Chest wall circumference measurements are common evaluation methods in clinical settings by therapists in order to obtain chest wall mobility. Previous published results have been conflicting, and there is a lot of variability in the method of testing, which needs testing in different conditions. Seventy subjects (25 healthy nonsmokers, 25 healthy smokers, and 20 COPD) aged between 18 and 70 years participated in the study. Upper and lower chest expansion (CE) measurements (2 levels) are performed with cloth inch tape. Intrarater (between day) and interrater (within-day) reliability of CE measurements was evaluated by two examiners. Lung function parameters, forced expiratory volume in first second (FEV1), forced vital capacity (FVC), FEV1/FVC, and vital capacity (VC) were measured using a computerized spirometer (Spiro lab 3). The intrarater reliability for upper and lower CE showed
Noninvasive methods of monitoring respiratory function have gained increasing interest recently, particularly measures of chest wall movement [
Evaluation of chest wall mobility is considered the most important tool for assessing abnormal respiratory patterns at rest and during exercise. Noninvasive methods are required to determine respiratory patterns, as invasive methods affect respiratory movement patterns [
Measurement of CE was first described by Moll et al. in 1972 [
CE seems to be diverse and variable within healthy and diseased subjects, ranging from 4–7 cm in healthy subjects [
Previous studies were conducted to see the relationship between CE and pulmonary function [
Healthy nonsmokers and healthy smokers were recruited for this cross-sectional study from King Khalid University, Saudi Arabia. COPD patients with mild, moderate, and severe symptoms were recruited from government hospitals of the local town (study duration: January to August 2017). Healthy nonsmokers are subjects that have never attempted smoking cigarettes. Healthy smokers are regular smokers that smoke at least 15 cigarettes per day. Other inclusion criteria include absence of musculoskeletal disorders, respiratory and neuromuscular disease, and no other factors present that might alter respiratory biomechanics. Inclusion criteria for COPD patients include stable with no recent changes in medication, not requiring supplemental oxygen, not taking oral corticosteroids, and no exacerbations present for the preceding 5 weeks. Patients were excluded if any comorbidities were present, such as heart disease, bronchial asthma, bronchiectasis, pulmonary fibrosis, ankylosing spondylitis, and any chest wall deformities. The university ethics committee approved this study (REC # 2016-08-06), and all subjects who met the inclusion criteria read the instructions and signed a written informed consent prior to commencement of the study.
A measuring tape was used to measure CE in centimeters (cm) at two levels of the rib cage. For upper CE (Figure
Measurement procedure of (a) upper chest expansion and (b) lower CE.
The instructions given by the therapist to subjects during breathing was standardized. Prior to the thoracic measurements, subjects were asked to “inhale slowly and rhythmically through the nose against the inch tape to open up the lungs as much as you can,” and then the subjects were asked to “exhale through the mouth completely.” CE measurement was taken at the end of the inspiration and expiration cycles, while the subject was in a standing position with their arms at the side of their body. The examiner placed the “0” point of the measuring tape (starting tip) on the spinous process of the vertebrae. The tape was secured by the index finger of the examiner between the subject’s body and the tape without generating extra pressure (Figure
A computerized spirometer (Spiro lab 3; Medical International Research MIR, Italy) with a standard mouthpiece was used to measure the lung function following the guidelines of the American Thoracic Society (ATS). This computerized spirometer conducts the breathing tests and calculates an index of test quality and control. FVC, FEV1, FEV1/FVC, VC, and IC measurements are made with subjects in a sitting position. The computer then gives a functional interpretation with 11 possible levels following the ATS and European Respiratory Society (ERS) classification [
Prior to commencement of the testing, all subjects were familiarized with the test procedures and were allowed to do multiple trials prior to the testing. While performing spirometry, a mouthpiece made of cardboard without teeth grip was used, and the subject held the mouthpiece tightly with the nose closed with the nose clip. All subjects completed a minimum of three trials with the best (highest) test result kept for analysis. A minimum 3-minute rest was given between each trial. All the subjects were given the same instructions while performing the tests to avoid bias.
