Lecture 4 - Acid/Base Abnormalities

Question 1

Describe acidosis and alkalosis

Answer 1

processes that tend to change pH in a given direction

Question 2

Describe academia and alkalemia

Answer 2

resultant pH of blood

Question 3

Acid-base homeostasis maintains an arterial pH within a range of ____ to ____

Answer 3

7. 35 to 7.45

* ideally we say 7.4 but it fluctuates

Question 4

what pH defines acidemia

Answer 4

pH < 7.4

Question 5

what pH defines alkalemia

Answer 5

pH > 7.4

Question 6

What are 3 sites of acid-base regulation

Answer 6

• chemical buffers
• lung
• kidney

Question 7

What defines metabolic acidosis?

Answer 7

serum bicarbonate < 24 mEq/L

normal range 18-24 mEq/L

Question 8

What defines metabolic alkalosis?

Answer 8

serum bicarbonate > 24 mEq/L

Question 9

What defines respiratory acidosis?

Answer 9

pCO2 > 40 mmHg

normal range 35-45 mmHg

Question 10

What defines respiratory alkalosis?

Answer 10

pCO2 < 40 mmHg

Question 11

What marker for metabolic acidosis or alkalosis?

Answer 11

serum bicarbonate

Question 12

What marker for respiratory acidosis or alkalosis?

Answer 12

pCO2

Question 13

One primary acid-base disturbance = _____ disorder

Answer 13

simple

Question 14

What is the major buffering system?

Answer 14

bicarbonate/carbonic acid system

Question 15

What is pH dependent on?

Answer 15

pH is dependent on the relative ratio between carbon dioxide (acid source) and bicarbonate (base)

Question 16

Normally, there are ___ parts of bicarbonate (HCO3-) to 1 part of carbonic acid (H2CO3)

Answer 16

20

Question 17

If this ratio of 20:1 is altered, then what happens?

Answer 17

an acid-base abnormality!

Question 18

Describe the respiratory regulation of CO2 elimination

Answer 18

Respiratory center: medullary chemoreceptors activated by cerebral arterial CO2

Lungs compensate for metabolic disturbances

Question 19

if HCO3 decreases, what disorder is present?

Answer 19

metabolic acidosis

*pH will also decrease

Question 20

Acidosis stimulates the _____ center

Answer 20

respiratory

*rate and depth of respiration increases which allows for a greater quantity of CO2 to be eliminated by the lungs

Question 21

respiratory response to the metabolic acidosis is called a _______ _______

Answer 21

compensatory response

Question 22

What does a compensatory response do?

Answer 22

allows for the 20:1 ratio to be closer to normal and therefore the pH is not affected as greatly

Question 23

_____ reabsorb filtered HCO3- and eliminates H+

Answer 23

kidneys

Question 24

In the presence of respiratory acidosis, how do the kidneys compensate?

Answer 24

the kidneys excrete hydrogen ions and conserve bicarbonate ions

Question 25

In the presence of respiratory and metabolic alkalosis, how do the kidneys compensate?

Answer 25

they kidneys retain hydrogen ions and excrete bicarbonate ions

Question 26

Respiratory acidosis: | Describe compensatory response in mmol

Answer 26

For every 10mmHg increase in pCO2, HCO3 increases by 1 mmol

Question 27

Respiratory alkalosis: | Describe compensatory response in mmol

Answer 27

For every 10mmHg decrease in pCO2, HCO3 decreases by 2 mmol

Question 28

Metabolic acidosis: | Describe compensatory response in mmol

Answer 28

For every mmol decrease in HCO3, the pCO2 decreases by 1 mmHg

Question 29

Metabolic alkalosis: | Describe compensatory response in mmol

Answer 29

For every mmol increase in HCO3, the pCO2 increases by 0.7 mmHg

Question 30

What indicates the presence of a second primary acid-base disorder (i.e. a mixed acid base disturbance) ?

Answer 30

absence of expected compensatory response!

Question 31

Anion Gap allows for ____ _____ to be divided into two forms

Answer 31

metabolic acidosis

Question 32

What are the two options for anion gap for metabolic acidosis?

Answer 32

- High Anion Gap | - Normal Anion Gap

Question 33

What is the law of electroneutrality ?

Answer 33

the net positive and negative charges of the serum must be equal

Question 34

Unmeasured cations

Answer 34

calcium and magnesium

Question 35

Unmeasured anions

Answer 35

phosphate, sulfate, albumin, ketons, and organic acids (eg. lactic acid)

Question 36

Sodium and potassium = ____% of extracellular cations

Answer 36

95

Question 37

Chloride and bicarbonate = ___% of extracellular anions

Answer 37

85

Question 38

Anion gap formula

Answer 38

AG = Na - (Cl + HCO3)

Question 39

Why is K+ taken out of anion gap formula?

Answer 39

K+ is largely intracellular cation and rarely alters the anion gap, it is often deleted from the equation of simplicity

Question 40

What is a normal anion gap

Answer 40

12 +/- 4 mEq/L

Question 41

What does a high anion gap mean?

Answer 41

increased unmeasured anions or decreased unmeasured cations

Question 42

Standard range for: | Na+

Answer 42

135-145 mEq/L

Question 43

Standard range for: | K+

Answer 43

3.5-5.0 mEq/L

Question 44

Standard range for: | Cl-

Answer 44

98-106 mEq/L

Question 45

Standard range for: | HCO3-

Answer 45

18-24 mEq/L

Question 46

Standard range for: | Lactate

Answer 46

<2 mEq/L

Question 47

Standard range for: | pCO2 (arterial)

Answer 47

35-45 mmHg

Question 48

Standard range for: | pO2 (arterial)

Answer 48

90-100 mmHg

Question 49

Standard range for: | pH

Answer 49

7.35-7.45

Question 50

Anion gap is useful to diagnose the underlying cause of ____ ______

Answer 50

metabolic acidosis

Question 51

Describe high AG metabolic acidosis

Answer 51

- generation of an acid which titrates the bicarbonate with an unmeasured ion (ex. lactic acid) - chloride concentration remains normal * *normochloremic acidosis

Question 52

high AG metabolic acidosis = _____chloremic acidosis

Answer 52

normo

Question 53

Describe normal AG metabolic acidosis

Answer 53

- processes that cause bicarbonate loss and chloride retention (ex. diarrhea) - absolute or relative chloride concentration higher than normal * *hyperchloremic acidosis

Question 54

normal AG metabolic acidosis = ______chloremic acidosis

Answer 54

hyper

Question 55

What are some causes of high anion gap metabolic acidosis? (normochloremic acidosis)

Answer 55

- Renal failure (accumulation of endogenous acids) - Lactic acidosis - Ketoacidosis (diabetic, alcoholic, starvation) - Drugs and Toxins (salicylates, caffeine, ibuprofen, theophylline)

Question 56

What are some causes of normal anion gap metabolic acidosis? (hyperchloremic acidosis)

Answer 56

1) Drugs (acetazolamide, acidifying agents, cholestyramine) 2) Gastrointestinal bicarbonate loss (diarrhea) 3) Chloride retention (renal acidosis)