UNIT 2 - Lecture 6: Acid Base 2

Question 1

Which diagnostic theory is clinically useful and involves alterations in pH due to just changes in HCO₃^- and H⁺?

Answer 1

classical model

Question 2

What acid base parameters do we measure with serum chemistry?

Answer 2

1. Bicarb or total CO₂
2. Anion Gap

Question 3

What acid base parameters can we measure with a blood gas?

Answer 3

1. pH
2. pCO₂
3. paO₂
4. Base excess

Question 4

What does bicarb on a chemistry mean?

Answer 4

[] of bicarb in serum

Question 5

What does total CO2 on a chemistry mean?

Answer 5

Cumulative [] of bicarb, carbonic acid, and CO2

Question 6

TCO2 is functionally the same thing as _____.

Answer 6

bicarb

Question 7

Bicarb and TCO2 can be modulated by the _____ and _____.

Answer 7

liver, kidneys

Question 8

What type of sample is a chemistry and how is it measured?

Answer 8

Serum sample, directly measured

Question 9

What type of sample is a blood gas and how is it measured?

Answer 9

Heparinized whole blood;

Calculated from other parameters

Question 10

Which diagnostic test is stable? How long is it good for?

Answer 10

Serum biochemistry - good @ 4ºC for 5 days

Question 11

Which diagnostic test is unstable? How long is it good for?

Answer 11

Blood gas - good @ 25ºC for 30 min

Question 12

What is the anion gap and what ions can we measure?

Answer 12

Difference between unmeasured anions and cations in blood;

Cations measured = Na⁺, K⁺

Anions measured = HCO₃^-, Cl^-

Question 13

T/F: Total positives in blood will always be less than total negatives in blood

Answer 13

False; they will always equal each other

Question 14

There will always be more unmeasured _____ than _____ in the blood; this is referred to as the anion gap.

Answer 14

anions, cations

Question 15

How is the anion gap calculated (what ions are used and how)?

Answer 15

Na⁺ + K⁺ - Cl^- - HCO₃^-

Question 16

What does an elevated anion gap indicate?

Answer 16

Buildup of organic acids

(EX: lactic acid, ketoacids, uremic acids, ethylene glycol, acetaminophen, abx)

Question 17

What are the guidelines for getting a sample for blood gas analysis?

Answer 17

Use lithium heparin syringe to get whole blood, no air bubbles trapped in sample, run within 30 min at 25 deg C

Question 18

What kind of blood is easier to draw for a blood gas?

Answer 18

venous

Question 19

What values can you get on a blood gas from venous and arterial blood? What value can only be measured from arterial blood?

Answer 19

Both = pH, pCO2, HCO3-

Arterial only = paO2

Question 20

If air bubbles occur or blood is exposed to atmosphere, what errors can occur in a blood gas?

Answer 20

Increased pH or paO2

Decreased pCO2 or HCO3-

Question 21

If it takes too long to analyze a blood gas, what can happen?

Answer 21

Decreased paO2 or pH

Question 22

What is pCO2?

Answer 22

Partial pressure of dissolved CO2 in blood

Question 23

What does hypoventilation cause?

Answer 23

Decreased pulm release of CO2 –> increased blood pCO2 –> acidification

Question 24

What is another term for hypoventilation in terms of CO2?

Answer 24

hypercapnia

Question 25

What does hyperventilation cause?

Answer 25

Increased pulm release of CO2 --\> decreased blood pCO2 --\> alkalinization

Question 26

What is another term for hyperventilation in terms of CO2?

Answer 26

hypocapnia

Question 27

T/F: pCO2 = TCO2

Answer 27

False!!

Question 28

Conceptually, we should think of pCO2 as a(n) \_\_\_\_\_.

Answer 28

acid

Question 29

What is paO2?

Answer 29

Partial P of dissolved oxygen in arterial blood

Question 30

T/F: paO2 does NOT reflect total oxygen content in blood

Answer 30

True

Question 31

What value is not included in paO2?

Answer 31

Hgb bound to oxygen

Question 32

What information does paO2 provide?

Answer 32

Info on how well pulmonary system is oxygenating blood

Question 33

What happens to paO2 during hypoxemia?

