arterial blood gas interpretation

ARTERIAL BLOOD GAS ANALYSIS

[ABG]

BLOOD Blood is a connective tissue

BLOOD CONSIST OF PLASMA

(55%) AND CELLS (45%).

FUNCTIONS Transport respiratory gases Transport nutrients Act as a vehicle (hormones & vitamins)

Drainage of waste productsMaintenance of water balanceMaintenance of acid equilibriumRegulation of body temperature

COMMON TERMINOLOGIES

ACIDS: Acid is a substance which when dissolved in water undergoes or splits into a hydrogen ion and anion.

BASES: Base is a substance which undergoes dissociation in water to give a hydroxyl ion and a cation.

SALTS: Salt is a substance which when dissolved in water dissociate to release a cation and anion neither of which is a hydogen ion nor a hydroxyl ion.

PH PH is the hydrogen ion

concentration in any solution.

1________________7________________14

Acid Base

Normal Blood PH- 7.35 – 7.45 mEq/L

BUFFER Buffer is a substance which is capable of converting strong acid into weak acid and strong base into weak base & does not undergo rapid ionisation & thereby does not contribute to alteration of pH.

THREE SYSTEMS: 1.Buffer system 2.Respiratory system 3. Renal system

BUFFER SYSTEMS

1. Carbonic acid bi-carbonate system2. Sodium salt of di-hydrogen and mono-hydrogen phosphate3. Protein buffer system

NORMAL ABG VALUES

pH PaO2 PaCO2 HCO3- Base excess SaO2

7.35 - 7.45 80 - 90 mm/Hg 35 – 45 mm/Hg 22-26 mEq/L +2 95 - 100%

INDICATIONSCardiac FailureRenal or Hepatic FailureMechanical ventilationDiabetic KetoacidosisRespiratory Failure Or Dysfunction.Sepsis and burnsPoisoningCardiopulmonary surgeryCardiac pulmonary exercise testingOxygen administration

CONTRAINDICATIONS:

Patients on anticoagulant & those with coagulopathies.

Obstructing thrombus in the artery. Patients with poor collateral flow.

PROCEDURE OF ABG ANALYSIS Arterial puncture sites:Wrist :most common site used.Radial arteryBrachial arteryFemoral arteryDorsalis pedis artery

EQUIPMENTS USED:Sterile Gloves

Heparinized syringe (2ml)Alcohol SwabsGauze piecesTape or PlasterPatient Label Ice bag or box.

ALLEN’S TEST

AFTER-CARE

Applies pressure to the puncture site for

10-15 mins to stop the bleeding.The patient should rest quietly while

applying the pressure to the puncture site.

Then place a dressing over the puncture.

Health care workers will observe the patient

for the signs of bleeding or circulation problem

COMPLICATIONSHematomaHemorrhageArteriospasmNosocomial BacteraemiaDistal IschemiaNumbness of HandSepsis Infection of health care worker.

UNCOMPENSATED ABG VALUES

pH PaCO2

HCO3

Respiratory acidosis

Normal

Respiratory alkalosis

Normal

Metabolicacidosis

Normal

Metabolicalkalosis

Normal

COMPENSATED ABG VALUES

pH PaCO2 HCO3-

RespiratoryAlkalosis Normal

MetabolicAlkalosis Normal