Date of Award

2026

Degree Name

Doctor of Philosophy (College of Medicine)

Schools and Centres

Medicine

First Supervisor

Prof Hans Van der Wall

Second Supervisor

Prof Gregory Falk

Third Supervisor

Dr Craig Smith

Abstract

Background

The accurate diagnosis of gastro-oesophageal reflux pulmonary micro-aspiration has only become possible recently with the introduction of a novel technique of reflux micro-aspiration scintigraphy study combined with single photon emission computed tomography (SPECT) combined with x-ray tomography (CT) in a hybrid instrument (1-3). This has allowed the accurate diagnosis of pulmonary and airway contamination with refluxate. Previously only patients with large volume symptomatic reflux aspiration were diagnosed clinically (Mendelson syndrome) or by 2-dimentional barium meal or an older plantar (2 dimensional) technique of scintigraphic aspiration studies. The concept of reflux micro-aspiration has been implicated in multiple pulmonary diseases but without absolute proof from an adequate diagnostic test (4). Little was known about the natural history, physiology, and response to treatment amongst patients with silent reflux micro-aspiration. The aim of this research project was to study the natural history of the disease, common presenting symptoms, pathophysiology and response to treatment.

Methods

A prospectively populated database of patients referred to a tertiary specialist reflux diagnostic service with atypical and/or treatment resistant reflux was evaluated. The database contained records of consecutive patients including demographic information, presenting symptoms, investigations including imaging, upper gastro-intestinal physiology studies and novel reflux micro-aspiration scintigraphy studies. Treatment details including medical and surgical treatment and post treatment clinical information and investigations. Multiple studies were conducted using the information from the database.

Results

The novel reflux micro-aspiration scintigraphy with SPECT/CT was compared with existing studies (multichannel intraluminal impedance and 24-hour pH monitoring) and was found to be sensitive to reflux occurring outside the oesophagus (5, 6). Patients with reflux micro-aspiration can present a wide variety of symptoms, commonly a combination of typical symptoms of gastro-oesophageal reflux disease (heartburn and regurgitation) and respiratory symptoms (7). Reflux micro-aspiration was associated with reduced lower oesophageal sphincter pressure, severe ineffective oesophageal motility (IOM), and pharyngeal contamination with refluxate on reflux scintigraphy (8). Delayed liquid gastric emptying was not associated with reflux micro-aspiration (9). Micro-aspiration was common in patients with giant hiatus hernias and mostly resolved with surgery (10-12). Anti-reflux surgery resulted in resolution of aspiration in the majority of patients, however severe IOM was associated with lesser rates of micro-aspiration resolution (13).

Conclusion

Reflux micro-aspiration appears to be a more common manifestation of GORD than previously thought. The work reviewed in this thesis discusses the presentation, physiological associations, and treatment of patients with reflux micro-aspiration.

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