DSA Acid Base Compensation

Question 1

What are two rules regarding compensation?

Answer 1

1. Compensation never gets back to normal
2. Compensation must occur through the other system: thus a respiratory disturbance must be fixed with a metabolic compensation

Question 2

How does our metabolic system compensate for respiratory disturbances?

Answer 2

DCT and CD cells in the distal convulated tubule can excrete and reabsorb H+ or bicarb when needed.

Question 3

Thus; if we have a respitory acidosis, how will our metabolic system compensate?

Answer 3

DCT/ CD cells are going to excrete H+ ions and reabsorb bicarb to increase our pH.

Thus, we see an increase in bicarb levels.

Question 4

How does our metabolic system compensate for respiratory alkalosis?

Answer 4

DCT/CD cells are going to excrete bicarb into the urine and reabsorb H+ ions, to decrease our pH.

–> As a result, you will see decreases in plasma bicarb levels.

Question 5

Steps in determining type of respiratory problems

Answer 5

1. Acidosis or alkalosis?
2. Respiratory or metabolic?
3. Is the body compensating for the problem?
   
   1. If yes, problem is chronic that the bodies are dealing with.
   2. If no, the problem is acute.

Question 6

For respiratory acidosis, to check if acute or chronic

Answer 6

If the problem is acute: Expected [bicarb]= 24 + ((PaCO2-40)/10)

If the problem is chronic: Expected [bicarb]=24+ 4 ((PaCO2-40/10)

–in both cases, if we have a respiratory acidosis, we expect our bicarb to increase.​

Question 7

For respiratory alkalosis, to check if acute or chronic

Answer 7

• Acute*: Expected [bicarb]= 24 – 2 ((40-PaCO2)/10)
• Chronic*: Expected [bicarb]= 24-5 ((40-PaCO2/10)

–in both cases, if we have a respiratory alkalosis, we expect our bicarb to decrease.

Question 8

If we have increase H+ in the blood (decreased pH), how can we fix?

Answer 8

Hyperventilation–> blow out CO2 and increase pH.

Question 9

Decreased H+ in the blood= increase pH.

How can we fix?

Answer 9

Hypoventilate–> retain CO2 and decrease pH.

Question 10

If metabolic system is compromised, __________ tries to fix the pH.

Answer 10

Respiratory tract

Question 11

Metabolic acidosis with respiratory compensation (_________)

Answer 11

Hyperventilation

Question 12

Metabolic alkalosis with respiratory compensation (________)

Answer 12

Hypoventilation

Question 13

If we have metabolic acidosis, how do we check is the respiratory compensation is adequate?

Answer 13

Expected PaCO2= (1.5[HCO3] + 8) +/- 2

Question 14

Why do we ask if respiratory response is adequate and not acute/chronic?

Answer 14

1. Because the respiratory response will be very quick and occur before the condition can be considered chronic.
2. The respiratory system can only influence a small part of the total HCO3, so it never gets the pH as close to normal as one would expect.

Question 15

If we determine that the problem is a metabolic acidosis, we have to calculate the anion gap. WHY?

Answer 15

Because we can use up our bicarb by making an acid we hadn’t planned on: lactic acids, ketoacids, etc.

Anion gap is based on the rule that the + and – should always balance themselves out.

Question 16

What is the anion gap?

Answer 16

Should be based on the one rule: + and - should always balance themselves out.

Anion gap= Na- (Cl+ HCO3)

If I am making an acid that is not measured via tests, HCO3- will decreae because it Is acting as a buffer for the acid. Thus, an anion gap occurs. The positives and negatives will not balance themselves out because we have lost the HCO3.

Question 17

Normal anion gap

Answer 17

< or equal to 12.

Question 18

What does an elevated anion gap mean?

Answer 18

unmeasured chemicals are present in the blood.

Example: in diabetic ketoacidosis, starvation or alcoholic ketoacidosis, lactic acids, salicylates (ASN)

Thus, these cause metabolic acidosis.

Question 19

If we have metabolic alkalosis, how can we check if respiratory compensation is adequate?

Answer 19

Change in PaCO2= (0.5 to 1.0) * change in bicarb

In this case, the change is an increase in CO2