EUSTACHIAN TUBE VENTILATORY FUNCTION IN CHILDREN ERDEM
I.
CANTEKIN,
PH.D.
PITTSBURGH, PENNSYLVANIA
CHARLES
D.
BLUESTONE,
M.D.
LEON P. PARKIN,
M.S.
MEDFORD, MASSACHUSETTS
PITTSBURGH, PENNSYLVANIA
SUMMARY - In order to establish a simple stimulus-response characteristic of Eustachian tube physiology in children, the tubal ventilatory function was studied. The parameters of active and passive opening of the tube were measured for three groups of patients with nonintact tympanic membranes. The group with traumatic perforations of the tympanic membrane without any history of middle ear disease had better active equilibration function than the group with chronic otitis media and perforations of the tympanic membrane and the group with tyrnpanostomy tubes in the tympanic membrane. Quantitatively, this could be expressed in terms of residual positive pressures. In the study of repeated inflation of the middle ear, all groups had lower second opening pressures which are attributed to the effect of surface forces.
The role of the Eustachian tube in relation to middle ear disease has been a controversial subject since the nineteenth century. Even though many investigators have postulated that Eustachian tube malfunction is the pathogenetic mechanism in middle ear effusions ( MEE ), satisfactory evidence of tubal pathophysiology is lacking. In the middle ear-Eustachian tube-nasopharynx system, the Eustachian tube has primarily three functions: ventilation of the middle ear, drainage of secretions from the middle ear, and, finally, protection of the middle ear from nasopharyngeal secretions and acoustic noise. To characterize such a system, a stimulus-response relationship must be established in which the testing stimulus should be derived from the functional physiology of the system. Quantification of Eustachian tube function for normal subjects and patients with middle ear disease has been attempted by a variety of methods. In this investigation, air pressure was chosen as a stimulus to evaluate the first and most fundamental function of the Eustachian tube. The purpose was to investigate the parameters of possible physiological significance during passive and active opening of the tube, and to
determine which of the measurable systern responses might distinguish normal from abnormal Eustachian tube function. The ultimate goal was to determine a precise, simple, unique stimulus with well-defined characteristics which would elicit a repeatable response pattern. Such a stimulus-response relation could be utilized to classify the different Eustachian tube ventilatory functions according to related pathologic conditions and would aid in understanding the pathogenesis of MEE. METHODS AND MATERIALS
The testing technique required the direct pressurization of the middle ear, therefore, only subjects with nonintact tympanic membranes were studied. The patient population was comprised of three groups: Group I consisted of patients who had had a history of recurrent acute otitis media, or persistent MEE or both, and had tympanostomy tubes in place; Group II consisted of patients with traumatic perforations of the tympanic membrane who had otherwise negative otologic histories; and Group III consisted of patients with chronic otitis media and dry perforations of the tympanic membrane. The population characteristics are shown in Table I. The age distribution of Group II is dissimilar to the age distribution of Group I. The Eustachian tube ventilatory function was assessed by a modification of the middle
From the Department of Otolaryngology, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, and Tufts University Department of Engineering, Medford, Massachusetts.
171
172
CANTEKIN ET AL. TABLE I POPULATION CHARACTERISTICS FOR THE THREE GROUPS
AGE (YEARS)
NUMBER OF SUBJECTS * GROUP I
GROUP II
2-6
66 (4.4 ±1.3)
3 (3.3 ± 0.9)
7 -12
59 (91±1.4)
> 12
12 1I6.2 ± 4.3)
ALL AGES
137 (7.4 ± 4.3
1;
3 (10
+
1.4)
GROUP ill
ALL GROUPS
5 (4.8 ± 0.4)
74 (4.4 ± 1.3)
13 (8.5 ± 1.5)
75 (9.1 ± 1.4)
16 51 23 (27.4 ± 10.8) (26.9 ± 15.8) (24.6 ± 12.8) 29 (23.1 ± 12.9)
34 (16.8 ± 14.5
200
MEAN ANIJ STANIJARIJ IJEVIATION OF THE AGES FOR EACH GROUP IS IN PARENTHESIS
ear air inflation-deflation technique described by Flisberg and his co-workers.' A total of two hundred Eustachian tube ventilation studies were recorded with the instrumentation described elsewhere: All patients were tested in the sitting position and all middle ears were noted to be dry by otoscopy. After obtaining a hermetic seal in the ear canal, the test procedure was started with the determination of passive opening pressure. Inflation of the middle ear was achieved by a linear displacement syringe pump, driven by a constant speed electric motor. The nominal air flow rate was 25 cc/min. The pump was manually stopped when the opening pressure was reached. Opening and closing pressures were recorded at a chart speed of 5 mm/sec. Then, the patient was instructed to swallow water for further equilibration after the closing pressure. A negative pressure of 200 mm H 20 was applied to test the active equilibration of negative middle ear pressure. Then, opening and closing pressures for a second middle ear inflation were recorded. A positive pressure between the opening and closing pressures was applied and active equilibration of positive middle ear pressure was assessed. Later, a double-lumen balloon catheter was inserted into one naris with the contralateral naris manually compressed during swallowing to simulate Toynbee's maneuver, thus equilibration of applied positive and negative middle ear pressures by closednose swallowing was also evaluated. Finally, the passive opening pressure of the tube by nasopharyngeal overpressure was determined. The patient was instructed to blow against the closed nose with the same catheter arrangement (Valsalva maneuver). Nasal catheter pressure recordings were taken as nasopharyngeal pressure values. The analog strip chart data for each patient were converted into an appropriate digital format for computer storage and analysis.
