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Airway obstruction and gastroesophageal reflux: an experimental study on the pathogenesis of this association
W Wang1, J A Tovar, I Eizaguirre
1Universidad del País Vasco, Hospital N.S. de Aranzazu, San Sebastián, Spain.
Insights
Partial upper airway obstruction in infants can cause gastroesophageal reflux (GER) by increasing pressure gradients. Prompt screening for GER in children with airway issues is recommended.
Area of Science:
- Pediatric Gastroenterology
- Respiratory Physiology
- Surgical Research
Background:
- Gastroesophageal reflux (GER) is common in children with upper airway obstruction (UAO).
- The relationship between UAO and GER pathogenesis requires further investigation.
- Understanding pressure dynamics is key to managing GER in these patients.
Purpose of the Study:
- To investigate if partial airway obstruction alters thoracoabdominal pressure gradients.
- To determine the impact of induced UAO on lower esophageal sphincter pressure and length.
- To elucidate the role of pressure gradients in GER development.
Main Methods:
- Measurements of end-inspiratory intrathoracic and intraabdominal pressures in anesthetized rats.
- Induction of UAO using progressively narrower tracheal cannulae.
- Assessment of lower esophageal sphincter pressure (LESP) and length (LESL), and calculation of thoracoabdominal end-inspiratory pressure gradient (TAEIPG).
Main Results:
- Neither LESP nor LESL showed significant changes with maximal tracheal obstruction.
- TAEIPG significantly increased under partial UAO, primarily due to increased negative intrathoracic pressure.
- The observed pressure changes suggest a mechanism for GER pathogenesis.
Conclusions:
- Partial UAO can generate significant thoracoabdominal pressure gradients, potentially contributing to GER.
- These findings support routine GER screening in children with obstructive airway conditions.
- Restoring normal respiratory function is crucial for treating GER in this population.
Abstract:
Gastroesophageal reflux (GER) frequently complicates the clinical course of children suffering from conditions leading to upper airway obstruction (UAO) (choanal atresia, tracheomalacia, esophageal atresia, vascular rings, etc). In an attempt to explore whether partial airway obstruction causes changes in the normal thoracoabdominal pressure gradients, we measured end-inspiratory intrathoracic and intraabdominal pressures in anesthetized rats under spontaneous breathing conditions, after tracheostomy, and under upper airway obstruction induced by tracheal intubation with three progressively narrower cannulae (inner diameters 1.0 mm, 0.5 mm, and 0.2 mm). We also measured the lower esophageal sphincter pressure (LESP) and length (LESL) and calculated the thoracoabdominal end-inspiratory pressure gradient (TAEIPG). Neither LESP nor LESL changed significantly before or after maximal tracheal obstruction (14.3 +/- 6.2 v 18 +/- 7.6 cm H2O [P > .05] and 0.34 +/- 0.09 v 0.41 +/- 0.1 cm H2O [P > .05] respectively) but TAEIPG significantly increased from 5.58 +/- 1.34 cm H2O to 17.62 +/- 4.27 cm H2O (P < .01) under the same conditions, mainly as a result of progressively increasing negative intrathoracic pressures during inspiration. These experiments prove that the powerful thoracoabdominal pressure gradients developed after partial UAO may contribute to the pathogenesis of GER by overcoming the antireflux barrier function. This study points out the convenience of routinely screening for GER all children with airway obstructive conditions, bearing in mind that the reestablishment of normal respiratory conditions should be the primary goal of treatment.