ABG Flashcards
ABG’s Provide information on:
- Acid-base status of blood
- O2 & CO2 levels
- Ventilation
pH Values
Range: 7.35-7.45
< 7.35 = Acidosis
Greater than 7.45 = Alkalosis
PaCO2 Value
Range 35-45 mm Hg
Greater than 45 mm Hg = Acidosis (hypoventilation)
<35 mm Hg = Alkalosis (hyperventilation)
PaO2 Value
80-100 mm Hg
HCO3- Value
Range 22-27
<22 = Acidosis
Greater than 27 = Alkalosis
What is respiratory acidosis caused by?
Hypoventilation
Respiratory Alkalosis is caused by what?
Hyperventilation
What is metabolic acidosis caused by?
Kidney Disease
What is metabolic alkalosis caused by?
- Excessive Vomiting
- Loss of K+
What are the three ways the body compensates for imbalances?
- Buffer in body fluids
- Respiratory system (Hyper/Hypo)
- Kidneys
6 Steps for ABG Interpretation
- Is the pH normal?
- Is the PaCO2 normal?
- Is the HCO3 normal?
- Match the pH status with PaCO2 or HCO3 (respiratory or metabolic cause)
- Does the other (PaCO2 or HCO3) go in the opposite direction (Compensated/Uncompensated)
- Are the PaO2 and the O2 Sat Normal? (>80 Normal; < 80 Hypoxemia)
Match the PaCO2 or HCO3 to pH
Match (link) the pH (acidic or alkalotic) with the Pa CO2 or HCO3 that is acidic or alkalotic
- If pH is acidotic (<7.35) and Pa CO2 is acidotic (Greater than 45) then it is due to respiratory; respiratory acidosis
OR - If pH is acidotic (<7.35) and HCO3 is acidotic (<22) then it is due to metabolic; metabolic acidosis
- If pH is alkalotic (Greater than 7.45) and PaCO2 is alkalotic (<35) then it is respiratory; respiratory alkalosis OR
- If pH is alkalotic (Greater than 7.45) and HCO3 is alkalotic (Greater than 27) then it is metabolic; metabolic alkalosis
Does PaCO2 or HCO3 go in the opposite direction of pH?
- Identify the respiratory or metabolic variable that did not match the pH (Pa CO2 or HCO3)
- If Pa CO2 or HCO3 goes in opposite direction from the pH there is compensation
Example:
pH = acidotic (<7.35)
Pa CO2 = acidotic (Greater than 45)
HCO3 = alkalotic not normal (Greater than 27)
Pa CO2 matches pH = respiratory acidosis
HCO3 opposite of pH
Compensation by metabolic system
PaO2 and O2 Sat
PaO2
* Less than 80 (normal 80-100 mm Hg) – evidence of hypoxemia
O2 Sat
* O2 Sat should be less than 95% if PaO2 less than 80
* O2 Sat of 95-100% = PaO2 80-100 mmHg
Hb and Hematocrit Values
Hb (transport O2)
* Men: 14-18 g/dL
* Women: 12-16 g/dL
Hematocrit (Ratio of volume in blood to RBC)
* Males: 42-52%
* Females: 37-48%
Hematocrit is often 3 times the Hb
H & H stands for Hb and Hematocrit