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Flashcards in Acid-Base Disorders Deck (24):
1

emia vs osis

emia: pH change aWAY from the reference range

osis: abnormal condition or process that CONTRIBUTES to pH change

2

Normal pH, pCO2, HCO3

7.4
40
24

3

What are implications of the Henderson Hasselbach equation?

If pCO2 increases then pH decreases

If HCO3 increases then pH increases

4

What are the steps to identify acid base disorders?

1. Henderson‐Hasselbalch equation
• to determine whether metabolic or respiratory process is the primary
process driving acidosis or alkalosis
2. Anion gap
• AG ≥ 20, metabolic acidosis is present
3. Expected pCO2 range
• Determines whether respiratory compensation is adequate, under‐,
or over‐compensation
4. Excess anion gap (ΔΔ)
• Used only if there is an anion gap
• Determines “corrected” bicarbonate to see whether there are any other metabolic disturbances

5

7.5
29
22

Alkalosis
CO2 LOW ---> Hyperventilation
HCO2 low normal

Primary respiratory alkalosis (acute)

6

7.34
60
31

Acidosis
CO2 HIGH --> Hypoventilation
HCO3 HIGH --> compensated/chronic?

Primary respiratory acidosis, chronic

7

7.20
21
8

Acidosis
CO2 LOW --> hyperventilation
HCO3 LOW --> Metabolic

Primary metabolic acidosis

8

How do you calculate the AG?

Na - Cl + HCO3

9

What does hte gap represent?

unmeasured anions (Phosphates, sulfates, albumin)

10

What is the normal range for the AG?

7-16 (12)

11

What is an AG acidosis?

pH decreases and acidosis

12

If AG is >20?

metabolic acidosis is present regardless of pH or HCO3

13

Why do we calculate the expected pCO2 range?

Determines whether respiratory compensation is adequate, under‐, or over‐compensation

14

How do you calculate hte expected pCO2 range?

Expected Range = 1.5 ×(measured HCO3‐) + 8 ±2

15

If pCO2 = 28

> the expected range, then respiratory acidosis even though pCO2 is below 40.

16

If pCO2 20

within the expected range, then normal respiratory compensation.

17

Why do we calculate the excess AG?

ONLY if there is an AG
determines "corrected" bicarb to see whether there are other metabolic disturbances

18

excess AG formula?

calculated AG - 12

19

Corrected HCO3

measured HCO3 + exccessAG

20

If corrected HCO3 > 30

underlying primary metabolic alkalosis

21

If corrected HCO3 <23

underlying primary metabolic acidosis

22

pH 7.5
pCO2 20

Na 140
Cl 103
HCO3 15

ONE:
Alkalosis
pCO2 LOW --> hyperventilation
**PRIMARY respiratory alkalosis

AG?:
AG = 140 - (103 + 15) = 22 (greater than 12!)
**Underlying primary metabolic acidosis

pCO2 range?:
1.5 x 15 + 8 = 30.5 (Greater than 18-22!)... Since a pCO2 of 20 is BELOW the expected range then respiratory alkalosis

Excess AG?
22-12 = 10
Corrected = 15 + 10 = 25 No hidden acid/alkalosis

23

7.20
25
Po2 130
O2 sat 94%

1. Primary:
Acidosis
CO2 LOW
HCO3 10
* Primary metabolic acidosis

2. AG
AG = 130 - (80+10) = 40
> 20 *metabolic acidosis is present

3. PCO2 range
Expected pCO2 = 1.5 x 10) + 8 +/-2= 21 -25
* PCO2 falls w/in the range so there is normal resp compensation

4. Expected AG
40-12 =28
Corrected HCO3 = 10 +28 = 38
* Primary metabolic alkalosis

24

Which of the following best represents the acid base disorder in this patient?
A. Primary metabolic acidosis with concomitant non‐ anion gap metabolic alkalosis
B. Mixed metabolic and respiratory acidosis with concomitant metabolic alkalosis
C. Anion‐gap metabolic acidosis with respiratory compensation and concomitant metabolic alkalosis
D. Anion‐gap metabolic alkalosis, respiratory alkalosis, and metabolic alkalosis
E. More information is required to determine the acid base disorder

Anion‐gap metabolic acidosis with respiratory compensation and concomitant metabolic alkalosis