ABG Flashcards
What is the purpose of the arterial blood gas test?
To assess acid-base status and to determine adequacy of oxygenation and ventilation.
True or false: Bicarbonate is not measured on ABG but has to be calculated.
True
Define primary event and give examples:
The problem that initiates the acid - base imbalance.
Hyperventilation, hypoventilation, vomiting, diarrhea
What is the normal serum CO2 level?
22-26
What is normal arterial CO2 level?
35-45
Describe what a primary disorder is:
What results from the primary event - respiratory acidosis or metabolic alkalosis
In metabolic acidosis, what is the direction of the pH, HCO3, and PaCO2. Which is the causative level and which is the compensation level?
pH = decrease
HCO3 = decreased (primary)
PaCO2 = decreased (compensation)
In metabolic alkalosis, what is the direction of the pH, HCO3, and PaCO2. Which is the causative level and which is the compensation level?
pH = increase
HCO3 = increased (primary)
PaCO2 = increased (compensation)
In respiratory acidosis, what is the direction of the pH, HCO3, and PaCO2. Which is the causative level and which is the compensation level?
pH = decrease
HCO3 = increase (compensatory)
PaCO2 = increase (primary)
In respiratory alkalosis, what is the direction of the pH, HCO3, and PaCO2. Which is the causative level and which is the compensation level?
pH = increase
HCO3 = decrease (compensation)
PaCO2 = decrease (primary)
What are the causes of metabolic alkalosis?
-Excess baking soda / alka-seltzer
-Prolonged vomiting
-NG tube
-Diuretics
What are the manifestations of metabolic alkalosis?
CNS over-excitability
Confusion
Tremors
Muscle cramps
Paraesthesia
Coma
N/V/D
Respiratory depression (this is a mechanism for compensation)
What are causes of respiratory alkalosis?
Hyperventilation
Increased metabolic demands (fever, sepsis)
Medication
Acute anxiety
Hypoxia
PO / lung disease
CNS lesions
Ventilation setting
What are the manifestations for respiratory alkalosis?
CNS over-excitability
Tachypnea
Confusion
Light headedness
Blurred vision
Paraesthesia
Hyperactive reflexes
Seizures
Coma
What levels are abnormal for acute respiratory acidosis vs chronic respiratory acidosis?
Acute = PaCO2 high (> 45) BUT normal HCO3 (bicarb - or may be serum CO2)
Chronic = HCO3 high (serum CO2)