Acid Base Balance Flashcards
What does the PaCO2 determine
If respiratory component is present
What does the calculated HCO3 identify
Metabolic component
What does PaO2 and PaCO2 provide
Information about alveolar gas exchange
What are causes of acid base dysfunction
Abnormalities in the respiratory and metabolic system
*any primary disturbance will invoke a compensatory response
What are the components of venous blood gas
- pH and HCO3
- PO2
What are the components of capillary blood gas
Easier to obtain and less traumatic than ABG
1. PH
2. PCO2
3. PO2
4. O2 saturation
*>70% acceptable
Where are capillary blood gas sites to obtain
Neonates
*heel stick
Adults
*earlobe
When is the pH alkaline or acidic
Alkaline
*>7.45
Acidity
*<7.35
What is the respiratory component of acid-base determination
PaCO2
*measurement of ventilation
*faster and deeper breathing, CO2 is blown off
*PaCO2 increases, pH decreases
*CO2 is acidic
What is the metabolic component of acid base determination
Bicarbonate ion
1. Regulated by the kidney
2. As HCO3 increases pH increases
3. Bicarbonate is alkalotic
What is ABG analysis an indirect measurement of
O2 in arterial blood
*PaO2 used to determine effectiveness O2 therapy
What happens to the pH and CO2 when there is a respiratory issue
They will move in opposite directions
What happens to the pH and HCO3 if there is a metabolic issue
They will move in the same direction
*both high = alkalosis
*both low = acidosis
When will there be a acidosis or alkalosis problem (pH)
Acidosis = <7.37
Alkalosis = >7.44
When will there be a acidosis or alkalosis problem (PaCO2)
Acidosis > 44mmHg
Alkalosis = <36mmHg
When will there be a acidosis or alkalosis problem (HCO3)
Acidosis = <22
Alkalosis = >26
If the pH and CO2 are both acidic where is the primary disturbance
Respiratory acidosis
If the pH and CO2 are both alkalotic where is the primary disturbance
Metabolic alkalosis
What are common causes of metabolic acidosis
- Severe diarrhea
- DKA
- Renal failure
- Trauma
- Shock
What are common causes of metabolic alkalosis
- Chronic vomiting
- Gastric suctioning
- Hypovolemia
- Diuretics
What are common causes of respiratory acidosis
- Respirator depression / failure
- Saddle PE
- Aspiration
- Pneumonia
What are the common causes of respiratory alkalosis
- Hyperventilation / pain / anxiety
- Hypoxemic conditions
- Pregnancy
What are the common causes of mixed acid / bases disorders
- Metabolic acidosis superimposed on respiratory alkalosis
*septic shock + Hepatorenal syndrome
*salicylate posioning
What are some causes of respiratory acidosis (decreased pH with increased pCO2)
- Hypoventiliation
- Impaired alveolar exchange
- COPD
