ABG's

Question 1

VBG

Answer 1

VBG can’t tell you about O2 but can tell you about CO2

Question 2

PO2

Answer 2

expected to be <10 of FiO2

e. g. room air is 21% so expect PO2 to be 11 (21-10)
e. g venturi is 35% so expect PO2 to be 25

Question 3

nasal cannula

Answer 3

1/Lmin 24%
2L/min 28%
3L/min 32%
4L/min 36%

simple mask
FiO2 30-40% at 5-10L/min

non re-breather mask
85% at 15L/min

venturi mask
bernoulli principle

blue 2L/min 24%
white 4L/min 28%
yellow 8L/min 35%
red 10L/min 40%
green 15/ min 60%

Question 4

respiratory acidosis

Answer 4

COPD / life threatening asthma
OSA- obesity, hyperventilation
neuromuskular (myasthenia gravis, gullian barre)
central depression (opioid toxicity)

Question 5

respiratory alkalosis

Answer 5

hyperventilation (pain, anxiety)
hyperventilating in response to hypoxia (acute asthma)
PE
pneumothroax

Question 6

base excess

Answer 6

< -2 more negative (metabolic acidosis) lost base

> 2 metaboic alkalsos (HCO3)

Question 7

metabolic acidoiss

Answer 7

DKA, alcohol, ethylene glycol, methanol, GI loss, renal tubular acidosis (holding on / not excreting HcO3)

? ocetazzolamide?

Question 8

metabolic alkalosis

Answer 8

vomiting (loose HCl)
diuretics
endocrine (cushings/conns/ectopic ACTH)
iatrogenic (steroids) (NaHCO3)

Question 9

anion gap

Answer 9

Na - Cl - Hco3 = anion gap
12 + / -2

a raised anion gap means that there is another negative ion being produced that is not in this calculation e.g. DKA/ lactic acidosis (lactate)