Acidosis and alkalosis

Question 1

Steps to working out ACID BASE

Answer 1

1- pH - acid or alkali
2 - PaCO2 - contributing or compensating (cause or not)
3 - Base - BE + HCO3 (acute or chronic)
4 - PaO2 - Type I or II resp failure

Question 2

What are the normal parameters for pH

Answer 2

7.35-7.45

Question 3

What does a low pH with a high PaCO2 signal?

Answer 3

Respiratory acidosis

Question 4

What does an acidic pH and a low PaCO2 signal?

Answer 4

Metabolic acidosis

Question 5

What does a raised pH and normal or increased PaCO2 signal>

Answer 5

Metabolic alkalosis

Question 6

What does a raised pH and decreased PaCO2 =

Answer 6

Respiratory alkalosis

Question 7

When is a pH problem acute?

Answer 7

When the base picture (metabolic) hasnt responded - takes hours to days to change, resp is much more sensitive

Question 8

What type of respiratory failure has both hypoxia and hypercapnia?

Answer 8

2

Question 9

What is the sign of type I respiratory failure?

Answer 9

Hypoxia alone

Question 10

What is the level of hypoxia?

Answer 10

Less thna 8 kpa PaO2

Question 11

What level is hypercapnia?

Answer 11

Over 6kpa PaCO2

Question 12

What causes the repiratory drive?

Answer 12

Level of carbon dioxide - very sensitive, RR changes in minutes to hours in response

Question 13

Why is type II resp failure also hypercapnia?

Answer 13

Drive becomes hypoxia, unable to blow off enough CO2 to keep levels normal

Question 14

What pH disorder will vomitting in Excess cause

Answer 14

Loss of H+ -> metabolic alkalosis ->

Question 15

Why is decreased ventilation seen in metabolic alkalosis?

Answer 15

To retain CO2 and raise acidity

Question 16

What can a high otuput ileostomy cause?

Answer 16

Metabolic acidosis - loss of HCO3- as high conc in GI tract

Question 17

What happens to ventialtion in metabolic acidosis

Answer 17

Increased RR -> Tachypnoea

Question 18

If metabolic compensation is seen for hypercpania (eg raised HCO3-), is the acidosis acute or chronic?

Answer 18

CHronic

Question 19

Parameters for PaCO2

Answer 19

4.6-6.4

Question 20

Parameters for HC03-

Answer 20

21-28

Question 21

Base excess parameters

Answer 21

-2 to +3 (any value away from 0 is not good)

Question 22

When is metabolic ocmpensation seen?

Answer 22

In a chronic problem

Question 23

When is a pH disorder fully compensated?

Answer 23

When the pH value is still in range

Question 24

What is the picture in COPD CO2 retainers?

Answer 24

Increased CO2
Increased HCO3- - metabolic compensation
pH in normal range
Chronic respiratory acidosis with full compensation

Question 25

What is the anion gap?

Answer 25

When HCO3- is mopped up by excess H+ so decreased HCO3- circulating

Question 26

An overdose with an acidic drug, causing respiratory depression, causes which pH disroder>

Answer 26

Both resp acidosis and metabolic acidosis

Question 27

Aspirin overdose causes what pH disorders?

Answer 27

1st pass -> Stimulates resp centres causing increased ventilation causing resp alkalosis
2nd pass -> produces salicyclic acid -> metabolic acidosis

Question 28

Enzymes that metabolise aspirin

Answer 28

COX-1 + COX-2

Question 29

What two things can metabolic acidosis be caused by?

Answer 29

Loss of HCO3- or Gain of H+