Acid-base Balance Flashcards
(84 cards)
1
Q
What is an acid
A
A compund that DONATES and H+ ion
Has a low pH
2
Q
The more ___ in a solution causes the pH to decrease
A
H+ ions
3
Q
What is a base
A
A compund that BINDS to H+ ions
Has a higher pH
4
Q
Increasing the levels of a ___ will increase the pH
A
Base
5
Q
Why are acid and base levels controlled in the body
A
To maintain a normal pH range
6
Q
What is the normal pH range for most domestic species
A
7.35 and 7.45
7
Q
pH is determined by the
A
Level of H+ ions
8
Q
How are pH ranges maintained
A
Buffering systems
9
Q
What happens with a deviation from the normal pH range
A
Enzyme and cell function will be negatively affected
Can cause death
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
11
Q
What is alkalosis
A
When an animal’s pH is above the normal range
Excess base or loss of acid
12
Q
What is buffering
A
The body’s way of balancing acid and base to maintain a constant pH
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
14
Q
What are the two metabolic buffering systems in the body
A
Chemical buffering
Ion excretion in the urine
15
Q
What is the chemical buffering system
A
K+ and H+ ion exchange between intracellular and extracellular space
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
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
18
Q
How long does it take for the two metabolic buffering systems to significantly alter pH?
A
3-5 days
19
Q
True or false
Respiratory rate can quickly alter pH
A
True
20
Q
In a blood gas analysis, whats are the normal ranges of arterial and venous pH
A
Arterial: 7.40
Venous: 7.35
21
Q
In a blood gas analysis, whats are the normal ranges of arterial and venous pCO2
A
Arterial: 40
Venous: 45
22
Q
In a blood gas analysis, whats are the normal ranges of arterial and venous HCO3
A
Arterial: 25
Venous: 24
23
Q
In a blood gas analysis, whats are the normal ranges of arterial and venous base excess (BE)
A
Both are 0
24
Q
In a blood gas analysis, whats are the normal ranges of arterial and venous pO2
A
Arterial: 95
Venous: 40
25
What is the biggest difference in arterial and venous blood on a blood gas analysis
The levels of oxygen (pO2)
26
Why is there such a large difference in pO2 levels in arterial and venous blood
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
27
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
Arterial
28
How does potassium (K+) work in a buffering system
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
29
What is a risk of the potassium buffering system
Can cause hyperkalemia
30
What are the symptoms of hyperkalemia
```
Decreased/irregular heart rate
Bradycardia: can slow until death
Decreased blood pressure
Muscle weakness
Lethargy
```
31
CO2 + H2O <> H2CO3 <> H+ + HCO3-
| What is this equation
The carbonic acid equilibrium equation
32
In the equation, if H+ increases then CO2____
Increases
33
True or false
| In the equation, H+ has a stronger effect than HCO3- (bicarbonate)
True
34
Cells produce CO2 as a by product of
Cellular metabolism/respiration
35
CO2 levels in the body are highly variable based on
Respiratory rate and depth
Pathology in the lungs
36
CO2 levels will ___ if gas exchange in the lungs is impaired or if respiratory rate or depth decreases
Increase
37
CO2 levels ____ if respiratory rate is increased (panting/hyperventilation)
Decrease
38
CO2 reacts with water to form
Carbonic acid (H2CO3)
39
Carbonic acid (H2CO3) is NOT stable, so it breaks down quickly to
Bicrbonate (HCO3-) and Hydrogen (H+)
40
What is the base in the carbonic acid equilibrium equation
Bicarbonate (HCO3-)
41
What is the acid in the carbonic acid equilibrium equation
Hydrogen (H+)
42
How does adding one molecule of base (bicarbonate) to extracellular fluid affect pH
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
How does adding one molecule of acid (H+) to extracellular fluid affect pH
There are very few hydrogen ions in extracellular fluid, so adding H+ causes a significant change in pH
44
If CO2 increases, H+ ____ and pH ____
H+ increases and pH decreases
45
What are the 4 categories of acid base disturbances seen in the body
Metabolic acidosis
Respiratory acidosis
Metabolic alkalosis
Respiratory alkalosis
46
What is metabolic acidosis
When the pH falls below 7.3
47
What are the 2 causes metabolic acidosis
Loss of bicarbonate (normally through DIARRHEA)
gain in organic acids (ingestion of acid, increase in acid production, decreased excretion of acid)
48
