SM_201a: Acid Base Integration II

Question 1

Acidemia is _____

Answer 1

Acidemia is an increase in [H⁺] in blood manifested by decreased pH

Question 2

Alkalemia is a _____ in [H+] in blood manifested by _____ pH

Answer 2

Alkalemia is a decrease in [H+] in blood manifested by increased pH

Question 3

Acidosis refers to a disorder that _____

Answer 3

Acidosis refers to a disorder that tends to lower pH and cause acidemia

Question 4

Aklalosis refers to a disorder that ______

Answer 4

Aklalosis refers to a disorder that tends to increase pH and cause alkalemia

Question 5

What is the Henderson-Hasselbach equation?

Answer 5

Question 6

Simple acid base disorders affect _____

Answer 6

Simple acid base disorders affect either HCO₃^- (metabolic) or PCO₂ (respiratory) and any assoicated changes in the other are compensatory and predictable based on expected physiological compensation

Question 7

Mixed acid base disorders affect ______

Answer 7

Mixed acid base disorders affect both the HCO₃^- (metabolic) and the PCO₂ (respiratory) as a result of at least two different disease processes and not physiological compensation

Question 8

Describe the compensatory responses

Answer 8

Question 9

In metabolic acidosis, the compensatory response is: _____

Answer 9

In metabolic acidosis, the compensatory response is: decrease in PCO₂ = 1.2 * ∆HCO₃^-

Question 10

In metabolic alkalosis, the compensatory response is: _____

Answer 10

In metabolic alkalosis, the compensatory response is: increase in PCO₂ = 0.6 * ∆HCO₃^-

Question 11

In chronic respiratory acidosis, the compensatory response is: _______

Answer 11

In chronic respiratory acidosis, the compensatory response is: increase in HCO₃^- = 0.4 * ∆PCO₂

Question 12

In chronic respiratory alkalosis, the compensatory response is: ______

Answer 12

In chronic respiratory alkalosis, the compensatory response is: decrease in HCO₃^- = 0.5 * ∆PCO₂

Question 13

In metabolic acidosis, pH _____ and blood [HCO₃^-] _____

Answer 13

In metabolic acidosis, pH decreases and blood [HCO₃^-] decreases

Question 14

Defense mechanisms against metabolic acidosis include _______ and _______

Answer 14

Defense mechanisms against metabolic acidosis include hyperventilation (decreases PCO₂) and increased renal acid excretion (leading to increase in blood HCO₃^-)

Question 15

In metabolic alkalosis, pH _____ and blood [HCO₃^-] _____

Answer 15

In metabolic alkalosis, pH increases and blood [HCO₃^-] increases

Question 16

Defense mechanisms against metabolic alkalosis include _______ and _______

Answer 16

Defense mechanisms against metabolic alkalosis include hypoventilation (increases PCO₂) and decreased net acid excretion which leads to a decrease in blood HCO₃^-

Question 17

In respiratory acidosis, blood pH _____ and PCO₂ _____

Answer 17

In respiratory acidosis, blood pH decreases and PCO₂ increases

Question 18

Defense mechanism against respiratory acidosis is ______

Answer 18

Defense mechanism against respiratory acidosis is increased renal net acid excretion which leads to an increase in blood HCO₃^-

Question 19

In respiratory alkalosis, blood pH _____ and PCO₂ _____

Answer 19

In respiratory alkalosis, blood pH increases and PCO₂ decreases

Question 20

Defense mechanism against respiratory alkalosis is ______

Answer 20

Defense mechanism against respiratory alkalosis is decreased renal net acid excretion which leads to decreased blood HCO₃^-

(excrete less acid -> bicarb decreases)

Question 21

Describe different types / causes of metabolic acidosis

Answer 21

Question 22

Metabolic acidosis is characterized by decreased ____, which ____ pH

Answer 22

Metabolic acidosis is characterized by decreased blood bicarbonate, which decreases pH

