Arterial Blood Gas and Acid Base di

Question 1

Specimen for ABG

Answer 1

Arterial blood (required if pO₂ will be measured)

Question 2

Specimen collection method for arterial blood gas

Answer 2

Collected without tourniquet in 1- to 3-mL sterile glass syringes

Question 3

Anticoagulant for ABG

Answer 3

Lyophilized heparin (preferred) or 0.05 mL liquid heparin (1000 IU/mL) per mL of blood

Question 4

Handling of ABG specimen

Answer 4

Anaerobic collection, kept on ice to retard WBC metabolism, assayed within 15 minutes

Question 5

Principle for pH, pCO₂, pO₂ measurement

Answer 5

Potentiometry

Question 6

pH instrument

Answer 6

pH electrode

Question 7

pCO₂ instrument

Answer 7

Severinghaus electrode

Question 8

pO₂ instrument

Answer 8

Clark method (pO₂ electrode)

Question 9

Calibration for pH and pCO₂

Answer 9

2 phosphate buffers (anaerobic, RT)

Question 10

pCO₂ calibration

Answer 10

2 gases of known pCO₂

Question 11

SaO₂ instrument

Answer 11

CO-oximeter

Question 12

SaO₂ principle

Answer 12

Spectrophotometric measurement of absorbance at isobestic and differential points

Question 13

SaO₂ calibration

Answer 13

Calibration curve prepared from specimens with 0% and 100% O₂ saturation

Question 14

Reference value pH

Answer 14

7.35-7.45

Question 15

Reference value pCO2

Answer 15

35-45 mmHg

Question 16

Reference value pO2

Answer 16

80-110 mmHg

Question 17

Reference value HCO3

Answer 17

22-26 mmol/L

Question 18

Reference value Total CO2 (HCO3- + H2CO3 + CO2)

Answer 18

23-27 mmol/L

Question 19

Reference value Base excess

Answer 19

-2 to +2

Question 20

Reference value O2 saturation

Answer 20

> 95%

Question 21

Panic value pH

Answer 21

</= 7.2; >/= 7.6

Question 22

Panic value pCO2

Answer 22

</= 2.0; >/= 60 mmHg

Question 23

Panic value pO2

Answer 23

</= 40 mmHg

Question 24

Panic value HCO3-

Answer 24

</= 10; >/= 40 mmol/L

Question 25

Factor affecting ABG values Temperature

Answer 25

Electrode chambers of blood gas analyzers are thermostatically controlled at 37 +/- 0.1°C. For every 1°C increase in body temperature, pCO2 increases by 3%; pO2 decreases by 7%; pH decreases by 0.015 unit.

Question 26

Factor affecting ABG values Specimen exposure to air

Answer 26

Bubbles with high oxygen levels cause ↓ pCO2, ↑ pO2, ↑ pH.

Question 27

Factor affecting ABG values Prolonged storage of specimen

Answer 27

Anaerobic storage at 1°C causes ↑ pCO2, ↓ pO2, ↓ pH.

Question 28

Factor affecting ABG values Excess anticoagulant

Answer 28

Acidic mucopolysaccharide (heparin) affects values: ↑ dry heparin → ↓ pH, ↑ liquid heparin → ↓ pCO2.

Question 29

Respiratory compensation

Answer 29

HCO3 for compensation.

Question 30

Metabolic compensation

Answer 30

pCO2 for compensation.

Question 31

Acid-Base Disorder Metabolic Acidosis

Answer 31

Ketoacidosis, hypoxic acidosis, renal failure, RTA, GI loss of bicarbonate.

Question 32

Acid-Base Disorder Metabolic Alkalosis

Answer 32

NaHCO3 overdose, hypokalemia, vomiting, GI suction, corticosteroid excess.

Question 33

Acid-Base Disorder Respiratory Acidosis

Answer 33

COPDs, acute airway obstruction, circulatory failure, impaired respiratory system.

Question 34

Acid-Base Disorder Respiratory Alkalosis

Answer 34

Anxiety, hypoxia-induced hyperventilation, pulmonary embolism, pulmonary edema.

Question 35

Metabolic Acidosis pH, HCO3, pCO2

Answer 35

↓ pH, ↓ HCO3, N/↓ pCO2. Compensation: Hyperventilation.

Question 36

Metabolic Alkalosis pH, HCO3, pCO2

Answer 36

↑ pH, ↑ HCO3, N/↑ pCO2. Compensation: Hypoventilation.

Question 37

Respiratory Acidosis pH, HCO3, pCO2

Answer 37

↓ pH, N/↑ HCO3, ↑ pCO2. Compensation: Reabsorption of HCO3.

Question 38

Respiratory Alkalosis pH, HCO3, pCO2

Answer 38

↑ pH, N/↓ HCO3, ↓ pCO2. Compensation: Excretion of HCO3.