Answer 33

It decreases

Question 34

What is hypoxemia usually due to?

Answer 34

Disorders of respiratory ventilation

Question 35

Acidosis is too much _____ or too little \_\_\_\_\_.

Answer 35

CO2, HCO3

Question 36

Alkalosis is too much _____ and too little \_\_\_\_\_.

Answer 36

HCO3, CO2

Question 37

What are the 4 steps to the diagnostic approach of acid base balance?

Answer 37

1. Assess pH 2. Assess HCO3 and pCO2 3. Assess anion gap 4. Summarize and interpret

Question 38

In the diagnostic approach, what does assessing pH determine?

Answer 38

Severity of acid base disturbance

Question 39

In the diagnostic approach, what does assessing HCO3 and pCO2 determine?

Answer 39

1. Determines df/dx of acid base disturbance 2. Determines compensation

Question 40

In the diagnostic approach, what does assessing the anion gap determine?

Answer 40

Subtype of metabolic acidosis

Question 41

What is normal blood pH?

Answer 41

~7.4

Question 42

What is the pH range for acidemia?

Answer 42

~6.8-7.3

Question 43

What is the pH range for alkalosis?

Answer 43

~7.5-7.8

Question 44

Why does a normal pH not necessarily rule out an acid base disturbance?

Answer 44

It might imply buffers and adaptation are maintaining pH in the normal range

Question 45

Low HCO3 = _____ \_\_\_\_\_

Answer 45

metabolic acidosis

Question 46

High HCO3 = _____ \_\_\_\_\_

Answer 46

metabolic alkalosis

Question 47

What are the two types of metabolic acidosis and what causes each?

Answer 47

1. Secretional acidosis = loss of HCO3 from body 2. Titrational acidosis = loss of HCO3 via neutralization of organic acid

Question 48

What is metabolic alkalosis?

Answer 48

Overproduction or retention of HCO3

Question 49

In what animals does metabolic alkalosis most commonly happen?

Answer 49

Cattle with bloat; Can also happen with accidental supplementation with bicarb

Question 50

Low pCO2 = _____ \_\_\_\_\_

Answer 50

respiratory alkalosis

Question 51

High pCO2 = _____ \_\_\_\_\_

Answer 51

respiratory acidosis

Question 52

Which pCO2 condition is seen more commonly?

Answer 52

respiratory acidosis

Question 53

What is respiratory acidosis and what does it lead to?

Answer 53

Retention of pCO2 --\> hypoventilatory disease

Question 54

What is respiratory alkalosis and what does it lead to?

Answer 54

Excess removal of pCO2 --\> hyperventilation

Question 55

How does the body respond to metabolic acidosis?

Answer 55

Compensatory respiratory alkalosis

Question 56

How does the body respond to metabolic alkalosis?

Answer 56

Compensatory respiratory acidosis

Question 57

How does the body respond to respiratory acidosis?

Answer 57

Compensatory metabolis alklaosis

Question 58

How does the body respond to respiratory alkalosis?

Answer 58

Compensatory metabolic acidosis

Question 59

When there is a primary metabolic acid base disturbance, how long does it take for the body to respond?

Answer 59

within minutes

Question 60

When there is a primary respiratory acid base disturbance, how long will it take the body to respond?

Answer 60

days

Question 61

If your patient is acidemic with a low pCO2 and a low HCO3, what is happening?

Answer 61

Primary metabolic acidosis with compensatory respiratory alkalosis

Question 62

What does increased AG indicate?

Answer 62

Presence of organic acid

Question 63

If you have a metabolic acidosis and the AG is increased, what does this mean?

Answer 63

Titrational metabolic acidosis HCO3 is low because it is *titrating* an organic acid

Question 64

If you have a metabolic acidosis and the AG is normal, what does this mean?

Answer 64

Secretional metabolic acidosis HCO3 low because it is *secreted* from the body

Question 65

If your patient is acidemic, has low HCO3, normal pCO2, and an elevated AG, what does this mean?

Answer 65

Acidemia caused by primary titrational metabolic acidosis with NO respiratory compensation