Can we rely on the orocecal transit time measured by the lactulose breath test? Simultaneous measurement of Tc99m colloid scintigraphy and lactulose breath hydrogen test in asymptomatic volunteers

Abstract

<title>Abstract</title> INTRODUCTION: The measurement of orofecal transit time (OCTT) has various challenges; its calculation through the detection of hydrogen in exhaled air with lactulose (H2 breath test), a non-invasive and widely used technique, is controversial and not validated in the local population. AIM: To demonstrate the correlation between techniques for measuring OCTT through the simultaneous use of intestinal scintigraphy with radiolabeled colloid (OCTT-R) and lactulose breath hydrogen test (OCTT-H2). METHOD: Healthy volunteers over 18 years old underwent a 12-hour fast, followed by oral administration of colloid sulfur mixed with lactulose. Simultaneously, abdominal images were obtained using a gamma camera, and breath samples were collected every 10 minutes for 180 minutes. The lactulose orocecal transit time (OCTT-H2) was considered when the curve elevation exceeded 20 ppm above the baseline value, after the first 60 minutes of the study. The orocecal transit time with radioisotopes (OCTT-R) corresponding to 50% activity of the tracer administered in the cecum was quantified. RESULTS: Seventeen patients aged between 22 and 77 years (82% women) were included. OCTT-R varied between 73 and 180 minutes and OCTT-H2 between 60 and 130 minutes. OCTT-R with radioisotopes and OCTT-H2 showed a good correlation (r: 0.794; 95% CI: 0.508 - 0.923). Results of orocecal transit time with radioisotopes versus H2 did not have significant differences (p= 0.959). CONCLUSION: OCTT-H2 is feasible to measure using lactulose as a substrate with a good correlation and no difference with isotopic technique.­­­