Arterial Blood Gas (ABGs) Parameters Flashcards
What does the acronym ABG stand for?
Arterial Blood Gas
What do ABGs tell us?
The acid - base status and arterial oxygenation status
How is the blood obtained?
Arterial puncture [from peripheral arteries] and Indwelling catheter [arterial line, central line, or PA line]
What is the most common and preferred artery to draw from?
Radial artery
What test must you complete before drawing arterial blood?
Alan’s Test
Define arterial puncture:
blood is drawn through a needle puncture from a peripheral artery
Why is the radial artery preferred do draw from?
It has collateral circulation
its near the surface
easy to palpate
not close to large veins
Other than an Allen’s test, what must you do before conducting an arterial puncture?
- Communicate with the patient about the purpose of the procedure
- Apply pressure for at least 5 min (or how ever long it takes)
- Ice and ABG sample unless its going to be analyzed within more than 10 - 15 min.
What DON’T you do before an arterial puncture?
- Palpate too firmly [inhibits blood flow]
- Reposition the needle without first withdrawing the tip to subcutaneous tissue
- Leave bubbles in the ABG syringe
- Fail to adequately heparinize a sample to prevent clotting
What are the normal values for the anion gap?
8-16 (anything above 20 requires a further test to see why its high)
What is going on in the body when there is a high anion gap?
Acidosis
High anion gap levels can be due to what?
Lactic acidosis
DKA
Poisoning
Kidney failure
What can low anion gap levels mean?
Hyponatremia and multiple myeloma
Normal ABG Value for: pH
7.35 - 7.45
Normal ABG Value for: PaCO2
35 - 45 mmHg
Normal ABG Value for: HCO3
22 - 26 mEq / L
Normal ABG Value for: PaO2
[greater than] > 80 mmHg
Normal ABG Value for: BE / BD
+ - 2 mmol / L
Normal ABG Value for: SaO2 [oxygen]
[greater than] > 95%
What does a pulse oximeter measure?
The percentage of hemoglobin that is saturated with oxygen
Acidosis Value for: pH
[less than] < 7.35
Acidosis Value for: PaCO2
[greater than] > 45 mmHg
Acidosis Value for: HCO3
[less than] < 22 mEq/ L
Acidosis Value for: BD
[less than] < -2 mmol /L
Alkalosis Value for: pH
[greater than] > 7.45
Alkalosis Value for: PaCO2
{less than] 35 mmHg
Alkalosis Value for: HCO3
[greater than] > 26 mEq /L
Alkalosis Value for: BE
[greater than] > +2 mmol / L
What is the cause of the abnormality?
Respiratory (lungs)
Metabolic (kidneys)
Combination
What does the metabolic (kidneys) system compensate for?
Primary respiratory acid/base problems
Define compensation:
The bodys attempt to maintain the pH within normal limits and return the balance of 1:20
How long does it take metabolic (kidneys) compensation to return back to normal?
24 - 48 hrs
What does the respiratory (lungs) system compensate for?
Primary metabolic acid/base problems
How long does it take respiratory compensation to return back to normal?
A few minutes
If the pH is normal, it the patient fully compensated?
Yes
If the pH is NOT normal, the patient is __________.
Partially compensated
Does the pH always reflect the side of the primary disorder?
Yes
When nothing lines up what does it mean and how do you reevaluate?
Full compensation = nothing lines up
Reevaluate using 7.4 as the normal value
List the causes of metabolic ACIDosis:
- DKA
- Diarrhea
- Renal failure
- Shock
- Salicylate overdose
- Sepsis
List the signs and symptoms of metabolic acidosis:
Headache Decreases BP Hyperkalemia Muscle twitching Warm flushed skin Nausea Vomiting Changes in LOC
List the signs and symptoms of respiratory acidosis:
Decreased BP w/ vasodilation Rapid shallow respirations Headache Hyperkalemia Muscle weakness Drowsiness Dizziness
List the causes of metabolic alkalosis:
Loss of gastric secretions
Overuse of antacids
Potassium wasting diuretics
List the causes of respiratory acidosis:
HYPOventilation may be related to: drug overdose chest trauma pulmonary edema airway obstruction COPD neuromuscular disorders
List the causes of respiratory alkalosis:
HYPERventilation may be related to: anxiety high altitude pregnancy fever hypoxia excessive tidal volume in ventilated patients initial stage of pulmonary embolus
If the CO2 is on the same side as the pH its related to________.
Respiratory
If the HCO3 is on the same side as the pH its related to _______.
Metabolic
If SaO2 or PaO2 is below 80 its ____________.
Hypoxia
What is the effect of hyperventilation on the lungs?
Decrease in PaCO2 level - blowing off CO2 too much
What could be an increase of carbonic acid?
Bradypnea (slow breathing) // you cant get rid of CO2 so it builds up in the lungs - you get ride of carbonic acid by normal breathing
