Effects of feeding on gastric tonometric measurements in critically ill children.

Objective: To determine the effect of gastric feeding on the measurement of gastric intramucosal PCO2 (PiCO2) and its derived gastric intramucosal PCO2-arterial PCO2 difference (PiCO2-PaCO2 difference) and gastric intramucosal pH (pHi) in a group of critically ill children using recirculating gas tonometry.

Design: Prospective clinical pilot study.

Setting: Sixteen bed pediatric intensive care unit.

Patients: Ten mechanically ventilated and hemodynamically stable children (median age, 20.1 months [interquartile range (IQR), 9.7-47.6 months] and median weight, 10.2 kg [IQR, 10-16.5 kg]).

Interventions: A 7-French recirculating gas tonometer was placed in the stomach via the orogastric route.

Measurements: In each patient, baseline fasted/unfed PiCO2, PiCO2-PaCO2 difference, and pHi were determined hourly over a 5-hr period. Gastric feeding was then reestablished (3 mL/kg/hr) within a median time of 3 hrs and a further 5 hourly measurements were determined. Concurrent arterial blood gas and lactate measurements were taken. Blood pressure and heart rate was monitored throughout.

Main Results: Hemodynamic parameters remained stable throughout the study period. When compared with the unfed/fasting state, PiCO2 measurements and PiCO2-PaCO2 difference were consistently lower and pHi values higher than when the patients were fed (two-way analysis of variance for repeated measures: all p <.001 between groups). Measurements did not vary over time.

Conclusions: In our patient group, gastric feeding decreased the PiCO2 and PiCO2-PaCO2 difference and increased pHi compared with the unfed state. These findings are in contrast to those found in adult studies.