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[Gastroesophageal reflux and ventilation with continuous positive pressure. Experimental study]
I Eizaguirre1, P Aldazábal, W Weilin
1Servicio de Cirugía Pediátrica, Hospital NaSa de Aránzazu, San Sebastián.
Insights
Continuous positive airway pressure (CPAP) in neonatal distress may increase gastroesophageal reflux (GER) risk. CPAP use weakens the antireflux barrier and elevates the gastroesophageal pressure gradient in infants.
Area of Science:
- Physiology
- Neonatal Medicine
Context:
- Gastroesophageal reflux (GER) is common in infants requiring respiratory support.
- Neonatal distress often necessitates respiratory assistance, such as continuous positive airway pressure (CPAP).
Purpose:
- To investigate the impact of increasing CPAP levels on the lower esophageal sphincter (LES) and the antireflux barrier in a rat model.
- To assess changes in thoracic and abdominal pressures under varying CPAP conditions.
Summary:
- Studies in rats demonstrated that CPAP use progressively shortens the intra-abdominal length of the esophagus (LIASE), weakening the antireflux barrier.
- While LES pressure and length remained unchanged, increased transdiaphragmatic pressure gradients were observed with higher CPAP levels.
- These findings suggest CPAP may increase GER risk by compromising the antireflux barrier and augmenting the gastroesophageal pressure gradient.
Impact:
- The study suggests a potential mechanism by which CPAP may contribute to GER in neonates.
- Highlights the need for further investigation into the clinical implications of CPAP use on GER in infants.
- Provides a basis for exploring strategies to mitigate GER in infants receiving respiratory support.
Abstract:
Gastroesophageal reflux (GER) often occurs in babies receiving respiratory assistance for neonatal distress. The authors examined the lower esophageal sphincter and the thoracic and abdominal pressure conditions in rats under progressively higher continuous positive airway pressure (CPAP) to test the efficacy of the antireflux barrier under such conditions. Intrathoracic and intraabdominal pressures were recorded within the esophagus and within the inferior vena cava in 10 anesthesized 250-g male rats. Pull-through techniques were used for lower esophageal sphincter pressure (LESP) and length (LESL) studies, and the length of the intraabdominal segment of the esophagus (LIASE) was also determined. Measurements were performed in baseline conditions and at CPAP levels of 0, 1, 3, 5 and 7 cm H2O. The respiratory effort progressively increased with prolonged expiration and decreased frequency. LESP and LESL did not change significantly, but the antireflux barrier was weakened by a progressive shortening of LIASE. Successive CPAP increases led to increasingly negative thoracic pressures during inspiration, and increasingly positive abdominal pressure during expiration yielded progressively greater transdiaphragmatic pressure gradients. The authors suggest that CPAP weakens the antireflux barrier and, at the same time, increases the gastroesophageal pressure gradient, thus increasing the risk of GER. Although transpolation of experimental data to the clinical setting is always hazardous, the authors believe this issue should be investigates in infants.