Mechanism

GORD is present only when the reflux of gastric contents causes frequent, severe symptoms or mucosal damage(1)

In the normal individual the pressure in the intra-abdominal pressure exceeds the intra-thoracic pressure. This differential is exacerbated in the obese person. Obesity has two effects:

• there is increased pressure driving stomach contents into the oesophagus
• the frequency of hiatus herniation is increased

Large meals and stooping may also increase the pressure differential across the gastro-oesophageal valve.

Gastro-oesophageal reflux occurs in the normal individual, however the normal subject rapidly neutralises the pH of the oesophagus by swallowing saliva. Patients with poor oesophageal function are unable to clear the acid from the lower oesophagus. Factors which impede oesophageal function include:

• anticholinergic drugs e.g. tricyclic antidepressants and antipsychotics
• autonomic neuropathy e.g. diabetes mellitus, Parkinson's disease, Shy-Drager syndrome
• systemic sclerosis

The gastro-oesphageal valve may become defective:

• with hiatus herniation
• following surgery e.g. for achalasia
• in pregnancy
• with smoking

Reference:

• (1) Mark Fox And Ian Forgacs. Gastro-Oesophageal Reflux Disease:Clinical Review. BMJ 2006; 332: 88 - 93