Volume 89, Issue 4, Pages 648-651 (April 2008)

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ABSTRACT

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Effect of Nasogastric Tubes on Incidence of Aspiration

Presented in part to the Dysphagia Research Society, October 8−10, 2007, Vancouver, BC, Canada.

Abstract

Leder SB, Suiter DM. Effect of nasogastric tubes on incidence of aspiration.

Objective

To determine what effect, if any, a nasogastric (NG) tube has on occurrence of anterograde aspiration during objective evaluation of swallowing using both liquid and puree bolus consistencies.

Design

Prospective, consecutive.

Setting

Large, urban, tertiary care, teaching hospital.

Participants

Referred sample of 1260 consecutively enrolled inpatients. Group 1 (n=630; 346 male, 284 female) had an NG tube and group 2 (n=630; 360 male, 270 female) did not have an NG tube at time of referral for dysphagia evaluation.

Intervention

Fiberoptic endoscopic evaluation of swallowing (FEES).

Main Outcome Measure

Aspiration status.

Results

A Pearson chi-square indicated no significant differences (P>.05) for aspiration of either liquid or puree food consistencies dependent on presence of an NG tube. Separate binary logistic regression analyses were used to determine if the presence of an NG tube interacted with participants’ age to affect the dependent variables of liquid and puree aspiration. There were no significant effects for liquid aspiration (odds ratio [OR]=1.004, P>.05; 95% confidence interval [CI], 0.987−1.021) or puree aspiration (OR=0.992, P>.05; 95% CI, 0.971−1.014). In addition, no significant interactions (P>.05) were found between NG tube status and sex, age, or diagnostic category, and presence of an NG tube did not significantly increase the odds of either liquid aspiration (OR=1.092, P>.05; 95% CI, 0.842−1.418) or puree aspiration (OR=0.975, P>.05; 95% CI, 0.713−1.333). Last, subjects between 60 and 90 years of age, regardless of NG tube status, aspirated more frequently than younger subjects.

Conclusions

No statistically significant differences were found regarding aspiration status for liquid or puree food consistencies between 2 separate but comparable groups, that is, one with and one without an NG tube, regardless of sex, age, or diagnostic category. Because objective swallowing evaluation, for example, FEES, can be performed with an NG tube in place, it is not necessary to remove an NG tube to evaluate dysphagia. Similarly, there is no contraindication to leaving an NG tube in place to supplement oral alimentation.

Key Words: Deglutition, Deglutition disorders, Enteral nutrition, Rehabilitation, Respiratory aspiration

Article Outline

• Abstract

• Methods

• Participants

• Procedures

• Results

• Discussion

• Study Strengths and Limitations

• Conclusions

• References

• Copyright

NASOGASTRIC (NG) TUBE feeding is the most widely used nonoral feeding method in patients who are incapable of taking oral alimentation or who require additional nutrition to supplement inadequate oral intake.1, 2, 3 NG tube placement is relatively atraumatic, minimally invasive, and usually well tolerated.4 Patients of all ages and spanning all medical specialties can benefit from enteral nutrition via NG tube.5

Aspiration coinciding with NG tube use is both common and a major complication.2, 3, 5, 6 However, due to the multifactorial nature of aspiration pneumonia, no causation has been documented among presence of an NG tube, aspiration, and development of aspiration pneumonia.2, 5, 6 Specifically, the contribution of anterograde aspiration (defined as aspiration during oral alimentation due to oropharyngeal dysphagia) versus retrograde aspiration (defined as aspiration of refluxed gastric contents) concurrent with NG tube use is not known.5, 6

An NG tube is a foreign object that traverses the same path as a food bolus in the pharynx and esophagus and could be assumed to impact negatively on safe and efficient swallowing ability. Manometry tube placement in 80 healthy swallowing volunteers resulted in longer durations for hyoid bone excursion and upper esophageal sphincter opening dependent on bolus consistency, age, and sex, but no aspiration was observed on any swallows.7 NG tube placement in 10 healthy adults resulted in slowed pharyngeal bolus transit, but neither fine-bore nor wide-bore tubes altered overall swallowing function.8 In a before-after NG tube trial with 22 stroke patients, no statistically significant differences were found for pharyngeal transit times or swallow functions and no aspiration occurred.9 Last, presence of a 3.6-mm diameter flexible fiberoptic endoscope in the nasopharynx of 14 healthy swallowing adult volunteers did not significantly alter specific temporal measures of swallowing, that is, durations of stage transition, pharyngeal transit, or maximum hyoid elevation, and had no effect on aspiration status.10 Therefore, a safe swallow without aspiration occurred at all times despite minor temporal differences and tubes of differing diameters present in the pharynx and esophagus.

