Development of new measurement system of thoracic excursion with biofeedback: reliability and validity
- Yukiko Nishigaki1Email author,
- Hiroko Mizuguchi1,
- Eriko Takeda1,
- Tomokazu Koike1,
- Takeshi Ando2, 3,
- Kazuya Kawamura3,
- Takuro Shimbo4,
- Hidetoshi Ishikawa1,
- Masashi Fujimoto1,
- Ikuko Saotome1,
- Reiko Odo1,
- Kazuko Omoda1,
- Shohei Yamashita1,
- Tomoko Yamada1,
- Toshihito Omi1,
- Yuya Matsushita1,
- Manami Takeda1,
- Sawako Sekiguchi1,
- Saki Tanaka1,
- Masakatsu Fujie3,
- Haruhi Inokuchi5 and
- Junko Fujitani1
© Nishigaki et al.; licensee BioMed Central Ltd. 2013
Received: 10 March 2012
Accepted: 14 May 2013
Published: 20 May 2013
Respiratory rehabilitation reduces breathlessness from patient with respiratory dysfunction. Chest expansion score, which represents the circumference magnitude of the thoracic cage, is used for a target when treating patients with respiratory disease. However, it is often difficult for patients to understand the changes in the respiratory status and be motivated for therapy continuously. We developed a new measurement system with biofeedback named BREATH which shows chest expansion scores in real time. The purpose of this study was to determine the reliability and validity of the novel system in advance of clinical application.
Three evaluators measured chest expansion in 33 healthy individuals using tape measure, which is used for the measurement traditionally, and BREATH. The wire for BREATH system was threaded over the thoracic continuously and the data was recorded automatically; whereas the tape was winded and measured each maximal expiration and inspiration timing by evaluator. All participants were performed both measurement simultaneously for three times during deep breath. In this study, we studied chest expansion score without using biofeedback data of BREATH to check the validity of the result. To confirm intra- and inter-evaluator reliability, we computed intra-class correlations (ICCs). We used Pearson’s correlation coefficient to evaluate the validity of measurement result by BREATH with reference to the tape measure results.
The average (standard deviation) chest expansion scores for all, men and women by the tape measure were 5.53 (1.88), 6.40 (1.69) and 5.22 (1.39) cm, respectively, and those by BREATH were 3.89 (2.04), 4.36 (1.83) and 2.89 (1.66) cm, respectively. ICC within and among the three evaluators for BREATH and the tape measure were 0.90-0.94 and 0.85-0.94 and 0.85 and 0.82, respectively. The correlation coefficient between the two methods was 0.76-0.87.
The novel measurement system, BREATH, has high intra- and inter-evaluator reliabilities and validity; therefore it can lead us more effective respiratory exercise. Using its biofeedback data, this system may help patients with respiratory disease to do exercises more efficiently and clinicians to assess the respiratory exercise more accurately.
KeywordsRespiratory rehabilitation Chest expansion score Biofeedback Reliability
Respiratory rehabilitation reduces breathlessness from patients with respiratory dysfunction; i.e. chronic obstructive pulmonary disease (COPD) and postoperative respiratory dysfunction. In COPD patients, flat diaphragm and overexpanded lungs reduce the expansion efficiency of lower chest. Breathing muscle stretching exercise improves chest expansion ability and pulmonary function .
We measure chest expansion to assess the effect of treatment for patient with respiratory disease. There are some devices to measure chest expansion; i.e. spirometry or respiratory inductive plethysmograph, which can measure both chest and abdominal expansion . In Japanese guidelines for pulmonary rehabilitation, the chest expansion scores, representing the thoracic cage movement while breathing, are described as a standardized evaluation for the exercise of respiratory ailments . The score represents the circumference magnitude of the thoracic cage from maximum inhalation to maximum exhalation, which is measured by tape traditionally [3–5]. It is known that the chest expansion score of patient with COPD at the level of 10th rib height significantly improved after chest mobilization .
Biofeedback is known to be useful for re-education of the dysfunctional muscles. Past study shows that it is effective to perform respiratory rehabilitation with biofeedback to strengthen the muscles which control breathing [7–9]. Other studies suggest that respiratory rehabilitation with biofeedback helped ventilator weaning for patients with various disease [10–13].