RESULTS
The recordings of the middle ear inflation studies are summarized in Figure 1, where for each group, means and standard deviations are shown. The first five variables are taken from actual recordings and the rest are computed. The first passive opening of the tube by middle ear overpressure is the opening pressure (OPI ), the closing of the tube after the first opening is the closing pressure (CLI), the difference in pressure between the first opening and the first closing is the pressure drop (DPI). The minimum residual positive pressure (MIN + ) is the pressure left in the middle ear after passive and active openings. This value is either the closing pressure or the residual positive pressure after further equilibration by swallowing. The duration of pressure decay from OPI to CLI was measured from the strip chart recording and is named the time interval of opening (TINI ). In the case of TINI, the vertical scale should be used as centi-seconds (chosen for the convenience of display). The slope (51) of the pressure decay was computed by taking the DPI and dividing it by the TIN!. For this purpose, the linear straight line slope was used since the time differential of the actual pressure decay curve was not recorded. For 51, the vertical scale of this figure has the dimensions in mm H 20/sec. The next variable, which is the difference between the first closing pres-
173
EUSTACHIAN TUBE VENTILATION
600
500
oN I
~ 400 w ~ 300 Ul Ul
w
1
a: a. 200
100
a I
VARIABLE NAME
QP1
I
I
eli
I
I
OP1
I
I
MIN+
I
I
TIN1
I
I
jll
I
I
ICL1-MIN+IICL1HLnSl~(MIN+)(LnS11
51
o GROUP I (TYMPANOSTOMY TUBE) o GROUP II (TRAUMATIC PERFORATION)
6. GROUpm(CHRONIC OTITIS WITHPERFORATION)
Fig. 1. Results of middle ear inflation studies (mean values and standard deviations).
sure and the minimum residual positive pressure (CLI - MIN +) is indicative of an effective muscle function with minimum middle ear positive pressure assist for tubal opening. The relationship between the pressure decay and the airflow rate through the Eustachian tube is exponential (see discussion). The natural logarithm of the decay curve slope (LnSl ) is used as a measure for the flow rate. The next two variables are combinations of this slope logarithm with closing and minimum residual positive pressures. Variable (CLl)' (LnSI) is the product of the closing pressure and the qualitative flow rate during the forced opening of the tube, whereas, the last variable ( MIN + ). (LnSI) combines the effect of active equilibration with this flow rate measure. The statistical analysis for these variables is shown in Table II, where F-test results and the sample size ( N) are shown. When F-values were significant at 95% confidence level, the least-significant differences between groups were computed and compared with the observed differences between means of each group. In Table II, the group was marked with an asterisk when the observed difference was larger than the least-significant difference. Group III pa-
tients had higher OPI and larger pressure drops (DPI) than the other two groups. Group II patients had lower MIN +, better muscle function with minimum positive pressure assist (high CLl - MIN + ), and lower (MIN + ). ( LnSI) than patients with a history of recurrent or chronic middle ear effusions TABLE II F-TEST STATISTICAL ANALYSIS FOR THE VARIABLES
0 LLI
0
a: 0 o LLI a: 0 LLI
f u
...J
I.
