systematic review of the effectiveness of breathing...
TRANSCRIPT
789
Review
www.expert-reviews.com ISSN 1747-6348© 2011 Expert Reviews Ltd10.1586/ERS.11.69
Complementary and alternative medicine (CAM) has been defined as “a broad domain of healing resources that encompasses all health systems, modalities and practices and their accompanying theories and beliefs, other than those intrinsic to the politically dominant health system of a particular society or culture in a given historical period” [1]. CAM is popular in the general community for the self-manage-ment of asthma. Between 20–30% of adults and 50–60% of children have been identified in more rigorously designed studies as having used CAM for asthma yet approximately half of CAM users do not inform their general prac-titioner of their CAM use [2]. Breathing retrain-ing, a popular form of CAM, is the subject of this review.
Prominent among breathing retraining thera-pies is the Buteyko breathing technique (BBT), based on the work of Konstantin Buteyko [3].
Buteyko theorized that hyperventilation was the pathological basis of many diseases including asthma, suggesting that hypocapnia consequent to hyperventilation initiates bronchospasm, and patented a formula based on breath-hold time which, he claimed, predicted end-tidal CO
2
[201]. BBT utilizes shallow, controlled breathing and respiratory pauses in an attempt to increase alveolar and arterial CO
2 tension, which BBT
proponents suggest may reverse bronchospasm. Other breathing retraining techniques
forming part of CAM include yoga, biofeed- yoga, biofeed-back and respiratory muscle training. Yoga techniques include deep-breathing exercises (pranayama), postures (asanas), mucus expec-toration (kriyas), meditation, prayer and often dietary changes to reduce asthma symptoms. Biofeedback aims to reduce symptoms through gain of voluntary control over autonomic pro-cesses. Direct biofeedback training consists of
John Burgess1, Buddhini Ekanayake1, Adrian Lowe1, David Dunt2, Francis Thien3 and Shyamali C Dharmage*1
1Centre for Molecular, Environmental, Analytic and Genetic Epidemiology, Melbourne School of Population Health, The University of Melbourne, Victoria 3010, Australia 2Centre for Health Program Evaluation, Melbourne School of Population Health, The University of Melbourne, Victoria 3010, Australia 3Department of Respiratory Medicine, Box Hill Hospital and Monash University, Nelson Road, Box Hill, Victoria 3138, Australia *Author for correspondence: [email protected]
In asthma management, complementary and alternative medicine is enjoying a growing popularity worldwide. This review synthesizes the literature on complementary and alternative medicine techniques that utilize breathing retraining as their primary component and compares evidence from controlled trials with before-and-after trials. Medline, PubMed, Cumulative Index to Nursing and Allied Health Literature and the Cochrane Library electronic databases were searched. Reference lists of all publications were manually checked to identify studies not found through electronic searching. The selection criteria were met by 41 articles. Most randomized controlled trials (RCTs) of the Buteyko breathing technique demonstrated a significant decrease in b2-agonist use while several found improvement in quality of life or decrease in inhaled corticosteroid use. Although few in number, RCTs of respiratory muscle training found a significant reduction in bronchodilator medication use. Where meta-analyses could be done, they provided evidence of benefit from yoga, Buteyko breathing technique and physiotherapist-led breathing training in improving asthma-related quality of life. However, considerable heterogeneity was noted in some RCTs of yoga. It is reasonable for clinicians to offer qualified support to patients with asthma undertaking these breathing retraining techniques.
Keywords: asthma • Buteyko breathing technique • complementary medicine • respiratory muscle retraining • systematic review
Systematic review of the effectiveness of breathing retraining in asthma managementExpert Rev. Respir. Med. 5(6), 789–807 (2011)
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790
Review
Expert Rev. Respir. Med. 5(6), (2011)
Tab
le 1
. Ran
do
miz
ed c
on
tro
lled
tri
als
of
bre
ath
ing
mo
difi
cati
on
tec
hn
iqu
es.
Stu
dy†
(yea
r)Sa
mp
leD
esig
nIn
terv
enti
on
Wit
hd
raw
als
Follo
w-u
pD
iffe
ren
ce b
etw
een
gro
up
s(i
nte
rven
tio
n v
s co
ntr
ol)
Ref
.
Bow
ler
et a
l. (1
998
)39
com
mun
ity
volu
ntee
rs w
ith
asth
ma
RCT
True
ran
dom
izat
ion
Dou
ble
blin
d
1-w
eek
trai
ning
with
Bu
teyk
o re
pres
enta
tive
vers
us r
elax
atio
n an
d as
thm
a ed
ucat
ion
2 (1
inte
rven
tion,
1
cont
rol)
12 w
eeks
↓ M
V: 3
.6 l/
min
(p =
0.0
04
)↓
b 2-ag
onis
t: 8
47 µ
g/d
ay (p
= 0
.002
)↑
AQ
OL
scor
e (p
tre
nd =
0.0
9)
No
betw
een-
grou
p di
ffer
ence
in P
EF o
r FE
V1
No
chan
ge in
ETC
O2
in e
ither
gro
up
[12]
Opa
t et
al.
