Using naso- and oro-intestinal catheters in physiological research for intestinal delivery and sampling in vivo: practical and technical aspects to be considered.

Abstract

Intestinal catheters have been used for decades in human nutrition, physiology, pharmacokinetics, and gut microbiome research, facilitating the delivery of compounds directly into the intestinal lumen or the aspiration of intestinal fluids in human subjects. Such research provides insights about (local) dynamic metabolic and other intestinal luminal processes, but working with catheters might pose challenges to biomedical researchers and clinicians. Here, we provide an overview of practical and technical aspects of applying naso- and oro-intestinal catheters for delivery of compounds and sampling luminal fluids from the jejunum, ileum, and colon in vivo. The recent literature was extensively reviewed, and combined with experiences and insights we gained through our own clinical trials. We included 60 studies that involved a total of 720 healthy subjects and 42 patients. Most of the studies investigated multiple intestinal regions (24 studies), followed by studies investigating only the jejunum (21 studies), ileum (13 studies), or colon (2 studies). The ileum and colon used to be relatively inaccessible regions in vivo. Custom-made state-of-the-art catheters are available with numerous options for the design, such as multiple lumina, side holes, and inflatable balloons for catheter progression or isolation of intestinal segments. These allow for multiple controlled sampling and compound delivery options in different intestinal regions. Intestinal catheters were often used for delivery (23 studies), sampling (10 studies), or both (27 studies). Sampling speed decreased with increasing distance from the sampling syringe to the specific intestinal segment (i.e., speed highest in duodenum, lowest in ileum/colon). No serious adverse events were reported in the literature, and a dropout rate of around 10% was found for these types of studies. This review is highly relevant for researchers who are active in various research areas and want to expand their research with the use of intestinal catheters in humans in vivo.

Gut microbiome and health: mechanistic insights

“…It is important to note that we can live without a colon but not without a small intestine that features the largest mucosal surfaces of our body where our food is further digested and taken up, contains most of the gut receptors, immune and nerve cells and is increasingly implied in essential microbe-host crosstalk. While hard to approach experimentally, a variety of new technologies have been developed in recent years, which include catheters or capsules to sample, deliver or inspect 16–18. In addition, small intestinal effluent obtained from ileostomies was studied and found to contain up to 100 million microbes per gram wet weight that formed personalised communities, showing day and night rhythms reflecting food intake and processing 19.…”

“…While hard to approach experimentally, a variety of new technologies have been developed in recent years, which include catheters or capsules to sample, deliver or inspect. [16][17][18] In addition, small intestinal effluent obtained from ileostomies was studied and found to contain up to 100 million microbes per gram wet weight that formed personalised communities, showing day and night rhythms reflecting food intake and processing. 19 Functional (transcriptomics and targeted metabolomics) and metagenomic analysis of such samples revealed the colonising Streptococcus and Lactobacillus spp to express a large reservoir of highly effective transport systems that compete with the host for sugar uptake and use, generating lactate and acetate that are substrates for Veillonella spp and are converted then into propionate.…”

Understanding the gastrointestinal tract in obesity: From gut motility patterns to enzyme secretion

“…43 With regard to the technique, nasogastric passage of catheters may interfere with gastrointestinal functioning and thus the luminal environment. 44 As an alternative, wireless motility capsules can be used to identify characteristic pH patterns along the gastrointestinal tract. Recently, our group did not find any difference in gastric pH between people with normal weight or obesity in fasted or fed state.…”

(Wh)olistic (E)ndocannabinoidome-Microbiome-Axis Modulation through (N)utrition (WHEN) to Curb Obesity and Related Disorders

“…Additionally, future studies must prioritize brain imaging and mapping [ 29 ] in the fasting as well as postprandial states, utilizing tracer isotopes enabling the tracking of changes in eCBome mediators within the cells as this system may change very rapidly. To this end, intestinal catheters [ 237 ] could have a supplemental advantage in reaching the intestinal segments, thus allowing the best representation of the gut-brain axis in combination with brain imaging approaches. When planning these studies, several outstanding questions need to be addressed, regarding, for instance, the anorectic and peripheral metabolism-altering properties of the lipid signalling mediators involved in eCBome.…”