Acid reflux attack
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Understanding Acid Reflux Attacks: Pathogenesis, Symptoms, and Mechanisms
Pathogenesis of Gastroesophageal Reflux Disease (GERD)
Epithelial Defense and Acid Exposure
Gastroesophageal reflux disease (GERD) is a multifactorial condition where acid exposure to the esophageal epithelium plays a central role. The disease manifests when the acid overwhelms the esophageal epithelial defenses, leading to symptoms, ulceration, and other complications. GERD patients often experience more frequent transient lower esophageal sphincter relaxations and may have impaired peristaltic frequency or weakened peristaltic contractility1.
Role of Duodenogastroesophageal Reflux (DGER)
Both acid and duodenogastroesophageal reflux (DGER) contribute to esophageal mucosal injury. Studies show a graded increase in acid and DGER severity across the GERD spectrum, with a significant correlation between acid exposure and bilirubin levels, indicating simultaneous occurrence of acid and DGER in most reflux episodes3.
Symptoms and Clinical Spectrum
Symptom Patterns and Esophageal Hypersensitivity
Patients with normal esophageal acid exposure can still experience reflux-related symptoms due to esophageal hypersensitivity to acid. These patients often report symptoms like belching, bloating, and nausea, which overlap with functional dyspepsia. The duration and minimum pH of reflux episodes in these patients are typically shorter and higher, respectively, compared to those with GERD2.
Age-Related Differences in Symptom Perception
Older patients with GERD tend to have more severe esophageal mucosal injury and acid exposure but report less severe symptoms compared to younger patients. This reduced symptom severity in the elderly is likely due to decreased chemosensitivity to acid6.
Mechanisms of Reflux and Esophageal Injury
Acid and Nonacid Reflux
Reflux episodes in GERD patients can be acid, nonacid, or a mixture of gas and liquid. Although the total number of reflux episodes is similar between GERD patients and healthy controls, GERD patients experience a higher proportion of acid reflux. Mixed reflux of gas and liquid is the most common pattern, with pure liquid reflux being more frequently acidic in GERD patients5.
Cytokine-Mediated Esophagitis
Recent studies suggest that reflux esophagitis may result from a cytokine-mediated mechanism rather than direct caustic acid injury. Exposure to acidified bile salts can cause esophageal epithelial cells to secrete chemokines, leading to immune cell migration and subsequent tissue damage8.
Airway Inflammation in Children
Weakly Acidic Reflux and Respiratory Symptoms
In children, both acid reflux (AR) and weakly acidic reflux (WAR) can induce respiratory symptoms. Studies show that WAR events are associated with significant airway inflammation and injury, which may not be fully preventable by anti-acid treatments. Higher proportions of epithelial cells in bronchoalveolar lavage fluid suggest greater airway damage in children with WAR4.
Prevalence and Associated Conditions
Population-Based Prevalence
GERD symptoms, such as heartburn and acid regurgitation, are common in the general population. These symptoms are significantly associated with noncardiac chest pain, dysphagia, dyspepsia, and globus sensation. Despite the high prevalence, the percentage of patients reporting severe complications is relatively low7.
Conclusion
Acid reflux attacks and GERD are complex conditions influenced by multiple factors, including epithelial defense mechanisms, acid and nonacid reflux, and cytokine-mediated inflammation. Understanding these mechanisms and the variability in symptom perception, especially across different age groups, is crucial for effective management and treatment of GERD.
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Most relevant research papers on this topic
The pathogenesis of gastroesophageal reflux disease: the relationship between epithelial defense, dysmotility, and acid exposure.
Gastroesophageal reflux disease (GERD) develops when acid overwhelms the esophageal epithelial defenses, leading to symptoms, ulceration, and complications.
Highly CitedReflux related symptoms in patients with normal oesophageal exposure to acid.
Patients with normal oesophageal acid exposure may experience symptoms like belching, bloating, and nausea, but the duration and minimum pH of reflux episodes are shorter and higher than those in patients with gastro-oesophageal reflux disease.
Observational StudyHighly CitedRole of acid and duodenogastroesophageal reflux in gastroesophageal reflux disease.
Both acid and duodenogastroesophageal reflux (DGER) show a graded increase in severity across the GERD spectrum, occurring simultaneously in the majority of reflux episodes.
Observational StudyHighly CitedAirway inflammation and injury in children with prevalent weakly acidic gastroesophageal refluxes.
Weakly acidic gastroesophageal reflux events in children can cause significant airway inflammation and injury, potentially not fully preventable or counteracted by anti-acid treatments.
Observational Study
Rigorous JournalAcid, nonacid, and gas reflux in patients with gastroesophageal reflux disease during ambulatory 24-hour pH-impedance recordings.
GERD patients experience more acidic reflux episodes than controls, suggesting differences in gastric acid secretion or distribution.
Observational StudyHighly CitedSymptom severity and oesophageal chemosensitivity to acid in older and young patients with gastro-oesophageal reflux.
Older patients with gastro-oesophageal reflux disease experience reduced symptom severity for heartburn despite increased oesophageal mucosal injury and acid exposure, possibly due to age-related reduction in chemosensitivity to acid.
Observational StudyHighly CitedPrevalence and clinical spectrum of gastroesophageal reflux: a population-based study in Olmsted County, Minnesota.
Gastroesophageal reflux is common among white men and women aged 25-74, and is associated with symptoms such as chest pain, dysphagia, dyspepsia, and globus sensation.
Observational StudyHighly CitedGastroesophageal reflux might cause esophagitis through a cytokine-mediated mechanism rather than caustic acid injury.
Gastroesophageal reflux may cause esophagitis through a cytokine-mediated mechanism rather than directly damaging the esophagus.
Non-RCT
Animal StudyHighly CitedThe Acid Pocket: A Target for Treatment in Reflux Disease?
The acid pocket, a reservoir of gastric acid in the proximal stomach, is a potential target for GERD therapy, with proton pump inhibitors and alginate/antacid combinations showing potential for selective targeting.
Rigorous JournalHighly CitedCharacteristics of Gastroesophageal Reflux in Symptomatic Patients With and Without Excessive Esophageal Acid Exposure
In pH- SAP+ GERD patients, a higher proportion of reflux episodes reach the proximal esophagus than in controls, which may partially explain their symptoms.
Observational StudyHighly Cited