Arterial blood gases Flashcards
What is the blood gas disribution in arteries?
P(a)O2 = >10kPa S(a)O2 = >95% P(a)CO2 = 4.7-6 kPa
What is the blood gas distribution in the veins?
P(v)O2 = 4.0-5.3 kPa S(v)O2 = 75% P(v)CO2 = 5.3-6.7 kPa
What is the pulmonary transit time?
avg .time across capillary networks
an indirect measure of preload and left ventricular function
What is the acid base equation?
H2O + CO2 H2CO3 H+ + HCO3-
What is respiratory acid?
Carbonic acid (99% of acid in the body)
What are metabolic acids?
HCL
lactic
keto acids
all the other acids in the body (1%)
How fast can the resp system fix acid base balance?
Rapid compensatory response
How fast can the kidneys fix acid base balance?
Slow compensatory response working with acids and bicarbonate
What are the aetiologies of imbalance?
respiratory acidosis/alkalaemia
metabolic acidosis/alkalosis
mixed (both resp and metabolic)
How would you report an arterial blood gas?
compensation
aetiology
disturbance
oxygenation
What are the types of compensation?
uncompensated
partially
fully
What are the types of oxygenation?
hypoxaemia
normoxaemia
hyperoxaemia
report this:
H+ is low
Pa(a)CO2 is low
PO2 is low
BE (base excess) is normal
- Alkalosis
- respiratory
- uncompensated
- hypoxaemic (moderate)
= uncompensated respiratory alkolosis hypoxaemiA
- when BE changes then it is being compensated
Using Sørensen’s equation calculate the change in [H+] between arterial blood and venous blood. What is it as a percentage?
Arterial pH = 7.4
Venous pH = 7.36
ARTERIAL pH = 3.981
VENOUS pH= 4.365
9.65%
Asses the acid-base status
what may have caused the imbalance?:
pH = 7.31 PaCO2 = 7.8 HCO3- = 24.1 BE = +1.6 PaO2 = 9.9
uncompensated respiratory acidosis with very mild hypoxaemia