Tape measurement of the chest expansion is generally performed during exercise in research or clinic, but it shows only temporary numerical value, which is difficult for subject or patient to interpret. Recently, new techniques for measuring the motion of the thoracic cage with biofeedback data have been developed [14, 15]; however, it is often difficult for subjects or patients to understand changes in the respiratory status and be motivated for therapy continuously by the data. Thus, to show clear-cut biofeedback data will become feasible for them if the differences in thoracic expansion is measured and visualized in real time with uncomplicated technique.
We developed a new measurement system with biofeedback, which displays chest expansion scores simply in real time . The purpose of the present study was to determine the reliability and validity of the novel system in advance of clinical application.
Chest expansion measurement device (BREATH)
The Institutional Review Board of our center had approved the study protocol. Each participant gave written informed consent prior to the study.
Healthy individuals from 20 to 60 years old with no history of lung or locomotor diseases were recruited for the study.
We measured the thoracic circumference by tape and BREATH. Participant was asked to wear a T-shirt and to seat comfortably. We chose tape measure as a comparison because it has been widely used in a clinical situation and can conduct simultaneously with BREARH measurement to check the validity. The wire was threaded over the thoracic continuously, whereas the tape was winded and measured each maximal expiration and inspiration timing. We placed the wire and the tape over the 10th rib edge to the sternum and wrapped them around the trunk horizontally. The height was chosen in regards of the past study result which showed the measurement result from the height had higher clinical value .
We randomized the order of two measurement methods; 16 participants underwent BREATH first, and the other 17 did the tape measure first. Before starting the measurement, all participants were instructed to “breathe as deeply as possible” and practiced to breath for several times. To check the validity of result from BREATH, they were blinded to the results of the test. The interval between each evaluation was at least 5 minutes to minimize participant’s fatigue among the study.
Three evaluators repeated measurements three times using both tape measurement and BREATH to all participants. Evaluator A had 6 years of experience as a physical therapist, and evaluators B and C had 2 and 10 years of experience, as occupational therapists, respectively. Each evaluator calculated and recorded chest expansion scores by tape measure data and by BREATH data. The evaluators were blinded to one another’s results.
We used two-sample t test to compare variables of men with those of women. To confirm the intra-evaluator reliability of the measurement result by each evaluator using tape measure and BREATH, the intra-class correlation coefficient (ICC) was computed. Similarly, the inter-evaluator reliability among the measurement results by all three evaluators was evaluated using ICC, computed from the average data of each evaluator. ICCs of >0.9, 0.8-0.9, 0.7-0.8, 0.6-0.7 and <0.6 were considered excellent, good, acceptable, marginal and unreliable, respectively .
The validity of measurement result by BREATH was evaluated using Pearson’s correlation coefficient with reference to the tape measure results. To visualize the validity, we also constructed a Bland-Altman plot in which the y axis showed the difference between both measurements and the x axis showed the average of both measurements . For all test, a p value < 0.05 was considered significant. All data were analyzed using IBM SPSS Statistics ver.19.
Characteristics of the participants
All (n = 33)
Men (n = 13)
Women (n = 20)
29.2 ± 7.7
28.1 ± 8.1
29.9 ± 7.6
166.6 ± 8.2
173.3 ± 6.4
162.2 ± 6.0
59.6 ± 11.5
68.0 ± 10.7
54.2 ± 8.3
21.4 ± 2.94
22.6 ± 3.30
20.5 ± 2.42
Chest expansion scores
Average chest expansion scores from three evaluators
All (n = 99)
Men (n = 39)
Women (n = 60)
Tape measure (cm)
5.53 ± 1.88
6.56 ± 1.80
4.86 ± 1.61
3.89 ± 2.04
5.00 ± 1.87
3.16 ± 1.82
Intra- evaluator reliability
Average chest expansion scores by each evaluator
3.46 ± 0.51
4.05 ± 0.44
4.14 ± 0.57
Tape measure (cm)
5.68 ± 0.51
5.44 ± 0.49
5.47 ± 0.62
Intra-evaluator reliability of BREATH and tape measure
Inter- evaluator reliability
The result from evaluator B, whose clinical experience was shorter than other two, did not differ from results from others. The ICCs among the three evaluators were 0.85 (95% confidence interval: 0.70-0.90) for BREATH and 0.82 (95% confidence interval: 0.73-0.92) for the tape measure, indicating that both measurement techniques were reliable.
