Advances in micro-gas sensors and electronic technologies have allowed for the development of convenient, real-time, cost-effective methods of assessing gastrointestinal health that are comprehensive and accurate.
Electrical and computer engineering researchers from RMIT University in Melbourne, Australia published a perspective article that reviews the most recent developments in gastrointestinal diagnostics. The article, published today, in the journal Trends in Biology, compares traditional gastrointestinal assessment via breath analysis with two newer diagnostic technologies: in vitro fecal fermentation and an ingestible, pill-like electronic gas sensor.
There are many issues with traditional means of collecting and testing samples of digestive gases, according to the authors, including the size and cost of equipment, the timeliness of results, the level of inconvenience for patients, and varying levels of reliability.
Senior author Kourosh Kalantar-zadeh, professor of computer and electrical engineering, states:
The human gut’s effect on gastrointestinal diseases consumes a significant portion of health care expenditure every year worldwide. Innovative point-of-care methodologies for assessing gut state and diagnosing relevant diseases […] will bring unprecedented benefits to the general public by providing medical and diagnostic devices that significantly reduce medical costs and improve the efficiency of the health care system.
Intestinal Gas as Biomarker for Disease
Intestinal gases affect human health, and can be used to assess gastrointestinal function, as well as to detect gastrointestinal-related disease. The presence of specific gases in the intestine can be used to diagnose carbohydrate malabsorption, constipation-dominant irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), and colon cancer.
Irritable Bowel Syndrome
IBS affects 10-15% of the population and, while the syndrome does not necessarily lead to premature death, IBS is not well understood and is a significant economic burden on health systems around the world. IBS is a long-term syndrome that impacts sensation and mobility in the large and small intestines. The syndrome leads to abdominal bloating and discomfort, frequent gaseousness, and changes in bowel habits (i.e., diarrhea, constipation, or a combination of both).
Constipation affects 1 in 6 people in the United States, and is responsible for 2.5 million physician visits per year, according to the International Foundation for Gastrointestinal Disorders. On the opposite side of the digestive spectrum, loss of bowel control is reported in 1 in 3 people with IBS.
People with IBS may be afraid to go out in public due to uncomfortable bloating and the embarrassment related to passing gas. They may limit their diet, take anti-depressants or anti-anxiety medication, and may be prescribed medication to aid in their bowel function.
Inflammatory Bowel Disease
IBD is chronic inflammation of the digestive track, and is generally diagnosed as Crohn’s disease or ulcerative colitis, according to the Mayo Clinic. Symptoms of IBD can vary according to the location of the inflammation, but generally include diarrhea, unintended weight loss, abdominal pain, fever and fatigue. Although IBD is not fatal, it can have life-threatening complications.
Global prevalence figures may not be highly reliable, especially in developing countries with less access to healthcare. However, according to a 2012 study published in Gastroenterology, the highest reported prevalence values were in Europe and North America. In Europe, 505 per 100,000 persons had ulcerative colitis and 322 per 100,000 persons had Crohn’s disease. In North America, 249 per 100,000 persons had ulcerative colitis and 319 per 100,000 persons had Crohn’s disease.
Colorectal cancer is the third most common cancer in the world. Roughly 54% of colorectal cancers were diagnosed in people living in more developed countries, according to the World Cancer Research Fund International. The Republic of Korea had the highest incidence, at 45 per 100,000 persons. Slovakia, with an incidence of 42.7 per 100,000 persons, and Hungary, with an incidence of 42.3 per 100,000 persons, followed close behind.
Signs and symptoms include changes in bowel habits, rectal bleeding, cramping or abdominal pain, weakness or fatigue, and unintended weight loss.
Detecting Intestinal Gas
The authors of the Trends in Biology article discuss two methods of assessing intestinal gas to aid in diagnosis of gastrointestinal disorders: in vitro fecal fermentation systems and in vivo human gas capsules.
In Vitro Fecal Fermentation Systems
In in vitro fecal fermentation, fecal samples are studied in an environment that mimics the conditions of the large intestine. The gas analysis systems, according to the authors, are bulky, expensive and require highly skilled operators, thus limiting their applications. The authors suggest that electrochemical gas sensing systems, such as calorimetric and optical gas sensors, might be a suitable alternative to the traditional fecal gas analysis systems.
Schematic of a real-time in vitro fecal fermentation gas-sensing system
Source: Nam Ha
In Vivo Human Gas Capsules
Direct sampling of gas species within the intestine could yield more accurate indicators of physiological abnormalities of the gut. Developments in microtechnology allow the integration of pressure and gas sensors with cameras into ingestible capsules that give physicians a more complete picture of the entire process of digestion.
There remains opportunity for innovation in this space, as current technologies consume a great deal of power. Once ingested, the capsule has a limited power source, and this is a significant issue as it can take several days for the capsule to pass completely.
Schematic of a swallowable gas capsule
Source: Nam Ha
As engineers continue to develop these new diagnostic technologies, it is hoped that physicians will be able to diagnose gastrointestinal diseases earlier, with greater accuracy, and at lower costs. Kalantar-zadeh told nuviun:
Both capsules and the in vitro feces culture-based systems can be invaluable as future diagnostic systems for humans, especially for the diseases of the gut. They are also important for demonstrating the efficiency of food transformation into energy in humans - altogether [to inform…] adjust[ments to] diet.