Page 82 - Effects and Efficacy of (Laparoscopic) Gastrostomy Placement in Children - Josephine Franken

MII tracings detect refluxes of boluses (either liquid of mixed liquid-gas) in the most distal channels irrespective of pH changes. The data was analyzed according to previously described definitions. 21,22 All MII measurements were manually analyzed by one single observer (JF). In case of uncertainty, another expert observer was consulted (FAM and/or MH).
Liquid reflux was defined as a fall in impedance of more than 50% of baseline impedance that moved in the retrograde direction over the two distal impedance sites. Mixed liquid–gas reflux was defined as gas reflux occurring during or immediately preceding liquid reflux. For adequate comparison, the number of reflux episodes was normalized to a 24-hour period.
Reflux episodes were classified as acid when the pH dropped below 4; reflux episodes were classified as weakly acidic when the lowest pH was between 4 and 7; and as non-acid when pH remained above 7.
Reflux episodes were also classified based on the most proximal impedance channel demonstrating an impedance drop of more than 50% from baseline: as proximal (reaching Z1), mid-esophageal (reaching Z3) or distal (reaching Z5).
The bolus clearance time was defined as the elapsed time from onset to recovery of the impedance signal recorded on the most distal impedance channel (Z6). 23
If symptoms were recorded, the symptom index (SI) and symptom association probability index (SAP) were calculated for all reflux episodes, with an SI of more than 50% and an SAP of more than 95% regarded as being positive.
Nutritional status
Weight and height measurements were converted to weight-for-height and height-for- age percentiles based on the Netherlands Organization for Applied Scientific Research (TNO) growth standards. 24 These percentiles allow comparison of an individual’s weight or height, adjusting for age and sex relative to a reference population.
statistical analysis
Variables were not normally distributed and therefore expressed as median with interquartile ranges (IQR 25-75th). To test differences between participants and non-participants in the MII-pH study, independent-samples t-tests were used for continuous variables and Fisher’s exact tests for dichotomous variables. To express the effect of surgery the paired t-test was used for paired, continuous data where differences were normally distributed. The
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