The Journal of Laryngology and Otology January 1990, Vol. 104, pp. 17-19
Effect of nasogastric tubes on Eustachian tube function M. WAKE, F.R.C.S., D. E. MCCULLOUGH, J. D. BINNINGTON (Dudley)
Abstract The Eustachian tube acts as pressure equalizing tube between the nasopharynx and the middle ear. It also functions as a conduit for removal of secretions from the middle ear and mastoid air cell system into the post nasal space. Eustachian tube function may be assessed objectively using tympanometric measurements. (Brooks, 1968, Lutman, 1987). The post-operative use of nasogastric Ryles tubes is associated with reduced peak middle ear pressure (mmH2O) and reduced peak compliance volumes (ml) as assessed by tympanometry. In addition changes in the appearance of the tympanic membrane may occur with the protracted use of Ryles tubes. This phenomenon is a transient one. Nasogastric tube-induced Eustachian tube dysfunction is a previously unreported entity.
Introduction The Eustachian tube runs from the nasopharynx to the anterior mesotympanum. In adults, it is approximately 3 cm long, one-third bone and two-thirds fibro-cartilage. It is lined with respiratory mucous membrane (pseudostratified ciliated columnar epithelium). The Eustachian tube orifice opens into the lateral wall of the nasopharynx at the tubal eminence. The prominence of the tubal eminence is related to the longer posterior cartilaginous flange and the presence of lymphoid tissue in the mucous membrane. Muscle attachments to the cartilaginous Eustachian tube include the tensor palatini, levator palati and salpingopharyngeus muscles. The action of these muscles during swallowing temporarily opens the Eustachian tube. (Last, 1988). The function of the Eustachian tube is the maintenance of equal middle ear and atmospheric pressure by intermittent tubal opening to compensate for gaseous reabsorption. In addition, the Eustachian tube acts as a conduit for the removal of middle ear and mastoid secretions into the nasopharynx. Abnormal Eustachian tube function may lead to (1) negative middle ear pressure, which adversely affects compliance of sound conduction (Pickles, 1987); (2) accumulation of middle ear secretions. Both of these abnormalities may occur with mucosal oedema at the Eustachian tube orifice (Browning, 1987). The presence of a 'foreign body' in the nasopharynx adjacent to the Eustachian tube orifice occurs with nasogastric tube usage. Furthermore constant irritation of the nasopharyngeal mucosa may occur during swallowing when a nasogastric tube is in situ. It was, therefore, decided to study the effects of indwelling nasogastric tubes on Eustachian tube function and middle ear pressures.
Material and methods Ten patients undergoing head and neck operations whose routine post-operative care involved the use of a nasogastric tube for feeding purposes were studied. The characteristics of the study population are shown in Table 1. Previous history of middle ear disease or evidence of active or quiescent middle ear disease was an exclusion criterion. The study was prospective. The ear considered under study was called the ipsilateral ear (with reference to the side of insertion of the nasogastric tube). The contralateral ear was studied as a control. The selection of which side to insert the nasogastric tube was random. In all patients a size 14 FG (French gauge), 120 cm standard Ryles tube was used. All patients were subject to an otological history and examination prior to surgery. A preoperative pure tone audiogram (air and bone conduction) and tympanogram was obtained. Post-operatively TABLE I CHARACTERISTICS OF STUDY POPULATION
Accepted for publication: 12 September 1989. 17
Patient
Age
Sex
No.
