acid base imbalance

How does respiratory acidosis occur?

when a person hypoventilates: alveolar ventilation <CO2 production, so there is an increase in blood CO2 levels or increased PCO2. CO2 reacts with water H2CO3 which dissociates into HCO3 and H+ which drops blood pH below 7.35 (more acidic)

How does respiratory alkalosis occur?

hyperventilation: CO2 is eliminated faster than it is produced. Decreased CO2 blood levels = Decreased PCO2 Decrease in H+ & HCO3- ions & pH of the blood rises above 7.45

How does metabolic acidosis occur?

Addition of metabolic acids to blood or loss of HCO3-.

Addition of acids: Lactic acid from heavy exercise, ketones from starvation or untreated diabetes, acetic acid from alcohol metabolism, or acetylsalicylic acid from aspirin poisoning.

Loss of bicarbonate: from severe diarrhea, bicarbonate not reabsorbed. Renal failure: inability of kidneys to secrete H+ ions

How does metabolic alkalosis occur?

Loss of metabolic acids or addition of HCO3- to blood.

Loss of acid: excess vomiting, H+ ions decrease in stomach so blood gives H+ ions to stomach

Addition of bicarbonate: Overuse of antiacids neutralizing stomach pH causing H+ from blood to shift into stomach

Will both H+ and HCO3- increase in respiratory acidosis or metabolic acidosis?

No both will increase

Respiratory acidosis: CO2 interacts with water which dissociates into these ions

Metabolic acidosis: H+ ions increase but HCO3- ions decrease

Will both H+ and HCO3- decrease in respiratory alkalosis or metabolic alkalosis?

yes both will decrease bc there is a lack of CO2 meaning H2CO3 levels decrease & don’t dissociate into H+ & HCO3. In metabolic alkalosis H+ decreases but HCO3- increased due to loss of acid or antiacids

Will H+ increase and HCO3- decrease in respiratory acidosis or metabolic acidosis?

No both will not increase

Respiratory acidosis: CO2 interacts with water which dissociates into these ions

Metabolic acidosis: H+ ions increase but HCO3- ions decrease

Will HCO3- increase and H+ decrease in respiratory alkalosis or metabolic alkalosis?

no both will decrease bc there is a lack of CO2 meaning H2CO3 levels decrease and they don’t dissociate into H+ and HCO3. In metabolic alkalosis H+ decreases but HCO3- increased due to loss of acid or antiacids

What type of acid-base imbalance develops due to vomiting and why?

Causes hyperemesis, develops into metabolic alkalosis. H+ ions decrease, ions shift from blood into stomach decreasing blood H+ & increasing pH of blood.

What type of acid-base imbalance develops due to diarrhea and why?

Metabolic acidosis bc HCO3- is lost not reabsorbed which causes bicarbonate to shift from blood into small intestine. increases concentration of H+ in blood causing a lower pH.

What type of acid-base imbalance develops as one moves to higher altitudes and why?

Respiratory alkalosis.

PO2 decreases as you increase altitude causing hyperventilation which eliminates CO2 faster than it is made, causing a decrease in blood PCO2 & H+ ions bc CO2 isn’t interacting with water as much. Decrease in H+ = increase in pH

What type of acid-base imbalance develops due to overuse of antacids and why?

Metabolic alkalosis. Increased anti acids causes neutral stomach acid meaning H+ ions go from blood into stomach to increase its acidity. Blood H+ levels decrease & pH increases

What type of acid-base imbalance develops due to aspirin poisoning?

metabolic acidosis as it is metabolized into acetylsalicylic acid pH drops

Discuss the compensatory mechanism/s for (a)metabolic acidosis (short-term and long-term)

Short: Hyperventilation to remove CO2 faster than it is produced which decreases H+ concentrations raising pH back to normal.

Long: Kidneys activate type A intercalated cells to increase H+ secretion & increase HCO3- reabsorption.

Discuss the compensatory mechanism/s for (b)metabolic alkalosis (short-term and long-term)

Short: hypoventilation to increase CO2 retention in blood, raises blood H+ to lower pH to normal range.

Long: Type B intercalated cells increase HCO3- secretion & increase H+ reabsorption.

Discuss the compensatory mechanism/s for (c) respiratory alkalosis

kidneys activate Type B intercalated cells to increase excretion of HCO₃⁻ (to increase free H⁺) & increase reabsorption of H⁺ into blood

Discuss the compensatory mechanism/s for (d)respiratory acidosis

kidneys activate Type A intercalated cells to increase H⁺ excretion & increase HCO₃⁻ reabsorption to neutralize excess blood H⁺.

A 66-year-old woman presented in the emergency department lethargic and hypoventilating. Her blood gases were as follows: low blood [H+] & high blood [HCO3-] & High blood PCO2:

low blood [H+]: alkalosis (pH above 7.45),

high blood [HCO3-]: metabolic alkalosis

High blood PCO2: hypoventilation causes PCO2 to increase

Based on her blood gases, what type of acid-base imbalance did the woman develop?

Metabolic alkalosis

The woman was hypoventilating, based on the blood gases, did hypoventilation cause the acid-base imbalance you have indicated above or was hypoventilation a compensatory mechanism?

compensatory mechanism bc increased pH is resolved by hypoventilation, increases CO2 retention in body.