Blood gas test
Medical measurement
- 2 min read
- 2 chapters
Related on Lably
Values measured
Blood samples for testing are taken from arterial blood by a radial artery puncture, and from venous blood by venipuncture. Samples of capillary blood are taken using a lancet and capillary action. Capillary samples from the earlobe or the fingertip can be used to predict blood pH and the arterial partial pressure of carbon dioxide in the blood. Samples from the earlobe are seen to be a more appropriate site for the prediction of the arterial partial pressure of oxygen.
Blood gas tests also measure the levels of bicarbonate and standard bicarbonate, base excess, oxygen saturation, and pH. Typically, an arterial blood gas test is used more often than venous blood gas tests.
Sign in to keep reading
One more chapter is free with a Lably account.
Clinical significance
Blood gas tests can be used in the diagnosis of a number of acidosis conditions such as lactic, metabolic, and respiratory acidosis, diabetic ketoacidosis, and also of respiratory alkalosis. Particularly, umbilical cord blood gas analysis can give an indication of preceding fetal hypoxic stress. In combination with other clinical information, normal paired arterial and venous cord blood gas results can usually provide a robust defence against a suggestion that an infant had an intrapartum hypoxic-ischaemic event.
Abnormal results may be due to a wide range of diseases, including poisoning and trauma as well as lung, kidney, or metabolic diseases. Drug overdose and uncontrolled diabetes may be determined from abnormal results. Head, neck or injuries that affect breathing can also lead to abnormal results.