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Continuous positive airway pressure and gastroesophageal reflux: an experimental study
W Wang1, J A Tovar, I Eizaguirre
1Universidad del País Vasco, Hospital N.S. de Aranzazu, San Sebastián, Spain.
Insights
Continuous positive airway pressure (CPAP) may increase the risk of gastroesophageal reflux (GER) in infants by weakening the antireflux barrier and increasing pressure gradients. Further investigation in infants is warranted.
Area of Science:
- Neonatology
- Gastroenterology
- Physiology
Background:
- Gastroesophageal reflux (GER) is common in infants requiring respiratory support.
- Continuous positive airway pressure (CPAP) is frequently used in neonatal distress.
Purpose of the Study:
- To evaluate the impact of CPAP on the antireflux barrier and gastroesophageal pressure gradients.
- To investigate the efficacy of the antireflux barrier under increasing CPAP levels.
Main Methods:
- Measurements of esophageal and inferior vena cava pressures in anesthetized rats.
- Assessment of lower esophageal sphincter pressure (LESP), length (LESL), and intra-abdominal esophageal segment length (LIASE).
- Data collected at baseline and varying CPAP levels (0-7 cm H2O).
Main Results:
- CPAP increased respiratory effort and transdiaphragmatic pressure gradients.
- LESP and LESL remained unchanged, but LIASE progressively shortened, weakening the antireflux barrier.
- Increased CPAP levels correlated with a higher risk of GER.
Conclusions:
- CPAP appears to compromise the antireflux barrier and elevate the gastroesophageal pressure gradient.
- These combined effects may increase the risk of GER in neonates receiving respiratory assistance.
- Clinical studies in infants are recommended to confirm these findings.
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 anaesthesized 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 pressures 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 investigated in infants.