(20
00
) 36
com
mun
ity
volu
ntee
rs w
ith
asth
ma
RCT
Sam
ple
size
est
imat
eTr
ue r
ando
miz
atio
n
4 w
eeks
BBT
tra
inin
g vi
deo
vers
us n
atur
e vi
deo
84
wee
ks↑
AQ
OL:
-1.2
9 fo
r to
tal s
core
(p =
0.0
43)
↓ b 2-
agon
ist:
210
µg
/day
(p =
0.0
08
)[20]
Thom
as e
t al
. (2
003
)33
vol
unte
ers
with
as
thm
a/dy
sfun
ctio
nal
brea
thin
g
RCT
Sam
ple
size
est
imat
eTr
ue r
ando
miz
atio
n
2 w
eeks
ret
rain
ing
with
ph
ysio
ther
apis
t ve
rsus
nu
rse-
led
asth
ma
educ
atio
n
5 (1
inte
rven
tion,
4 co
ntro
l [3
at
6 m
onth
s])
1 an
d 6
mon
ths
At
1 m
onth
: ↑ A
QLQ
tot
al s
core
‡
At
6 m
onth
s: ↑
AQ
LQ a
ctiv
ities
sco
re‡
At
6 m
onth
s: ↓
Nijm
egen
sco
re‡
[22]
Coo
per
et a
l. (2
003
)89
com
mun
ity
volu
ntee
rs w
ith
asth
ma
RCT
Sam
ple
size
est
imat
eTr
ue r
ando
miz
atio
nD
oubl
e bl
ind
2 w
eeks
BBT
with
ce
rtifi
ed p
ract
ition
er
veru
ss P
CLE
or
plac
ebo
20 (7
inte
rven
tion,
6
PCLE
, 7 p
lace
bo)
6 m
onth
s↓
sym
ptom
sco
res
by t
wo
poin
ts (p
= 0
.003
)↓
b 2-ag
onis
t: t
wo
puff
s/da
y (p
= 0
.005
)N
o be
twee
n-gr
oup
diff
eren
ce in
FEV
1, IC
S us
e, a
sthm
a ex
acer
batio
ns o
r A
QLQ
sco
res
[15]
McH
ugh
et a
l. (2
003
)
38 c
omm
unit
y vo
lunt
eers
with
as
thm
a
RCT
Sam
ple
size
est
imat
eTr
ue r
ando
miz
atio
nD
oubl
e bl
ind
1-w
eek
BBT
with
But
eyko
re
pres
enta
tive
vers
us
asth
ma
educ
atio
n
46
wee
ks,
3 m
onth
s,6
mon
ths
↓ b 2-
agon
ist
6 w
eeks
; 38%
bet
wee
n-gr
oup
diff
eren
ce§
3 m
onth
s: 3
5% b
etw
een-
grou
p di
ffer
ence
§
↓ IC
S 6
wee
ks: 2
4% b
etw
een-
grou
p di
ffer
ence
§
3 m
onth
s: 3
4% b
etw
een-
grou
p di
ffer
ence
§
6 m
onth
s: 5
1% b
etw
een-
grou
p di
ffer
ence
§
No
diff
eren
ce in
lung
fun
ctio
n
[16]
Slad
er e
t al
. (2
00
6)
57 c
omm
unit
y vo
lunt
eers
with
as
thm
a
RCT
Sam
ple
size
est
imat
eTr
ue r
ando
miz
atio
nD
oubl
e bl
ind
28 w
eeks
BBT
tau
ght
by
vide
o ve
rsus
28
wee
ks
non-
spec
ific
uppe
r bo
dy
exer
cise
s ta
ught
by
vide
o
7 (3
inte
rven
tion,
4
cont
rol)
12 a
nd
28 w
eeks
↑
b 2-ag
onis
t-fr
ee d
ays
at 1
2 w
eeks
in b
oth
grou
ps c
ompa
red
with
bas
elin
e (p
< 0
.001
) N
o be
twee
n-gr
oup
diff
eren
ce in
b2-
agon
ist-
free
day
s at
12
or 2
8 w
eeks
↓
ICS
use
(50%
) in
each
gro
up a
t 13
wee
ks
com
pare
d w
ith b
asel
ine
(p <
0.0
001
) N
o lu
ng f
unct
ion
or E
TCO
2 ch
ange
[17]
† Stu
dies
list
ed in
ord
er o
f ye
ar o
f pu
blic
atio
n.‡ A
ll p
-val
ues
<0.
02.
§A
ll p
-val
ues
<0.
04.
↑: In
crea
se in
↓: D
ecre
ase
in; A
CT:
Air
way
con
trol
tes
t; A
QLQ
: Ast
hma
Rela
ted
Qua
lity-
of-L
ife Q
uest
ionn
aire
; AQ
OL:
Ast
hma-
rela
ted
qual
ity
of li
fe; B
BT: B
utey
ko b
reat
hing
tec
hniq
ue; B
T: B
reat
hing
tra
inin
g;
CC
MA
S: C
hine
se C
hild
ren’
s M
anife
st A
nxie
ty S
cale
; ETC
O2:
End
tid
al c
arbo
n di
oxid
e; F
EV1:
For
ced
expi
rato
ry v
olum
e in
1 s
; GA
SCC
: Gen
eral
Anx
iety
Sca
le f
or C
hine
se C
hild
ren
; HA
D: H
ospi
tal A
nxie
ty a
nd
Dep
ress
ion
Que
stio
nnai
re; I
CS:
Inha
led
cort
icos
tero
id; M
AQ
OLQ
: Min
i Ast
hma
Qua
lity-
of-L
ife q
uest
ionn
aire
(Jun
iper
); M
V: M
inut
e vo
lum
e; N
Q: N
ijmeg
en q
uest
ionn
aire
; PC
LE: P
ink
Cit
y Lu
ng E
xerc
iser
; PEF
: Pea
k ex
pira
tory
flow
; PEF
R: P
eak
expi
rato
ry fl
ow r
ate;
RC
T: R
ando
miz
ed c
ontr
olle
d tr
ial;
SF-3
6v2
PC: S
hort
For
m-3
6 ve
rsio
n 2
Hea
lth S
urve
y ph
ysic
al c
ompo
nent
; SG
RQ: S
t G
eorg
e Re
spira
tory
Que
stio
nnai
re.
Burgess, Ekanayake, Lowe, Dunt, Thien & Dharmage
www.expert-reviews.com 791
ReviewTa
ble
1. R
and
om
ized
co
ntr
olle
d t
rial
s o
f b
reat
hin
g m
od
ifica
tio
n t
ech
niq
ues
(co
nt.
).
Stu
dy†
(yea
r)Sa
mp
leD
esig
nIn
terv
enti
on
Wit
hd
raw
als
Follo
w-u
pD
iffe
ren
ce b
etw
een
gro
up
s(i
nte
rven
tio
n v
s co
ntr
ol)
Ref
.
