Elsevier

Clinical Nutrition

Volume 34, Issue 4, August 2015, Pages 572-578
Clinical Nutrition

Randomized control trials
Impact of nasogastric tubes on swallowing physiology in older, healthy subjects: A randomized controlled crossover trial

https://doi.org/10.1016/j.clnu.2014.09.002Get rights and content

Summary

Background & aims

The presence of a nasogastric tube (NGT) affects swallowing physiology but not function in healthy young adults. The swallowing mechanism changes with increasing age, therefore the impact of a NGT on swallowing in elderly individuals is likely to be different but is not yet known. The aims of this study were to determine the effects of NGTs of different diameter on (1) airway penetration-aspiration, (2) pharyngeal residue, and (3) pharyngeal transit, in older healthy subjects.

Methods

Randomized controlled crossover design. Healthy elderly volunteers underwent 3 modified barium swallow studies in which multiple diet and fluid consistencies were swallowed under the following conditions: (A) no NGT (control), (B) fine bore NGT, and (C) wide bore NGT. The control condition was assessed first to establish baseline swallowing function, then NGT order was randomly allocated.

Results

Of the 15 volunteers (median age 65 years, range 60–81) complete data sets were obtained for 9 (4 with allocation order ABC; 5 with ACB). Wide bore NGT data could not be obtained for 6 volunteers mainly due to tube intolerance. The presence of a NGT was associated with: (i) an increase in airway penetration-aspiration (fine bore NGT with serial liquid swallows and puree) (p < 0.01); (ii) increased pharyngeal residue (p < 0.05) in the pyriform sinus (fine bore NGT with puree); and in the valleculae (both fine and wide bore NGT with soft solids); and (iii) an increase in pharyngeal transit duration regardless of consistency (p < 0.01), with longest swallowing durations with the widest tube.

Conclusions

NGT presence increases airway penetration-aspiration, pharyngeal residue and prolongs transit through the pharynx in older healthy individuals. Consideration of NGT impact on swallowing during concurrent oral and enteral feeding is recommended, with further systematic investigation required in elderly patients recovering from critical illness.

Clinical trial registry Australia & New Zealand Clinical Trials Registry (ACTRN12613000577718).

Introduction

Nasogastric tubes (NGTs) are widely regarded as a safe short-term strategy to administer tube feeding, hydration and/or medications to patients who are unable to eat and drink, or to maintain adequate nutrition [1], [2]. Presence of a NGT however is not without complication risk [1]. Fine bore feeding tubes are assumed to be more comfortable for the patient and minimize the risk of mucosal ulceration [3] while wide bore NGTs are preferred for drainage or to check gastric residuals during tube feeding [2].

As a patient transitions from enteral to oral feeding with improving condition and/or bulbar function, combined oral intake and NGT nutrition may be administered to increase calorie delivery. Furthermore, the timing of NGT removal is often dependent on achieving adequate oral nutrition, yet clinical experience suggests this may be difficult for some patients while the NGT remains in the pharynx.

Investigations of the impact of pharyngeal tubes (nasogastric or manometry) on the swallowing physiology of healthy volunteers [4], [5], [6] or clinical populations [7], [8], [9], [10] are limited, with considerable methodological variation. To date evidence does not suggest that NGT presence increases aspiration risk [4], [5], [6], [7], [8], [9], [10] however the impact on swallowing physiology and function remains unclear [4], [5], [6], [7], [10]. Durational changes (i.e. a change in timing of swallowing events) associated with tube presence have been reported in two studies [5], [6] with one (a randomized controlled trial [RCT] on young volunteers) documenting an effect associated with tube size – i.e. the wider the tube, the greater the change [5]. Another RCT on normal ageing reported an age effect [6]: in the presence of a manometry tube, durational changes were observed amongst all age groups but in the oldest participants they noted an increased frequency of airway penetration while drinking [6]. Observed changes in swallowing patterns in the elderly may be attributed to the effects of ageing on the swallowing mechanism, which is already slower, weaker, and more susceptible to airway penetration and aspiration [11], [12], [13], [14].

As the ageing population accounts for a large proportion of hospitalised and enterally fed patients, there is a need to understand any potential impact NGTs may have on the swallowing mechanism against a background of an ageing swallow. To clarify this issue, the current study was designed to assess the impact of both a fine bore NGT and wide bore NGT on swallowing in older healthy volunteers. Specific aims were to determine if NGT presence, including NGTs of different diameters, would affect: (1) airway penetration-aspiration, (2) pharyngeal residue, and (3) pharyngeal transit when swallowing multiple different food and fluid consistencies.

Section snippets

Materials and methods

The study was a randomized controlled crossover design of fine and wide bore NGTs (control, no tube) and the effect on swallowing in older healthy volunteers. The study was approved by the Royal Adelaide Hospital Research Ethics Committee for 12 months recruitment and carried out in accordance with the Helsinki Declaration of 1975 as revised in 1983 (Australian & New Zealand Clinical Trials Registry ACTRN12613000577718).

Healthy older volunteers were recruited through advertisement, provided

Results

Complete data sets were collected for 9 participants (Fig. 1) with 4 in one arm (control, fine bore, wide bore NGT) and 5 in the other (control, wide bore, fine bore NGT). Fifteen participants completed 2 conditions: control and the fine bore NGT. Wide bore NGT data was unavailable for 6 subjects mainly due to intolerance of tube insertion.

The median group age was 65 years (range 60–81) and 8 of the 15 participants were male. All had functional dentition and were within the normal weight range

Discussion

The key findings from this study were that the presence of a nasogastric tube in older individuals was associated with increased penetration or aspiration of the bolus into the airway, greater pharyngeal residue post-swallow, and prolonged duration of bolus transit through the pharynx. These data have implications for the initiation of oral feeding while a nasogastric tube is in place and for nasogastric supplementation of oral feeding to increase calorie delivery.

The most concerning finding

Conclusions

Though limited by sample size, the current data contributes to our current understanding of how swallowing physiology can be altered by presence of a NGT. Our results suggest the presence of a NGT when eating and/or drinking can increase airway penetration-aspiration and pharyngeal residue, and prolong the duration of pharyngeal transit in older healthy adults. As such, consideration of NGT impact on swallowing during combined oral and NGT feeding is recommended. This warrants further

Contributors and authorship

LNP, ECW, PLC, SNO and MJC conceived and designed the study; LNP, ECW and SNO conducted the research; MEF performed statistical analysis; LNP, ECW, PLC and MJC wrote the paper; LNP had primary responsibility for final content. All authors read and approved the final manuscript.

Conflict of interest

None declared.

Funding sources

The Royal Adelaide Hospital Research Foundation (Allied Health Grant) provided financial support to conduct the research. The funding source had no involvement in any part of the study.

Acknowledgements

We thank staff from the Royal Adelaide Hospital Departments of Radiology and Speech Pathology for their participation in obtaining and/or analysing the data.

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