pCO2 (increases with acidosis and decreased with alkalosis)

Look at bicarbonate value ( decreased with acidosis and increased with alkalosis)

Is there evidence of compensation? (Buffering) (do the bicarbonate and CO2 values correspond with the pH abnormality, if not, then the body is likely compensating)

69
Q

If a patient has a pH of 7.55, a pCO2 of 23mmHg, and bicarbonate of 25mEq/L

What is the diagnosis

A

High pH indicated alkalosis

Low CO2 levels contribute to low H+ production and therefore a higher pH

A normal level of bicarbonate indicates there is no compensation occuring

Therefore, it is respiratory alkalosis with no metabolic compensation

70
Q

A patient has:
PH of 7.28, pCO2 of 20 mmHg and HCO3- of 20 mEq/L

What is the diagnosis

A

Ph is decreased: acidotic
CO2 levels are decreased: which makes H+ decrease which would lead to alkalosis (so it is NOT contributing to the acidosis)
bicarbonate is decreased which would contribute to the acidosis

Therefore: it is metabolic acidosis with respiratory compensation

71
Q

Patient has:
Kidney disease
Resp rate of 60/min and increased effort
Fever and high heart rate
Blood gas shows: pH of 7.2, bicarb of 20mEq/L
Diagnosis: pneumonia

A

Low pH: acidosis

Pneumonia: decrease in lung function means an increase in CO2 and an increase in H+

Low bicarb: if there was compensation the bicarb would be high

Therefore: it is non compensatory respiratory acidosis

72
Q

Patient has pH of 7.48, pCO2 of 48mmHg, and HCO3 of 32 mEq/L

A

High pH: alkalosis

High pCO2: means a high H+ therefore it does NOT contribute to the alkalosis

Bicarb is high: which increases pH

Therefore, it is metabolic alkalosis with respiratory compensation

73
Q

Patient is vomiting

Has low CO2 levels
Has a high pH
Bicarb is high

A

High pH: alkalosis

Vomitting and high bicarb: loosing H+ from vomitting stomach acid, and high bicarb is left

CO2 is low: which would increase pH

Therefore: metabolic alkalosis with no respiratory compensation

74
Q

How does bicarb increase pH

A

Bicarb binds with acid to make carbonic acid (H2CO3) to neutralize the acid and increase pH

75
Q

Why does throwing up increase pH

A

Because you are losing stomach acid (H+) and you are left with more bicarb

76
Q

Why does diarrhea decrease pH

A

Because diarrhea results in the excessive loss of bicarb from the intestines, which leaves more H+ leftover which decreases pH

77
Q

Patient has:
Pneumonia
pH: 7.2 pCO2: 55 and bicarb of 33

A

Pneumonia: decreased lung function
Low pH: acidosis
High pCO2: high H+ therefore decreases pH
High bicarb: would increase pH

Therefore: it is respiratory acidosis with metabolic compensation

78
Q
Patient:
Ataxia, abnormal behaviour
pH: 7.15 
pCO2: 30
HCO3: 10
BE: -5
A

pH: low = acidosis
CO2: low (would decrease H+ and increase pH)
HCO3: low: would decrease pH
BE: a negative value indicates metabolic acidosis

Therefore: it is metabolic acidosis with respiratory compensation

79
Q

If there is a negative BE value, it can be assumed that there is

A

Metabolic acidosis

80
Q

If there is a positive BE value, it can be assumed that there is

A

Metabolic alkalosis

81
Q

A decrease in lung function (like in pneumonia) would cause an ___ CO2 levels

A

increase in CO2 levels

82
Q

Hypoventilation during anesthesia would cause

A

A build up of CO2 and therefore a decrease in pH

83
Q

Hyperventilation would cause

A

Decreased CO2 levels, and an increased pH

84
Q

What is scours in pigs

A

Diarrhea in pigs - very common in young

Diarrhea causes metabolic acidosis