4. Q. What is the difference between :
-Blood gas analysis
&
-Blood gas monitoring
Ans : Blood gas monitor is a patient dedicated
device that measures arterial pH, PaCO2 and
PaO2 without permanently removing blood.
For blood gas analysis – Blood is removed
from patient
5. Q. What are the principles of Gas analysis ?
Ans :
•Chemical (Haldane, Orsat-Henderson & Van Slyke)
•Physical (Magnetic, infrared, gas chromatography)
•Specific electrodes
6. Q. What is the difference between electrode &
optode ?
Ans :
•Electrode : Sensor that operates via electrochemical
properties
•Optode : Sensor that operates via optical detection
of altered light
11. Q. What are the sites from where blood can be
drawn for blood gas analysis ?
Ans :
•Usually from peripheral art. (Radial, Brachial,
Femoral or Dorsalis pedis)
•Arterialised capillary sample
•Rare cases venous blood is used
12. Q. What are indications & contraindications of
arterial blood gas analysis ?
Ans :
•Indications:
•To evaluate the adequacy of ventilation
•To Quantitate patient’s response to therapeutic intervention
•To monitor severity & progression of documented disease process
Contraindications:
•-ve result of Allen’s test
•Coagulopathy or medium to high dose anticoagulation therapy
(Heparin, Coumadin, streptokinase, Caprostat)
•Femoral puncture avoided outside hospital
•Arterial puncture not performed distal to surgical shunt
13. Q. What are the complications of Arterial Puncture?
•Arteriospasm,
• Haematoma,
•Emboli (Air or clotted blood),
•Anaphylaxis if LA is used,
•Haemorrhage,
•Trauma to vessel,
•Arterial occlusion,
•Vasovagal response and Pain
14. Q. How Allen’s test is performed ? What precautions
should be taken while taking the sample ?
Ans : Allen E.V. (1929)
•Pt. closes hand as tightly as possible for 1 minute in order to squeeze out
blood
•Compress radial art. at wrist
•Open the hand (extend fingers)
•Note the return of colour
•Full blushing – 7 seconds
•Borderline – 8 – 14 seconds
•Abnormal (-ve test) - > 14 seconds
•LA – prevents arterial spasm, softens skin, increases subcutaneous space
(working room),
•Ringe syringe with Heparin 1 in 1000
15. Q. How arterialised capillary sample is taken ?
Ans :
•Site – Finger, toe, heel or ear lobe
•Wrapping in warm pad (40-430 C) for 10 minutes
•Or
•Massage ear lobe for 2-3 minutes
•Heparinised capillary tube should be sealed after
collecting sample with clay at one end
•Short steel wire is inserted then other end is sealed
•Steel wire is moved with magnet to mix the sample
16. Q. How to take an arterial blood gas sample ?
Ans :
•Syringe with 22 to 23 G needle for radial artery
puncture
•Bevel facing up 20-300 angle, wrist extended 20-
300
•0.25 mL Heparin 1000 IU/mL concentration do
coating and discard rest
•Send for analysis within 5-10 minutes or else store
in Ice child water (40C) maximum upto 60 minutes
