Acid-Base Imbalances (Patho)
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- Acids are _____ by bases
- Neutralized
- What does pH represent?
- concentration of H+ in the blood
- Lower pH means...
- more acidic (higher concentration of H+)
- Higher pH means...
- less acidic (lower concentration of H+)
- What are volatile acids?
-
can form a gas
- can be eliminated by lungs - What are the sources of volatile acids?
- metabolism of glucose & fat
- What are nonvolatile acids?
-
can't be converted to form a gas
- ex. HCO3-
- excreted by kidneys - What are the sources of nonvolatile acids?
- anaerobic glycolysis and P-protein/P-lipid metabolism
- What is the importance of pH? (List 3)
-
1. changes the ionization of molecules [add or removes charge (+ or - )]
2. ionization - affects ability to cross CM
3. ionization - affects the shape of the molecule - What are 3 key mechanisms in regulating pH?
-
1. Buffering System (H2CO3-)
2. Respiration System (ventilation)
3. Renal System - What is the normal pH range?
- 7.35-7.45
- What is the most important acid-base reaction to remember?
- H+ + HCO3- H2CO3 H2O + CO2
- What are the 3 major buffering systems?
-
1. Bicarbonate Buffer System (key)
2. Protein Buffer System (all plasma proteins & IC proteins such as Hgb)
3. Phosphate & Ammonia (key in nephron to promote excretion) - What are 3 characteristics of the respiratory system?
-
1. If bicarbonate system does not correct imbalance within a few minutes, the respiratory system will be activated
2. Focuses on maintaining CO2 levels
3. consists of hyperventilation (blowing off CO2) & hypoventilation (retaining CO2) - What are 3 characteristics of the renal system?
-
1. if the bicarbonate buffer system and respiratory systems do not correct imbalances, the renal system will be activated
2. Slower initiation (few hours) / slow acting (several days to restore balance)
3. Primary mechanism: HCO3- is reabsorbed
Secondary mechanism: H+ excreted (if imbalance still persists after all possible HCO3- is reabsorbed) - Which system corrects imbalances?
- Renal System
- Which systems compensate for imbalances?
- Buffering System & Respiratory System
- What is acidosis?
- too much acid
- What is alkalosis?
- too much base relative to acid
- If H+ concentrations are high, pH levels are _____.
- low
- If H+ concentrations are low, pH levels are _____.
- high
- What is compensation?
-
- partial compensation: pH remains abnormal
- full compensation: pH is normal but all other values are abnormal - What does ABG stand for?
- Arterial Blood Gas
- What are 5 arterial blood gas values?
-
1. pH
2. HCO3-
3. pCO2 or PaCO2
4. pO2
5. O2 saturation - Why are arterial blood gases used for analysis as opposed to venous blood?
- Because venous blood is used blood and is deoxygenated. Arteries carry O2.
- What are 4 acid-base disturbances?
-
Metabolic Disturbances:
1. Metabolic Acidosis
2. Metabolic Alkalosis
Respiratory Disturbances:
3. Respiratory Acidosis
4. Respiratory Alkalosis - What are primary metabolic defects?
- disturbances that arise from either a problem with H+ or HCO3- ions
- What are primary respiratory defects?
- disturbances that arise from a problem with CO2
- What is metabolic acidosis and what is the primary defect?
-
- occurs when there is an increase of any metabolic acid or decrease of HCO3-
- primary defect: high [H+] relative to HCO3- - What are 4 causes of metabolic acidosis?
-
1. Hypoxia - (anaerobic metabolism to generate ATP --> buildup of lactic acid --> increased [H+])
2. Diabetes complication (ketone bodies)
3. Aspirin poisoning (acetylsalicylic acid)
4. Diarrhea (loss of HCO3- from lower GI) - What is hypoxia?
- lack of O2 supply reaching body tissues
-
What are 3 characteristics of the bicarbonate buffer system?
-
1. Chemical rxn is reversible
2. if equation is not in equilibrium, H2CO3 will break down in the direction of the lower concentration
3. Occurs rapidly (within minutes) - If there is too much H+, there will be a _____ shift.
- right
- Why is HCO3- decreased during metabolic acidosis?
-
- first H+ ions produced will be neutralized by HCO3-
- eventually too many H+ produced and HCO3- gets used up
- therefore, HCO3- decreases - Why is CO2 decreased during metabolic acidosis?
- high [H+] causes an increase in CO2 which stimulates respiratory system to hyperventilate (blow off more CO2) resulting in decreased CO2 levels (partial compensation)
- What are 5 S&S of metabolic acidosis?
-
1. Kussmaul's respirations (deep, gasping)
2. Restlessness
3. Seizures
4. N/V (nausea/vomiting)
5. Hyperkalemia (initial buffering: K+ inside exchanged with H+ outside) - What is metabolic alkalosis and what is the primary defect?
-
- occurs when there is a loss of acid or excess intake of base
- primary defect: low [H+] relative to HCO3- - What are 3 causes of metabolic alkalosis?
-
1. Excessive vomiting (lose H+)
2. NG (nasogastric) suctioning (lose H+)
3. Excessive intake of alkaline drugs (antacids) - What are ABG findings for metabolic alkalosis?
-
- lose H+ ions --> excess HCO3-
- increased pH since [H+] is lower
- CO2 is initially decreased but then it increases to keep the reaction going to the left (hypoventilation occurs - retains CO2) - partial compensation - What are 3 S&S of metabolic alkalosis?
-
1. Disorientation
2. Muscle twitches
3. Tetany - muscle spasms - ***NOTE: with metabolic imbalances, the pH, HCO3-, & CO2 move in the ______ direction.
- same