What are some examples of organic acids that could cause metabolic acidosis
Ketoacids
Uremic acids
Lactic acids
Ingested toxins
49
What is Base excess
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
When used with a patient with metabolic alkalosis the base excess number will be
POSITIVE
| Have to ADD an acid to bring it down
51
When used with a patient with metabolic acidosis the base excess number will be
NEGATIVE
| Essentially have to REMOVE the acid from the solution
52
Clinical signs of metabolic acidosis include
```
Depression
Weakness
Recumbency
Ataxia (drunken gait)
Alterations in cardiovascular system (hyperkalemia)
Death
```
53
In metabolis acidosis, treatment for a mild-moderate case (pH of 7.2-7.35) includes
Addressing underlying issue as well as fluid therapy will often be enough (oral electrolytes, sodium bicarbonate via IV)
54
In metabolis acidosis, treatment for a moderate to severe case (pH <7.2) includes
Treatment of the acidosis (addition of sodium bicarbonate to IV fluids)
55
What is respiratory acidosis
The accumulation of CO2 (hypercapnia) causes an increase in production of H+ and a decrease in pH
56
An increase in CO2 levels occurs when
Lung is diseased (asthma, pulmonary edema, neoplasia)
Anesthetized patients thats are too deep (too much anesthetic gas)
57
Why does receiving too much anesthetic gas increase CO2 levels
Causes the respiratory center to become depressed and therefore the respiratory rate will decrease (wont be able to blow of CO2 efficiently)!
58
Treatment of respiratory acidosis includes
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
What is metabolic alkalosis
When pH exceeeds 7.45
60
What are the 2 causes of metabolic alkalosis
Excess bicarbonate (can be iatrogenic)
Loss of H+ (VOMITTING or upper GI obstruction)
61
Treatment of metabolic alkalosis includes
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
What is respiratory alkalosis
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
CO2 levels will be decreased with
Hyperventilation (anxious/stressed animals)
aggressive manual ventilation during anesthesia
64
A slow resp rate can result in
Increase on CO2 levels
65
A fast resp rate can result in a
Decrease in CO2 levels
66
Treatment of respiratory alkalosis includes
Addressing underlying issues
Decreased resp rate with manual bagging
Try and calm anxious animals down
67
A blood gas analysis is useful for evaluating
pH abnormalities
Whether the body has employed its buffering systems to try and normalize the pH
68
What 5 things should you consider when looking through a blood gas analysis and determining the pH abnormality
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
If a patient has a pH of 7.55, a pCO2 of 23mmHg, and bicarbonate of 25mEq/L
What is the diagnosis
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
A patient has:
PH of 7.28, pCO2 of 20 mmHg and HCO3- of 20 mEq/L
What is the diagnosis
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
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
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
Patient has pH of 7.48, pCO2 of 48mmHg, and HCO3 of 32 mEq/L
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
Patient is vomiting
Has low CO2 levels
Has a high pH
Bicarb is high
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
How does bicarb increase pH
Bicarb binds with acid to make carbonic acid (H2CO3) to neutralize the acid and increase pH
75
Why does throwing up increase pH
Because you are losing stomach acid (H+) and you are left with more bicarb
76
Why does diarrhea decrease pH
Because diarrhea results in the excessive loss of bicarb from the intestines, which leaves more H+ leftover which decreases pH
77
Patient has:
Pneumonia
pH: 7.2 pCO2: 55 and bicarb of 33
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
```
Patient:
Ataxia, abnormal behaviour
pH: 7.15
pCO2: 30
HCO3: 10
BE: -5
```
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
If there is a negative BE value, it can be assumed that there is
Metabolic acidosis
80
If there is a positive BE value, it can be assumed that there is
Metabolic alkalosis
81
A decrease in lung function (like in pneumonia) would cause an ___ CO2 levels
increase in CO2 levels
82
Hypoventilation during anesthesia would cause
A build up of CO2 and therefore a decrease in pH
83
Hyperventilation would cause
Decreased CO2 levels, and an increased pH
84
What is scours in pigs
Diarrhea in pigs - very common in young
Diarrhea causes metabolic acidosis
