Evaluating ABGs for Acid-Base

Question 1

How to determine the cause of the pH change (respiratory or metabolic)

Answer 1

In resp imbalances, pH and PaCO2 move in opposite directions

In metabolic imbalances, pH and Bicarb are both high or both low (move in same direction)

Question 2

👇🏼pH

👇🏼 HCO3-

👇🏼PaCO2

Answer 2

Metabolic acidosis with compensation

Question 3

Increased pH with low PaCO2 and normal Bicarb

Answer 3

Respiratory alkalosis

Question 4

Partial compensation

Answer 4

pH abnormal with one component abnormal and 2nd component beginning to change

Question 5

👆🏼pH

👆🏼HCO3-

👆🏼PaCO2

Answer 5

Metabolic alkalosis with compensation

Question 6

☝🏼️pH with 👇🏼PaCO2 and 👇🏼HCO3-

Answer 6

Respiratory alkalosis with compensation

Question 7

Decreased pH with decreased HCO3- and normal PaCO2

Answer 7

Metabolic acidosis

Question 8

Decreased pH with increased PaCO2 and normal Bicarb

Answer 8

Respiratory acidosis

Question 9

Compensation absent

Answer 9

PH is abnormal with one component abnormal and 2nd component normal

Question 10

Decreased pH with increased PaCO2 and increased HCO3-

Answer 10

Respiratory acidosis with compensation

Question 11

Complete compensation

Answer 11

pH is normal (making it complete) with one abnormal component and the second component changed to move pH into normal range
*with compensation, PaCO2 and HCO3- will always move the same direction

Question 12

Increased pH with increased Bicarb and normal carbon dioxide

Answer 12

Metabolic alkalosis

Question 13

Steps for evaluating ABGs for acid-base

Answer 13

1. Determine if acidotic or alkalotic (pH)
2. Check the cause of the pH change (PaCO2 or HCO3-)
3. Determine whether the body is compensating
4. Look at the total picture