ABGs as Easy as 1, 2, 3
- RN PN Tutor Staff
- May 9, 2016
- 2 min read
Buffers of the body include: the kidneys (metabolic system) and lung (respiratory system).
Lungs: breathing controls CO2 levels and affects blood pH
Kidneys: help regulate pH by gaining or losing H+ (Hydrogen) as needed
• Acid-base imbalance are related to either respiratory and metabolic systems
• Imbalances can be respiratory acidosis or alkalosis, metabolic alkalosis and acidosis
• Imbalances may be compensated for by the kidneys and lungs
• Acid-base balance is monitored by analyzing the Arterial blood gas of pH, PO2, PCO2, and HCO3, values
Normal Arterial Blood Gas Values
pH 7.35 - 7.45
PaC02 35 – 45 -
HC03 22 - 26
PaO2 80- 100
O2 Sat 97% or >
Normal pH of Blood is 7.35 - 7.45 <7.35 acidosis > 7.45 alkalosis
PaCO2 is ACID
HCO3 is ALKALINE/BASE
How to interpret arterial blood gas readings?
If abnormality in PaCO2 matches ph then problem is Respiratory.
If abnormality in HCO3 matches ph then problem is Metabolic
.1. The first value to look at is the pH; if it is below 7.35, the primary problem is acidosis. If it is above 7.45, alkalosis.
2. If the PaCO2 is below 35 (low on acid). respiratory alkalosis is the imbalance. If it is above 45 (high acid or lots of carbonic acid), respiratory acidosis is the problem.
3. If the HCO3 is below 22 meq/l, then metabolic acidosis is present
4. If the HCO3 is above 26, then metabolic alkalosis is the issue
5. If all the values are abnormal but not in the same direction, the body is attempting compensation
6. The ph still indicates what the problem is, whatever value is normal and compatible with the pH indicates the main problem
7. The other abnormality indicates compensation
ALSO, write arrows beside your values to help see the direction of the values.
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