Despite widespread use there is a paucity of data concerning the impact that an NG tube has on the occurrence of aspiration during swallowing. This is due to small sample sizes, noncomparable population samples, and differing methodologies that preclude a definitive answer as to whether or not an NG tube affects swallowing success. In addition, epidemiologic data are questionable because witnessed aspiration events are both infrequent and unreliable, determination of pharyngeal versus reflux aspiration is difficult,5 and aspiration is often silent.11 The purpose of the present investigation was to determine what effect, if any, an NG tube has on occurrence of anterograde aspiration during objective evaluation of swallowing using both liquid and puree bolus consistencies.

Methods

Participants

This study was approved by the Human Investigation Committee of Yale University School of Medicine. In a prospective manner, from December 1999 to September 2006, 1260 consecutive inpatients from a large, urban, tertiary care, teaching hospital referred for dysphagia evaluations participated. Group 1 (n=630 [346 male, 284 female]) had an NG tube and group 2 (n=630 [360 male, 270 female]) did not have an NG tube. A sample of consecutive subjects accrued over 1 month indicated that approximately 61% had small-bore tubes (8 French [Fr]; diameter, 2.65mm) and 39% had large-bore tubes (18Fr; diameter, 6.0mm).

Table 1 shows the number of participants based on NG tube status and sex. Table 2 shows the number of participants based on NG tube status and age (decade). Median age for participants with an NG tube was 66.0 years (95% confidence interval [CI], 64.6−67.4) and median age for participants without an NG tube was 73.5 years (95% CI, 72.1−74.9). Table 3 shows number of participants based on NG tube status and diagnostic category.

Table 1.

NG Tube Status and Sex


Subjects	NG Tube		Total
Subjects	Yes (%)	No (%)	Total
Male	346(49.0)	360(51.0)	706
Female	284(51.3)	270(48.7)	554
Total	630(50.0)	630(50.0)	1260

Table 2.

NG Tube Status and Age


Decade (y)	NG Tube		Total
Decade (y)	Yes (%)	No (%)	Total
0−9	5(83.3)	1(16.7)	6
10−19	8(53.3)	7(46.7)	15
20−29	19(57.6)	14(42.4)	33
30−39	30(55.6)	24(44.4)	54
40−49	64(56.1)	50(43.9)	114
50−59	109(60.2)	72(39.8)	181
60−69	137(59.3)	94(40.7)	231
70−79	149(46.9)	169(53.1)	318
80−89	93(36.8)	160(63.2)	253
90−99	16(29.6)	38(70.4)	54
100−104	0(0.0)	1(100.0)	1
Total	630(50.0)	630(50.0)	1260

Table 3.

NG Tube Status and Diagnostic Category


Category	NG Tube		Total
Category	Yes (%)	No (%)	Total
Iatrogenic
Cardiothoracic surgery	47(57.3)	35(42.7)	82
Esophageal surgery	38(84.4)	7(15.6)	45
Head and neck surgery	36(81.8)	8(18.2)	44
Neurosurgery	64(70.3)	27(29.7)	91
Idiopathic
Medical	116(51.8)	108(48.2)	224
Pulmonary	93(52.0)	86(48.0)	179
Cancer	15(33.3)	30(66.7)	45
Other	42(34.4)	80(65.6)	122
Neurologic
Left stroke	42(42.4)	57(57.6)	99
Right stroke	40(41.2)	57(58.8)	97
Brainstem stroke	7(38.9)	11(61.1)	18
Parkinson’s disease	4(80.0)	1(20.0)	5
Dementia	9(29.0)	22(71.0)	31
Other	76(44.4)	95(55.6)	171
Total	629(50.2)	625(49.8)	1253⁎

⁎

Missing data for 7 subjects.

Procedures

We followed the standard fiberoptic endoscopic evaluation of swallowing (FEES) protocol with slight modifications.12, 13 All FEES ratings were recorded on a data collection form and performed by 1 endoscopist (SBL) with 15 years of experience. Briefly, each naris was examined visually and the scope passed through the most patent naris without administration of a topical anesthetic or vasoconstrictor to the nasal mucosa, thereby eliminating any potential adverse anesthetic reaction and assuring the endoscopist of a safe physiologic examination.14 The base of tongue, pharynx, and larynx were viewed and swallowing was evaluated directly with 6 food boluses of approximately 5mL volume each. The first food challenge consisted of 3 boluses of puree consistency (yellow pudding) followed by 3 liquid boluses (white milk), because these colors have excellent contrast with pharyngeal and laryngeal mucosa.15 All patients were allowed to swallow spontaneously, that is, without a verbal command to swallow. Aspiration was defined as entry of material into the airway below the level of the true vocal folds16 and silent aspiration occurred when there were no external behavioral signs such as coughing or choking.11 A safe and successful swallow was defined as no aspiration during FEES.

