Journal of Asthma Research
ISSN: 0021-9134 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/ijas19
Clinical Application of Quiet Breathing Airway Resistance Warren C. Miller & Warren W. Simi To cite this article: Warren C. Miller & Warren W. Simi (1976) Clinical Application of Quiet Breathing Airway Resistance, Journal of Asthma Research, 13:3, 137-141, DOI: 10.3109/02770907609104166 To link to this article: http://dx.doi.org/10.3109/02770907609104166
Published online: 02 Jul 2009.
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Citing articles: 1 View citing articles
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Date: 08 May 2016, At: 09:53
The Journal of Asthma Research.
Vol. 13. No. 3, March, 1976
Clinical Application of Quiet Breathing Airway Resistancet.
Downloaded by [UQ Library] at 09:53 08 May 2016
WARRENC. MILLER,M.D.*
AND
WARRENW. SIMI,M.D.**
Introduction The measurement of airway resistance by the body plethysmograph has come to be widely applied in the diagnosis and evaluation of patients with obstructive airway disease. Indeed such measurement has been utilized in routine clinical practice in an office population. In a constant-volume plethysmograph, the determination is usually performed with the subject panting. The panting method was developed in part to reduce the effects of signal drift, small box leaks, and gradual thermal changes, but especially to eliminate the looping artifact caused by instantaneous changes in temperature and humidity of tidal air such as occurs in normal quiet breathing.2 This artifact is decreased because rapid shallow breathing retains within the pneumotachograph the interface between ambient plethysmograph air and the warm moist air of the patient. In addition, panting minimizes the effect of glottis size, abdominal pressure changes, and tidal lung volume change^.^ However, panting is not usual physiologic condition. The thoracic gas volume during panting differs from normal functional residual capacity. Rapid, shallow breathing may effect intra-pulmonary gas distribution, with gas following the pathway of least resistance. In subjects with bronchial obstruction, resistance may decrease with increasing respiratory frequencies. Panting may produce considerable alterations in PC02, either in the airways or systemically, affecting the resistance measurement. 2, Finally, the panting maneuver is difficult for some subjects to perform. Methods for plethysmographic determination of airway resistance a t quiet breathing have been devised. The artifact induced by by temperature and humidity may be reduced by having the subject re-breathe from an air bag maintained a t BTPS conditions. This procedure requires elaborate equipment and technical expertise and may produce further alterations due to CO, accumulation, variable compliance of the air bag, and other factors. As an alternative, it is possible to compensate for the artifact with loop closure by electronic means. 6 - 8 Because the measurement of airway resistance is rapidly becoming a routine determination in clinical laboratories, and because plethysmographs with electronic compemation are being commercially marketed, studies assessing the use of these instruments and the comparability of
t Presented at the Southern Section, American Federation for Clinical Research, New Orleans, Louisiana, January 31, 1975. *Assistant Professor and Director, Pulmonary Division, University of Texas Medical School, Houston, Texas. ** Fellow, Pulmonary Division, University of Texas Medical School, Houston, Texas. 137
138
WARREN C . MILLER AND WARREN W. SIMI
this technique are needed. We have recently evaluated the clinical application of the quiet breathing method with electronic simulation of BTPS conditions and compared i t to the panting procedure.
Downloaded by [UQ Library] at 09:53 08 May 2016
Materials and Methods Airway resistance (Raw) and thoracic gas volume (Vtg) were measured in a constant-volume body plethysmograph (Cardiopulmonary Instruments Model 2000) providing capabilities for determination of airway resistance a t panting (RawP) by the method of Dubois, et a12 a n d a t quiet breathing (RawQB) with electronic compensation for temperature and humidity artifact similar to that first described by Bargeton et aL7 The plethysmograph technicians randomized the order and alternated the performance of the measurement so that non became unduly proficient in only one technique, nor was any aware of the others' results. Th e reported airway resistance, both a t panting and quiet breathing, represents the average of three measurements each. At the end of the study the technicians were queried with regard to the ease a n d efficiency of the two methods. In order to compensate for differences in the lung volume at which airway resistance was measured, specific resistance (SRaw) was calculated: SRaw QB = RawQB X FRC, SRawP = RawP X Vtg. Spirometry was performed on a waterless, low resistant, piston-displaced, electronic spirometer (Cardiopulmonary Instruments model #840). Normal values for FEVJFVC ratio were those of Berglung, et aL9 One hundred non-selected patients presenting to our laboratory in a routine fashion formed the subjects of the study. They were consecutive except for six, who were unwilling or unable to cooperate for complete plethysmographic measurements. They were later divided into two groups. T h e first group included those whose FEVJFVC ratio was greater than, or equal to, 90 percent predicted and, therefore, presumably had minimal or no airway obstruction. The second group were those with moderate to severe obstruction as demonstrated by an FEVJFVC ratio less than 90 percent predicted. Regression, correlation, Student t-test for paired variables, a n d other statistical analysis of the data were performed by computer (IBM Remote Access Statistical System). Results The mean values of RawP, RawQB, S RawP, and S RawQB for all subjects are shown in the table. Although there is excellent correlation between RawP TABLE Mean Values for Resistance and Specific Resistance
.