Hol
low
ay e
t al
.(2
007
) 85
sub
ject
s w
ith
mild
or
wel
l- co
ntro
lled
asth
ma
recr
uite
d fr
om
sem
irura
l gen
eral
pr
actic
e
RCT
Sam
ple
size
est
imat
eTr
ue r
ando
miz
atio
n
Five
1-h
ses
sion
s
phys
ioth
erap
y (P
apw
orth
m
etho
d) p
lus
usua
l tr
eatm
ent
vers
us u
sual
tr
eatm
ent
13 (7
inte
rven
tion,
6
cont
rol)
6 an
d 12
mon
ths
↓ SG
RQ s
ympt
om s
core
at
6 an
d 12
mon
ths:
be
twee
n-gr
oup
diff
eren
ce 8
.6 p
oint
s (p
= 0
.007
) ↓
HA
D a
nxie
ty s
core
at
6 an
d 12
mon
ths:
be
twee
n-gr
oup
diff
eren
ce 1
.5 p
oint
s (p
= 0
.00
6)
↓ H
AD
dep
ress
ion
scor
e at
12
mon
ths:
be
twee
n-gr
oup
diff
eren
ce 0
.5 p
oint
s (p
= 0
.03
)↓
NQ
tot
al s
core
at
6 an
d 12
mon
ths:
be
twee
n-gr
oup
diff
eren
ce 2
.3 p
oint
s (p
= 0
.015
)N
o be
twee
n-gr
oup
diff
eren
ce in
lung
fu
nctio
n at
eith
er f
ollo
w-u
p
[19]
Meu
ret
et a
l.(2
007
)12
adu
lts
with
as
thm
a re
crui
ted
by a
dver
tisem
ent
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
Cap
nom
etry
-ass
iste
d br
eath
ing
retr
aini
ng p
lus
usua
l tre
atm
ent
vers
us
usua
l tre
atm
ent
Non
e8
wee
ks in
in
terv
entio
n gr
oup
(n =
8)
In in
terv
entio
n gr
oup:
↓ A
CQ
sco
re (p
< 0
.05)
↓ St
een
asth
ma
sym
ptom
sco
re (p
< 0
.01)
↓ PE
F va
riabi
lity
(p <
0.0
5)N
o ch
ange
in F
EV1
[13]
Cow
ie e
t al
. (2
00
8)
129
subj
ects
fro
m
univ
ersi
ty-b
ased
as
thm
a pr
ogra
m
RCT
Sam
ple
size
est
imat
eTr
ue r
ando
miz
atio
n
Five
ses
sion
s of
BBT
fro
m
accr
edite
d pr
actit
ione
r ve
rsus
five
ses
sion
s of
BT
from
phy
siot
hera
pist
11 (
9 in
terv
entio
n,
2 co
ntro
l)3
and
6 m
onth
sA
t 6
mon
ths:
↑ in
ast
hma
cont
rol (
79 v
s 72
% c
ontr
olle
d)
but
no b
etw
een-
grou
p di
ffer
ence
(p =
0.4
)↑
MA
QO
LQ s
core
s sa
me
in b
oth
grou
ps
(0.9
6 vs
0.9
5)↓
ICS
use:
317
vs
56 µ
g/d
ay (p
= 0
.02)
[21]
Thom
as e
t al
.(2
009
)18
3 ge
nera
l pr
actic
e as
thm
a pa
tient
s w
ith
mod
erat
e ↓
AQ
LQ
scor
e
RCT
True
ran
dom
izat
ion
Phys
ioth
erap
ist-
supe
rvis
ed B
T ve
rsus
nu
rse-
led
asth
ma
educ
atio
n
14 B
T an
d 8
cont
rol f
ollo
win
g ra
ndom
izat
ion.
Fu
rthe
r 7
BT a
nd
2 co
ntro
l did
not
at
tend
1-m
onth
fo
llow
-up
1 an
d 6
mon
ths
↑ A
QLQ
tot
al s
core
: bet
wee
n-gr
oup
diff
eren
ce 0
.38
unit
s at
6 m
onth
s.↓
NQ
sco
re, ↓
HA
D a
nxie
ty a
nd d
epre
ssio
n sc
ores
at
6 m
onth
s(A
ll be
twee
n-gr
oup
diff
eren
ce p
≤ 0
.03
) N
o be
twee
n-gr
oup
diff
eren
ce in
FEV
1, M
V o
r ET
CO
2 at
1-m
onth
fol
low
-up
[14]
† Stu
dies
list
ed in
ord
er o
f ye
ar o
f pu
blic
atio
n.‡ A
ll p
-val
ues
<0.
02.
§A
ll p
-val
ues
<0.
04.
↑: In
crea
se in
↓: D
ecre
ase
in; A
CT:
Air
way
con
trol
tes
t; A
QLQ
: Ast
hma
Rela
ted
Qua
lity-
of-L
ife Q
uest
ionn
aire
; AQ
OL:
Ast
hma-
rela
ted
qual
ity
of li
fe; B
BT: B
utey
ko b
reat
hing
tec
hniq
ue; B
T: B
reat
hing
tra
inin
g;
CC
MA
S: C
hine
se C
hild
ren’
s M
anife
st A
nxie
ty S
cale
; ETC
O2:
End
tid
al c
arbo
n di
oxid
e; F
EV1:
For
ced
expi
rato
ry v
olum
e in
1 s
; GA
SCC
: Gen
eral
Anx
iety
Sca
le f
or C
hine
se C
hild
ren
; HA
D: H
ospi
tal A
nxie
ty a
nd
Dep
ress
ion
Que
stio
nnai
re; I
CS:
Inha
led
cort
icos
tero
id; M
AQ
OLQ
: Min
i Ast
hma
Qua
lity-
of-L
ife q
uest
ionn
aire
(Jun
iper
); M
V: M
inut
e vo
lum
e; N
Q: N
ijmeg
en q
uest
ionn
aire
; PC
LE: P
ink
Cit
y Lu
ng E
xerc
iser
; PEF
: Pea
k ex
pira
tory
flow
; PEF
R: P
eak
expi
rato
ry fl
ow r
ate;
RC
T: R
ando
miz
ed c
ontr
olle
d tr
ial;
SF-3
6v2
PC: S
hort
For
m-3
6 ve
rsio
n 2
Hea
lth S
urve
y ph
ysic
al c
ompo
nent
; SG
RQ: S
t G
eorg
e Re
spira
tory
Que
stio
nnai
re.
