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Arterial Blood Gas (ABG) Interpretation: Practice Problems, Answers, & Cheatsheet
Review ABG Interpretation with Cathy!
| Value | Normal Range | Abnormal Values |
|
pH |
7.35-7.45 |
pH < 7.35 indicates ACIDOSIS (ACID) ph > 7.45 indicates ALKALOSIS (BASE) |
|
PaCO2(Respiratory System) |
35-45 |
PaCO2 < 35 indicates ALKALOSIS (BASE) PaCO2 > 45 indicates ACIDOSIS (ACID) |
|
HCO3(Metabolic System) |
22-26 |
HCO3 < 22 indicates ACIDOSIS (ACID) HCO3 > 26 indicates ALKALOSIS (BASE) |
If pH, PaCO2 and HCO3 are all in NORMAL range, we have HOMEOSTASIS!
With ABG interpretation problems, we are trying to figure out 3 things:
- Is acidosis or alkalosis present (based on pH)?
- If acidosis or alkalosis is present, which system is to blame: Respiratory system (PaCO2) or Metabolic system (HCO3)?
- Who is acting up?
- Is compensation occurring? If so, is the acid/base imbalance partially or fully compensated?
- If the Respiratory system is acting up, is the Metabolic system trying to fix the situation?
- If the Metabolic system is acting up, is the Respiratory system trying to fix the situation?
Acid/Base Imbalance
Respiratory Acidosis
Learn more in our article on respiratory acidosis.
| pH | PaCO2 | HCO3 | Interpretation |
|
Acid |
Acid |
Normal |
Uncompensated respiratory acidosis.(Respiratory system is acting up, Metabolic system is NOT trying to fix the situation). |
|
Acid |
Acid |
Base |
Partially compensated respiratory acidosis.(Respiratory system is acting up, Metabolic system is TRYING to fix the situation). |
|
Normal (but closer to acidic) |
Acid |
Base |
Fully compensated respiratory acidosis.(Respiratory system is acting up, Metabolic system has FIXED the situation). |
Respiratory Alkalosis
| pH | PaCO2 | HCO3 | Interpretation |
|
Base |
Base |
Normal |
Uncompensated respiratory alkalosis.(Respiratory system is acting up, Metabolic system is NOT trying to fix the situation). |
|
Base |
Base |
Acid |
Partially compensated respiratory alkalosis.(Respiratory system is acting up, Metabolic system is TRYING to fix the situation). |
|
Normal (but closer to basic) |
Base |
Acid |
Fully compensated respiratory alkalosis.(Respiratory system is acting up, Metabolic system has FIXED the situation). |
Metabolic Acidosis
| pH | PaCO2 | HCO3 | Interpretation |
|
Acid |
Normal |
Acid |
Uncompensated metabolic acidosis.(Metabolic system is acting up, Respiratory system is NOT trying to fix the situation). |
|
Acid |
Base |
Acid |
Partially compensated metabolic acidosis.(Metabolic system is acting up, Respiratory system is TRYING to fix the situation). |
|
Normal (but closer to acidic) |
Base |
Acid |
Fully compensated metabolic acidosis.(Metabolic system is acting up, Respiratory system has FIXED the situation). |
Metabolic Alkalosis
| pH | PaCO2 | HCO3 | Interpretation |
|
Base |
Normal |
Base |
Uncompensated metabolic alkalosis.(Metabolic system is acting up, Respiratory system is NOT trying to fix the situation). |
|
Base |
Acid |
Base |
Partially compensated metabolic alkalosis.(Metabolic system is acting up, Respiratory system is TRYING to fix the situation). |
|
Normal (but closer to basic) |
Acid |
Base |
Fully compensated metabolic alkalosis.(Metabolic system is acting up, Respiratory system has FIXED the situation). |
Review ABG Interpretation with Cathy!
| Value | Normal Range | Abnormal Values |
|
pH |
7.35-7.45 |
pH < 7.35 indicates ACIDOSIS (ACID) ph > 7.45 indicates ALKALOSIS (BASE) |
|
PaCO2(Respiratory System) |
35-45 |
PaCO2 < 35 indicates ALKALOSIS (BASE) PaCO2 > 45 indicates ACIDOSIS (ACID) |
|
HCO3(Metabolic System) |
22-26 |
HCO3 < 22 indicates ACIDOSIS (ACID) HCO3 > 26 indicates ALKALOSIS (BASE) |
If pH, PaCO2 and HCO3 are all in NORMAL range, we have HOMEOSTASIS!
With ABG interpretation problems, we are trying to figure out 3 things:
- Is acidosis or alkalosis present (based on pH)?
- If acidosis or alkalosis is present, which system is to blame: Respiratory system (PaCO2) or Metabolic system (HCO3)?
- Who is acting up?
- Is compensation occurring? If so, is the acid/base imbalance partially or fully compensated?
- If the Respiratory system is acting up, is the Metabolic system trying to fix the situation?
- If the Metabolic system is acting up, is the Respiratory system trying to fix the situation?
Acid/Base Imbalance
Respiratory Acidosis
Learn more in our article on respiratory acidosis.
| pH | PaCO2 | HCO3 | Interpretation |
|
Acid |
Acid |
Normal |
Uncompensated respiratory acidosis.(Respiratory system is acting up, Metabolic system is NOT trying to fix the situation). |
|
Acid |
Acid |
Base |
Partially compensated respiratory acidosis.(Respiratory system is acting up, Metabolic system is TRYING to fix the situation). |
|
Normal (but closer to acidic) |
Acid |
Base |
Fully compensated respiratory acidosis.(Respiratory system is acting up, Metabolic system has FIXED the situation). |
Respiratory Alkalosis
| pH | PaCO2 | HCO3 | Interpretation |
|
Base |
Base |
Normal |
Uncompensated respiratory alkalosis.(Respiratory system is acting up, Metabolic system is NOT trying to fix the situation). |
|
Base |
Base |
Acid |
Partially compensated respiratory alkalosis.(Respiratory system is acting up, Metabolic system is TRYING to fix the situation). |
|
Normal (but closer to basic) |
Base |
Acid |
Fully compensated respiratory alkalosis.(Respiratory system is acting up, Metabolic system has FIXED the situation). |
Metabolic Acidosis
| pH | PaCO2 | HCO3 | Interpretation |
|
Acid |
Normal |
Acid |
Uncompensated metabolic acidosis.(Metabolic system is acting up, Respiratory system is NOT trying to fix the situation). |
|
Acid |
Base |
Acid |
Partially compensated metabolic acidosis.(Metabolic system is acting up, Respiratory system is TRYING to fix the situation). |
|
Normal (but closer to acidic) |
Base |
Acid |
Fully compensated metabolic acidosis.(Metabolic system is acting up, Respiratory system has FIXED the situation). |
Metabolic Alkalosis
| pH | PaCO2 | HCO3 | Interpretation |
|
Base |
Normal |
Base |
Uncompensated metabolic alkalosis.(Metabolic system is acting up, Respiratory system is NOT trying to fix the situation). |
|
Base |
Acid |
Base |
Partially compensated metabolic alkalosis.(Metabolic system is acting up, Respiratory system is TRYING to fix the situation). |
|
Normal (but closer to basic) |
Acid |
Base |
Fully compensated metabolic alkalosis.(Metabolic system is acting up, Respiratory system has FIXED the situation). |
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Daniella
December 22, 2021
Thank you for letteing me understand. I really appreciate it