All subjects
RawQB RawP SRawQB SRawP
* Standard Deviation
2.99 (2.48)* 2.45 (1.48) 14.4 (17.6) 13.0 (13.2)
Minimal obstruction
Significant obstruction
1.72 (.60) 1.65 (.48) 6.26 (3.50) 6.60 (2.49)
3.39 (2.22) 2.75 (1.53) 19.8 (17.7) 18.0 (14.2)
CLINICAL APPLICATION OF QUIET BREATHING AIRWAY RESISTANCE
139
and RawQB ( r = .913, regression: RawQB = 1.58RawP .70, SEE = 1.16), it is apparent th at the quiet breathing method yields a mean resistance 18 percent higher than panting. Because resistance is related to lung volume in a hyperbolic fashion, and because in our subjects the volume a t panting was a mean of 0.53 liters greater than the volume a t quiet breathing, it is likely th a t a part of the increased RawQB reflects measurement a t a lower lung volume. When SRaw is computed to obviate the effects of volume, a n even better correlation is obtained (r = .951, regression SRawQB = 1.27SRawP - 2.09, SEE = 6.15). Nevertheless, the mean SRawQB is 11 percent greater than mean SRawP. When the data were analyzed by subgroups, it was found that the patients with little or no airway obstruction by spirometry had no significant difference between RawP and RawQB, or between SRawP and SRawQB by paired t-testing. Mean SRawP was actually slightly but insignificantly higher than Downloaded by [UQ Library] at 09:53 08 May 2016
~
90-
80-
70-
60-
0
50-
z
a
UJ
40-
-
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0
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- 0 0
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I
10
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I
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40
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i
S Raw P
FIG. Individual values for SRawQB and SRawP in subjects with established obstructive lung disease.
140
WARREN C. MILLER AND WARREN
W.
SIMl
Downloaded by [UQ Library] at 09:53 08 May 2016
SRawQB (6.60 versus 6.26 respectively). T h e patients with moderate to severe obstruction demonstrated statistically significant differences in RawP and RawQB, and SRawP and SRawQB ( p < .01). SRaw in obstructed subjects is shown in t he figure. Universally, the technicicans preferred the quiet breathing technique as being less time-consuming in performance, allowing measurement in subjects who cannot seem to perform the panting maneuver reproductibly, and requiring less calculation. A separate computation of thoracic gas volume apart from FRC is not necessary.
Discussion In our patients without significant airway obstruction, the resistance measurements a t panting an d quiet breathing were essentially interchangeable. This is compatible with previous studies in normal subjects utilizing an air bag system" and the minimal frequency dependence of resistance found in normal subjects (Whol, M.E., Gross, P., and Mead, J., unpublished observations cited by Grimby, et al"). However, Jaeger and Otis have described increased airway resistance at quiet breathing in normal subjects. l 2 This discrepancy may be d u e to difference in experimental technique, i.e. the use of a volume displacement plethysmograph. In our subjects with obvious airway obstruction, although good correlation exists between panting and quiet breathing methods, the measured airway resistance is greater by the quiet breathing technique. Similar studies in patients with obstructive lung disease have demonstrated this difference. l 3 The reasons for this finding remain unclear. Although the size of the glottis may play a role, l 4 it seems insufficient to account for the magnitude of the difference in measured airway resistance.13 It is not observed in relatively normal subjects. Respiratory frequency may be the prime determinant. Frequency dependence of resistance has been demonstrated by forced oscillations in patients with obstructive lung disease." Regardless of the etiology of the differences between panting and quiet breathing methods, in subjects with little or no airway obstruction, the two techniques appear interchangeable, and in patients with obstructive lung disease, they are well correlated. From a purely practical standpoint the quiet breathing method with electronic simulation of BTPS conditions is easier for the subject and the technician. I t permits resistance measurements in those subjects unable to pant and provides increased efficiency in a high volume clinical laboratory. References 1. COHEN,B. M., AND MCILREATH, F. J. Airway resistance measurements in the internists office, J. Asthma Res. 6:23, 1968. 2. DUBOIS,A. B., BOTHELHOK, S. Y., AND COMROE, J. H., J R . A new method for measuring airway resistance in man using a body plethysmograph. Values in normal subjects and in patients with respiratory disease, J . Clin. Invest 35:326, 1956. 3. DUBOIS,A. B., in progress, in Respiration Research, Vol. 4. International symposium on body plethysmography: Nijmegen, 1968, Karger, N.Y., 1969, p. 109.