Systematic review of the effectiveness of breathing retraining in asthma management
792
Review
Expert Rev. Respir. Med. 5(6), (2011)
‘rewards’ (visual or auditory signals) if the subject maintains a measured respiratory parameter within predetermined limits. Respiratory muscle training aims to strengthen muscles to meet the increased work of breathing in asthma.
A Cochrane review updated in 2004 analyzed evidence for some of these techniques [4]. The review included only random-ized controlled trials (RCTs) and only those with methods not using a device. Seven studies were included, with the review authors stating that the evidence was insufficient to allow any conclusions. Another review of six RCTs (three of which were also in the Cochrane Review) could not draw a firm conclusion [5]. Both reviews suggested further investigation was warranted.
While an RCT is the ‘gold standard’ for estimating benefits and risks of interventions, such studies are difficult to implement in CAM because of problems finding convincing placebos and hence difficulty maintaining blinding. Another problem is funding for CAM research as, unlike pharmacotherapy, there is no industry supporter. Thus it is important to examine all available trials, including those that are uncontrolled, as these might provide additional evidence concerning CAM. Recent reviews suggested that nonrandomized trials can either over- or under-estimate treatment effect [6] but usually provide useful information [7].
Supporters of CAM point out that for asthma management, these techniques are less costly and have fewer unwanted side-effects than pharmaceutical products. In this review, we aim to identify evidence from controlled and uncontrolled trials as to the benefits and risks of one form of CAM, breathing retraining techniques, in asthma management.
Research design & methodsStudy designA systematic literature search was conducted to identify all trials published from 1954 to July 12th 2011 in peer-reviewed journals on breathing retraining techniques in asthma management.
Search strategyMedline, PubMed, Embase, Cumulative Index to Nursing and Allied Health Literature and the Cochrane Library electronic databases were searched using the keywords “asthma” and “com-plementary medicine” or “breathing exercises” or “breathing ther-apy” or “breathing retraining” or “buteyko” or “yoga” or “bio-feedback” or “relaxation” both as free text and Medical Subject Headings (MESH) terms. Reference lists were manually checked to identify studies not found through electronic searching.
Inclusion criteriaAll peer-reviewed journal articles related to the use of breathing techniques as a treatment for asthma were examined. Asthma had to be either diagnosed by a clinician or fulfill the criteria of the American Thoracic Society [8], British Thoracic Society [9] or those of Crofton and Douglas [10]. Breathing modification had to be the primary component of the intervention and the technique used had to be described in detail. Studies in chronic asthma and acute exercised-induced asthma were included. Studies were included if they reported spirometry, respiratory resistance, provocation Ta
ble
1. R
and
om
ized
co
ntr
olle
d t
rial
s o
f b
reat
hin
g m
od
ifica
tio
n t
ech
niq
ues
(co
nt.
).
Stu
dy†
(yea
r)Sa
mp
leD
esig
nIn
terv
enti
on
Wit
hd
raw
als
Follo
w-u
pD
iffe
ren
ce b
etw
een
gro
up
s(i
nte
rven
tio
n v
s co
ntr
ol)
Ref
.
Chi
ang
et a
l. 20
094
8 ch
ildre
n w
ith
mod
erat
e/se
vere
as
thm
a fr
om a
ho
spita
l clin
ic
RCT
Sam
ple
size
est
imat
eTr
ue r
ando
miz
atio
nN
ot c
lear
whe
ther
do
uble
blin
d
Brea
thin
g/r
elax
atio
n tr
aini
ng p
lus
self-
m
anag
emen
t pl
an v
ersu
s se
lf-m
anag
emen
t pl
an
11 (4
exp
erim
enta
l an
d 7
cont
rol)
from
orig
inal
co
hort
(n =
59
) di
d no
t co
mpl
ete
the
stud
y
12 w
eeks
In b
oth
grou
ps:
↑ PE
FR, ↓
med
icat
ion
use,
↓ a
sthm
asy
mpt
oms
but
no b
etw
een-
grou
p di
ffer
ence
sIn
exp
erim
enta
l gro
up o
nly:
↓ C
CM
AS
scor
e ↓
GA
SCC
sco
re
↓ ov
eral
l ast
hma
med
icat
ion
use
[24]
Gra
mm
atop
oulo
u et
al.
(201
1)4
0 ho
spita
l clin
ic
adul
ts w
ith m
ild/
mod
erat
e as
thm
a
RCT
Sam
ple
size
est
imat
eTr
ue r
ando
miz
atio
n
Phys
ioth
erap
ist-
led
BT
plus
usu
al t
reat
men
t ve
rsus
usu
al t
reat
men
t
Non
e 6
mon
ths
test
ing
at 0
, 1,
3 a
nd
6 m
onth
s
↑ ET
CO
2 at
1, 3
and
6 m
onth
s ↓
resp
irato
ry r
ate
at 1
, 3 a
nd 6
mon
ths
↑ A
CT
at 1
and
3 m
onth
s↑
SF-3
6v2
PC s
core
at
1 an
d 3
mon
ths
No
betw
een-
grou
p di
ffer
ence
FEV
1%
pred
icte
d at
any
tim
e
[18]
† Stu
dies
list
ed in
ord
er o
f ye
ar o
f pu
blic
atio
n.‡ A
ll p
-val
ues
<0.
02.
§A
ll p
-val
ues
<0.
04.
