ABGs

Question 1

normal ranges 
CO2
O2
HCO3
BE

Answer 1

CO2 4.7-6
O2 11-13
HCO3 22-26
BE -2 to +2

Question 2

in what 2 situations may a normal value be abnormal

Answer 2

normal Pao2 in pt on high flow O2 - should have O2 well above normal range

normal PaCo2 in a hypoxic asthmatic pt. usually their CO2 is low (respiratory alkalosis) as the hypoxia causes them to hyperventilate and blow off the CO2. if their CO2 is normal then they are tiring and need ITU. you should be worried if you see this!!!! if CO2 is raised it is “near fatal asthma”

Question 3

what should your first q be when looking at a blood gas

Answer 3

is the pt hypoxic (this will kill them long before anything else does)

Question 4

definition of hypoxaemic and then severely hypoxaemic

Answer 4

<10kPa = hypoxaemic
<8 = severely hypoxaemic and in RESP FAILURE

Question 5

type 1 vs type 2 resp failure

Answer 5

type 1 = low O2, normal CO2

type 2 = low O2, normal or raised CO2

Question 6

are the lungs or kidneys faster at compensating

Answer 6

resp compensation can occur quickly. metabolic compensation takes at least a few days .,. if you see met compensation for a resp disorder you can assume the resp derangement has been ongoing for a few days

Question 7

causes of resp acidosis

Answer 7

resp depression (opiates)
guillain barre (paralysis of resp muscles)
asthma
COPD

Question 8

causes of resp alkalosis

Answer 8

anxiety
pain (increases resp rate)
hypoxia (incfrease alveolar ventilation in attempt to compensate)
PE
pneumothorax

Question 9

causes of met acidosis

Answer 9

DKA
lactic acidosis (causes of this see next card)
aspirin overdose
GI HCO3 loss (diarrhoea, -ostomy)
renal tubular acidosis (retaining H+)
addison's (retain H+)

Question 10

causes of lactic acidosis

Answer 10

cardiogenic shock
hypovolemic shock
severe HF
sepsis
severe trauma
(inadequate perfusion -> cell hypoxia -> energy deficity -> anaerobic metabolism -> lactic acid accumulation

Question 11

causes of metabolic alkalosis

Answer 11

GI loss of H+

renal loss of H+ - loop and thiazide diuretics, HF, nephrotic syndrome, cirrhosis, Conn’s

Question 12

what is the anion gap used for

Answer 12

To work out if the metabolic acidosis is due to increased acid or decreased HCO3-

Question 13

what does an increase in the anion gap mean

Answer 13

increased acid production or digestion

The anion gap is affected by changes in unmeasured ions. H+ increases. HCO3- decreases by acting as a buffer against the H+. Results in a high anion gap.

Na+ - (Cl- + HCO3-)
increase bc HCO3- decreases

Question 14

what does a decrease in the anion gap mean

Answer 14

decreased acid excretion or loss of HCO3-

GI loss

Question 15

examples of situations where there is an INCREASED anion gap

Answer 15

DKA
lactic acidosis incl sepsis
aspirin overdose

Question 16

abg in bowel obstruction

Answer 16

metabolica alkalosis (vomiting -> loss of H+, K+ and Na+)

Question 17

how to calculate the anion gap

Answer 17

anion gap = Na+ - (Cl- + HCO3-)

H+ is not included as it is immeasurable
K+ is usually left out as the concentration is so small