Impact of enteral feeding on gastric tonometry in ICU patients

Objective

This study investigates the impact of jejunal and gastric feeding on gastric mucosal pCO₂ (PiCO₂) in ICU patients.

Patients and methods

Seven stable mechanically ventilated ICU patients receiving ranitidine were studied. Nasojejunal and pHi nasogastric tubes were inserted and piCO₂ measured with air tonometry. Jejunal (J) and gastric feeding (G) was performed in 1 h intervals as follows (period 1–9): 1 = baseline; 2 = J 40 ml/h; 3 = J 100 ml/h; 4 = no feeding; 5 = G 40 ml/h; 6 = G 100 ml/h; 7 = G bolus 200 ml; 8 = gastric emptying; 9 = no feeding.

Values are provided as means ± SD. ANOVA for repeated measures and Wilcoxon test were used for statistical analysis; P < 0.05 was considered significant.

Results

Patients remained stable during the study. Baseline pCO₂ gap (piCO₂-paCO₂) was 1.91 ± 0.66 kPa and did not change during the study (ANOVA P = 0.44; Fig. 1)

Marked interindividual variability was observed during gastric feeding mainly.

Results

Conclusion

In ICU patients jejunal feeding does not influence piCO₂. The effect of gastric feeding is much less predictable and needs to be tested in each patient.