24-H pharyngeal pH monitoring in healthy volunteers: A normative study

Background: Gastropharyngeal reflux has been associated with disorders of t he upper and lower airways. It may be shown by pharyngeal pH-metry, but rep orts on normality in healthy volunteers are scarce. No definite consensus h as been reached considering the upper limit of normality (ULN). The aim of the present study was therefore to quantify the occurrence of pharyngeal ac id exposure (pH < 4) in healthy volunteers and, further, to examine its rel ation to acid exposure of the oesophagus and oesophageal motility and its o ccurrence in relation to age, sex, and body position. Methods: Forty health y volunteers underwent ambulator, 24-h pH-metry, using antimony electrodes positioned 2 cm above the upper oesophageal sphincter and 5 cm above the lo wer oesophageal sphincter on the basis of manometry. Technical artefacts we re excluded before calculation of all results. Results: Gastropharyngeal re flux occurred in most healthy volunteers without any significant relation t o age, sex, or body weight. Pharyngeal acid reflux occurred mainly in the u pright position. The ULN for pharyngeal acid exposure time was assessed to 0.9% (0.2% after exclusion of mealtimes). The ULN for the number of acid ev ents in the pharynx was 18 (6.1). The corresponding ULNs for the oesophagus were 7% and 84. Conclusion: Gastropharyngeal reflux may be effectively mon itored by ambulatory pH-metry. The present study provides reference limits, a prerequisite for evaluating the pathophysiologic importance of the pheno menon.