Validity of BREATH compared with the tape measure
We developed the novel BREATH system that displays chest expansion scores in real time , and, thus, renders feasible training by visual biofeedback. Moreover, tasks such as calibration, measurement start and stop, and printing results can be easily performed with only three mouse clicks, which allow us to use it in a clinical setting. We got high reproducibility and reliability of BREATH and high validity compared with the conventional tape measure method. Though, there are some other devices to measure respiratory function , they have no visible biofeedback information. With its high validity as a measurement system and with its biofeedback data, BREATH would also help to increase efficacy of respiratory rehabilitation.
Intra- evaluator reliability for BREATH and tape measure was high, with ICC values of ≥0.8. The reproducibility and reliability of automated measurements taken by BREATH were higher than those obtained manually by the tape measure. We presume the high reliability of BREATH is due to the location invariance of the wire compared to the tape. As the tape was removed between each measurement, the position might be changed; whereas wire for BREATH was remained during all measurement. Therefore, we believe that BREARH can measure chest expansion score accurately regardless of the evaluator’s work experience.
We suggest that the chest circumference measured by BREATH describes more precise data than tape measurement. Although the values obtained by BREATH and the tape measure closely correlated, those by BREATH were lower with an average of -1.65 cm. We hypothesize the wire used in BREATH system fits more tightly to participant’s body than the tape used in the conventional method; therefore, it served smaller numerical values. The difference should be taken into account when we compare the results from both methods.
We think we should use chest expansion score from men and women data separately. In both measurements, men showed higher score than women. We presume that men have lager rib cage and larger magnitude than women.
We confirmed that our measurement system was feasible and, thus, chest expansion training would be more effective by using the system with biofeedback. We need further study using biofeedback system because we did not give biofeedback data for the participants in this study. The present results suggest a promising future for chest measurement system with biofeedback in respiratory rehabilitation. It would be important to compare BREATH and other measurement for respiratory function. Other limitation of the present study is that we included only healthy adults as participants and excluded elderly persons and patients with thoracic cage abnormalities. We should confirm the accuracy of measurement for such individuals before we use BREATH for routine clinical applications.
The novel biofeedback technology, BREATH, is reliable and valid and can lead us more effective respiratory exercise. This system may help patients with respiratory disease to do exercises more efficiently and clinicians to assess the respiratory exercise more accurately.
We sincerely thank all participants who took part in this study. And we thank the technical assistance of Faculty of Science and Engineering, Waseda University.
