SmartPill Monitoring for Assessment of GI Function in SCI

Total Transit Time Total transit time (TTT) is simply the amount of time (hours) it takes for a meal to travel from the mouth, through the digestive tract and for its waste by-products to be eliminated through a bowel movement. Inter-individual TTT can vary greatly due to dietary habits, age, climate, exercise habits, immobility, medications and other lifestyle variables. Due to these multiple variables, a general TTT for the public cannot be determined. It is clear however, that a healthy person should have a total transit time ranging from 8 to 14 hours, resulting in one to three loose bowel movements every 24 hours. People who are in good physical condition, consume fiber-rich diets, and take no constipating medications are most likely to have a normal TTT. Colonic transit time (CTT) is the amount of time it takes for a partially digested meal to travel from the terminal ileum, through the large bowel and for its waste by-products to be eliminated through a bowel movement.

There are several ways to measure TTT. Each requires ingesting a tracking device or a tracer that can be monitored as it moves throughout the digestive system.

Total transit time has been traditionally measured using radiopaque markers1. This technique is simple and inexpensive and can be performed in any radiology department. Several other methods have been suggested, including the single-marker bolus technique (ingestion of markers on a specific day followed by several x-rays until all markers are passed) or multiple-marker bolus technique (ingestion of markers each day for several days followed by single or multiple abdominal x-rays). Radiopaque markers have been widely used to measure total transit. This technique provides valuable clinical information and has been proven to be reliable and reproducible.

Scintigraphy can be used as an alternative to the radiopaque marker technique for measuring TTT. The tagged material is surrounded by a substance that dissolves once it arrives at the colon. Another technique widely used in the past is the Hydrogen Breath Test which measures the transit time of the meal from the mouth to the cecum. The meal reaching the colon is indicated by a rise in the relative hydrogen content in exhaled air2,3. While many valid GI assessment techniques exist, many are invasive and impose many inconveniences for patients.

A relatively new device, the SmartPill, offers the ability to assess many GI variables including temperature, pressure, pH, and transit time while minimizing the invasive nature of investigation. The SmartPill is a small wireless capsule that is ingested by the patient. Values for pressure, temperature, and pH are transmitted continuously from the capsule to a receiver carried by the patient until the capsule is excreted during normal evacuation. This information is then downloaded onto a master computer and expressed graphically for comparative purposes.