↑: In
crea
se in
↓: D
ecre
ase
in; A
CT:
Air
way
con
trol
tes
t; A
QLQ
: Ast
hma
Rela
ted
Qua
lity-
of-L
ife Q
uest
ionn
aire
; AQ
OL:
Ast
hma-
rela
ted
qual
ity
of li
fe; B
BT: B
utey
ko b
reat
hing
tec
hniq
ue; B
T: B
reat
hing
tra
inin
g;
CC
MA
S: C
hine
se C
hild
ren’
s M
anife
st A
nxie
ty S
cale
; ETC
O2:
End
tid
al c
arbo
n di
oxid
e; F
EV1:
For
ced
expi
rato
ry v
olum
e in
1 s
; GA
SCC
: Gen
eral
Anx
iety
Sca
le f
or C
hine
se C
hild
ren
; HA
D: H
ospi
tal A
nxie
ty a
nd
Dep
ress
ion
Que
stio
nnai
re; I
CS:
Inha
led
cort
icos
tero
id; M
AQ
OLQ
: Min
i Ast
hma
Qua
lity-
of-L
ife q
uest
ionn
aire
(Jun
iper
); M
V: M
inut
e vo
lum
e; N
Q: N
ijmeg
en q
uest
ionn
aire
; PC
LE: P
ink
Cit
y Lu
ng E
xerc
iser
; PEF
: Pea
k ex
pira
tory
flow
; PEF
R: P
eak
expi
rato
ry fl
ow r
ate;
RC
T: R
ando
miz
ed c
ontr
olle
d tr
ial;
SF-3
6v2
PC: S
hort
For
m-3
6 ve
rsio
n 2
Hea
lth S
urve
y ph
ysic
al c
ompo
nent
; SG
RQ: S
t G
eorg
e Re
spira
tory
Que
stio
nnai
re.
Burgess, Ekanayake, Lowe, Dunt, Thien & Dharmage
www.expert-reviews.com 793
ReviewTa
ble
2. R
and
om
ized
co
ntr
olle
d t
rial
s o
f yo
ga
tech
niq
ues
.
Stu
dy
(yea
r)Sa
mp
leD
esig
nIn
terv
enti
on
Wit
hd
raw
als/
dro
p o
uts
Fo
llow
-up
Dif
fere
nce
bet
wee
n g
rou
ps
(in
terv
enti
on
vs
con
tro
l)R
ef.
Nag
arat
hna
et a
l. (1
985)
106
asth
ma
patie
nts
from
yo
ga c
linic
RCT
(mat
ched
pai
rs)
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
2 w
eeks
2.5
h/d
ay
inte
grat
ed y
oga
plus
us
ual m
anag
emen
t ve
rsus
us
ual m
anag
emen
t
25 w
ithdr
awal
s (g
roup
num
bers
no
t st
ated
)
54 m
onth
s↓
atta
cks
per
wee
k↓
bron
chod
ilato
r m
edic
atio
n pe
r w
eek
↑ PE
FA
ll be
twee
n-gr
oup
com
paris
ons:
p <
0.0
1
[28]
Sing
h et
al.
(199
0)
22 a
dult
sRC
T (c
ase-
cros
sove
r)N
ot c
lear
whe
ther
tr
uly
rand
omiz
ed o
r do
uble
-blin
d
2 w
eeks
PC
LE (
I:E
1:2)
2 w
eeks
PC
LE p
lace
bo
devi
ce
42
wee
ks4
wee
ks↑
hist
amin
e PD
20: 0
.96
mg
(p =
0.0
13)
No
sign
ifica
nt c
hang
e in
lung
fun
ctio
n[29]
Ceu
gnie
t et
al.
(199
4)
27 m
ales
with
se
vere
ast
hma
age
<19
year
s
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
Exer
cise
tra
inin
g –
thre
e gr
oups
: I:E
1:1
ver
sus
I:E
1:3
vers
us n
o in
stru
ctio
ns
3 fr
om ‘n
o in
stru
ctio
ns’
grou
p
Imm
edia
teN
o be
twee
n-gr
oup
diff
eren
ce in
FEV
1/FV
C
Tren
d fo
r le
sser
fal
l in
FEV
1 w
ith e
xerc
ise
in I:
E 1:
1 an
d 1:
3 gr
oups
(p =
0.0
41)
[26]
Ceu
gnie
t et
al.
(199
6)
16 a
sthm
a pa
tient
s ag
e <1
9 ye
ars
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
Nin
e se
ssio
ns o
f ex
erci
se
trai
ning
with
I:E
2:1
brea
thin
g (g
roup
1)
vers
us n
o br
eath
ing
inst
ruct
ions
(gro
up 2
)
Non
eIm
med
iate
↓ re
spira
tory
rat
e (p
= 0
.00
02)
↑ tid
al v
olum
e (p
= 0
.00
09)
↑ tid
al v
olum
e/FV
C b
y 25
%
↓ de
ad s
pace
/tid
al v
olum
e by
12%
↓
SaO
2 by
4%
(p =
0.0
18)
[27]
Ved
anth
an
et a
l. (1
998
)
17 a
dult
asth
ma
clin
ic
outp
atie
nts
RCT
True
ran
dom
izat
ion
16 w
eeks
45 m
in t
hree
tim
es a
w
eek
inte
grat
ed y
oga
vers
us u
sual
man
agem
ent
Non
eRe
sults
rep
orte
d at
w
eeks
4 a
nd 6
of
stud
y PE
FR r
epor
ted
for
7 yo
ga
and
7 co
ntro
ls o
nly
No
betw
een-
grou
p di
ffer
ence
in m
edic
atio
n us
e, s
piro
met
ry, m
orni
ng a
nd e
veni
ng P
EFR
at w
eeks
4 a
nd 6
of
the
stud
y
[32]
Man
ocha
et
al.