Statistical analyses were performed using SPSS 20.0 (IBM-SPSS Inc., Armonk, NY). The data were expressed as mean ± SD. One-way ANOVA was performed to see baseline characteristics and CE differences among three groups. Turkey Post hoc analysis was performed to know the respective difference of each group compared to the others. Intrarater and interrater reliability were assessed using intraclass correlation (ICC) agreement values (two-way mixed effects model, consistency definition) with 95% confidence interval (CI). For evaluating agreement between rater scores, Bland–Altman’s limits of agreements (LOA) was used [
Seventy subjects (25 healthy nonsmokers, 25 healthy smokers, and 20 COPD) aged between 18 and 70 years participated in the study. Anthropometric characteristics and lung function data for the study population are summarized in Table
Demographic and lung parameter characteristics of healthy nonsmokers, healthy smokers, and COPD patients.
Healthy nonsmokers ( |
Healthy smokers ( |
COPD patients ( |
| |
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Age (years) | 23.6 ± 5.3 | 23.6 ± 3.8 | 52.0 ± 13.7 | <0.001 |
BMI (kg/m2) | 24.1 ± 3.8 | 23.8 ± 4.9 | 29.5 ± 6.7 | 0.001 |
FEV1 (L) | 5.1 ± 0.6 | 4.2 ± 0.9 | 2.5 ± 0.8 | <0.001 |
FVC (L) | 5.1 ± 0.8 | 5.2 ± 1.0 | 3.0 ± 0.7 | <0.001 |
FEV1/FVC | 90.7 ± 3.6 | 88.0 ± 3.5 | 73.7 ± 5.6 | <0.001 |
VC (L) | 5.2 ± 1.0 | 4.8 ± 0.9 | 3.1 ± 1.0 | <0.001 |
COPD = chronic obstructive pulmonary disease; BMI = body mass index; FEV1 = forced expiratory volume in 1 second; FVC = forced vital capacity. Values are mean ± SD unless otherwise indicated.
The mean upper CE in healthy nonsmokers ranged from 5.6 to 6.4 cm, in healthy smokers it ranged from 5.4 to 5.9 cm, and COPD subjects ranged from 3.7 to 4.4 cm (Table
Chest expansion values and difference between the groups.
Examiner A, first assessment | Examiner A, second assessment | Examiner B, first assessment | Examiner B, second assessment | ||||||
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Upper CE (cm) | Lower CE (cm) | Upper CE (cm) | Lower CE (cm) | Upper CE (cm) | Lower CE (cm) | Upper CE (cm) | Lower CE (cm) | ||
Healthy nonsmokers | Mean | 5.6 | 7.0 | 5.6 | 7.2 | 6.1 | 7.2 | 6.4 | 7.5 |
SD | 1.8 | 2.0 | 1.5 | 1.8 | 1.7 | 1.9 | 1.7 | 2.0 | |
Variance | 3.4 | 2.0 | 2.4 | 2.5 | 3.1 | 2.9 | 3.0 | 2.3 | |
Minimum | 2.1 | 2.5 | 2.2 | 2.6 | 2.4 | 2.6 | 2.3 | 2.5 | |
Maximum | 8.9 | 11 | 9.0 | 10.8 | 9.9 | 10.8 | 9.0 | 11.0 | |
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Healthy smokers | Mean | 5.4 | 7.7 | 5.9 | 7.5 | 5.9 | 7.6 | 5.5 | 8.0 |
SD | 0.8 | 2.6 | 0.8 | 1.6 | 0.8 | 1.5 | 1.0 | 1.2 | |
Variance | 0.7 | 2.0 | 0.7 | 2.6 | 0.7 | 2.3 | 1.0 | 1.6 | |
Minimum | 4.1 | 6.0 | 5.0 | 5.0 | 5.0 | 5.0 | 4.1 | 6.0 | |
Maximum | 7.3 | 10.3 | 8.0 | 11.0 | 7.7 | 11.0 | 7.9 | 10.8 | |
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COPD | Mean | 3.7 | 4.9 | 4.2 | 4.8 | 4.3 | 5.2 | 4.4 | 4.7 |
SD | 0.8 | 1.4 | 1.0 | 1.8 | 1.3 | 2.2 | 1.6 | 2.6 | |
Variance | 0.7 | 2.1 | 1.1 | 2.4 | 1.7 | 2.5 | 2.7 | 1.8 | |
Minimum | 1.8 | 2.1 | 1.6 | 2.2 | 1.8 | 2.2 | 2.0 | 2.1 | |
Maximum | 4.9 | 8.0 | 5.8 | 7.8 | 6.2 | 8.6 | 6.3 | 7.4 | |
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<0.001 | <0.001 | <0.001 | <0.001 | 0.001 | <0.001 | 0.040 | 0.011 |
The intrarater reliability for upper and lower CE showed
Intrarater and interrater reliability for upper and lower chest expansions.
