Gastrotonometry is a method developed for the measurement of the partial pressure of carbon dioxide (PgCO₂) in the gastrointestinal tract. Its main purpose is to monitor the circulation condition of patients in critical states.

With the help of gastrotonometry the partial carbon dioxide tension (PgCO₂) of the gastrointestinal tract became measurable, and thus the condition of the splanchnic perfusion is adequately assessable.
The technique became extensively used in clinical practice.
Since the deterioration of the visceral circulation is one of the first signs of circulation insufficiency and it is also a sensitive indicator of morbidity and mortality, the main field of application of gastrotonometry is monitoring the condition of patients in critical states. However, so far – aside from a few experimental studies – the procedure has only been performed on adult patients, mainly because in case of children the application of the technique has been rather too difficult, and technically difficult to carry out. In case of newborns it was almost impossible.