Gastric tonometry

The principle of the method is regional measurement of partial pressure CO2 (PtCO2) of the gastric mucosa. Using this method, we can detect perfusion disorders of the splanchnic area very soon, which will manifest itself in a very early rise in mucosal PtCO2.

We have two possibilities how to explain this rise:


 * In ischemia, there is a transition to anaerobic metabolism. Tissue metabolic acidosis develops with an increase in CO2 production as a result of the bicarbonate buffering reaction.


 * In hypovolemia, aerobic metabolism may still be maintained, but CO2 elimination is impaired due to reduced splanchnic blood flow.

This method probably has a great future, because it monitors hemodynamic disorders well in advance in all types of shock conditions and is minimally invasive.

Realization of the method:


 * It is performed by inserting a special catheter with a balloon into the stomach. It lies on the gastric mucosa and after 10 minutes the concentration of CO2 in the balloon and in the cells of the gastric mucosa equalizes thanks to diffusion through the semipermeable membrane.


 * The CO2 value in the balloon is then measured, which is the PtCO2 value.


 * Furthermore, the regional pH is calculated using the etCO2 and arterial pH values.


 * According to these values, further therapy is being carried out with the aim of improving the perfusion of tissues in a shock state. This is another method that monitors the quality of organ perfusion in addition to diuresis values.

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