FEES equipment consisted of a 3.6mm diameter flexible fiberoptic rhinolaryngoscope (Olympus, ENF-P3),a light source (Olympus, CLK-4),a camera,b and color monitor.c

The same endoscopist who performed all FEES ratings in the present study also participated in a recent investigation that determined intrarater reliability with FEES using nonblue dyed food trials.15 Intrarater agreement was 100% for tracheal aspiration.

Results

Results of separate univariate analyses of variance revealed no significant differences for NG tube status based on sex (P>.05) (see table 1) or age (P>.05) (see table 2). However, subjects between 20 and 79 years of age had a greater percentage of NG tube placements than older (80−99y) subjects. Regardless of NG tube status, subjects between 60 and 90 years of age exhibited aspiration more often than younger subjects. There were some differences in percentage of NG tube use dependent on diagnostic category (see table 3). Iatrogenic causes (ie, surgery) accounted for the highest percentage of NG tube use (70.6%) followed by idiopathic (ie, medical and pulmonary) (51.9%), and then neurologic (ie, strokes) (41.6%).

A Pearson chi-square test indicated no significant differences for aspiration of either liquid (=.442, P=.506) or puree (=.025, P=.873) food consistencies dependent on presence of an NG tube (table 4). In addition, presence of an NG tube did not significantly increase the odds of either liquid aspiration (odds ratio [OR]=1.092, P>.05; CI, 0.842−1.418) or puree aspiration (OR=0.975, P>.05; 95% CI, 0.713−1.333). A power analysis revealed that with 630 participants per group, there is 80% power to detect an absolute difference in liquid aspiration percentage of ±7% and in puree aspiration of ±6%, assuming a 2-tailed test and a type I error rate of 5%. Observed differences are much smaller and clinically unimportant, that is, 1.6% for liquids and 0.4% for puree, indicating no differences in aspiration rate based on food consistency and NG tube status.

Table 4.

Aspiration Status of Liquid and Puree Consistencies Based on Presence of an NG Tube


Aspiration Status	NG Tube		Total
Aspiration Status	Yes (%)	No (%)	Total
Liquid aspiration
Yes	153(24.3)	143(22.7)	296
No	477(75.7)	487(77.3)	964
Total	630	630	1260
Puree aspiration
Yes	91(14.4)	93(14.8)	184
No	539(85.6)	537(85.2)	1076
Total	630	630	1260

Separate binary logistic regression analyses were used to determine if the presence of an NG tube interacted with participants’ age to affect the dependent variables of liquid and puree aspiration. There were no significant effects for liquid aspiration (OR=1.004, P>.05; 95% CI, 0.987−1.021) or puree aspiration (OR=.992, P>.05; 95% CI, 0.971−1.014).

Discussion

For the first time with both an adequately large and heterogeneous population sample and objective determination of aspiration during ingestion of both liquid and puree food consistencies, it has been shown that the presence of an NG tube did not affect swallowing success. Specifically, the occurrence of aspiration for both liquid and puree food consistencies was the same between 2 separate but comparable groups, that is, one with and one without an NG tube in place. Although previous research reported minor temporal measurement differences during swallowing, there was no reported increase in the most important nontemporal swallowing indicator (ie, aspiration), when a tube was present in the pharynx and esophagus.7, 8, 9, 10 The present study confirms that a safe and successful swallow, defined as no aspiration during FEES, was not affected by the presence of an NG tube.

Although an NG tube did not increase the occurrence of aspiration, this does not mean that all aspiration events are of equal importance. Patients who received NG tube feeding are usually older and, regardless of NG tube status, patients between 60 and 90 years of age aspirated more frequently than younger subjects. In addition, patients who required NG tube feeding prior to FEES had risk factors that predisposed them to the development of aspiration pneumonia, for example, dementia, nonambulatory, severely ill, malnourished, postsurgery, and compromised immune and defense systems.2, 3, 5 Whenever an NG tube is used an appropriate assessment followed by implementation of measures to reduce aspiration risk is necessary.2, 5

Study Strengths and Limitations

This study’s major strength is that it had a large sample size with adequate statistical power to answer confidently the research question. Other strengths that increased generalizability of the results included a wide variety of diagnoses, consecutive accrual, equivalent sex distribution, and spanning of the age spectrum.

Limitations of this study were use of a referred population sample versus a randomized controlled research design, and that one experienced rater (albeit with documented very high intrarater agreement) determined aspiration status. Future research should explore NG tube placement and aspiration status in very young (0−10y) and very old (90−100+y) subjects, the impact of duration of NG tube use on swallowing success, and aspiration status based on presence or absence of an NG tube in the same person.