(years)
(M/F)
1 2 3 4
54 70 76 67
M F M M
5 6
89 62
F M
7 8 9 10
46 63 65 76
M F F M
Operation Total laryngectomy Total laryngectomy Oesophagogastrectomy Repair pharyngocutaneous fistula Excision pharyngeal pouch Total laryngectomy/partial pharyngectomy Total laryngectomy Excision pharyngeal pouch Total laryngectomy Total laryngectomy
18
M. WAKE. D. E. MCCULLOUGH AND J. D. BINNINGTON
TABLE II ABNORMAL CLINICAL FINDINGS IN STUDY EARS AFTER THE USE OF NASOGASTRIC TUBES (RYLES)
Patient No. (see Table I)
Abnormal signs Ipsilateral
Day of onset
Contralateral
Injection of tympanic membrane Fluid containing Retraction of tympanic membrane Absent light reflex Fluid containing injection of tympanic membrane
the patients were assessed daily as per the following protocol: Day 1: Otological history and examination; Day 2: Pure tone audiogram and tympanogram; Day 3: Otological history and examination; Day 4: Pure tone audiogram and tympanogram (continued as necessary). All patients were re-examined prior to discharge from hospital. The following variables were studied: (1) Otological symptoms; (2) Appearance of tympanic membrane; (3) Free field hearing test and Rinne tests; (4) Pure tone audiometry; (5) Tympanometry. The audiograms were performed on a Grayson Stadler GSI 16 audiometer in a sound-proofed audiometry room. The audiometry followed British Society of Audiology recommended procedures. Tympanometry was performed using a Grayson Stadler GSI 33 impedance audiometer. Audiological and clinical assessments were made independently of each other by the
5th 3rd 3rd 3rd 4th
Injection of tympanic membrane
authors. The timing of removal of the nasogastric tubes was made on clinical grounds only. Results (1) Otological symptoms Nine of the ten patients developed any new otological symptoms after the use of nasogastric (Ryles) tubes. Enquiry was made about the development of otalgia, deafness, tinnitus and vertigo on the first post-operative day and on alternative days thereafter. One patient (no. 9) developed otalgia on the third to sixth postoperative day. (Table I). (2) Otological signs The patients' ears were examined on the first postoperative day and alternate days thereafter. Five of the ten patients developed ipsilateral clinical evidence of Eustachian tube dysfunction during the
TABLE III PEAK MIDDLE EAR PRESSURE ( m m H 2 0 ) BEFORE AND AFTER THE USE OF NASOGASTRIC (RYLES) TUBES
Peak middle ear press (mmH 20) ipsilateral ear
Peak middle ear pressure (mmH 20) contralateral ear
Case number (see Table I)
Pre-operative
Post-operative
1 2
-10 0
-190 -300
-5 0
-115 -100
4 5 6 7 8 9 10
-5 -25 0 5
-385 -120 -150
-15 5 0 0 5 -10 0
-25 -10 -10 0 0 -50 0
0
-95 -65
-15 5
-350 -110
Pre-operative
Post-operative
TABLE IV PEAK COMPLIANCE VALUES BEFORE AND AFTER THE USE OF NASOGASTRIC (RYLES) TUBES
Peak compliance values (ml) ipsilateral ear
Peak compliance values (ml) contralateral ear
Case number (see Table I)
Pre-operative
Post-operative
Pre-operative
Post-operative
1 2
0.5 0.5
0.2 0.3
0.3 0.6
0.3 0.5
4 5 6 7 8 9 10
0.4 0.7 0.7 0.8 1.0 0.6 0.7
0.2 0.7 0.7 0.7 0.8 0.2 0.6
0.5 1.0 1.0 0.7 0.8 0.7 0.8
0.4 1.0 1.0 0.7 0.7 0.7 0.8
19
EFFECT OF NASOGASTRIC TUBES ON EUSTACHIAN TUBE FUNCTION
study period. The abnormal signs and time of onset are outlined in Table II. The contralateral ears remained unchanged throughout except in one patient. All ears returned to normal following removal of the nasogastric tubes. (3) Clinical hearing tests Free field speech and Rinne test were performed on the patients on the first post-operative day and alternative days thereafter. None of the patients developed any new hearing loss as assessed by clinical means. Free field speech and Rinne tuning fork tests remained unchanged. (4) Pure tone audiometry Pure tone audiograms were recorded on the second post-operative day and alternate days thereafter. Abnormal results were considered as the development of a new 'significant' air bone gap in the post-operative period. A 10 dB air-bone gap is considered significant when averaged over 0.5, 1, 2 kHz (hence allowing for measurement limitations). None of the patients developed a 'significant' new air bone gap by this criteria.