(physiological compensation attenuates the fall in pH)

Question 23

Describe general mechanisms of metabolic acidosis

Answer 23

General mechanisms of metabolic acidosis: low HCO₃^- state

• Loss of HCO₃^- externally - by GI tract (diarrhea) or kidney (proximal RTA)
• Failure of the kidneys to excrete acid (distal RTA) and CKD
• Addition of H⁺ which titrates HCO₃^-
• H⁺ buildup in the circulation (blood) can occur as an organic acid (e.g. lactic acidosis / ketoacidosis)

Question 24

Hallmark of RTA is ______

Answer 24

Hallmark of RTA is bicarbonate wasting (lot of bicarbonate in urine)

Question 25

Metabolic acidosis from loss of HCO₃^- can result from _____

Answer 25

Metabolic acidosis from loss of HCO₃^-​ can result from proximal renal tubular acidosis (PRTA)

• clinical features: Fanconi syndrome (bicarbonate wastage, glycosuria, phosphaturia, hyperuricosuria, aminoaciduria), hypokalemia, no nephrocalcinosis or kidney stones, rickets

Question 26

Metabolic acidosis from failure of the kidneys to excrete acid can result from _____

Answer 26

Metabolic acidosis from failure of the kidneys to excrete acid can result from distal renal tubular acidosis (DRTA)

• hyperchloremic metabolic acidosis, hypokalemia, nephrocalcinosis, kidney stones, and inability to lower urinary pH below 5.5 despite acidemia

(can occur if AE1 or CA2 do not work)

Question 27

H⁺ buildup in the blood can occur as an organic acid such as _____

Answer 27

H⁺ buildup in the blood can occur as an organic acid such as lactic acidosis

• Lactic acidosis is the most frequent and severe cause of this type of metabolic acidosis
• Increased lactic acid generation (Type A): tissue hypoxia as in severe hypotension, cardiac arrest, and sepsis
• Decreased utilization of lactic acid (Type B): liver failure, drugs, and malignancies

Question 28

Diabetic ketoacidosis results from ____ and ____

Answer 28

Diabetic ketoacidosis results from insulin deficiency and relative glucagon excess

Question 29

Anion gap = _____

Answer 29

Anion gap = [Na⁺] - ([Cl^-] + [HCO₃^-])

anion gap: normal is 12 ± 2 mEq/L

Question 30

_______ are the causes of anion gap metabolic acidosis

Answer 30

MUD PILES are the causes of anion gap metabolic acidosis

Question 31

_____ are the causes of non-anion gap metabolic acidosis

Answer 31

USED CARS are the causes of non-anion gap metabolic acidosis

Question 32

When bicarbonate decreases, anion gap _____

Answer 32

When bicarbonate decreases, anion gap increases

Question 33

In non-anion gap metabolic acidosis, Cl^- is ______

Answer 33

In non-anion gap metabolic acidosis, Cl^- is elevated

Question 34

Net acid excretion = _____

Answer 34

Net acid excretion = (NH₄⁺ + titratable acid) - HCO₃^-

Question 35

____ net acid excretion leads to metabolic acidosis

Answer 35

Low net acid excretion leads to metabolic acidosis

Question 36

Distal RTA and CKS are mainly due to _____ and _____

Answer 36

Distal RTA and CKS are mainly due to low NH₄⁺ and titratable acid excretion

Question 37

Proximal RTA is due to ______

Answer 37

Proximal RTA is due to bicarbonate wastage

Question 38

Urine anion gap = ______

Answer 38

Urine anion gap = (Na⁺ + K⁺) - (Cl^-)

Question 39

If NH₄⁺ increases, urine anion gap _____

Answer 39

If NH₄⁺ increases, urine anion gap decreases

(occurs in metabolic acidosis caused by diarrhea)