CANTEKIN,
PH.D.
PITTSBURGH, PENNSYLVANIA
CHARLES
D.
BLUESTONE,
M.D.
LEON P. PARKIN,
M.S.
MEDFORD, MASSACHUSETTS
PITTSBURGH, PENNSYLVANIA
SUMMARY - In order to establish a simple stimulus-response characteristic of Eustachian tube physiology in children, the tubal ventilatory function was studied. The parameters of active and passive opening of the tube were measured for three groups of patients with nonintact tympanic membranes. The group with traumatic perforations of the tympanic membrane without any history of middle ear disease had better active equilibration function than the group with chronic otitis media and perforations of the tympanic membrane and the group with tyrnpanostomy tubes in the tympanic membrane. Quantitatively, this could be expressed in terms of residual positive pressures. In the study of repeated inflation of the middle ear, all groups had lower second opening pressures which are attributed to the effect of surface forces.
The role of the Eustachian tube in relation to middle ear disease has been a controversial subject since the nineteenth century. Even though many investigators have postulated that Eustachian tube malfunction is the pathogenetic mechanism in middle ear effusions ( MEE ), satisfactory evidence of tubal pathophysiology is lacking. In the middle ear-Eustachian tube-nasopharynx system, the Eustachian tube has primarily three functions: ventilation of the middle ear, drainage of secretions from the middle ear, and, finally, protection of the middle ear from nasopharyngeal secretions and acoustic noise. To characterize such a system, a stimulus-response relationship must be established in which the testing stimulus should be derived from the functional physiology of the system. Quantification of Eustachian tube function for normal subjects and patients with middle ear disease has been attempted by a variety of methods. In this investigation, air pressure was chosen as a stimulus to evaluate the first and most fundamental function of the Eustachian tube. The purpose was to investigate the parameters of possible physiological significance during passive and active opening of the tube, and to
determine which of the measurable systern responses might distinguish normal from abnormal Eustachian tube function. The ultimate goal was to determine a precise, simple, unique stimulus with well-defined characteristics which would elicit a repeatable response pattern. Such a stimulus-response relation could be utilized to classify the different Eustachian tube ventilatory functions according to related pathologic conditions and would aid in understanding the pathogenesis of MEE. METHODS AND MATERIALS
The testing technique required the direct pressurization of the middle ear, therefore, only subjects with nonintact tympanic membranes were studied. The patient population was comprised of three groups: Group I consisted of patients who had had a history of recurrent acute otitis media, or persistent MEE or both, and had tympanostomy tubes in place; Group II consisted of patients with traumatic perforations of the tympanic membrane who had otherwise negative otologic histories; and Group III consisted of patients with chronic otitis media and dry perforations of the tympanic membrane. The population characteristics are shown in Table I. The age distribution of Group II is dissimilar to the age distribution of Group I. The Eustachian tube ventilatory function was assessed by a modification of the middle
From the Department of Otolaryngology, Children's Hospital of Pittsburgh, University of Pittsburgh School of Medicine, and Tufts University Department of Engineering, Medford, Massachusetts.
171
172
CANTEKIN ET AL. TABLE I POPULATION CHARACTERISTICS FOR THE THREE GROUPS
AGE (YEARS)
NUMBER OF SUBJECTS * GROUP I
GROUP II
2-6
66 (4.4 ±1.3)
3 (3.3 ± 0.9)
7 -12
59 (91±1.4)
> 12
12 1I6.2 ± 4.3)
ALL AGES
137 (7.4 ± 4.3
1;
3 (10
+
1.4)
GROUP ill
ALL GROUPS
5 (4.8 ± 0.4)
74 (4.4 ± 1.3)
13 (8.5 ± 1.5)
75 (9.1 ± 1.4)
16 51 23 (27.4 ± 10.8) (26.9 ± 15.8) (24.6 ± 12.8) 29 (23.1 ± 12.9)
34 (16.8 ± 14.5
200
MEAN ANIJ STANIJARIJ IJEVIATION OF THE AGES FOR EACH GROUP IS IN PARENTHESIS
ear air inflation-deflation technique described by Flisberg and his co-workers.' A total of two hundred Eustachian tube ventilation studies were recorded with the instrumentation described elsewhere: All patients were tested in the sitting position and all middle ears were noted to be dry by otoscopy. After obtaining a hermetic seal in the ear canal, the test procedure was started with the determination of passive opening pressure. Inflation of the middle ear was achieved by a linear displacement syringe pump, driven by a constant speed electric motor. The nominal air flow rate was 25 cc/min. The pump was manually stopped when the opening pressure was reached. Opening and closing pressures were recorded at a chart speed of 5 mm/sec. Then, the patient was instructed to swallow water for further equilibration after the closing pressure. A negative pressure of 200 mm H 20 was applied to test the active equilibration of negative middle ear pressure. Then, opening and closing pressures for a second middle ear inflation were recorded. A positive pressure between the opening and closing pressures was applied and active equilibration of positive middle ear pressure was assessed. Later, a double-lumen balloon catheter was inserted into one naris with the contralateral naris manually compressed during swallowing to simulate Toynbee's maneuver, thus equilibration of applied positive and negative middle ear pressures by closednose swallowing was also evaluated. Finally, the passive opening pressure of the tube by nasopharyngeal overpressure was determined. The patient was instructed to blow against the closed nose with the same catheter arrangement (Valsalva maneuver). Nasal catheter pressure recordings were taken as nasopharyngeal pressure values. The analog strip chart data for each patient were converted into an appropriate digital format for computer storage and analysis.
