Why is Acid Base Balance Important?
- Necessary to maintain homeostasis-
- The relative acidity or alkalinity of a solution can be indicated by its pH.
- Refers to balance of hydrogen ions (H+)
- Hydrogen ion concentration is expressed as pH level
- pH is inversely proportional to concentration of H+ ions
-If the hydrogen (H+) ion concentration goes UP then the pH…. Down
PH levels
-If the hydrogen ion concentration goes up
the level of acidity goes up and the pH goes down
-The lower the pH indicates higher levels of acidity
- <7.35 is acidosis
- > 7.45 is alkalosis
Body Fluids: Acids or Bases
- Acids: Body produces acids
- H+: positive Charge and can causes electrolyte imbalances
- Body produces Bases
- Neutralize and excrete acids
Acid Base Basics
Acids
Form hydrogen ion in solution
Bases
Combine with hydrogen ions in solution
Acid Base Regulation
Metabolic processes produce acids
These acids must be neutralized and excreted
3 Mechanisms to regulate acid base balance and maintain pH: Buffer system, Respiratory system & Renal system
Buffers
First line of defense
Chemical actions
Change acids, or neutralize acids
Can also release needed H+ ions
Respiratory system
Changing level of CO2
Hypercarbic drive
Hypoxic drive
renal
Changing level of HCO3
Kidneys regulate H+ ions or bicarbonate ions
symptoms of acid bace imbalances
- CNS Depression: in both acidosis and alkalosis
- HA, lethargy, weakness, confusion…..
- May also lead to coma and death - Compensatory mechanisms :
- Also produce clinical changes
- Example metabolic acidosis: deep rapid respirations as the respiratory system attempts to compensate
-Example: Alkalosis: S/S are usually from electrolyte disturbances
-With alkalosis, hypocalcemia may result
S/S of hypocalcemia: muscle cramping, numbness, tetany….
ph normal
7.35-7.45
PaCO2
35-45
HCO3
22-26
Pa02
80-100
Sa02
> 95%
Respiratory Acidosis
-Low ph
-high CO2
Build up of CO2
Pulmonary issues
HYPOVentilation
Accumulation/excess: carbonic acid in blood –
This leaves extra H+
pH ↓ decreases
respiratory alkalosis
High pH Low CO2 Increased CO2 excretion Carbonic acid deficit HYPERventilation Lower partial pressure of CO2 = decreased carbonic acids and alkalosis pH ↑ increases
metabolic acidosis
ACIDS ACCUMULATE
Ketoacids
Or
Lactic acids
Or bicarb is lost
pH is low
HCO3 is low
PCO2 could be normal
If bicarb is lost = more acid than base = acidosis
In renal disease: kidneys have poor reabsorption of HCO3 and secrete H+
metabolic alkalosis
Loss of acids
Gastric loss
Or increase HCO3
Increased Intake
pH high
HCO3 high
compensation
Blood Gases are more specifically defined by Compensation
Degree of compensation.
ABGs are defined as :
uncompensated,partially compensated, andfully compensated.
To determine the level of compensation, the pH, PaCO2, and HCO3-are analyzed
If primary acid base disorder is Metabolic…
- Respiratory system may COMPENSATE
- By retaining CO2 or removing CO2
- Respiratory compensation : Rapid
If primary acid base disorder is Respiratory
Renal system may compensate
By excreting or retaining hydrogen and bicarb
Renal compensation is slower and can take up to 24 hours
diarrhea
-Dehydration
-Loss of HCO3
-Metabolic acidosis
What will the body do to compensate?*
Lungs: ↑ RR to blow off CO2
Kidneys:
Retain HCO3
Excrete H+
vomiting
Acid Base
Loss of acids
Metabolic Alkalosis
What will the body do to compensate?* Lungs: ↓ or maintain Regular RR Kidneys: Excrete HCO3 Retain H+ To help correct pH
Symptoms in both acidosis and alkalosis
- CNS depression
- HA, lethargy, Weakness, confusion, coma, death
