Background
Gastric tonometry was developed for measuring the partial pressure of carbon dioxide in the gastrointestinal tract and particularly for monitoring the clinical condition of patients in critical states. The ballooned catheter used in this technique has proved to be a reliable tool in adult patients, but its use in pediatrics is limited because of technical difficulties. The aims of this paper are to describe the technique of application of a recently developed gastric tonometric probe especially suitable for performing measurements on neonates and infants and to present the first human results.
Material and Method
Thirty-two neonates and infants requiring intensive care were monitored (age: 2-456 days, weight: 1200-6700 g), of whom 10 died. The pediatric index of mortality, acid-base parameters, PCO2 gap values, and intramucosal pH and pH gap values were measured or calculated. The new gastric tonometric probe, made of silicone rubber tubes, is balloon free. It is introduced into the stomach orally or nasopharyngeally through the use of a guide wire. After equilibration, the PCO2 level of the air inside the probe is measured with a capnograph.
Results
Application of the new probe proved simple. The pediatric index of mortality scores (35.1%+/-19.6% vs. 14.6%+/-14.8%), PCO2 gap values (13.48+/-9.30 mmHg vs. 8.43+/-6.54 mmHg), and the systemic-intramucosal pH differences (0.124+/-0.074 vs. 0.079+/-0.054) were significantly higher in the non-surviving patients.
Conclusions
The new probe is well applicable for measurements of gastric PCO2 levels in infants.

Keywords: Prospective Studies, Manometry - instrumentation, Partial Pressure, Intensive Care Units, Neonatal, Infant Mortality, Infant, Newborn, Stomach - metabolism, Carbon Dioxide - analysis