ABGs Flashcards
Normal pH
7.35-7.45
What does <7.35 pH indicate?
Acidosis (more H+ ions)
What does >7.45 pH indicate?
Alkalosis (less H+ ions)
What does PaO2 show?
- Partial pressure of O2 dissolved in plasma (3-5% of total oxygen content of arterial blood)
- tells us how well oxygen is moving from alveoli into the blood
Normal PaO2 value
80-100 mmHg
PaO2 indicating hypoxemia
<60 mmHg
What does PaCO2 show us?
- Partial pressure of CO2 dissolved in plasma (5% of total CO2 content in arterial blood)
*Measure of carbonic acid
*Direct reflection of alveolar ventilation (how well the pt is ventilating, NOT oxygenation)
Normal PaCO2 range
35-45 mmHg
What does a PaCO2 <35 indicate?
Hyperventilation (blowing off too much CO2 = alkalosis)
What does a PaCO2 >45 indicate?
Hypoventilation (CO2 buildup = **Respiratory acidosis)
Causes of respiratory acidosis
- CNS depression
- Impaired neuromuscular function
- Chest wall trauma
- Large pneumo or Hemothorax
- Airway disease or obstruction
- Overdose (causing CNS depression)
- Electrolyte imbalances - low phosphate, low potassium
Manifestations of respiratory acidosis
- CNS depression (lethargy, dizziness, mental cloudiness, HA, coma) *Remember acid is a depressant
- Depression of myocardial contractility
- V fib
- Increased RR
- Decreased affinity of Hg for O2 (Hgb wont pick up as much O2 now)
Treatment for respiratory acidosis
- Increase alveolar ventilation
- TCDB/incentive spirometer
- Suction
- Mechanical ventilation - Correct the cause
- Administer O2
What does a PaCO2 <35mmHg indicate?
Respiratory Alkalosis (alveolar hyperventilation)
Causes of respiratory alkalosis
- Hypoxemia (too much compensation)
- Artificial ventilation (over compensation)
- Stress
- Anxiety
- Fear
Respiratory alkalosis manifestations
CNS excitability (tingling, twitching, tremors, seizures)
Arrhythmias (premature beats & tachys)
Decreased ventilation (trying to compensate)
Increased affinity of Hg for O2 (hgb doesn’t drop O2 off to cells as well)
Treatment for respiratory alkalosis
- Decrease alveolar ventilation
- Correct the cause
What does HCO3 measure?
Metabolic base (which is regulated by the kidneys)
Normal HCO3 range
22-28 mEq/L
What does an HCO3 <22 indicate?
Metabolic acidosis (base deficit)
What does an HCO3 >28 mEq/L indicate?
Metabolic Alkalosis (Base excess)
Causes of metabolic acidosis
- Increased production of acids (ex: DKA)
- Reduced excretion of acids (Renal Failure)
- Excessive loss of base (diarrhea)
Manifestations of metabolic acidosis
- HA
- Confusion
- Drowsiness
- N/V
- Hyperventilation
Treatment of metabolic acidosis
- Correct the cause
- If severe, administer bicarbonate (pH <7)
