clinical blood gases Flashcards
how is haemoglobin saturation measured
absorption spectrometry using a finger probe
what is most healthy peoples oxygen saturation
97%
2 different ways of measuring arterial blood gases (ABG)
single arterial puncture technique
in-dwelling arterial catheter or A-line
which artery is most commonly used for ABG measurement and which other 2 are used less often
radial artery
less commonly used:
femoral artery
brachial artery
what does a blood gas measure
PaO2
PaCO2
Hydrogen ion/pH
Bicarbonate
may also measure electrolytes and Hb
difference between PA and Pa
PA - partial pressure in alveolus
Pa - partial pressure in arterial circulation
normal blood gas values: H+
36-44nmol/l
normal blood gas values: PO2
12-15kPa
normal blood gas values: PCO2
4.4-6.1
normal blood gas values: HCO3 (bicarbonate)
21-27.5
what is BE
base excess (to do with metabolic blood gases)
normal blood gas values: BE
+2 to -2 mmol/l
difference between PAO2 and PaO2 values and why
PaO2: 12-15kPa
PAO2: 14-15kPa
oxygen dilution
what do carbon dioxide levels tell us about
ventilation
what happens to pCO2 and pO2 during hyperventilation
pO2 same, low pCO2
what happens to pCO2 and pO2 during hypoventilation
low pO2, high pCO2
what does increase of CO2 in blood lead to
acidosis
what is carbon monoxide (CO) produced from
incomplete combustion (mainly faulty gas boilers)
what does CO form when it binds to haemoglobin
carboxyhaemoglobin
how does CO damage the body
higher affinity to haemoglobin than oxygen so displaces it
also toxin to mitochondria