HYPOXIA

Question 1

HYPOXIA

Answer 1

• A-a difference gradient normal 5-10 mm Hg MOST IMPORTANT INITIAL TEST TO DO
• alveolar O2 and arterial O2
• PAO2 = 100 mm Hg
• PaO2 = 95 mm Hg

Question 2

severe HYPOXIA

Answer 2

• PaO2

Question 3

hypoventilation

Answer 3

• PaO2 must be decreased
• A-a difference in ZERO to 7
• A = (Patm - 47) fO2 - PCO2/R
• a = 80
• A= 80 - a= 80 =ZERO

Question 4

A-a difference of ZERO

Answer 4

• rules out hypoventilation

Question 5

perfusion limited situation-

e.g pulmonary shunt, ATELECTASIS

Answer 5

• Tx give 100% O2 for 15 mins then repeat ABG
• decrease in PaO2
• A-a difference >ZERO
• no significant increase in PaO2

Question 6

diffusion impairment

e.g fibrosis of the lung

Answer 6

• Tx give 100% O2 for 15 mins then repeat ABG
• significant increase in PaO2 > 10 mm Hg starting from 80 mm Hg
• high pressure force the O2 across the impairment due to viable alveoli

Question 7

hypoventilation treatment

Answer 7

• give O2

- increasing PaO2