Acid-Base

Question 1

Normal values for ABG

pH

Answer 1

7.40 (7.35-7.45)

Acidosis: below 7.4
Alkalosis: above 7.4

Question 2

Normal values for ABG

PaCO2

Answer 2

40 mmHg (35-45)

Hypoventilation: elevated
Hyperventilation: lower

Question 3

Normal values for ABG

PaO2

Answer 3

> 90mmHg (80-100)

Question 4

Normal values for ABG

HCO3

Answer 4

24 mEq/L (22-26)

Question 5

Normal values for ABG

SaO2

Answer 5

> 95% (93-98)

If low may be a venous sample (40-50% saturated)

Arterial; 70 or less patient needs supplemental oxygen

Question 6

Normal values for ABG

PB

Answer 6

760 mmHg (sea level)

Question 7

Normal values for ABG

PH20

Answer 7

47 mmHg

Question 8

If patient is hypoxemic what do you do next?

Answer 8

Determine A-a gradient

A: alveolar oxygen
a: arteriole oxygen

Question 9

Alveolar-Arterial (A-a) Gradient equation

Answer 9

PAO2-PaO2

PaO2 = (PB - PH20) * FIO2 - (PaCO2/0.8) 
PaCO2 = 150 - (PaCO2/0.8)

Question 10

Alveolar-Arterial (A-a) Gradient

Normal Value

Answer 10

0-10

Question 11

Alveolar-Arterial (A-a) Gradient

Probably Normal Value

Answer 11

10-20

Question 12

Alveolar-Arterial (A-a) Gradient

Probable Gas Exchange Impairment

Answer 12

21-30

Question 13

Alveolar-Arterial (A-a) Gradient

Gas Exchange Impairment

Answer 13

> 30

Pneumonia, CHF, fibrosis

Question 14

Alveolar-Arterial (A-a) Gradient

Supplemental Oxygen Equation (with values)

Answer 14

PaO2/FIO2

Normal >300
ALI (acute lung injury) = 201-299
ARDS (acute respiratory distress syndrome) = <200

Question 15

Inspired Oxygen-Arterial Tension Relationship

Principles

Answer 15

FIO2 x 5 = Minimally Acceptable PaO2

Question 16

If the pH is 7.5, the primary disorder is…

Answer 16

Alkalosis

Question 17

If the pH is 7.3, the primary disorder is…

Answer 17

Acidosis