Measurement of gastric-to-end-tidal carbon dioxide difference in neonates requiring intensive care

Abstract

Objective: Gastric-arterial partial CO₂ pressure gap (P_g-aCO₂ gap) measured by gastric tonometry may detect the disturbance of splanchnic perfusion. As in the neonatal age it is very difficult to follow up the circulatory condition with frequent acid-base examinations, we wanted to compare the P_g-aCO₂ gap with an alternative gap of P_gCO₂ – end-tidal carbon dioxide (P_g-ETCO₂ gap). Methods: A prospective study was performed on ventilated neonates requiring intensive therapy (n = 44, weight: 1813 ± 977 g). P_ETCO₂ and P_gCO₂ were measured with a side stream capnograph. We applied a newly developed gastric tonometric probe. Patients were divided into two groups: Group 1 of patients in stable condition (n = 35) and Group 2 of patients with severe condition (i.e. Clinical Risk Index for Babies [CRIB] score higher than 10; n = 9). For main statistical analysis a mixed model repeated measurements ANOVA, Bland–Altman analysis were applied. Results: P_g-ETCO₂ gap was higher than P_g-aCO₂ gap (11.40 ± 7.79 versus 3.63 ± 7.98 mmHg, p < 0.01). Both gaps were higher in Group 2 (8.71 ± 10.89 and 18.27 ± 10.49 versus 2.53 ± 6.78 and 9.92 ± 6.22 mmHg, p < 0.01 and p < 0.05). Bland–Altman analysis of the two gaps showed an acceptable correspondence. Conclusions: P_g-ETCO₂ gap may be used as a method for continuous estimation of splanchnic perfusion and a prognostic index also in critically ill neonates. However, the P_g-aCO₂ gap should not be abandoned.

Keywords::

• Gastric tonometry
• gastrointestinal perfusion
• neonate
• neonatal intensive care
• partial carbon dioxide pressure

Declarations of interest: This study comprises part of a project funded by the EU and the Hungarian Ministry of Economic Affairs (GVOP-3.3.1-05/.-2005-0153/3.0) and part of the innovation programme of the University of Szeged.