clinical examination, audiometry and tympanometry (Hayes and Jerger, 1978; Lutman, 1987). In this study the post-operative use of nasogastric (Ryles) tubes for feeding purposes has been shown to be associated with abnormalities of Eustachian tube function using these accepted criteria. The most noticeable affect of nasogastric tubes on Eustachian tube function is the reduction in peak middle ear pressure as measured by tympanometry. This is also associated with reduced peak compliance values. Clinical changes in the appearance of the tympanic membrane may also occur and is well correlated with tympanometric measurements. Nasogastric tube induced Eustachian tube dysfunction is not associated with clinical or audiometric hearing loss in this study. Although it is accepted that the anatomical and physiological affects of surgery have not been accounted for in this study the use of the contralateral ear as controls suggests that Eustachian tube dysfunction may occur as a result of the use of nasogastric (Ryles) tubes independently of surgical variables. Nasogastric tube induced Eustachian tube dysfunction appears to be a transient phenomenon and although correlated with clinical evidence of dysfunction it generally remains an asymptomatic entity. Acknowledgements
(5) Tympanometry Tympanometry was performed on the second postoperative day and on alternative days thereafter. Nine of the ten patients developed changes in the tympanogram as determined by peak middle ear pressure (mmH2O) and peak compliance (ml) volumes. Postoperative volumes are taken from the 'most abnormal' tympanogram. The most noticeable alteration in the shape of the tympanogram always occurred before or on the fourth post-operative day. A recorded trend towards negative values of middle ear pressure and compliance was noted in ipsilateral ears throughout the study period. In eight of these patients the ipsilateral changes (increasingly negative values for peak middle ear pressure and/or reduced compliance values) were much more marked than in the contralateral ear. In case three, peak values could not be correlated with the fiat tympanogram. These results are outlined in Tables III and IV. Conclusions
Eustachian tube dysfunction is generally assessed by
We are once again grateful to Corinne Phillips and Claire Holme for preparing this manuscript. References
Brooks, D. N. (1968). An objective method of detectingfluidin the middle ear. International Audiology, 7: 280-286. Browning, G. G. (1987). Pathology of inflammatory conditions of the external and middle ear. In: Scott-Brown's Otolaryngology 5th Edition, Volume 3 (Kerr, A. G. and Booth, J. B. eds.) Butterworth: London, p. 63-64. Hayes, D., Jerger, J. (1978). Title: Otolaryngologic Clinics of North America, 11 (3): 759-765. Last, R. J. (1988). Anatomy regional and applied (7th edition). Churchill Livingstone: p. 455-456. Lutman, M. E. (1987). Diagnostic Audiometry. In: Scott-Brown's Otolaryngology, 5th Edition, Volume 2 (Kerr, A. G. and Stephens, S. D. G., eds). p. 254-256. Pickles, J. O. (1987). Physiology of the ear. In: Scott-Brown's Otolaryngology, 5th Edition, Volume 1 (Kerr, A. G. and Wright, D. A., eds). Butterworths: London, p. 60. Address for correspondence: Mr M. Wake, Dudley Road Hospital, Dudley Road, Birmingham B18 7QH.
Effect of nasogastric tubes on Eustachian tube function M. WAKE, F.R.C.S., D. E. MCCULLOUGH, J. D. BINNINGTON (Dudley)
Abstract The Eustachian tube acts as pressure equalizing tube between the nasopharynx and the middle ear. It also functions as a conduit for removal of secretions from the middle ear and mastoid air cell system into the post nasal space. Eustachian tube function may be assessed objectively using tympanometric measurements. (Brooks, 1968, Lutman, 1987). The post-operative use of nasogastric Ryles tubes is associated with reduced peak middle ear pressure (mmH2O) and reduced peak compliance volumes (ml) as assessed by tympanometry. In addition changes in the appearance of the tympanic membrane may occur with the protracted use of Ryles tubes. This phenomenon is a transient one. Nasogastric tube-induced Eustachian tube dysfunction is a previously unreported entity.
Introduction The Eustachian tube runs from the nasopharynx to the anterior mesotympanum. In adults, it is approximately 3 cm long, one-third bone and two-thirds fibro-cartilage. It is lined with respiratory mucous membrane (pseudostratified ciliated columnar epithelium). The Eustachian tube orifice opens into the lateral wall of the nasopharynx at the tubal eminence. The prominence of the tubal eminence is related to the longer posterior cartilaginous flange and the presence of lymphoid tissue in the mucous membrane. Muscle attachments to the cartilaginous Eustachian tube include the tensor palatini, levator palati and salpingopharyngeus muscles. The action of these muscles during swallowing temporarily opens the Eustachian tube. (Last, 1988). The function of the Eustachian tube is the maintenance of equal middle ear and atmospheric pressure by intermittent tubal opening to compensate for gaseous reabsorption. In addition, the Eustachian tube acts as a conduit for the removal of middle ear and mastoid secretions into the nasopharynx. Abnormal Eustachian tube function may lead to (1) negative middle ear pressure, which adversely affects compliance of sound conduction (Pickles, 1987); (2) accumulation of middle ear secretions. Both of these abnormalities may occur with mucosal oedema at the Eustachian tube orifice (Browning, 1987). The presence of a 'foreign body' in the nasopharynx adjacent to the Eustachian tube orifice occurs with nasogastric tube usage. Furthermore constant irritation of the nasopharyngeal mucosa may occur during swallowing when a nasogastric tube is in situ. It was, therefore, decided to study the effects of indwelling nasogastric tubes on Eustachian tube function and middle ear pressures.