(20
02)
59 a
dult
s sy
mpt
omat
ic
on m
oder
ate/
high
dos
e IC
S
RCT
True
ran
dom
izat
ion
Dou
ble-
blin
d
Wee
kly
for
4 m
onth
s 2
h Sa
haja
yog
a ve
rsus
2 h
re
laxa
tion,
dis
cuss
ion,
CB
exer
cise
s
12 (
9 in
terv
entio
n,3
cont
rol)
4 m
onth
s6
mon
ths
↓ m
etha
chol
ine
PD20
: 1.5
dou
blin
g do
ses
grea
ter
(p =
0.0
47).
↑ in
AQ
LQ a
nd P
OM
S (p
= 0
.05)
No
betw
een-
grou
p di
ffer
ence
in a
ny p
aram
eter
.
[33]
Sabi
na
et a
l.(2
005
)
62 a
dult
s w
ith m
ild/
mod
erat
e as
thm
a
RCT
Sam
ple
size
est
imat
eTr
ue r
ando
miz
atio
nD
oubl
e-bl
ind
4 w
eeks
18
0 m
in/w
eek
inte
grat
ed Iy
enga
r yo
ga
vers
us s
tret
chin
g ex
erci
ses
178
wee
ks12
wee
ks16
wee
ks
At
16 w
eeks
fol
low
-up,
sig
nific
ant
impr
ovem
ent
in A
QO
L, r
escu
e in
hale
r us
e, s
piro
met
ry in
bot
h gr
oups
but
no
betw
een-
grou
p di
ffer
ence
s
[34]
Sodh
i et
al.
(20
09)
120
adul
ts
(hos
pita
l clin
ic
and
yoga
ca
mps
)
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
45 m
in y
oga
trai
ning
/w
eek
for
8 w
eeks
plu
s us
ual c
are
vers
us u
sual
ca
re o
nly
Non
e 4
wee
ks
8 w
eeks
↑ al
l lun
g fu
nctio
n pa
ram
eter
s at
4 a
nd 8
wee
ks
in in
terv
entio
n gr
oup
(p <
0.0
1) c
ompa
red
with
ba
selin
e. N
o be
twee
n-gr
oup
com
paris
ons
done
[30]
Vem
pati
et a
l.(2
009
)
60 a
dult
s in
In
tegr
al
Hea
lth C
linic
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
40
h yo
ga t
each
ing,
die
t,
lect
ures
, reg
ular
pho
ne
follo
w-u
p an
d us
ual c
are
vers
us u
sual
car
e
3 (1
inte
rven
tion,
2
cont
rol),
re
sult
s fo
r 29
in
yoga
gro
up, 2
8 in
con
trol
gro
up
8 w
eeks
↑ lu
ng f
unct
ion
only
in y
oga
grou
p (P
EFR
bett
er
in y
oga
grou
p at
bas
elin
e; p
= 0
.03
)↓
EIB
No
chan
ge in
ser
um E
CP
↑ to
tal A
QO
L sc
ore
(bot
h gr
oups
)
[31]
↑: In
crea
se in
↓: D
ecre
ase
in; A
QLQ
: Ast
hma
Rela
ted
Qua
lity-
of-L
ife
Que
stio
nnai
re; A
QO
L: A
sthm
a re
late
d qu
ality
of
life;
CB:
Cog
nitiv
e be
havi
or; E
CP:
Eos
inop
hilic
cat
ioni
c pr
otei
n; E
IB: E
xerc
ise-
indu
ced
bron
choc
onst
rictio
n;
FEV
1: Fo
rced
exp
irato
ry v
olum
e in
1 s
; FEV
1/FV
C: F
orce
d ex
pira
tory
vol
ume/
forc
ed v
ital c
apac
ity (%
); FV
C: F
orce
d vi
tal c
apac
ity; I
CS:
Inha
led
cort
icos
tero
id; I
:E: I
nspi
rato
ry:e
xpira
tory
rat
io; P
CLE
: Pin
k C
ity L
ung
Exer
cise
r;
PD20
: Pro
voca
tion
dose
nee
ded
to c
ause
a 2
0% fa
ll in
forc
ed e
xpira
tory
vol
ume
in 1
s; P
EF: P
eak
expi
rato
ry fl
ow; P
EFR
: Pea
k ex
pira
tory
flow
rat
es; P
OM
S: P
rofil
e of
moo
d st
ates
; RC
T: R
ando
miz
ed c
ontr
olle
d tr
ials
.
Systematic review of the effectiveness of breathing retraining in asthma management
794
Review
Expert Rev. Respir. Med. 5(6), (2011)
tests, quality-of-life indices, medication use or asthma symptoms as outcomes.
Exclusion criteriaStudies were excluded if they did not report original data, were not related to breathing retraining or the patient population was not asthmatic (i.e., hyperventilation syndrome, panic disorder or chronic obstructive pul-monary disease), where chronic obstructive pulmonary disease was a comorbid condi-tion and study outcomes were either not measured or not reported.
Data extractionTitles and abstracts were reviewed by two authors (J Burgess and B Ekanayake) to assess potential eligibility. For studies where eligibility could not be determined from the abstract, the full text was reviewed. For those papers that met the inclusion criteria, design characteristics including participant recruit-ment, blinding, sample size, power calcula-tions, duration of training period, run-in and follow-up (where applicable), and par-ticipant characteristics including age, gender, treatment location (hospital/outpatient) and baseline parameters were extracted from the full text. Allocation was considered to be truly randomized if it employed a method that used chance to assign participants to comparison groups in a trial, for example, by using a random numbers table or a computer-generated random sequence [101]. Baseline measures of the objective and subjective assessment of asthma severity were also extracted. These included spirometry values, peak expiratory flow rates, respiratory resis-tance, symptoms, quality-of-life and health care utilization. Type and duration of the intervention and where applicable, control therapy, were noted. Primary and second-ary outcomes and adverse events were noted together with tests of statistical significance. Where the RCTs listed in Tables 1–4 presented data in a format that did not allow inclusion in a meta-analysis, an attempt was made to contact the corresponding author. Where the data could be obtained in a suitable format, the studies were included in a meta-analysis.