Conclusions

No statistically significant differences were found regarding aspiration status for liquid or puree food consistencies between 2 separate but comparable groups, that is, one with and one without an NG tube, regardless of sex, age, or diagnostic category. Given that an objective swallowing evaluation, that is, either fiberoptic or fluoroscopic, can be performed with an NG tube in place, it is not necessary to remove an NG tube to evaluate dysphagia. Similarly, there is no contraindication to leaving an NG tube in place to supplement oral alimentation until prandial nutrition is adequate.

Suppliers

References

1. 1Finucaine P, Aslan SM, Duncan D. Percutaneous endoscopic gastrostomy in elderly patients. Postgrad Med J. 1991;67:371–373. MEDLINE | CrossRef

2. 2DiSario JA. Future considerations in aspiration pneumonia in the critically ill patient: what is not known, areas for future research, and experimental methods. JPEN J Parent Enter Nutr. 2002;26(6 Suppl):S75–S78discussion S79.

3. 3Dennis MS, Lewis SC, Warlow CFOOD Trial Collaboration. Effect of timing and method of enteral tube feeding for dysphagic stroke patients (FOOD): a multicentre randomized controlled trial. Lancet. 2005;365:764-2.

4. 4Dharmarajan TS, Unnikrishnan D. Tube feeding in the elderly (The technique, complications, and outcome). Postgrad Med. 2004;115:51–54. MEDLINE

5. 5McClave SA, DeMeo MT, DeLegge MH, et al. North American Summit on Aspiration in the Critically Ill Patient: consensus statement. JPEN J Parent Enter Nutr. 2002;26(6 Suppl):S80–S85.

6. 6Gomes GF, Pisani JC, Macedo ED, Campos AC. The nasogastric feeding tube as a risk factor for aspiration and aspiration pneumonia. Clin Nutr Metabol Care. 2003;6:327–333.

7. 7Robbins J, Hamilton JW, Lof GL, Kempster GB. Oropharyngeal swallowing in normal adults of different ages. Gastroenterology. 1992;103:823–829. Abstract

8. 8Huggins PS, Tuomi SK, Young C. Effects of nasogastric tubes on the young, normal swallowing mechanism. Dysphagia. 1999;14:157–161. CrossRef

9. 9Wang TG, Wu MC, Chang YC, Hsia TY, Lien IN. The effect of nasogastric tubes on swallowing function in persons with dysphagia following stroke. Arch Phys Med Rehabil. 2006;87:1270–1273. Abstract | Full Text | Full-Text PDF (84 KB) | CrossRef

10. 10Suiter DM, Moorhead MK. Effects of flexible fiberoptic endoscopy on pharyngeal swallow physiology. Otolaryngol Head Neck Surg. 2007;137:956–958. Abstract | Full Text | Full-Text PDF (46 KB) | CrossRef

11. 11Leder SB, Sasaki CT, Burrell MI. Fiberoptic endoscopic evaluation of dysphagia to identify silent aspiration. Dysphagia. 1998;13:19–21. CrossRef

12. 12Langmore SE, Schatz K, Olson N. Fiberoptic endoscopic examination of swallowing safety: a new procedure. Dysphagia. 1988;2:216–217.

13. 13Langmore SE, Schatz K, Olson N. Endoscopic and videofluoroscopic evaluations of swallowing and aspiration. Ann Otol Rhinol Laryngol. 1991;100:678–681. MEDLINE

14. 14Leder SB, Ross DA, Briskin KB, Sasaki CT. A prospective, double-blind, randomized study on the use of a topical anesthetic, vasoconstrictor, and placebo transnasal flexible fiberoptic endoscopy. J Speech Lang Hear Res. 1997;40:1352–1357. MEDLINE

15. 15Leder SB, Acton LA, Lisitano HL, Murray JT. Fiberoptic endoscopic evaluation of swallowing (FEES) with and without blue dyed food. Dysphagia. 2005;20:157–162. CrossRef

16. 16Logemann JA. Evaluation and treatment of swallowing disorders. 2nd ed.. Austin: Pro-Ed; 1998;.

a Department of Surgery, Section of Otolaryngology, Yale University School of Medicine, New Haven, CT

b School of Audiology & Speech-Language Pathology, University of Memphis, Memphis, TN.

Correspondence to Steven B. Leder, PhD, Dept of Surgery, Section of Otolaryngology, Yale University School of Medicine, PO Box 208041, New Haven, CT 06520-8041

No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated.

Reprints not available from the author.

a Olympus America Inc, 3500 Corporate Pkwy, PO Box 610, Center Valley, PA 18034-0610.

b Model MN401E; Elmo Co, 1478 Old Country Rd, Plainview, NY 11803.

c Model J4049WA01; Panasonic Canada Inc, 5770 Ambler Dr, Mississauga, ON L4W 2T3, Canada.

PII: S0003-9993(07)01845-X

doi:10.1016/j.apmr.2007.09.038

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