Question 40

If NH₄⁺ does not increases, urine anion gap ______

Answer 40

If NH₄⁺ does not increases, urine anion gap does not decrease

(occurs in distal RTA, which is a disease with metabolic acidosis because NH₄⁺ is excreted in the urine in low amounts)

Question 41

A large negative urine anion gap occurs in ______

Answer 41

A large negative urine anion gap occurs in metabolic acidosis caused by diarrhea

(NH₄⁺ high in urine)

Question 42

A positive urine anion gap occurs in _____

Answer 42

A positive urine anion gap occurs in distal RTA

(Low NH₄⁺ in urine)

Question 43

Metabolic alkalosis is characterized by _____, leading to _____ pH

Answer 43

Metabolic alkalosis is characterized by increase in blood [HCO₃^-], leading to increase in blood pH

Question 44

Metabolic alkalemia is sensed by _____, which result in _____

Answer 44

Metabolic alkalemia is sensed by peripheral chemoreceptors, which results in a decrease in respiratory ventilation and thus CO₂ retention

(for every 1.0 mEq/L increase in HCO₃^-, expect an increase in PCO₂ of 0.6 mmHg)

Question 45

Respiratory compensation for metabolic alkalosis is _______

Answer 45

Respiratory compensation for metabolic alkalosis is not effective

(if it was very effective, ventilation would decrease too much and cause hypoxemia)

Question 46

Describe the steps to calculate expected compensation in metabolic alkalosis

Answer 46

Calculating expected compensation in metabolic alkalosis

1. Calculate ∆HCO₃^-: plasma HCO₃^- – normal
2. Verify expected PCO₂: 0.6 * ∆HCO₃^-
3. Add expected PCO₂ + plasma PCO₂

Question 47

Compensatory response to metabolic alklalosis is ______

Answer 47

Compensatory response to metabolic alklalosis is increasing excretion of HCO₃^-

(reduce HCO₃^- reabsorption along the nephron and increase its secretion by beta-intercalated cells)

Question 48

Causes of metabolic alkalosis include _____ and _____

Answer 48

Causes of metabolic alkalosis include loss of hydrogen ions (gains of HCO₃^-) and retention of administed bicarbonate

Question 49

The pathophysiologic approach to metabolic alkalosis includes a _____, _____, and _____

Answer 49

The pathophysiologic approach to metabolic alkalosis includes a generation phase and maintenance phase

Question 50

In the generation phase of metabolic alklaosis, ______ is the initiating event

Answer 50

In the generation phase of metabolic alklaosis, loss of acid from the stomach is the initiating event (vomiting or nasogastric suction)

Question 51

In the maintenance phase of metabolic alkalosis, there is _____, _____, and _____

Answer 51

In the maintenance phase of metabolic alkalosis, there is decreased GFR, increased proximal bicarbonate reabsorption, and increased distal tubular bicarbonate reabsorption

• Increased proximal bicarbonate reabsorption: volume depletion, potassium depletion
• Increased distal tubular bicarbonate reabsorption: mineralocorticoid excess, hypokalemia

Question 52

In the recovery phase of metabolic alkalosis, use _____ or _____

Answer 52

In the recovery phase of metabolic alkalosis, use Cl^- administration (usually normal saline) to reexpand volume and correct the Cl^- deficit or KCl administration if hypokalemia is present

Question 53

Kidney responds to metabolic alkalosis resulting from vomiting by retaining _____ and secreting ______

Answer 53

Kidney responds to metabolic alkalosis resulting from vomiting by retaining Cl^- and secreting K⁺

Question 54

Differential diagnosis of metabolic alkalosis with hypokalemia is _____, _____, and _____

Answer 54

Differential diagnosis of metabolic alkalosis with hypokalemia is diuretics, vomiting, and Bartter’s and Gitelman syndrome

Question 55

In metabolic alkalosis with hypokalemia due to vomiting, urine Cl^- is ____

Answer 55

In metabolic alkalosis with hypokalemia due to vomiting, urine Cl^-​ is low