- Izumizaki M, Kakizaki F, Tanaka K, Homma I: Immediate effects of thixotropy conditioning of inspiratory muscles on chest wall volume in chronic obstructive pulmonary disease. Respir Care 2006, 51: 750-757.PubMedGoogle Scholar
- Leino K, Nunes S, Valta P, Takala J: Validation of a new respiratory inductive plethysmograph. Acta Anaesthesiol Scand 2001,45(1):104-111. 10.1034/j.1399-6576.2001.450116.xView ArticlePubMedGoogle Scholar
- The Japan Society for Respiratory Care and Rehabilitation, The Japanese Respiratory Society, The Japanese Association of Rehabilitation Medicine, and The Japanese Physical Therapy Association: Current condition of respiratory rehabilitation: Guidelines for pulmonary rehabilitation: manual for exercise and training. Tokyo, JAPAN; 2003:17-28. in JapaneseGoogle Scholar
- Bockenhauer SE, Chen H, Julliard KN, Weedon J: Measuring thoracic excursion: reliability of the cloth tape measure technique. J Am Osteopath Assoc 2007, 107: 191-196.PubMedGoogle Scholar
- Custers JW, Arets HG, Engelbert RH, Kooijmans FT, van der Ent CK, Helders PJ: Thoracic excursion measurement in children with cystic fibrosis. J Cyst Fibros 2005, 4: 129-133. 10.1016/j.jcf.2004.12.007View ArticlePubMedGoogle Scholar
- Kazuyuki T, Noriko S, Motoki I, Kawato S, Sekikawa K, Kawamata M, Oike T: The immediate effect of chest mobilization technique in patients with chronic obstructive pulmonary disease. Japanese physical therapy 2007,34(2):59-64. (in Japanese)Google Scholar
- Tawa H, Yonezawa Y, Maki H, Ogawa H, Ninomiya I, Sada K, Hamada S, Caldwell WMA wireless breathing-training support system for kinesitherapy. In Conference Proceeding of IEEE Eng Med Biol Soc:2–6Sept 2009; Minneapolis; Edited by 2009: 5178-5182Google Scholar
- Wade OL: Movements of the thoracic cage and diaphragm in respiration. J Physiol 1954, 124: 193-212.PubMed CentralView ArticlePubMedGoogle Scholar
- Riener R, Lünenburger L, Colombo G: Human-centered robotics applied to gait training and assessment. J Rehabil Res Dev 2006, 43: 679-694. 10.1682/JRRD.2005.02.0046View ArticlePubMedGoogle Scholar
- Gallego J, Perez de la Sota A, Vardon G, Jaeger-Denavit O: Electromyographic feedback for learning to activate thoracic inspiratory muscles. Am J Phys Med Rehabil 1991, 70: 186-190. 10.1097/00002060-199108000-00005View ArticlePubMedGoogle Scholar
- Gallego J, Perez de la Sota A, Vardon G, Jaeger-Denavit O: Learned activation of thoracic inspiratory muscles in tetraplegics. Am J Phys Med Rehabil 1993, 72: 312-317. 10.1097/00002060-199310000-00011View ArticlePubMedGoogle Scholar
- Delk KK, Gevirtz R, Hicks DA, Carden F, Rucker R: The effects of biofeedback assisted breathing retraining on lung functions in patients with cystic fibrosis. Chest 1993, 105: 23-28.View ArticleGoogle Scholar
- Corson JA, Grant JL, Moulton DP, Green RL, Dunkel PT: Use of biofeedback in weaning paralyzed patients from respirators. Chest 1979, 76: 543-545. 10.1378/chest.76.5.543View ArticlePubMedGoogle Scholar
- LaRiccia PJ, Katz RH, Peters JW, Atkinson GW, Weiss T: Biofeedback and hypnosis in weaning from mechanical ventilators. Chest 1985, 87: 267-269. 10.1378/chest.87.2.267View ArticlePubMedGoogle Scholar
- Holliday JE, Veremakis C, Chris V: Reduction in ventilator response to CO 2 with relaxation feedback during CO 2 rebreathing in normal adults. Chest 1999, 115: 1285-1292. 10.1378/chest.115.5.1285View ArticlePubMedGoogle Scholar
- Kössler W, Lahrmann H, Brath H, Wei T, Frank W, Wild M, Zwick H, Wanke T: Feedback-controlled negative pressure ventilation in patients with stable severe hypercapnic chronic obstructive pulmonary disease. Respiration 2000, 67: 362-366. 10.1159/000029531View ArticlePubMedGoogle Scholar
- Ando T, Kawamura K, Fujitani J, Koike T, Nishigaki Y, Mizuguchi H, Fujimoto M, Fujie M: Biofeedback effect of thracic excursion in chest expansion training. J Biomechanical Science and Engineering 2012, 7: 328-334. 10.1299/jbse.7.328View ArticleGoogle Scholar
- Bland JM, Altman DG: Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1986,1(8476):307-310.View ArticlePubMedGoogle Scholar
- Rankin G, Stokes M: Reliability of assessment tools in rehabilitation: an illustration of appropriate statistical analyses. Clin Rehabil 1998, 12: 187-199. 10.1191/026921598672178340View ArticlePubMedGoogle Scholar
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