Respiratory muscle training with NH for patients with chronic SCI
been published on the effects of NH training in patients
with chronic SCI with regard to their patient-reported
outcome measures (PROMs), which is a very important
aspect of patient-centred healthcare (7). Khazaeipour et
al. reported a high prevalence of depression in patients
with SCI (8). Postma et al. found that impaired respira-
tory function was associated with lower health-related
quality of life (9). We hypothesize that improving lung
function may also improve patients’ quality of life and
reduce levels of depression.
The aim of the present study was to investigate the
effects of NH training on quality of life, pulmonary
function and the incidence of respiratory symptoms in
patients with chronic SCI. Whether the improvements
were related to the neurological level of injury was
also examined.
METHODS
The study was approved by the ethics committee of Bei-
jing Rehabilitation Hospital of Capital Medical University
(Y20180012). In this single-centre preliminary randomized
controlled trial, patient recruitment was performed in June
2018 with consecutive inpatients who met the inclusion criteria.
Written informed consent was obtained from all patients prior
to the study. Patients with SCI with a time post-injury > 24
months and without regular respiratory muscle training prior
to study inclusion were included prospectively. Patients were
randomly assigned to either NH training or control groups,
using a computer-generated randomization table. Since limited
data were published on the effects of NH training in patients
with chronic SCI with regard to their level of depression, the
Table I. Demographics of patients in the normocapnic hyperpnoea
and control groups
Patient
Normocapnic
1
2
3
4
5
6
7
8
Mean
(SD)
Age, Height,
years cm
hyperpnoea
62.0
165.0
56.0
175.0
50.0
173.0
60.0
168.0
41.0
163.0
52.0
167.0
58.0
187.0
55.0
170.0
54.3
171.0
(6.6) (7.1)
Weight,
kg TSI,
Lesion
months level 62.0
70.0
76.0
65.0
67.0
80.0
85.0
90.0
74.4
(9.3) 48
47
60
56
39
32
27
40
43.6
(11.3) T12 (low)
C3–C4 (high)
C4–C6 (high)
T12 (low)
T9 (low)
T11 (low)
C6–C7 (low)
C2 (high)
high: low
3: 5 No
No
No
Yes
No
No
No
Yes
Y: N 2: 6
T10 (low)
T9 (low)
C4–C6 (high)
C5 (low)
C3–C4 (high)
T7 (low)
C4 (high)
C4 (high)
T11–T12
(low)
C5 (low)
high: low
4: 6 No
Yes
No
No
No
No
No
No
No
Control
1
2
3
4
5
6
7
8
9 53.0
52.0
48.0
55.0
63.0
52.0
34.0
56.0
54.0 170.0
173.0
165.0
178.0
714.0
175.0
173.0
170.0
175.0 65.0
59.0
55.0
83.0
90.0
65.0
72.0
70.0
77.0 27
24
53
50
32
45
28
43
26
10
Mean
(SD) 62.0
52.9
(8.0) 178.0
173.1
(3.8) 80.0
71.7
(10.5) 51
37.9
(11.6)
Smoking
No
Y: N 1: 9
TSI: time since injury; SD: standard deviation; C: cervical; T: thoracic.
617
sample size estimation was based on the difference in forced
vital capacity (FVC) reported with a delta of 0.12 L (5). A priori
power analysis determined that a sample size of 6 subjects in
each group with SCI was required to obtain a statistical power
of 0.80 (10). Considering possible drop out during the study, a
total of 18 patients were randomized (see Table I for detailed
demographics). For later data analysis, lesion level higher or
equal to the fourth cervical vertebrae was considered “high”
neurological level of injury. Other low cervical and thoracic
SCI were referred to as “low” lesion level.
The patients in the NH group performed the RMT for 15–20
min per day, 5 times a week for 4 weeks with Spirotiger (Idiag
AG, Volketswil, Switzerland). The patients hyperventilated
through partial re-breathing of ventilated air (50% forced vital
capacity (FVC)) and were supported by visual and acoustic
feedback of breathing volume and frequency. The workload
was adjusted during the training period to maintain a Borg CR-
10 score (11) of 5–6/10. The control group received no RMT.
Other rehabilitative programmes were performed identically
in both groups (1~2 times/day, 5 days/week), such as passive
range of movement (5 min/limb for all joints), mattress exercise
(including trunk rolling, sit-ups, moving on bed, etc., 10 min),
dynamic sitting balance (with increasing difficulty of catching
ball, 5 min), or upper limb functional training (upper limb mus-
cle power and endurance training, 20 min). The training was
conducted by physiotherapists, who had a Bachelor’s degree
and more than 5 years of clinical experience.
Lung function testing was performed in both groups in the
sitting position prior to and after the study (MasterScreen, Ca-
reFusion, Höchberg, Germany). In addition, patients were asked
to assess: the presence and severity of depressive symptoms,
using the Patient Health Questionnaire-9 (PHQ-9) (12); impact
on overall health, daily life, and perceived well-being, using the
St George’s Respiratory Questionnaire (SGRQ) (13); the global
impact on health status (due to cough, sputum, dyspnoea, chest
tightness), using the Chronic Obstructive Pulmonary Disease
Assessment Test (CAT) (14); and the level of perceived exertion
and shortness of breath, using the Borg score.
Data and statistical analysis
The primary endpoint was the differences in PHQ-9 between
NH and control groups. Exploratory endpoints included the
lung function and PROMs differences between groups (NH and
control) and between lesion levels (high and low).
Statistical analysis of the data was performed using the MAT-
LAB 7.2 statistic toolbox (The MathWorks Inc., Natick, MA,
USA). Due to the small sample size and a mix of ratio-scale
and ordinal-scale variables, non-parametric statistical methods
were applied. The values in each group are expressed as medians
and interquartile ranges. The differences in lung function and
PROMs changes between pre- and post-study within the same
groups were compared using the Wilcoxon signed-rank test.
Mann–Whitney U test was used to compare high and low lesion
levels. A p-value < 0.05 was considered statistically significant.
Bonferroni’s post-hoc test was used to modify p-values for
multiple comparisons.
RESULTS
All training sections were conducted as planned and no
adverse events were recorded. Patient demographics
for NH and control groups are summarized in Table
J Rehabil Med 51, 2019