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