Data synthesisContinuous outcomes were expressed as weighted mean differences (95% CI) or as standardized mean differences (95% CI) if Ta
ble
3. R
and
om
ized
co
ntr
olle
d t
rial
s o
f re
spir
ato
ry m
usc
le t
rain
ing
.
Stu
dy
(yea
r)Sa
mp
leD
esig
nIn
terv
enti
on
Wit
hd
raw
als/
dro
p o
uts
Fo
llow
-up
Dif
fere
nce
bet
wee
n g
rou
ps
(in
terv
enti
on
vs
con
tro
l)R
ef.
Giro
do
et a
l. (1
992)
67 c
omm
unit
y vo
lunt
eers
RCT
True
ra
ndom
izat
ion
16 w
eeks
dee
p di
aphr
agm
atic
bre
athi
ng
vers
us p
hysi
cal e
xerc
ise
25 f
rom
the
orig
inal
92
26 w
eeks
↓ m
edic
atio
n at
16
wee
ks: 5
0%↓
seve
rity
↑ di
aphr
agm
atic
bre
athi
ng: 2
62%
[40]
Wei
ner
et a
l. (1
992)
30 a
sthm
a cl
inic
ou
tpat
ient
s
RCT
Dou
ble-
blin
d6
mon
ths
thre
shol
d in
spira
tory
mus
cle
trai
ner
with
incr
easi
ng r
esis
tanc
e ve
rsus
sha
m
06
mon
ths
↑ PI
max
at
RV: 2
4.1
cmH
2O↓
PMpe
ak/P
I max
: 6.7
%↓
nigh
t tim
e as
thm
a ↓
dayt
ime
asth
ma
↓ m
orni
ng t
ight
ness
↓ c
ough
A
ll co
mpa
red
with
bas
elin
e in
inte
rven
tion
grou
p (p
< 0
.05)
N
o ch
ange
in c
ontr
ols
[41]
Wei
ner
et a
l. (2
00
0)
82 r
espi
rato
ry
clin
ic
outp
atie
nts
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
Dou
ble-
blin
d
4 m
onth
s as
abo
ve1
(inte
rven
tion)
4 m
onth
s↑
PIm
ax a
t RV
: 15.
2 cm
H2O
↓ Bo
rg s
core
with
incr
easi
ng p
ress
ures
↓ b 2-
agon
ist
/wee
k: t
wo
puff
s A
ll co
mpa
red
with
bas
elin
e in
inte
rven
tion
grou
p (p
< 0
.05)
N
o ch
ange
in c
ontr
ols
[42]
Wei
ner
et a
l. (2
002
)
22 f
emal
e cl
inic
ou
tpat
ient
s
RCT
Dou
ble-
blin
dN
ot c
lear
whe
ther
tr
uly
rand
omiz
ed
20 w
eeks
as
abov
e3
(1 in
terv
entio
n,
2 co
ntro
ls)
20 w
eeks
PIm
ax a
t RV
: 30
cmH
2O↓
b 2-ag
onis
t /d
ay: 0
.9 p
uffs
↓ Bo
rg s
core
with
incr
easi
ng p
ress
ures
All
com
pare
d w
ith b
asel
ine
in in
terv
entio
n gr
oup
(p <
0.0
5)
No
chan
ge in
con
trol
s
[43]
↑: In
crea
se in
; ↓: D
ecre
ase
in; P
I max
: Max
imal
insp
irato
ry m
outh
pre
ssur
e; P
Mp
eak:
Peak
pre
ssur
e; R
CT:
Ran
dom
ized
con
trol
tria
l; RV
: Res
idua
l vol
ume.
Burgess, Ekanayake, Lowe, Dunt, Thien & Dharmage
www.expert-reviews.com 795
ReviewTa
ble
4. R
and
om
ized
co
ntr
olle
d t
rial
s o
f b
iofe
edb
ack
trai
nin
g.
Stu
dy
(yea
r)Sa
mp
leD
esig
nIn
terv
enti
on
Wit
hd
raw
als/
dro
p o
uts
Fo
llow
-up
Dif
fere
nce
bet
wee
n g
rou
ps
(in
terv
enti
on
vs
con
tro
l)R
ef.
Kah
n et
al.
(197
3)
20 c
hild
ren
atte
ndin
g al
lerg
y cl
inic
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
Five
ses
sion
s/m
onth
of
biof
eedb
ack
cond
ition
ing
to ↑
FEV
1 ve
rsus
wee
kly
FEV
1 m
onito
ring
Non
e9
mon
ths
↓ ED
vis
its
3.9
/yea
r (p
< 0
.05)
↓ m
edic
atio
n 6.
2/y
ear
(p <
0.0
1)↓
asth
ma
atta
cks
33.1
/yea
r (p
< 0
.05)
[46]
Kah
n et
al.
(197
7)8
08
–15
year
old
s at
tend
ing
alle
rgy
clin
ic
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
Five
to
eigh
t se
ssio
ns v
isua
l fee
dbac
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FE
V1
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us w
eekl
y m
onito
ring
ten
sess
ions
of
indu
ced
obst
ruct
ion
412
mon
ths
↓ as
thm
a se
verit
y↓
atta
ck n
umbe
r [45]
Jans
on-
Bjer
klie
et
al.
