Lecture 18: Acid-Base Disturbances

Question 1

What is the primary defect of respiratory acidosis?

Answer 1

Hypoventilation: more arterial Carbon dioxide

-lowers pH

Question 2

What is the compensatory response to respiratory acidosis?

Answer 2

Increased renal bicarbonate reabsorption

Question 3

What is the primary defect of respiratory alkalosis?

Answer 3

Hyperventilation: less arterial Carbon dioxide

-increases pH

Question 4

What is the compensatory response to respiratory alkalosis?

Answer 4

Decreased renal bicarbonate reabsorption

Question 5

What is the primary defect of metabolic acidosis?

Answer 5

Loss of bicarbonate

Gain of hydrogen

Question 6

What is the compensatory response to metabolic acidosis?

Answer 6

Hyperventilation: less arterial carbon dioxide

Question 7

What is the primary defect of metabolic alkalosis?

Answer 7

Gain of bicarbonate

Loss of hydrogen

Question 8

What is the compensatory response to metabolic alkalosis?

Answer 8

Hypoventilation: more arterial carbon dioxide

Question 9

How is serum anion gap calculated?

Answer 9

[Na+] - {[Cl-] - [HCO3-]}

Question 10

What is the normal range for serum anion gap?

Answer 10

8-16

Question 11

How is serum osmolal gaps calculated?

Answer 11

Serum osmolarity measured - [ 2 x ([Na+] + [K+]) + glucose/18 + BUN/2.8]

Question 12

What is the normal range for an osmolal gap?

Answer 12

< 10 mOsm/kg

Question 13

How is Δ gap calculated?

Answer 13

Δ gap = calculated anion gap - normal anion gap

Δ gap = calculated anion gap - 12

Question 14

How Δ[HCO3-] calculated?

Answer 14

Δ[HCO3-] = [normal HCO3-] - Δ gap

Question 15

If measured [HCO3-] is about the same as Δ[HCO3-] what does that mean?

Answer 15

Simple acid-base disorder

Question 16

If measured [HCO3-] > Δ[HCO3-] what does that mean?

Answer 16

Metabolic alkalosis

HAGMA (high anion gap metabolic acidosis)

Question 17

If measured [HCO3-] < Δ[HCO3-] what does that mean?

Answer 17

Non-gap metabolic acidosis

HAGMA (high anion gap metabolic acidosis)

Question 18

What are causes of acute respiratory acidosis?

Answer 18

CANS

• CNS depression (e.g. from opioids)
• Airway obstruction
• Neuromuscular disorders
• severe pneumonia, embolism, edema

Question 19

What are causes of chronic respiratory acidosis?

Answer 19

COPD

Anything chronic that leads to impaired ventilation

Question 20

For every 10 mmHg increase in arterial carbon dioxide, bicarbonate increases by ___ in acute respiratory acidosis and by ___ in chronic respiratory acidosis.

Answer 20

For every 10 mmHg increase in arterial carbon dioxide, bicarbonate increases by 1 in acute respiratory acidosis and by 3.5 in chronic respiratory acidosis.

Question 21

What are causes of respiratory alkalosis?

Answer 21

CHAMPS

• CNS disease
• Hypoxia
• Anxiety
• Mechanical ventilators
• Progesterone
• Salicylates/sepsis

Question 22

For every 10 mmHg decrease in arterial carbon dioxide, bicarbonate increases by ___ in acute respiratory alkalosis and by ___ in chronic respiratory alkalosis.

Answer 22

For every 10 mmHg decrease in arterial carbon dioxide, bicarbonate increases by 2 in acute respiratory alkalosis and by 5 in chronic respiratory alkalosis.

Question 23

What are causes of high anion gap metabolic acidosis (HAGMA)?

Answer 23

GOLDMARK

• Glycolysis
• Oxoproline
• L-lactate
• D-lactate
• Methanol
• Aspirin
• Renal failure
• Ketoacidosis

Question 24

What are causes of non-anion gap metabolic acidosis?

Answer 24

HARDUPS

• Hyperalimentation
• Acetazolamide
• Renal Tubular acidosis
• Diarrhea
• Ureterosigmoid fistula
• Post hypocapnia
• Spironolactone

Question 25

What are causes of metabolic alkalosis?

Answer 25

CLEVER PD

• Contraction
• Licorice
• Endocrinology issues
• Vomiting (losing HCl)
• Excess Alkali
• Refeeding alkalosis
• post-hyercapnia
• Diuretics