Material and methods Ten patients undergoing head and neck operations whose routine post-operative care involved the use of a nasogastric tube for feeding purposes were studied. The characteristics of the study population are shown in Table 1. Previous history of middle ear disease or evidence of active or quiescent middle ear disease was an exclusion criterion. The study was prospective. The ear considered under study was called the ipsilateral ear (with reference to the side of insertion of the nasogastric tube). The contralateral ear was studied as a control. The selection of which side to insert the nasogastric tube was random. In all patients a size 14 FG (French gauge), 120 cm standard Ryles tube was used. All patients were subject to an otological history and examination prior to surgery. A preoperative pure tone audiogram (air and bone conduction) and tympanogram was obtained. Post-operatively TABLE I CHARACTERISTICS OF STUDY POPULATION
Accepted for publication: 12 September 1989. 17
Patient
Age
Sex
No.
(years)
(M/F)
1 2 3 4
54 70 76 67
M F M M
5 6
89 62
F M
7 8 9 10
46 63 65 76
M F F M
Operation Total laryngectomy Total laryngectomy Oesophagogastrectomy Repair pharyngocutaneous fistula Excision pharyngeal pouch Total laryngectomy/partial pharyngectomy Total laryngectomy Excision pharyngeal pouch Total laryngectomy Total laryngectomy
18
M. WAKE. D. E. MCCULLOUGH AND J. D. BINNINGTON
TABLE II ABNORMAL CLINICAL FINDINGS IN STUDY EARS AFTER THE USE OF NASOGASTRIC TUBES (RYLES)
Patient No. (see Table I)
Abnormal signs Ipsilateral
Day of onset
Contralateral
Injection of tympanic membrane Fluid containing Retraction of tympanic membrane Absent light reflex Fluid containing injection of tympanic membrane
the patients were assessed daily as per the following protocol: Day 1: Otological history and examination; Day 2: Pure tone audiogram and tympanogram; Day 3: Otological history and examination; Day 4: Pure tone audiogram and tympanogram (continued as necessary). All patients were re-examined prior to discharge from hospital. The following variables were studied: (1) Otological symptoms; (2) Appearance of tympanic membrane; (3) Free field hearing test and Rinne tests; (4) Pure tone audiometry; (5) Tympanometry. The audiograms were performed on a Grayson Stadler GSI 16 audiometer in a sound-proofed audiometry room. The audiometry followed British Society of Audiology recommended procedures. Tympanometry was performed using a Grayson Stadler GSI 33 impedance audiometer. Audiological and clinical assessments were made independently of each other by the
5th 3rd 3rd 3rd 4th
Injection of tympanic membrane
authors. The timing of removal of the nasogastric tubes was made on clinical grounds only. Results (1) Otological symptoms Nine of the ten patients developed any new otological symptoms after the use of nasogastric (Ryles) tubes. Enquiry was made about the development of otalgia, deafness, tinnitus and vertigo on the first post-operative day and on alternative days thereafter. One patient (no. 9) developed otalgia on the third to sixth postoperative day. (Table I). (2) Otological signs The patients' ears were examined on the first postoperative day and alternate days thereafter. Five of the ten patients developed ipsilateral clinical evidence of Eustachian tube dysfunction during the
TABLE III PEAK MIDDLE EAR PRESSURE ( m m H 2 0 ) BEFORE AND AFTER THE USE OF NASOGASTRIC (RYLES) TUBES
Peak middle ear press (mmH 20) ipsilateral ear
Peak middle ear pressure (mmH 20) contralateral ear
Case number (see Table I)
Pre-operative
Post-operative
1 2
-10 0
-190 -300
-5 0
-115 -100
4 5 6 7 8 9 10
-5 -25 0 5
-385 -120 -150
-15 5 0 0 5 -10 0
-25 -10 -10 0 0 -50 0
0
-95 -65
-15 5
-350 -110
Pre-operative
Post-operative
TABLE IV PEAK COMPLIANCE VALUES BEFORE AND AFTER THE USE OF NASOGASTRIC (RYLES) TUBES
Peak compliance values (ml) ipsilateral ear
Peak compliance values (ml) contralateral ear
Case number (see Table I)
Pre-operative
Post-operative
Pre-operative
Post-operative
1 2
0.5 0.5
0.2 0.3
0.3 0.6
0.3 0.5
4 5 6 7 8 9 10
0.4 0.7 0.7 0.8 1.0 0.6 0.7
0.2 0.7 0.7 0.7 0.8 0.2 0.6
0.5 1.0 1.0 0.7 0.8 0.7 0.8
0.4 1.0 1.0 0.7 0.7 0.7 0.8
19
EFFECT OF NASOGASTRIC TUBES ON EUSTACHIAN TUBE FUNCTION
study period. The abnormal signs and time of onset are outlined in Table II. The contralateral ears remained unchanged throughout except in one patient. All ears returned to normal following removal of the nasogastric tubes. (3) Clinical hearing tests Free field speech and Rinne test were performed on the patients on the first post-operative day and alternative days thereafter. None of the patients developed any new hearing loss as assessed by clinical means. Free field speech and Rinne tuning fork tests remained unchanged. (4) Pure tone audiometry Pure tone audiograms were recorded on the second post-operative day and alternate days thereafter. Abnormal results were considered as the development of a new 'significant' air bone gap in the post-operative period. A 10 dB air-bone gap is considered significant when averaged over 0.5, 1, 2 kHz (hence allowing for measurement limitations). None of the patients developed a 'significant' new air bone gap by this criteria.