CLINICAL APPLICATION OF QUIET BREATHING AIRWAY RESISTANCE
141
4. OTIS, A. B., MCKERROW, C. B., BARTLETT, R. A,, MEAD,J., MCILROY, M. B., SELVERSTONE, J.
J., AND RADFORD, E. P., JR. Mechanical factors in distribution of pulmonary ventilation, J. Appl Physiol. 8:427, 1956. 5. CUTILLO,A,, OMBORI,E., PERONDI, R., AND TANA, F. Effect of hypocapenia on pulmonary mechanics in normal subjects and in patients with chronic obstructive lung disease, Amer. Reu. Resp. Dis. 110:25, 1974. 6. WOITOWITZ, H. J . , GUNTHER, AND WOITOWITZ, R. In progress, in Respiration Research, Vol. 4, International symposium on body plethysmography, Nijmegen, 1968, Karger, N.Y., 1969, p. 50. 7. BARGETON, D., BARRES,G., LEFEBURE DES NOETTES, R., AND GAUGE,0. Mesure de la resistance des voies aeriennes de l’homme dans la respirat,ion normale, J . Physiol. Paris 49:37, 1957. 8. SMIDT,U., NUYSERS,K., A N D BUCHHEIN, W. In progress, in Respiration Research, Vol. 4, International symposium on body plethysmography, Nijmegen 1968, Kargen, N.Y., 1969, p. 36. 9. BERGULUND, E., BIRATH,G., BJURE, J., GRIMBY,G., KJELLMER,I., SANDQUIST, L., AND SODERHOLM, B. Spirometric studies in normal subjects, Acta Med. Scand. 273:185, 1963. P. H., AND TAMMELING, G. J . In progress, in Respiration Research, Vol. 10. PESET,R., QUANJER, 4, International symposium on body plethysmography, Nijmegen, 1968, Karger, N.Y., 1969, p. 215. 11. GRIMBY, G., TASKISHIMA, T., GRAHAM, W., MACKLEM, P., ANDMEAD, J . Frequency dependence of flow resistance in patients with obstructive lung disease J. Clin. Inuest. 47:1455, 1968. 12. JAEGER, M . J., AND OTIS,A. B. Measurement of airway resistance with a volume displacement body plethysmograph J . Appl. Physiol. 29:813, 1964. 13. BARTER, C. E., A N D CAMPBELL, A. H. Comparison of airways resistance measurements during panting and quiet breathing. Respiration, 30:l, 1973. 14. STANESCU, D. C., PATTIJM, J., CLEMENT, J., A N D VANDE WOESTIJNE, K. P. Glottis opening and airway resistance. J. Appl. Physiol., 32460, 1972.
Downloaded by [UQ Library] at 09:53 08 May 2016
w.,
ANNOUNCEMENT The Asthmatic Children’s Foundation Residential Treatment Centers provide convalescent care for children aged 5 to 13 years. The policy of the Asthmatic Children’s Foundation is to encourage admission of children with persistent asthma who fail to respond satisfactorily to allergy management, preferably before they become critical. Vacancies are periodically available. Admission can be arranged for periods of three months to two years. Patient care cost is defrayed by charitable contributions. For further information: Asthmatic Children’s Foundat.ion of New York 133 East 58th St.-Suite 310 New York, N. Y. 10022 Tel: 212-355-2872 Asthmatic Children’s Foundation of Florida 1800 N. E. 168th St., N. Miami Beach, Fla. 33162 Tel: 305-947-3445
ISSN: 0021-9134 (Print) (Online) Journal homepage: http://www.tandfonline.com/loi/ijas19
Clinical Application of Quiet Breathing Airway Resistance Warren C. Miller & Warren W. Simi To cite this article: Warren C. Miller & Warren W. Simi (1976) Clinical Application of Quiet Breathing Airway Resistance, Journal of Asthma Research, 13:3, 137-141, DOI: 10.3109/02770907609104166 To link to this article: http://dx.doi.org/10.3109/02770907609104166
Published online: 02 Jul 2009.