ICC agreement | 95% CI | Mean diff._AB (SD) | SEM consistency | LOA | SDC | |
---|---|---|---|---|---|---|
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Upper chest expansion | 0.90 | 0.83–0.94 | −0.33 (0.80) | 0.88 | 1.23–1.89 | 2.43 |
Lower chest expansion | 0.86 | 0.78–0.91 | −0.01 (1.36) | 1.41 | 2.65–2.67 | 3.90 |
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Upper chest expansion | 0.93 | 0.89–0.95 | 0.80 (0.08) | 0.81 | −0.64–0.95 | 2.24 |
Lower chest expansion | 0.85 | 0.77–0.90 | −0.15 (1.05) | 1.45 | 1.90–2.20 | 4.01 |
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Upper chest expansion | 0.83 | 0.64–0.91 | −0.59 (1.03) | 1.18 | 1.42–2.60 | 3.27 |
Lower chest expansion | 0.84 | 0.74–0.90 | −0.38 (1.37) | 1.42 | 2.30–3.06 | 3.93 |
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Upper chest expansion | 0.78 | 0.66–0.86 | −0.18 (1.27) | 1.30 | 2.30–2.66 | 3.60 |
Lower chest expansion | 0.82 | 0.70–0.89 | −0.52 (1.52) | 1.59 | 2.45–3.49 | 4.40 |
95% CI = 95% confidence interval; ICC agreement = intraclass correlation coefficients. Mean diff_AB = mean difference between examiner A and B; SEM = standard error of measurement; LOA = limits of agreements; SDC = smallest detectable change.
Bland–Altman plots of intrarater reliability for upper (a, c) and lower (b, d) CE measurements by examiners A and B. The solid lines indicate the reference mean. The dotted lines indicate the upper and lower limits of agreement.
Overall, the interrater reliability for upper CE showed
Bland–Altman plots of interrater reliability for upper (a, c) and lower (b, d) CE measurements by examiners A and B. The solid lines indicate the reference mean. The dotted lines indicate the upper and lower limits of agreement.
Pearson correlation coefficients indicate positive correlations between CE values and lung function parameters (Figures
Relationship between upper CE measurement (cm) and (a) forced vital capacity (FVC), (b) forced expiratory volume in first second (FEV1), (c) FEV1/FVC, and (d) vital capacity (VC).
Relationship between lower CE measurement (cm) and (a) forced vital capacity (FVC), (b) forced expiratory volume in first second (FEV1), (c) FEV1/FVC, and (d) vital capacity (VC).
Coefficient of correlation between chest expansions and lung function parameters.
