ABG

Question 1

Normal pH:

Answer 1

7.35-7.45

Question 2

Nomal PaO2:

Answer 2

80 - 100 mm Hg

Question 3

Normal PaCO2:

Answer 3

35-45 mm Hg

Question 4

Normal HCO3:

Answer 4

22-26 mmol/L

Question 5

Normal BE:

Answer 5

-2 to 2 mEq/L

Question 6

Normal SaO2:

Answer 6

> 95%

Question 7

Changes in pH are ___ related to changes H+ concentration.

Answer 7

inversely

Question 8

As PaO2 increases SaO2

Answer 8

increases

Question 9

Acidosis

Answer 9

Respiratory: Increased CO2
Metabolic: Decreased HCO3

Question 10

Alkalosis

Answer 10

Respiratory: Decreased CO2
Metabolic: Increased HCO3

Question 11

Acid/Base Relationship Equation

Answer 11

H2O + CO2 -> H2CO3 -> HCO3 + H+

Question 12

2 organs that maintain acid and base balance:

Answer 12

Lungs and kidneys

Question 13

Buffers

Answer 13

H2CO3 (carbonic acid) and NaHCO3 (Base bicarbonate) [work in pairs]

Question 14

H2CO3

Answer 14

Respiratory buffer response (in minutes); triggers increase or decrease in rate and depth of ventilation

Question 15

HCO3- (bicarbonate)

Answer 15

If pH decreases, kidneys will retain HCO3 (take hours to days to correct)

Question 16

Respiratory Acidosis: Causes

Answer 16

(Decreased pH, Increased CO2, Decreased ventilation)

1. CNS Depression
2. Pleural disease
3. COPD/ARDS
4. Musculoskeletal diorders
5. Compensation for metabolic alkalosis

Question 17

Respiratory Acidosis: Acute vs Chronic

Answer 17

Acute - little kidney involvement; for every 0.08 decrease in pH, 10 mm Hg increase in CO2
Chronic - renal compensation via retention of HCO3; for every 0.03 decrease for 10 mm Hg increase in CO2

Question 18

Respiratory Alkalosis: Causes

Answer 18

(Increase pH, Decreased CO2, increased ventilation)
Decreased CO2 -> decreased HCO3 (increased Cl to balance charges -> hyperchloremia)
1. Intracerebral hemorrhage
2. Salicylate and progesterone drug usage
3. Anxiety -> lung compliance
4. Cirrhosis of the liver
5. Sepsis

Question 19

Respiratory Alkalosis: Acute vs Chronic

Answer 19

Acute: Decreased HCO3 by 2 mEq/L for every 10 mm Hg decrease in PCO2

Chronic- ratio increases to 4 mEq/L of HCO3 for every 10 mm Hg decreased in PCO2

Question 20

Metabolic Acidosis:

Answer 20

1. Bicarb less than 22 mEq/L with a pH of less tan 7.35
2. Decreased pH and HCO3
3. 12 - 24 hours for complete activation of respiratory compensation
4. Decreased PCO2 by 1.2 mm HG for every 1 mEq/L decrease HCO3
5. Degree of compensation is assessed via the Winter’s formula: PCO2 = 1.5(HCO3) + 8 ± 2

Question 21

Metabolic Gap Acidosis Causes (MUDPILES)

Answer 21

Methanol
Uremia
DKA
Paraldehyde
INH
Lactic Acidosis
Ethylene Glycol
Salicylate

Question 22

Non Gap Metabolic Acidosis Causes: (HARDP)

Answer 22

Hyperalimentation
Acetazolamide
RTA
Diarrhea
Pancreatic Fistula

Question 23

Metabolic Alkalosis

Answer 23

1. Bicarb > 26 mEq/L with a ph > 7.45
2. Increased pH and HCO3
3. Increased PCO2 by 0,7 for every 1 mEq/L increase in HCO3

Question 24

Metabolic Alkalosis Causes:

Answer 24

1. Vomitting
2. Diuretics
3. Chronic diarrhea
4. Hypokalemia
5. Renal Failure

Question 25

Mixed Acid-Base DIsorders

Answer 25

• May have 2 or more disorders at one time

- Delta gap

Question 26

Steps to ABG Analysis: Step 1

Answer 26

Acidemic or Alkalemic

Question 27

Step 2

Answer 27

Respiratory or metabolic

Question 28

Step 3

Answer 28

Asses PaO2 (< 80 mm Hg = hypoxemia)

Question 29

Step 4

Answer 29

Metabolic acidosis? Is there an anion gap?

Question 30

Step 5

Answer 30

Normal compensation by respiratory system for metabolic disturbance?

Question 31

Base Excess

Answer 31

Estimate of amount of strong acid or base need to correct the metabolic component of a acid base disorde

Question 32

B.E. Formula

Answer 32

0.3 X body weight X BE = amount of Bicarb needed to correct

Question 33

Anion Gap Formula

Answer 33

AG = (Na+ K) - (Cl - HCO3)

Question 34

Full vs Patial vs Uncompensated

Answer 34

Compensation