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

Abstract

Objective: Gastric-arterial partial CO(2) pressure gap (P(g-)(a)CO(2) 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-)(a)CO(2) gap with an alternative gap of P(g)CO(2) - end-tidal carbon dioxide (P(g)(-)(ET)CO(2) gap).

Methods: A prospective study was performed on ventilated neonates requiring intensive therapy (n = 44, weight: 1813 ± 977 g). P(ET)CO(2) and P(g)CO(2) 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)(-)(ET)CO(2) gap was higher than P(g-)(a)CO(2) 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)(-)(ET)CO(2) 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-)(a)CO(2) gap should not be abandoned.