Esophageal Bolus Transit in Newborns With Gastroesophageal Reflux Disease

The aim of this study was to evaluate esophageal swallow (ES) frequency and characteristics in term and preterm newborns with GERD symptoms using MII and to investigate the possible relationship between ES and GER events.

MATERIAL AND METHODS

The MII tracings from the beginning of the second feeding up to 3 hours after the end of the meal were visually analyzed by two independent investigators using Bioview Analysis software (Sandhill Scientific Inc., Highlands Ranch, Colorado, USA) to identify and characterize ES and GER events.

ES events An ES event was identified as a rapid increase in impedance which precedes a drop in impedance to 50% of baseline beginning in the proximal channel and preceding in an anterograde direction to the most distal channel, followed by the recovery of baseline values at each channel.13 The ES events detected by MII/pH were grouped into mealtime events (the first nine consecutive ES events with no artifacts after the beginning of the meal) and postprandial period events (all the ES events detected in the 3 hours following the end of the meal).

ES event frequency (ES events/hour) was measured, along with the following ES event characteristics:

bolus presence time (BPT): time between bolus entrance and exit recorded in the distal channel, measured in seconds; bolus head advancing time (BHAT): time between the bolus entrance recorded in the proximal channel and the bolus entrance recorded in the distal channel, measured in seconds; bolus head advancing time corrected (BHATc): BHAT corrected for esophageal length, expressed in seconds/cm. BHATc was calculated using the formula BHATc = BHAT / esophageal length where esophageal length is the distance between proximal and distal impedance channels, measured in cm.

GER events

A GER event was defined as a retrograde drop in impedance to 50% of baseline, beginning in the most distal channel and proceding to one or more proximal channels, of at least 5 seconds, followed by an impedance recovery of baseline values.GER event frequency was measured (GER events/hour), along with the following event characteristics:

bolus reflux extent (BRE):the proximal extent reached by the refluxate, shown by the number of channels sequentially involved in the impedance drop,measured in number of channels; bolus clearance time (BCT):time from onset, at the 50% drop in impedance signal from baseline, to the end of the event, at the 50% recovery point from nadir to baseline, recorded in the distal impedance channel, measured in second.

Statistical Analysis The distribution of all the continuous variables was assessed by the Shapiro-Wilk test. The differences in MII variables between different groups of infants were evaluated with the Mann-Whitney test; the Wilcoxon test was used to compare paired data. Group correlations were analyzedwith the Spearman correlation test. Statistical significance was set at p\<0.05.