BLOOD GAS ANALYSIS

Dr. T.C. KriplaniProfessor & Head

Department of AnaesthesiologyNSCB Medical College & Hospital,

JABALPUR (M.P.)

POLIO – EPIDEMIC 1952- COPENHAGEN (DENMARK)

DR. BJORN IBSEN

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

Q. What are the principles of Gas analysis ?

Ans :

•Chemical (Haldane, Orsat-Henderson & Van Slyke)

•Physical (Magnetic, infrared, gas chromatography)

•Specific electrodes

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

Q. Who developed O2 electrode

Ans : Dr. Leland Clark in 1956

8

Q. Who developed CO2 electrode

Ans : Dr. John Severinghaus in 1959

PHOTOGRAPH OF pH ELECTRODE

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

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 processContraindications:

• -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

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

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

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

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