Introduction Oesophago-gastric junction (OGJ) incompetence is a primary determinant of gastrooesophageal reflux disease (GORD) severity. Especially, the pressure-flow gradients across the OGJ during lower oesophageal sphincter (LOS) relaxation have important implications in GORD pathogenesis and subsequent planning of its treatment. Our aim was to evaluate the pressure-flow dynamic changes occurring at GOJ barrier during transient lower oesophageal sphincter relaxation (TLOSRs) and study the impact of gastric emptying after a meal on those events using combined high-resolution manometery and high-resolution impedance monitoring (HRMZ, ManoScan Z™).

Methods HRMZ was performed in eight healthy subjects (6M and 2F, 27±7 years) for 4 h after a refluxogenic meal (1000 kcal). Pressure–flow dynamics of OGJ during TLOSR events including their frequency, duration, gastro-oesophageal pressure gradient (GO pressure gradient) and proximal extent of migration of the reflux episodes were computed. Gastric emptying of the meal was assessed by 13C-labelled octanoic acid breath test and gastric emptying lag time, half emptying time and gastric retention time were calculated.

Results All subjects completed the study. During TLOSR events there was reciprocal relationship between GE pressure grad. and retrograde flow of gastric contents, the gradient was greatest at the onset of retrograde flow, decreasing progressively as the flow continued and became lowest by the end of flow across the OGJ (GO pressure gradient start of flow=9.5±2.6, peak flow=6.05±2.5 (p=<0.05), end of flow=2.3±2.5 (p=<0.001). GE pressure gradient was significantly higher for TLOSRs accompanied by significant retrograde flow (obvious flow on HRMZ display) compared with episodes with limited flow (<3 impedance channels) (12.90±1.101 vs 6.858±1.388, p=0.01). TLOSR episodes accompanied by significant flow reached the upper oesophagus much more frequently than those episodes with limited flow (mean height of reflux episodes=13.46±3.4 vs 5.16±1.3, p=0.001). Significant correlation between height of reflux episodes and gastric retention time (r=0.7, p=0.04) week correlation trends were observed with gastric emptying lag time (r=0.4) and half emptying times (r=0.3).

Conclusion Our results suggest HRMZ is effective in elucidating the pressure-flow dynamics of OGJ. The proximal extent of the reflux episode correlates with gastric retention time of the meal; however other gastric emptying parameters did not show significant correlation despite promising trends. Further studies involving GORD patients might give us important insights into the role of OGJ pressure flow dynamics in the pathophysiology of GORD.