A laboratory evaluation of the risk of enteral tube blockages with bolus blended feeding

Background Interest in feeding blended (pureed) food via gastrostomy tube is increasing (1). However, this is not currently recommended and health professionals have raised a number of concerns associated with this practice including potentially increased risk of blocking tubes (2). A blocked tube may lead to disruption of feeding and, if efforts to unblock it are unsuccessful, tube replacement. Therefore, risks of tube blocking should be minimised. Although the risk of blocking is referred to in many clinical papers, there is limited experimental evidence to support or refute this. Therefore, the aim of this study was to undertake a laboratory evaluation of the frequency of blocking and time taken when administering a bolus blended feed prepared using different methods through feeding tubes of different diameters. Method A blended feed was designed for a hypothetical man aged 70 years, aiming to meet his estimated energy and macronutrient requirements and prepared using three methods: (1) a professional blender + extra fine sieve (2) jug blended + standard sieve (3) stick blender without sieving. Samples from each of the three feeds were administered in triplicate using a 60 ml syringe through three clean enteral tubes, size 10, 12 and 14 French, into empty container i.e. 3 x 3 x 3 design. The number of blockages, attempts to unblock, time taken to administer the feed and the researcher’s observations of the process were recorded. The effect of the three feeds and tube size on blockages was analysed descriptively and multivariate two-way ANOVA was used to examine differences in time taken to deliver the bolus. Ethical permission was not required.Results During the 27 feed administrations, two blockages occurred and both of these were with the feed prepared using the professional blender and extra fine sieve, once with the size 10 French tube and once with size 12 French. A single 10 ml cold water flush was sufficient to resolve both blockages. No blockages occurred with the size 14 French. The time taken to deliver one 60 ml bolus varied between 66-157 seconds (Table 1). There was no significant difference between the time taken to deliver feeds prepared using different methods (P=0.949) but the time increased significantly as tube size decreased (P<0.001). The researcher observed that substantial force was required to deliver the bolus feeds using the syringe. Sieving led to greater food waste and associated loss of nutrients which were not quantified. Table 1 Time taken in seconds to deliver one 60 ml bolus of feed through tubes, mean (SD) [CANNOT BE DISPLAYED]Discussion These results indicate that the risk of blocking a 14 French enteral feeding tube when administering bolus blended feeds prepared using any of three trialled methods is low. This is compatible with anecdotal comments posted on social media by carers who routinely use blended feeds without major problems associated with blockages3. The findings may not be transferrable to a clinical situation and are limited to the single recipe that was used in the study. The consistency of feed produced using the three methods varied with the thickest being produced using the professional blender. Although the time associated with administering the feed via the 14 French tube was significantly quicker than for narrower tubes, extrapolating to delivering the whole day’s feed as well as making it, would be time consuming for carers. In addition, the force required to empty the syringe may be challenging for frail carers; both require further investigation.Conclusion This small laboratory-based evaluation of one blended feed recipe found little risk of tube blockages associated with delivery via a 14 French tube and this was not influenced by the method preparation.References1Breaks, A., Smith, C., Bloch, S et al. (2018) Blended diets for gastrostomy fed children and young people: a scoping review. J. Hum. Nutr. Diet. doi: 10.1111/jhn.12563.2Coad, J., Toft, A., Lapwood, S. et al. (2017) Blended foods for tube-fed children: a safe and realistic option? A rapid review of the evidence. Arch. Dis. Child. 102:274-278.3Food for Tubies (2018) https://en-gb.facebook.com/pg/foodfortubies/posts/ accessed 16 June 2018.