ARTERIAL BLOOD GAS

INTRODUCTION:

Arterial blood gas analysis is an essential part for diagnosing and managing the patient’s oxygenation status, ventilation status and acid base balance.

Blood is drawn from arteries (radial, brachial and femoral).

DEFINITION:

It is a diagnostic procedure in which blood is obtained from an artery directly by an arterial puncture or accessed by a way of indwelling catheter.

COMPONENTS OF ABG

PaO2- Partial pressure of oxygen in blood.

SaO2- Partial pressure of saturated oxygen in hemoglobin.

PCO2- Partial pressure of carbon dioxide.

PH- Hydrogen ions concentration.

HCO3- Bicarbonate ions, it reflect the kidney ability to retain and excrete bicarbonates.

Purposes:

•   To determine the presence and type of acid base balance.

•   To check for severe breathing problems and lung disease.

•   To assess the response to the therapeutic intervention such as mechanical ventilator.

INDICATIONS:

•   Respiratory failure

•   Ventilated patient

•   Cardiac failure

•   Renal failure

•   Sepsis and burn

•  Poisoning

PROCEDURE OF ARTERIAL BLOOD GAS

EQUIPMENT REQUIRED

v  A CLEAN TRAY CONTAINING:

v  Gloves

v  Antiseptic solution

v  Local anesthesia

v  Heparinized syringe

v  Kidney tray

Step 1: Allen test

v  Put on clean gloves.

v  Instruct the patient hold the wrist in supine position.

v  Now perform Allen’s test for collateral flow.

ALLEN TEST

The Allen test is done to assess the arterial blood flow to the hand.

This test can be performed for either the ulnar or radial artery.

PROCEDURE:

v  Instruct the patient to clench fist.

v  Now apply firm pressure to radial and ulnar arteries.

v  Instruct the patient to relax his or her arm.

v  Now release the pressure on ulnar artery.

v  If patient’s palm flush within 5-15 seconds then Allen test is considered negative and person can go for arterial puncture. 

Step 2: Palpate artery and clean

1.   Palpate the radial artery with the index finger and index fingers with non-dominant hand.

2.   The clean the insertion site with alcohol swab.

Step 3: Position and advance needle

1.   Palpate the artery gently to landmark for puncture.

2.   Hold syringe in the dominant hand and draw blood by puncturing the artery of the patient.

         ANGLE FOR DRAWING BLOOD FROM VARIOUS ARTERIES.

             RADIAL ARTERY- 45 Degree.

             BRACHIAL ARTERY- 45-60 degree.

             FEMORAL ARTERY- 90 degree.

Step 4: Apply pressure after removing needle

 After removing needle immediately apply the pressure on the site with the help of gauze as to               prevent hematoma formation. Pressure should be applied for at least five minutes.

Step 5: evacuate air from the syringe

Inspect the syringe carefully for air as it may vary results of ABG. There should be continuous column of blood up to hub of needle then syringe is then capped, labeled and placed in the bag with ice and sent for analysis.

COMPLICATION:

• Hematoma

•  Arteriospasm

•  Air or clotted- blood emboli

•  Anaphylaxis from local anesthetic

•  Hemorrhage

•  Trauma to the vessel

•   Arterial occlusion

•   Vasovagal response