Abstract
Background:
COPD causes, other than a not fully reversible airway obstruction, changes in the thoracic conformation and respiratory muscle structure, causing functional inefficiency. More specifically the diaphragm undergoes a progressive process of muscle fiber shortening that follows lung hyperinflation and dead space increase, resulting in a chronic mechanical disadvantage impairing its mobility. M-mode ultrasonography can measure directly the dome craniocaudal displacement. It can be a useful and safe tool to assess the diaphragmatic impairment in COPD subjects and verify the impact of lung hyperinflation and airway obstruction in the muscle mechanics. Objectives: To correlate the diaphragmatic mobility impairment to lung function loss according to COPD severity using M- mode Ultrasonography in moderate to very severe COPD subjects.
Methods:
We used M-mode ultrasonography to access diaphragmatic mobility during rest breathing and deep inspiration on 46 COPD individuals and 16 healthy subjects. Lung function tests were correlated to the diaphragmatic mobility during pulmonary rehabilitation.
Results:
The mean anthropometrics, lung function and diaphragmatic mobility in healthy individuals and COPD subjects are presented in the table. The diaphragmatic mobility during Rest Breathing and Deep Inspirations were correlated to FEV1 decrease (r=-0.74; P<0.01 and r=0.8; P<0.01, respectively). And the FEV1 % predicted (r=-0.74, with a p <0.001 for Rest Breathing) and (r= 0.796 with a P<0.001 for Deep Inspirations), n=45. The correlations were also positive between the Deep Inspiration and the IC (r= 0.64 with P<0.001) and the Expiratory Reserve Volume (r= 0.63 with P<0.001), n=45. (figure 4). The diaphragmatic mobility correlations between Rest Breathing and Deep Inspiration and the IC/TLC were both moderate and respectively negative (r=-0.51 with P<0.01) and positive (r=0.50 with P<0.01).
Conclusions:
M-mode ultrasonography showed that diaphragmatic mobility impairment correlates to lung function loss in COPD subjects.
PR: Pulmonary rehabilitation; Yrs: years; *p=0.05, ¥p=0.02, βp=0.02, †p<0.001 for Student t test to compare COPD severity subgroups to healthy individuals. View all access options for this article.Table
Healthy Individuals
All COPD subjects
GOLD 2
GOLD 3
GOLD 4
Subjects (female)
15(9)
46(11)
6(0)
13(6)
11(1)
Age yrs
34±9
72 ±10
76.5±7
70±8
65±15
Weight Kg
74±32
61.5±11.5
71.2±13.7
62±15
57.8±10.6
Height m
1.62±26
1.62± 9.3
1.66±9
1.60±8
1.61±7.5
BMI Kg.m-2
22±6
23.5±4.3
25.8±5.5
24.1±5
22±4.5
FVC % pred
106±30
72±17
88.6±8.6
71.4±12.8
57±13
FEV1 L
4.04±1.36
0.88±0.36
1.46±0.2
0.82±0.1
0.5±0.1
FEV1 % pre
103±30
40.6±16
60±7
38.5±5.7
21.7±4
ERV L
1.28±0.55
0.76±0.31*
0.96±0.4*
0.67±0.3*
0.8±0.3*
RV %pred
115±45
208±75
186±40.6
212±65
262±83
IC L
3.26±1.01
1.54±0.41*
2.19±0.3¥
1.53±0.3†
1.24±0.2†
IC/TLC (%)
47.5±8
22.6±7
28.2±5
23.9±5
16.7±3
Diaphragmatic MobilityRest Breathing (mean) cm
1.27±0.3
2.09±0.8
2.74±0.7†
1.95±0.8β
2.52±0.6†
Diaphragmatic MobilityDeep Inspiration cm
6.93±1.15
4.75±1.58
5.61±1.6*
4.4±1.7†
4.6±2β
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