Page 65 - Effects and Efficacy of (Laparoscopic) Gastrostomy Placement in Children - Josephine Franken

studies. This variability is comparable with or even better than the variation reported by other techniques for GE measurement. 14
Subjects fasted for at least 6 hours before the study. In children >4 years of age, a solid 13CGEBT was performed with a 375-g pancake containing 45mg of 13C labeled Na-octanoate (a stable isotope). For younger children or children who were unable to eat the pancake within 15 minutes, 100mg of 13C labeled Na-octanoate was added to a liquid formula (infant formula, full cream milk or chocolate milk). Breath samples were obtained in duplicate at 15-minute intervals during the course of 4 hours (for the liquid test, breath samples were obtained at 5-minute intervals during the first 30 minutes). The ratio between 12CO2 and 13CO2 content in breath samples was analysed with an isotope ratio mass spectrometer.
With this 13CGEBT, three parameters were calculated. Gastric half-emptying time (GE- T1⁄2) was defined as the time when the first half of the 13C-labeled substrate had been metabolized, that is, when the cumulative excretion of 13C in the breath was half the ingested amount. GE percentiles (P) were calculated according to the reference values obtained by M. van den Driessche et al. 15 GE percentiles higher than 95 were considered delayed. The GE coefficient (GEC) reflects a global index for GE, influenced by both the rate of appearance and disappearance of 13C in breath.
24-hour pH-monitoring
After 72-hour cessation of antireflux medication, ambulatory 24-hour pH-monitoring was thoracic X-ray performed. A single-use multichannel intraluminal impedance pH-catheter (Unisensor AG, Attikon, Switzerland) was calibrated in two different pH solutions and positioned transnasally into the distal esophagus with the probe located proximal to the lower esophageal sphincter. Correct catheter position was confirmed by For a 24-hour period, acidity values were recorded in an ambulatory recorder. In a symptom diary, mealtimes, symptoms, body position (supine and upright) and other relevant events (e.g. correction of the catheter position) were documented. Automated analysis was performed with software designed for pH impedance analysis (Medical Measurement Systems). Pathological esophageal acid exposure was defined as total acid exposure time ≥6%, ≥9% in upright, and ≥3% in the supine body position. 16
statistical analysis
Continuous variables were expressed as mean ± standard deviations (SD) for symmetric variables or as median with interquartile ranges (IQR) for skewed variables. Pre- and postoperative results were compared using the McNemar’s test for binary outcomes and the paired T-test for continuous outcomes. Associations between categorical data were
Chapter 4
63