Lecture 19: Introduction to Acid Base Disturbances

Question 1

Know how to read the davenport diagram in the slides

Answer 1

Ok

Question 2

What is the difference between acute and chronic respiratory acidosis/alkalosis?

Answer 2

In chronic, kidney has learned to compensate for respiratory disturbance and is able to drive the pH to normal

Question 3

If you have a metabolic problem _____ will compensate and ______ will correct
If you have a respiratory problem _____ will compensate

Answer 3

• lungs, kidneys

- kidneys

Question 4

What does anion gap mean?

How is this calculated?

Answer 4

-how many cations are there than anions in the blood/urine? High means you lost anions you shouldn’t have lost (like HCO3-)

Plasma: Na - Cl + HCO3 = should be 11-12
Urine: Na+ + K+ - Cl- = should 20 - 90

Question 5

What does osmolal gap mean?

How is this calculated?

Answer 5

• how many more solutes are there in the blood/urine compared to normal.\
• Serum Osm/Urine Osm - 2(Na) + K + glucose/18 + BUN/2.8

Question 6

How do you calculate Delta Gap?

How do you calculate Delta HCO3-?

Answer 6

Anion Gap - 12

Normal HCO3- - Delta Gap

Question 7

If [HCO3-] = delta[HCO3-]
If [HCO3-] > delta[HCO3-]
If [HCO3-] < delta[HCO3-]

Answer 7

Acid base disorder
Metabolic alkalosis + HAGMA
NAGMA + HAGMA

Question 8

If AG/HCO3- ratio is 
1:1 =
<1 =
>1-2 = 
>2 =

Answer 8

HAGMA
Losing HCO3-
Lactic acidosis
Metabolic alkalosis

Question 9

Respiratory acidosis
Primary defect
Compensatory response

Answer 9

Alveolar hypoventilation (keeping too much CO2)
Kidneys absorb more HCO3- back in

Question 10

Causes of Respiratory Acidosis

Answer 10

Acute (CANS): 
CNS depression
Airway obstruction
Neuromuscular dz
Severe lung issues

Chronic:
COPD

Question 11

In acute respiratory acidosis, for every 10 increase in CO2, kidneys should reabsorb how much HCO3-?

In chronic respiratory acidosis, for every 10 increase in CO2, kidneys should reabsorb how much HCO3-?

Answer 11

Increase by 1

Increase by 3.5

Question 12

Respiratory Alkalosis
Primary defect
Compensatory response

Answer 12

Alveolar hyperventilation (exhaling too much CO2)
Kidneys will excrete HCO3-

Question 13

In acute respiratory alkalosis, for every decrease 10 in CO2, kidneys should excrete how much HCO3-?

In chronic respiratory alkalosis, for every decrease 10 in CO2, kidneys should excrete how much HCO3-?

Answer 13

Decrease by 2

Decrease by 5

Question 14

What are the causes of respiratory alkalosis?

Answer 14

CHAMPS

CNS disease
Hypoxia
Anxiety
Mechanical Ventilators
Progesterone
Salicylates/Sepsis

Question 15

Symptoms of acute and chronic respiratory alkalosis

Answer 15

Acute: Tachypnea, hyperpnea
Chronic: asymptomatic

Question 16

Metabolic acidosis
Primary defect
Compensatory response
Renal correction

Answer 16

• Kidneys excrete too much HCO3-
• Hyperventilation to expel CO2
• kidneys will excrete more H+ in urine and reabsorb more HCO3-

Question 17

Why is a high serum anion gap indicative of metabolic acidosis (HAGMA)?

Answer 17

If you have more cations than anions in the blood than normal (high anion gap), you have lost anions you shouldn’t have lost (HCO3-)

Question 18

What is NAGMA?

Answer 18

Non anion gap metabolic acidosis. Anion gap stays the same, but that’s because you kept more Cl- which covered up the fact that you lost HCO3-

Question 19

What are the causes of HAGMA?

Answer 19

GOLDMARK

Glycols
Okoproline
Lactate
D-lactate
Methanol
Aspirin
Renal failure
Ketoacidosis

Question 20

What are the causes of NAGMA?

Answer 20

HARDUPS

Hyperalimentation 
Acetazolamide
Renal tubular acidosis
Diarrhea
Uterosigmoid fistula
Posthypocapnia
Spironolacton

Question 21

What are the symptoms of metabolic acidosis?

Answer 21

Long deep breaths, normal rate

Vomiting nausea and malaise when pH drops below 7.10

Question 22

How do you calculate how much PaCO2 is in the blood during metabolic acidosis/Winter’s formula?

Answer 22

PaCO2 = 40 - (1.2 x (24 -HCO3-))

Winter Formula: (PaCO2 = 1.5 (HCO3-)) + 8 (+/-2)

Question 23

How do you calculate how much PaCO2 is in the blood during metabolic alkalosis?

Answer 23

PaCO2 = 40+ (0.7 x (HCO3-) - 34)

Question 24

If a patient with NAGMA exhibits HCO3- loss, normal AG and hyperchloremia, what is the most likely cause?

Answer 24

Type 2 RTA (diarrhea)

Question 25

If a patient with NAGMA is unable to excrete H+ in the urine, what is the most likely cause?

Answer 25

Type 1 RTA

Question 26

If a patient with NAGMA exhibits hypoaldosteronism and hyperkalemia, what is the most likely cause?

Answer 26

Type 4 RTA

Question 27

Metabolic alkalosis
Primary defect
Compensatory response
Renal correction

Answer 27

Kidneys absorb too much HCO3-
Hypoventilation (try to keep CO2 in)
Kidneys excrete HCO3- and decrease H+ in urine

Question 28

What are the causes of Metabolic alkalosis?

Answer 28

CLEVER PD

Contraction (volume)
Licorice
Endo problems
Vomiting
Excess Alkali
Refeeding Alkalosis
Post hypercapnia
Diuretics

Question 29

What are the symptoms of severe metabolic alkalosis?

Answer 29

Hypocalcemia (Ca2+ binds to proteins)

Question 30

Chloride responsive metabolic alkalosis is caused by….

Treated by?

Answer 30

Losing Cl- so you can’t regulate acid properly

Normal saline

Question 31

Chloride resistant metabolic alkalosis

Answer 31

Something else is causing the acid loss, not Cl- imbalance

Question 32

If your predicted compensation does not match what happens, this means

Answer 32

Patient has mixed acid-base disorder