Submit your article to this journal
View related articles
Citing articles: 1 View citing articles
Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=ijas19 Download by: [UQ Library]
Date: 08 May 2016, At: 09:53
The Journal of Asthma Research.
Vol. 13. No. 3, March, 1976
Clinical Application of Quiet Breathing Airway Resistancet.
Downloaded by [UQ Library] at 09:53 08 May 2016
WARRENC. MILLER,M.D.*
AND
WARRENW. SIMI,M.D.**
Introduction The measurement of airway resistance by the body plethysmograph has come to be widely applied in the diagnosis and evaluation of patients with obstructive airway disease. Indeed such measurement has been utilized in routine clinical practice in an office population. In a constant-volume plethysmograph, the determination is usually performed with the subject panting. The panting method was developed in part to reduce the effects of signal drift, small box leaks, and gradual thermal changes, but especially to eliminate the looping artifact caused by instantaneous changes in temperature and humidity of tidal air such as occurs in normal quiet breathing.2 This artifact is decreased because rapid shallow breathing retains within the pneumotachograph the interface between ambient plethysmograph air and the warm moist air of the patient. In addition, panting minimizes the effect of glottis size, abdominal pressure changes, and tidal lung volume change^.^ However, panting is not usual physiologic condition. The thoracic gas volume during panting differs from normal functional residual capacity. Rapid, shallow breathing may effect intra-pulmonary gas distribution, with gas following the pathway of least resistance. In subjects with bronchial obstruction, resistance may decrease with increasing respiratory frequencies. Panting may produce considerable alterations in PC02, either in the airways or systemically, affecting the resistance measurement. 2, Finally, the panting maneuver is difficult for some subjects to perform. Methods for plethysmographic determination of airway resistance a t quiet breathing have been devised. The artifact induced by by temperature and humidity may be reduced by having the subject re-breathe from an air bag maintained a t BTPS conditions. This procedure requires elaborate equipment and technical expertise and may produce further alterations due to CO, accumulation, variable compliance of the air bag, and other factors. As an alternative, it is possible to compensate for the artifact with loop closure by electronic means. 6 - 8 Because the measurement of airway resistance is rapidly becoming a routine determination in clinical laboratories, and because plethysmographs with electronic compemation are being commercially marketed, studies assessing the use of these instruments and the comparability of
t Presented at the Southern Section, American Federation for Clinical Research, New Orleans, Louisiana, January 31, 1975. *Assistant Professor and Director, Pulmonary Division, University of Texas Medical School, Houston, Texas. ** Fellow, Pulmonary Division, University of Texas Medical School, Houston, Texas. 137
138
WARREN C . MILLER AND WARREN W. SIMI
this technique are needed. We have recently evaluated the clinical application of the quiet breathing method with electronic simulation of BTPS conditions and compared i t to the panting procedure.
Downloaded by [UQ Library] at 09:53 08 May 2016
Materials and Methods Airway resistance (Raw) and thoracic gas volume (Vtg) were measured in a constant-volume body plethysmograph (Cardiopulmonary Instruments Model 2000) providing capabilities for determination of airway resistance a t panting (RawP) by the method of Dubois, et a12 a n d a t quiet breathing (RawQB) with electronic compensation for temperature and humidity artifact similar to that first described by Bargeton et aL7 The plethysmograph technicians randomized the order and alternated the performance of the measurement so that non became unduly proficient in only one technique, nor was any aware of the others' results. Th e reported airway resistance, both a t panting and quiet breathing, represents the average of three measurements each. At the end of the study the technicians were queried with regard to the ease a n d efficiency of the two methods. In order to compensate for differences in the lung volume at which airway resistance was measured, specific resistance (SRaw) was calculated: SRaw QB = RawQB X FRC, SRawP = RawP X Vtg. Spirometry was performed on a waterless, low resistant, piston-displaced, electronic spirometer (Cardiopulmonary Instruments model #840). Normal values for FEVJFVC ratio were those of Berglung, et aL9 One hundred non-selected patients presenting to our laboratory in a routine fashion formed the subjects of the study. They were consecutive except for six, who were unwilling or unable to cooperate for complete plethysmographic measurements. They were later divided into two groups. T h e first group included those whose FEVJFVC ratio was greater than, or equal to, 90 percent predicted and, therefore, presumably had minimal or no airway obstruction. The second group were those with moderate to severe obstruction as demonstrated by an FEVJFVC ratio less than 90 percent predicted. Regression, correlation, Student t-test for paired variables, a n d other statistical analysis of the data were performed by computer (IBM Remote Access Statistical System). Results The mean values of RawP, RawQB, S RawP, and S RawQB for all subjects are shown in the table. Although there is excellent correlation between RawP TABLE Mean Values for Resistance and Specific Resistance
.