RESULTS
The recordings of the middle ear inflation studies are summarized in Figure 1, where for each group, means and standard deviations are shown. The first five variables are taken from actual recordings and the rest are computed. The first passive opening of the tube by middle ear overpressure is the opening pressure (OPI ), the closing of the tube after the first opening is the closing pressure (CLI), the difference in pressure between the first opening and the first closing is the pressure drop (DPI). The minimum residual positive pressure (MIN + ) is the pressure left in the middle ear after passive and active openings. This value is either the closing pressure or the residual positive pressure after further equilibration by swallowing. The duration of pressure decay from OPI to CLI was measured from the strip chart recording and is named the time interval of opening (TINI ). In the case of TINI, the vertical scale should be used as centi-seconds (chosen for the convenience of display). The slope (51) of the pressure decay was computed by taking the DPI and dividing it by the TIN!. For this purpose, the linear straight line slope was used since the time differential of the actual pressure decay curve was not recorded. For 51, the vertical scale of this figure has the dimensions in mm H 20/sec. The next variable, which is the difference between the first closing pres-
173
EUSTACHIAN TUBE VENTILATION
600
500
oN I
~ 400 w ~ 300 Ul Ul
w
1
a: a. 200
100
a I
VARIABLE NAME
QP1
I
I
eli
I
I
OP1
I
I
MIN+
I
I
TIN1
I
I
jll
I
I
ICL1-MIN+IICL1HLnSl~(MIN+)(LnS11
51
o GROUP I (TYMPANOSTOMY TUBE) o GROUP II (TRAUMATIC PERFORATION)
6. GROUpm(CHRONIC OTITIS WITHPERFORATION)
Fig. 1. Results of middle ear inflation studies (mean values and standard deviations).
sure and the minimum residual positive pressure (CLI - MIN +) is indicative of an effective muscle function with minimum middle ear positive pressure assist for tubal opening. The relationship between the pressure decay and the airflow rate through the Eustachian tube is exponential (see discussion). The natural logarithm of the decay curve slope (LnSl ) is used as a measure for the flow rate. The next two variables are combinations of this slope logarithm with closing and minimum residual positive pressures. Variable (CLl)' (LnSI) is the product of the closing pressure and the qualitative flow rate during the forced opening of the tube, whereas, the last variable ( MIN + ). (LnSI) combines the effect of active equilibration with this flow rate measure. The statistical analysis for these variables is shown in Table II, where F-test results and the sample size ( N) are shown. When F-values were significant at 95% confidence level, the least-significant differences between groups were computed and compared with the observed differences between means of each group. In Table II, the group was marked with an asterisk when the observed difference was larger than the least-significant difference. Group III pa-
tients had higher OPI and larger pressure drops (DPI) than the other two groups. Group II patients had lower MIN +, better muscle function with minimum positive pressure assist (high CLl - MIN + ), and lower (MIN + ). ( LnSI) than patients with a history of recurrent or chronic middle ear effusions TABLE II F-TEST STATISTICAL ANALYSIS FOR THE VARIABLES
0 LLI
0
a: 0 o LLI a: 0 LLI
f u
...J
