Metabolic Acidosis

Question 1

Between what pHs is intracellular pH maintained?

Answer 1

7.0 and 7.3

Question 2

How does metabolic acidosis occur?

Answer 2

• Loss of CO2 drives formation of H+ into H2O

- Therefore, you become acidotic if have a lot of H+ and can’t blow off enough CO2

Question 3

How does respiratory acidosis?

Answer 3

If you can’t blow off enough CO2, the equation goes in the other direction, increasing H+

Question 4

What is the primary disturbance in metabolic acidosis?

Answer 4

Decreased bicarbonate

Question 5

What is the primary disturbance in metabolic alkalosis?

Answer 5

Increased bicarbonate

Question 6

What is the primary disturbance in respiratory acidosis?

Answer 6

Increased pCO2

Question 7

What is the primary disturbance in respiratory alkalosis?

Answer 7

Decreased pCO2

Question 8

What is the compensatory response in metabolic acidosis?

Answer 8

Decreased pCO2

Question 9

What is the compensatory response in metabolic alkalosis?

Answer 9

Increased pCO2

Question 10

What is the compensatory response in respiratory acidosis?

Answer 10

Increased bicarbonate

Question 11

What is the compensatory response in respiratory alkalosis?

Answer 11

Decreased bicarbonate

Question 12

What is the definition of metabolic acidosis?

Answer 12

A low arterial blood pH in conjunction with a reduced serum bicarbonate concentration

Question 13

Why is it important to detect metabolic acidosis?

Answer 13

• Acidic environment associated with lots of significant medical conditions
• Metabolic acidosis → increased mortality
• Easy identified and potentially correctable

Question 14

What is metabolic acidosis not?

Answer 14

A diagnosis → it is a sign of something else you need to diagnose

Question 15

What is the anion gap due to?

Answer 15

Not measuring many anions (many proteins) → measure fewer anions than cations, causing an anion gap (even though we know it is equal

Question 16

What are the measured cations?

Answer 16

Na+ and K+

Question 17

What are the measured anions?

Answer 17

HCO3- and Cl-

Question 18

What does an increased anion gap indicate?

Answer 18

An increase in the concentration of anions other than chloride or bicarbonate

Question 19

What is the equation showing that plasma is always electroneutral?

Answer 19

Measured cations + unmeasured cations = measured anions + unmeasured anions

Question 20

Why does low bicarbonate mean an increased anion gap?

Answer 20

Bc there is a higher concentration of an unmeasured anion

Question 21

What happens during normal anion gap acidosis?

Answer 21

• Have lost bicarbonate but chloride has compensated

- Bicarbonate loss but chloride reabsorption

Question 22

What are causes of normal anion gap acidosis?

Answer 22

1) GI losses of bicarbonate → diarrhoea, surgical drains/fistulae
2) Renal losses of bicarbonate → renal tubular acidosis

Question 23

What is the mnemonic to remember for increase anion gap acidosis?

Answer 23

GOLDMARK

Question 24

What are causes of increased anion gap acidosis?

Answer 24

1) Glycols (ethylene, propylene) - antifreeze
2) Oxyproline
3) L-lactate (common when sick)
4) D-lactate (common when sick)
5) Methanol
6) Aspirin
7) Renal failure
8) Ketoacidosis

Question 25

What is lactic acidosis?

Answer 25

The result of lactic production in anaerobic respiration

Question 26

When does lactic acidosis happen?

Answer 26

In any form of shock

Question 27

What is ketoacidosis?

Answer 27

The result of ketone production from fat metabolism when cells can't take up glucose

Question 28

What are ketones?

Answer 28

Unmeasured anions

Question 29

What are the main causes of ketoacidosis?

Answer 29

Diabetes, alcohol and starvation

Question 30

What are the most common causes if increased anion gap?

Answer 30

Lactic acidosis and ketoacidosis

Question 31

Describe taking ABGs

Answer 31

- Commonly use radial artery or femoral artery - Can be painful - Low resistance - Don't need vacuum - BP pushes plunger up and fills up syringe on its own

Question 32

What is the desired range of pCO2?

Answer 32

4.5-6.0 kPa

Question 33

What is the desired range of pO2?

Answer 33

10-13 kPa

Question 34

What is the desired range of HCO3-?

Answer 34

24-26 mmol/L

Question 35

What is the desired range of SpO2 (on ABG)?

Answer 35

96-100% (more accurate than finger probe)

Question 36

What is the desired range of base excess?

Answer 36

+2 → -2

Question 37

What does a low base excess (-3 or lower) indicate?

Answer 37

(Metabolic) acidosis

Question 38

What does a high base excess indicate?

Answer 38

Alkalosis

Question 39

What is the base deficit?

Answer 39

Same as base excess but opposite numbers

Question 40

What H+ concentration is alkalosis?

Answer 40

H+ < 35 nmol

Question 41

What H+ concentration is acidosis?

Answer 41

H+ > 45 nmol/L

Question 42

What PaCO2 level indicates respiratory acidosis or respiratory compensation for a metabolic acidosis?

Answer 42

> 6.0 kPa/45 mmHg

Question 43

What PaCO2 level indicates respiratory alkalosis or respiratory compensation for a metabolic acidosis?

Answer 43

< 4.7 kPa/35 mmHg

Question 44

What HCO3- level indicates metabolic acidosis or renal compensation for a respiratory alkalosis?

Answer 44

< 22mmol/L

Question 45

What HCO3- level indicates metabolic alkalosis or renal compensation for a respiratory acidosis?

Answer 45

>26 mmol/L

Question 46

When is acidosis/alkalosis truly compensated?

Answer 46

When you have normal pH

Question 47

When is acidosis partially compensated?

Answer 47

When pH is higher than expected but still not normal

Question 48

What do you need for respiratory compensation?

Answer 48

Capacity of lungs

Question 49

In what case could you have mixed metabolic and respiratory acidosis?

Answer 49

In someone with COPD and CKD → pt might not be able to compensate for acute respiratory/metabolic acidosis

Question 50

What does not happen with regard to compensation?

Answer 50

Over compensation

Question 51

What is the normal anion gap range?

Answer 51

8-12 mmol/L

Question 52

Which test is most important to do if you suspect diabetic ketoacidosis and why?

Answer 52

Urinalysis → bc can see ketones and glucose (compared to blood glucose)

Question 53

Generally what should pO2 be?

Answer 53

10 less than the % you are breathing → so at sea level, 21% (11kPa)

Question 54

Why do GI losses lead to metabolic acidosis with a normal anion gap and high chloride?

Answer 54

1) Chloride reabsorbed balances bicarbonate lost | 2) No generation of extra acid e.g. lactate or ketones

Question 55

Why does increased anion gap occur?

Answer 55

Production of acids which are also anions