Acid-Base Physiology

Question 1

What is the normal pH range?

Answer 1

7.40 (7.38-7.43)

Question 2

What are two types of buffers?

Answer 2

Intracellular and extracellular

Question 3

Name some intracellular buffers.

Answer 3

Organic phosphates and proteins

Hemoglobin- deoxyhemoglobin

Question 4

Name some extracellular buffers

Answer 4

Phosphate
Bicarbonate
Plasma protein (albumin)

Question 5

What is the most important buffer? Why?

Answer 5

Bicarbonate.
Because it is present in high concentrations, pKa is closer to arterial pH, and the conjugate CO2 is excreted by lungs and kidneys

Question 6

What is the Henderson-Hasselbach equation?

Answer 6

pH = pKa + log ([A-] / [HA])

Question 7

Name two ways in which acid/base can be altered.

Answer 7

1. Changes in Pco2- Respiratory disorder

2. Too much or too little acid- Metabolic disorder

Question 8

True or False: Compensation never completely corrects and acid base disorder

Answer 8

TRUE

Question 9

What is the main disorder in a respiratory acidosis?

Answer 9

Increased Pco2 that leads to a decreased pH

Question 10

What are four causes of hypoventilation leading to a respiratory acidosis?

Answer 10

1. Obesity
2. ALS
3. Drugs (acute)
4. Muscle fatigue- pneumonia

Question 11

How do patients compensate for a respiratory acidosis?

Answer 11

Compensation through the preservation of bicarbonate in the kidneys which is slow

Question 12

What is the main disorder in respiratory alkalosis?

Answer 12

Decreased Pco2 leading to increased pH

Question 13

What are three causes of chronic hyperventilation in respiratory alkalosis?

Answer 13

Altitude
Neurological disorders
aspirin toxicity

Question 14

What are two causes of acute hyperventilation in respiratory alkalosis?

Answer 14

Anxiety

Minute volume too high on ventilation

Question 15

How do patients compensate for respiratory alkalosis?

Answer 15

Kidney increase excretion of bicarbonate (slow)

Question 16

How do you calculate an anion gap?

Answer 16

Na+ - (Cl- + HCO3-) = 12+/- 2

Question 17

What are the common causes of metabolic alkalosis?

Answer 17

MUDPILES
M- methanol
U- uremia
D- diabetic 
P- propylene glycol 
I- isoniazid
L- lactate
E- ethylene glycol
S- salicylates

Question 18

What are three causes of an anion gap with normal pH?

Answer 18

GI losses
Renal losses
Too much saline

Question 19

How does a patient compensate for a metabolic acidosis?

Answer 19

Increased ventilation which is a quick response

Question 20

How can you determine if a patient is compensating appropriately?

Answer 20

Use Winter’s Formula:

expected Pco2 =
1.5[HCO3-] + 8 +/- 2

If pCO2 is in range then the patient is compensating if not they aren’t

Question 21

What causes a metabolic alkalosis?

Answer 21

Metabolic alkalosis is either caused by increased bicarbonate or decreased CO2

Question 22

What are two causes of too much bicarbonate?

Answer 22

too much antacid or hypovolemia (kidneys hanging onto bicarb)

Question 23

What is a cause of decrease CO2 in metabolic alkalosis?

Answer 23

Vomiting

Question 24

How does a patient compensate for a metabolic alkalosis?

Answer 24

Decrease in ventilation and increase in Pco2

Question 25

For acute respiratory disturbances, a change in PaCO2 of 10 Torr yields a pH change of about ______ in pH.

Answer 25

0.08

Question 26

For chronic respiratory disturbances, a change in PaCO2 of 1 Torr should lead to compensatory change in [HCO3-] of ____ in the same direction.

Answer 26

0.4 meq/L

Question 27

For metabolic disturbances, a decrease in [HCO3-] of 1meq/L should result in an increase in PaCO2 of _____.

Answer 27

0.7 Torr