Gastric mucosal-to-end-tidal PCO2 difference during major abdominal surgery: influence of the arterial-to-end-tidal PCO2 difference?

Intraoperative gastric tonometric examinations in children and infants with a new probe, combined with measurement of the endtidal PCO2

BACKGROUND

Important progress relating to the early prediction of postoperative complications was recently achieved through the combined use of endtidal PCO(2) (P(ET)CO(2)) and gastric tonometry. The aim of this article was to present results obtained with a new tonometric instrument, proving its feasibility and extending its use to the control of anesthetized infants and children.

METHODS

The new tonometric probe, which is balloon free, consists basically of silicone rubber tubing. The room air initially inside the tubes of the probe equilibrates with the PCO(2) of the body cavity throughout its full length. The PCO(2) content of the gastric cavity (P(g)CO(2)) and simultaneously P(ET)CO(2) were measured with a microcapnograph. A total of 108 measurements were performed intraoperatively on 25 infants and young children operated on at the Surgical Unit of the Department of Pediatrics. The patients were divided into elective surgery cases <2 years of age, group I; elective surgery cases >2 years of age, group II; and acute surgery cases, independently of age, group III. To examine the degree of agreement between the measurements, Pearson's correlation coefficients were determined and Bland-Altman analysis was performed. A mixed model repeated measurements anova was used to compare the differences between the groups.

RESULTS

P(ET)CO(2) and P(g)CO(2) for groups I and II were nearly identical, and statistically not significantly different (mean difference 0.10 mmHg and 0.85 mmHg, P = 0.96 and 0.45, respectively), whereas the corresponding data for group III differed significantly from those for groups I and II (P = 0.03 and 0.001, respectively). On Bland-Altman analysis, the bias value for groups proved to be statistically significantly different (P = 0.001).

CONCLUSIONS

The tested new probe worked very well in small children. The clinical implications of the large gaps found between P(ET)CO(2) and P(g)CO(2) values in acutely ill children and children undergoing elective operations must be investigated further.