All subjects
RawQB RawP SRawQB SRawP
* Standard Deviation
2.99 (2.48)* 2.45 (1.48) 14.4 (17.6) 13.0 (13.2)
Minimal obstruction
Significant obstruction
1.72 (.60) 1.65 (.48) 6.26 (3.50) 6.60 (2.49)
3.39 (2.22) 2.75 (1.53) 19.8 (17.7) 18.0 (14.2)
CLINICAL APPLICATION OF QUIET BREATHING AIRWAY RESISTANCE
139
and RawQB ( r = .913, regression: RawQB = 1.58RawP .70, SEE = 1.16), it is apparent th at the quiet breathing method yields a mean resistance 18 percent higher than panting. Because resistance is related to lung volume in a hyperbolic fashion, and because in our subjects the volume a t panting was a mean of 0.53 liters greater than the volume a t quiet breathing, it is likely th a t a part of the increased RawQB reflects measurement a t a lower lung volume. When SRaw is computed to obviate the effects of volume, a n even better correlation is obtained (r = .951, regression SRawQB = 1.27SRawP - 2.09, SEE = 6.15). Nevertheless, the mean SRawQB is 11 percent greater than mean SRawP. When the data were analyzed by subgroups, it was found that the patients with little or no airway obstruction by spirometry had no significant difference between RawP and RawQB, or between SRawP and SRawQB by paired t-testing. Mean SRawP was actually slightly but insignificantly higher than Downloaded by [UQ Library] at 09:53 08 May 2016
~
90-
80-
70-
60-
0
50-
z
a
UJ
40-
-
30
0
20-
e
*
10-
e
" @
- 0 0
e e
* e I
I
10
I
20
I
30
I
I
1
40
50
60
i
S Raw P
FIG. Individual values for SRawQB and SRawP in subjects with established obstructive lung disease.
140
WARREN C. MILLER AND WARREN
W.
SIMl
Downloaded by [UQ Library] at 09:53 08 May 2016
SRawQB (6.60 versus 6.26 respectively). T h e patients with moderate to severe obstruction demonstrated statistically significant differences in RawP and RawQB, and SRawP and SRawQB ( p < .01). SRaw in obstructed subjects is shown in t he figure. Universally, the technicicans preferred the quiet breathing technique as being less time-consuming in performance, allowing measurement in subjects who cannot seem to perform the panting maneuver reproductibly, and requiring less calculation. A separate computation of thoracic gas volume apart from FRC is not necessary.
Discussion In our patients without significant airway obstruction, the resistance measurements a t panting an d quiet breathing were essentially interchangeable. This is compatible with previous studies in normal subjects utilizing an air bag system" and the minimal frequency dependence of resistance found in normal subjects (Whol, M.E., Gross, P., and Mead, J., unpublished observations cited by Grimby, et al"). However, Jaeger and Otis have described increased airway resistance at quiet breathing in normal subjects. l 2 This discrepancy may be d u e to difference in experimental technique, i.e. the use of a volume displacement plethysmograph. In our subjects with obvious airway obstruction, although good correlation exists between panting and quiet breathing methods, the measured airway resistance is greater by the quiet breathing technique. Similar studies in patients with obstructive lung disease have demonstrated this difference. l 3 The reasons for this finding remain unclear. Although the size of the glottis may play a role, l 4 it seems insufficient to account for the magnitude of the difference in measured airway resistance.13 It is not observed in relatively normal subjects. Respiratory frequency may be the prime determinant. Frequency dependence of resistance has been demonstrated by forced oscillations in patients with obstructive lung disease." Regardless of the etiology of the differences between panting and quiet breathing methods, in subjects with little or no airway obstruction, the two techniques appear interchangeable, and in patients with obstructive lung disease, they are well correlated. From a purely practical standpoint the quiet breathing method with electronic simulation of BTPS conditions is easier for the subject and the technician. I t permits resistance measurements in those subjects unable to pant and provides increased efficiency in a high volume clinical laboratory. References 1. COHEN,B. M., AND MCILREATH, F. J. Airway resistance measurements in the internists office, J. Asthma Res. 6:23, 1968. 2. DUBOIS,A. B., BOTHELHOK, S. Y., AND COMROE, J. H., J R . A new method for measuring airway resistance in man using a body plethysmograph. Values in normal subjects and in patients with respiratory disease, J . Clin. Invest 35:326, 1956. 3. DUBOIS,A. B., in progress, in Respiration Research, Vol. 4. International symposium on body plethysmography: Nijmegen, 1968, Karger, N.Y., 1969, p. 109.
