Blood Gases

Question 1

pH

Answer 1

7.35 - 7.45

Question 2

PO2

Answer 2

10 - 14 kPa

Question 3

PCO2

Answer 3

4.5 - 6 kPa

Question 4

Base excessive

Answer 4

-2 - 2 mmol/l

Question 5

HCO3

Answer 5

22 - 26 mmol/l

Question 6

1

Answer 6

Acidaemia or alkalaemia?

Question 7

Look at pco2 and bicarb

Answer 7

If either abnormal may be mixed

Question 8

Co2 changes

Answer 8

Resp

Question 9

Bicarb changes

Answer 9

Metabolic

Question 10

Resp alkalosis

Answer 10

Pneumothorax
Asthma
PE
Hypervent
Pneumonia
Pulmonary oedema

Question 11

Met alkalosis

Answer 11

Gi - vom/diarrhoea
Renal - Conn’s, Cushing’s, loop or thiazide diuretic, post hypercapnic
Hypokalaemia
Diuretics: h ion loss of contraction

Question 12

Normal anion gap

Answer 12

8-16

Question 13

Anion gap

Answer 13

Reflects unmeasured anions

Na-(hco3+cl)

Question 14

High anion gap

Answer 14

Incr acid:
Exog: methanol, aspirin, ethylene glycol
Renal failure
Ketoacidosis: alcohol, starvation, diabetes
lactic acidosis: type a tissue hypoperfusion, b

Question 15

Compensation

Answer 15

Ventilatory response: mins - hrs (resp)

Renal response: days (metabolic)

Question 16

Chronic resp acidosis

Answer 16

High bicarb to concentrate

Question 17

Acute resp acidosis

Answer 17

Bicarb normal can’t compensate quickly

Question 18

Acute metabolic acidosis

Answer 18

Low CO2 to compensate

Question 19

Metabolic alkalosis

Answer 19

Hypovent to compensate

CO2 incr

Question 20

Simple acid base disorders

Answer 20

pH will be abnormal

Bicarb follows CO2

Question 21

Resp acidosis

Answer 21

COPD,pneumonia, asthma, pulm oedema
Obstructive sleep apnoea,
Obesity, kyphosis, flail, scleroderma
Mnd

Question 22

For every 1.3 incr in pco2 above 5.3

Answer 22

Hco3 incr by 3.5