Measurement of Gastric-to-end-tidal Carbon Dioxide Difference in Neonates Requiring Intensive Care

Objective: Gastric-arterial partial CO2 pressure gap (Pg-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 Pg-aCO2 gap with an alternative gap of PgCO2 – end-tidal carbon dioxide (Pg-ETCO2 gap). Methods: A prospective study was performed on ventilated neonates requiring intensive therapy (n = 44, weight: 1813 ± 977 g). PETCO2 and PgCO2 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: Pg-ETCO2 gap was higher than Pg-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: Pg-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 Pg-aCO2 gap should not be abandoned.