clinical examination, audiometry and tympanometry (Hayes and Jerger, 1978; Lutman, 1987). In this study the post-operative use of nasogastric (Ryles) tubes for feeding purposes has been shown to be associated with abnormalities of Eustachian tube function using these accepted criteria. The most noticeable affect of nasogastric tubes on Eustachian tube function is the reduction in peak middle ear pressure as measured by tympanometry. This is also associated with reduced peak compliance values. Clinical changes in the appearance of the tympanic membrane may also occur and is well correlated with tympanometric measurements. Nasogastric tube induced Eustachian tube dysfunction is not associated with clinical or audiometric hearing loss in this study. Although it is accepted that the anatomical and physiological affects of surgery have not been accounted for in this study the use of the contralateral ear as controls suggests that Eustachian tube dysfunction may occur as a result of the use of nasogastric (Ryles) tubes independently of surgical variables. Nasogastric tube induced Eustachian tube dysfunction appears to be a transient phenomenon and although correlated with clinical evidence of dysfunction it generally remains an asymptomatic entity. Acknowledgements
(5) Tympanometry Tympanometry was performed on the second postoperative day and on alternative days thereafter. Nine of the ten patients developed changes in the tympanogram as determined by peak middle ear pressure (mmH2O) and peak compliance (ml) volumes. Postoperative volumes are taken from the 'most abnormal' tympanogram. The most noticeable alteration in the shape of the tympanogram always occurred before or on the fourth post-operative day. A recorded trend towards negative values of middle ear pressure and compliance was noted in ipsilateral ears throughout the study period. In eight of these patients the ipsilateral changes (increasingly negative values for peak middle ear pressure and/or reduced compliance values) were much more marked than in the contralateral ear. In case three, peak values could not be correlated with the fiat tympanogram. These results are outlined in Tables III and IV. Conclusions
Eustachian tube dysfunction is generally assessed by
We are once again grateful to Corinne Phillips and Claire Holme for preparing this manuscript. References
Brooks, D. N. (1968). An objective method of detectingfluidin the middle ear. International Audiology, 7: 280-286. Browning, G. G. (1987). Pathology of inflammatory conditions of the external and middle ear. In: Scott-Brown's Otolaryngology 5th Edition, Volume 3 (Kerr, A. G. and Booth, J. B. eds.) Butterworth: London, p. 63-64. Hayes, D., Jerger, J. (1978). Title: Otolaryngologic Clinics of North America, 11 (3): 759-765. Last, R. J. (1988). Anatomy regional and applied (7th edition). Churchill Livingstone: p. 455-456. Lutman, M. E. (1987). Diagnostic Audiometry. In: Scott-Brown's Otolaryngology, 5th Edition, Volume 2 (Kerr, A. G. and Stephens, S. D. G., eds). p. 254-256. Pickles, J. O. (1987). Physiology of the ear. In: Scott-Brown's Otolaryngology, 5th Edition, Volume 1 (Kerr, A. G. and Wright, D. A., eds). Butterworths: London, p. 60. Address for correspondence: Mr M. Wake, Dudley Road Hospital, Dudley Road, Birmingham B18 7QH.
