الفهرس 
OXYGEN EXCHANGEOnly 14 pages are availabe for public view
 |  | from | 159 |  |  |
| | | from | 159 | | |
Abstract
Arterial Blood Gas (ABG) analysis is the gold standerd for assessing respiratory function. ABG are frequently requested for the management of patient during anesthesia and in the ICU to evaluate the adequacy of oxygenation, ventilation, and acid-base status.
Before doing arterial sampling, the clinician should always be aware of the patient’s primary diagnosis and current status. In adult a 20 to 22 guage, short beveled needle Anticoagulated with sodium heparin (1,000 units|ml), is used for arterial sampling. A 25 guage, 1 to 3 ml syringe may be preferable in children and neonate. The sample should be immediately placed in ice to decrease the metabolic rate and so keeping blood gas values fairly stable for 1 to 2 hours.
The insertion of an arterial catheter will ensure the availability of accurate and continuous arterial sampling and direct arterial blood pressure measurement. The radial artery is usually the vessel of choice for arterial cannulation. Arterial puncture and cannulation may be complicated by hematoma, thrombosis, arteriospasm, infection, vasovagal response, and peripheral nerve damage.
Errors in blood gas sampling that may interfere with the accurate interpretation of ABG include; presense of air, venous sampling or admixture, anticoagulant effect or metabolism.
The actual analysis of blood gas values is accomplished via electrochemical devices commonly referred to as electrodes. 3 electrodes are used; PO2 electrode, PH electrode, and PCO2 electrode.
Interpretation of acid-base status from analysis of blood gases showing that the disorder is either acid-base disturbance or oxygenation defect. This interpretation requires a systemic approach depend on analysis of PH, PaCO2, HCO3-, and PaO2.
When one of the acid-base components (respiratory or metabolic) is abnormal and the other is normal, the abnormal condition is said to be uncompensated.
When the respiratory and metabolic components are in opposite directions (acidosis & alkalosis) compensation is assumed.
If the compensation response or the change in PH is more or less than expected, a mixed acid-base disorder exists.