CLINICAL APPLICATION OF QUIET BREATHING AIRWAY RESISTANCE
141
4. OTIS, A. B., MCKERROW, C. B., BARTLETT, R. A,, MEAD,J., MCILROY, M. B., SELVERSTONE, J.
J., AND RADFORD, E. P., JR. Mechanical factors in distribution of pulmonary ventilation, J. Appl Physiol. 8:427, 1956. 5. CUTILLO,A,, OMBORI,E., PERONDI, R., AND TANA, F. Effect of hypocapenia on pulmonary mechanics in normal subjects and in patients with chronic obstructive lung disease, Amer. Reu. Resp. Dis. 110:25, 1974. 6. WOITOWITZ, H. J . , GUNTHER, AND WOITOWITZ, R. In progress, in Respiration Research, Vol. 4, International symposium on body plethysmography, Nijmegen, 1968, Karger, N.Y., 1969, p. 50. 7. BARGETON, D., BARRES,G., LEFEBURE DES NOETTES, R., AND GAUGE,0. Mesure de la resistance des voies aeriennes de l’homme dans la respirat,ion normale, J . Physiol. Paris 49:37, 1957. 8. SMIDT,U., NUYSERS,K., A N D BUCHHEIN, W. In progress, in Respiration Research, Vol. 4, International symposium on body plethysmography, Nijmegen 1968, Kargen, N.Y., 1969, p. 36. 9. BERGULUND, E., BIRATH,G., BJURE, J., GRIMBY,G., KJELLMER,I., SANDQUIST, L., AND SODERHOLM, B. Spirometric studies in normal subjects, Acta Med. Scand. 273:185, 1963. P. H., AND TAMMELING, G. J . In progress, in Respiration Research, Vol. 10. PESET,R., QUANJER, 4, International symposium on body plethysmography, Nijmegen, 1968, Karger, N.Y., 1969, p. 215. 11. GRIMBY, G., TASKISHIMA, T., GRAHAM, W., MACKLEM, P., ANDMEAD, J . Frequency dependence of flow resistance in patients with obstructive lung disease J. Clin. Inuest. 47:1455, 1968. 12. JAEGER, M . J., AND OTIS,A. B. Measurement of airway resistance with a volume displacement body plethysmograph J . Appl. Physiol. 29:813, 1964. 13. BARTER, C. E., A N D CAMPBELL, A. H. Comparison of airways resistance measurements during panting and quiet breathing. Respiration, 30:l, 1973. 14. STANESCU, D. C., PATTIJM, J., CLEMENT, J., A N D VANDE WOESTIJNE, K. P. Glottis opening and airway resistance. J. Appl. Physiol., 32460, 1972.
Downloaded by [UQ Library] at 09:53 08 May 2016
w.,
ANNOUNCEMENT The Asthmatic Children’s Foundation Residential Treatment Centers provide convalescent care for children aged 5 to 13 years. The policy of the Asthmatic Children’s Foundation is to encourage admission of children with persistent asthma who fail to respond satisfactorily to allergy management, preferably before they become critical. Vacancies are periodically available. Admission can be arranged for periods of three months to two years. Patient care cost is defrayed by charitable contributions. For further information: Asthmatic Children’s Foundat.ion of New York 133 East 58th St.-Suite 310 New York, N. Y. 10022 Tel: 212-355-2872 Asthmatic Children’s Foundation of Florida 1800 N. E. 168th St., N. Miami Beach, Fla. 33162 Tel: 305-947-3445