FVC | FEV1 | FEV1/FVC | VC | ||
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Upper CE | r | 0.678 | 0.595 | 0.785 | 0.668 |
p | <0.001 | <0.001 | <0.001 | <0.001 | |
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Lower CE | r | 0.611 | 0.557 | 0.689 | 0.658 |
p | <0.001 | <0.001 | <0.001 | <0.001 |
CE = chest expansion; VC = vital capacity; FVC = forced vital capacity; FEV1 = forced expiratory volume in 1 second (this table is reproduced from Debouche et al. [
To our knowledge, this study is first to demonstrate the reliability of chest wall measurements in healthy nonsmokers, healthy smokers, and COPD tested together and to confirm that chest wall measurement correlates with lung function. ICC showed that intra- and interrater reliability of upper and lower CE measurements was
Reliability studies are necessary to determine the variability of an assessment method. Knowing the variability of an assessment method is crucial to prevent interpretation errors when using an assessment to compare measures pre- and posttreatment (or other interventions). Previous studies have assessed the reliability of frequently performed tests and assessments in clinical practice and rehabilitation setups, such as walking tests, spirometry, quality of life, and others [
In this study, a wide range of upper and lower CE values was observed among subjects, indicating that there is variability in the measure. The same variability has been noted in previously published studies [
Upper and lower CE measurements in this study showed good intra- and interrater reliability. Previously published research on upper and lower levels of CE measurements have found good to very good intra- and interreliability, ranging from 0.69 to 0 0.93 and 0.64 to 0.95, respectively, with results statistically significant [
This study included subjects that were healthy nonsmokers, healthy smokers, and COPD; all were measured by two therapists to assess the coefficient of variability for CE, and good reproducibility was seen for both upper and lower CE measurements. The mean differences between therapists were 0.33 and 0.80 cm for upper CE, and 0.01 and 0.05 cm for lower CE. 0.18 cm and 0.59 cm between days. The mean between day differences of first and second assessment of upper and lower CE of examiner A was 0.59 cm and 0.38 cm and of examiner B was 0.18 cm and 0.52 cm. These small differences are within acceptable limits and are not statistically or clinically significant.
Monitoring the effects of treatment is of well-recognized importance and is the foundation of modern evidence-based health care. SDC and minimal clinically important difference (MCID) can be used as benchmarks for the interpretability of a CE to determine whether the observed change is beneficial to the patients. To determine whether a change score on an individual patient level is clinically important and not just measurement error, the SDC score must not exceed the MCID change score [
The results of this study shows upper and lower CE measurements significantly correlate with lung function parameters (FVC, FEV1, FEV1/FVC, and VC). The strongest correlation was between CE and FEV1/FVC (
This study used a standing position for measuring a subject’s upper and lower CE, as it is a similar position as those chosen in several previous studies although different positions have also been used [
In this study, all the subjects participated were male; the external validity may be compromised, considering the respiratory patterns among sex. In the present study, the ICC for intrarater and intertester reliability appears higher. This is, in part, possibly due to the method of calculation. The average from six trials of CE score on two occasions for each tester was used to calculate the reliability. According to Portney and Watkins, the ICC based on mean rating always shows higher reliability than one based on single ratings [
Upper and lower CE measurements taken with a measuring tape have good intra- and interrater reliability and reproducibility in healthy nonsmokers, healthy smokers, and COPD subjects. The reliability found in the present study can be credited to anatomical landmarks selected with standardized procedure. Though reliability is good, the usefulness of CE and its usefulness for interpreting disease progression and efficacy of intervention needs caution. Upper and lower CE measures correlated with lung function parameters measured by spirometer (FVC, FEV1, FEV1/FVC, and VC). Upper and lower CE may be more useful in clinical practice to evaluate chest mobility and to give indirect information on lung function, but interpretation with caution is required when considering implementation into clinical setting.
The data used to support the findings of this study are included within the supplementary information files.
The authors declare that they have no conflicts of interest.
This work was funded by a grant (G.R.P–136-39) from the King Khalid University, Abha, Saudi Arabia.
The Supplementary Materials file is the SPSS data set used to support the findings of this study.