Transcutaneous measurement of blood gas pressure

 The electrode is attached to a small plastic ring that is placed on the baby's skin. A small amount of contact fluid is dropped on the plastic ring to ensure that the electrode comes into contact with the baby's skin. The electrode then heats the skin to a preset temperature which improves skin penetration.

The most common reading, TcPCO2 , measures the release of carbon dioxide from the blood. The electrode is heated to a lower temperature and can therefore take readings over a longer period of time. The TcPO2 reading measures the oxygen pressure in the tissue and requires that the electrode is heated to a higher temperature. How long this type of electrode can remain on the skin depends on how well developed the baby's skin is.