Characteristics of oxygen concentration and the role of correction factor in real-time GI breath test.

OBJECTIVE: A high quality end-expiratory breath sample is required for a reliable gastrointestinal breath test result. Oxygen (O2) concentration in the breath sample can be used as a quality marker. This study investigated the characteristics of O2 concentration in the breath sample and the impact of using a correction factor in real-time breath measurement. DESIGN: This study includes two separate groups of patient data. Part 1 of the study analysed the patient's ability to deliver end-expiratory breath samples over a 2-year period (n=564). Part 2 of the study analysed a separate group of patients (n=47) with additional data to investigate the O2 characteristics and the role of correction factor in breath test. RESULTS: The results indicated 95.4% of 564 patients were able to achieve an O2 concentration below 14% in their end-expiratory breath. Part 2 of the study revealed that the distribution of O2 concentration was between 9.5% and 16.2%. Applying a correction factor to predict the end-expiratory H2 and CH4 values led to an average measurement error of -36.4% and -12.8%, respectively. CONCLUSION: The majority of patients are able to deliver a high quality end-expiratory breath sample, regardless of age or gender. The correction factor algorithm is unreliable when predicting the end-expiratory result at 15% O2 and it would have resulted in false negative result for 50% of the positive cases in this study. It has also indicated that the continuous O2 measurement is essential to ensure breath sample quality by preventing secondary breathing during real-time breath collection.