(198
2)
16 a
sthm
a su
bjec
tsRC
TD
oubl
e bl
ind
Not
cle
ar w
heth
er
trul
y ra
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ized
Five
ses
sion
s of
con
tinge
nt f
eedb
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us n
onco
ntin
gent
(ran
dom
) fe
edba
ck
1 fr
om c
ontr
ol
grou
p2
wee
ks↓
mea
n TR
R by
40%
at
2 w
eeks
(p =
0.0
49)
[44]
Mus
sell
et a
l. (1
988
)16
ast
hmat
ic
adul
tsRC
TD
oubl
e bl
ind
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
Five
ses
sion
s of
indu
ced
bron
chos
pasm
, th
en T
NBF
, non
cont
inge
nt T
NBF
, br
onch
odila
tor
inha
ler,
plac
ebo
inha
ler
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onse
ver
sus
no in
terv
entio
n
Non
eN
one
↑ no
nsig
nific
ant
impr
ovem
ent
in r
ate
of
reco
very
fro
m b
ronc
hosp
asm
with
TN
BF
com
pare
d w
ith n
o in
terv
entio
n
[50]
Lehr
er e
t al
.(1
997)
17 a
sthm
atic
ad
ults
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
Six
sess
ions
RSA
fee
dbac
k ve
rsus
th
orac
ic E
MG
and
ince
ntiv
e sp
irom
etry
ve
rsus
sel
f-re
laxa
tion
Non
e6
wee
ksW
ith R
SA:
↓ Ri
23%
↑
PEF
by 2
03 m
l (p
< 0
.003
)↓
ETC
O2
by 0
.91%
(p =
0.1
5)↓
RR (p
< 0
.00
03)
↑ re
spira
tion
dept
h (p
< 0
.00
6)
[47]
Lehr
er e
t al
.(2
00
4)
94 v
olun
teer
ad
ult
asth
ma
subj
ects
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
1) H
RV b
iofe
edba
ck a
nd B
T2)
HRV
bio
feed
back
onl
y3
) Pla
cebo
EEG
bio
feed
back
4) W
aitin
g lis
t
18 (6 f
rom
gro
up 1
5 fr
om g
roup
25
from
gro
up 3
2 fr
om g
roup
4)
10 w
eeks
↓ co
ntro
ller
med
icat
ion
use
in g
roup
s 1
and
2 (p
< 0
.00
01) a
nd g
roup
3 (p
< 0
.02)
↓ ai
rway
res
ista
nce
in g
roup
1 (p
< 0
.00
07)
and
grou
p 2
(p <
0.0
02)
FEV
1 un
chan
ged
any
grou
p
[49]
Lehr
er e
t al
.(2
00
6)
45 v
olun
teer
ad
ult
asth
ma
subj
ects
RCT
Not
cle
ar w
heth
er
trul
y ra
ndom
ized
1) H
RV b
iofe
edba
ck a
nd B
T: a
ge ≥
40
com
pare
d w
ith a
ge <
40
2) H
RV b
iofe
edba
ck o
nly:
age ≥4
0 co
mpa
red
with
age
<4
0
9 (4 f
rom
gro
up 1
5 fr
om g
roup
2)
10 w
eeks
↓ co
ntro
ller
med
icat
ion
use
in b
oth
grou
ps
(p <
0.0
01)
No
with
in-g
roup
dif
fere
nce
by a
ge.
↓ A
irw
ay r
esis
tanc
e in
gro
up 2
with
no
diff
eren
ce b
y ag
e
[48]
↑: In
crea
se in
; ↓: D
ecre
ase
in; B
T: B
reat
hing
tra
inin
g; E
D: E
mer
genc
y de
part
men
t; E
MG
: Ele
ctro
myo
grap
hy;E
TCO
2: E
nd t
idal
car
bon
diox
ide;
FEV
1: F
orce
d ex
pira
tory
vol
ume
in 1
s; H
RV: H
eart
rat
e va
riabi
lity;
PEF
: Pea
k ex
pira
tory
flow
; RC
T: R
ando
miz
ed c
ontr
olle
d tr
ial;
Ri: R
espi
rato
ry im
peda
nce;
RR
: Res
pira
tory
rat
e; R
SA: R
espi
rato
ry s
inus
arr
hyth
mia
; TN
BF: T
rach
ea n
oise
bio
feed
back
; TRR
: Tot
al r
espi
rato
ry r
esis
tanc
e.
Systematic review of the effectiveness of breathing retraining in asthma management
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Expert Rev. Respir. Med. 5(6), (2011)
different methods of measuring outcomes were used. A fixed-effects model was the default method of meta-analysis but a random-effects model was used when heterogeneity was judged important (I2 ≥ 25%) [11]. Where heterogeneity was judged extreme (I2 ≥ 80%), a pooled estimate and forest plot were not presented. All meta-analyses were done using Stata Statistical Software: Release 10.1 (Stata Corporation, College Station, TX, USA).
ResultsSearch resultsThe initial search strategy identified 101 original articles of which 60 were excluded for various reasons, leaving 41 articles that were analyzed (Figure 1).
Breathing modification techniques A total of 12 RCTs examined the effect of breathing modifica-tion techniques compared with control interventions. Six RCTs employed the BBT and six employed respiratory physiotherapy aimed at eliminating over-breathing and developing slow, con-trolled breathing (Table 1). Participants were recruited from the community via advertisements (n = 7), through a hospital- or university-based asthma clinic (n = 2) or through their general practitioner (n = 4). All subjects were free from cardiorespira-tory comorbidities. All but three studies [12–14] reported and met sample-size estimates designed to detect a significant change in the outcome measure. Double blinding was effected in four
studies [12,15–17] and true randomization in all but one [13]. Active intervention varied from 1 week of training with a therapist to 28 weeks of watching an instruction video daily. A defined control intervention was present in all but three studies [13,18,19] and follow-up periods ranged from 4 to 28 weeks (Table 1). Four out of six RCTs of BBT found a significant decrease in b
2-agonist use in
the BBT group compared with controls [12,15,16,20], while another found a decrease in b
2-agonist and inhaled corticosteroid (ICS)
use in both BBT and control groups with no between-group difference [17]. Two BBT trials observed a significant decrease in ICS use over 6 months [16,21], while seven studies (four BBT and three physiotherapy) found improvement in one or more quality-of-life parameters or anxiety/depression scores [12,14,18–22]. No breathing modification trial
showed an improvement in lung function in the intervention group compared with controls.
Bowler et al. examined BBT taught by an accredited BBT rep-resentative versus relaxation and asthma education in 39 asthma subjects and found a significant decrease in minute volume in the BBT group, in keeping with BBT theory, as well as a decrease in daily b
2-agonist use and a trend towards improved quality of life
in the BBT group [12]. No change was found in lung function or in end-tidal CO
2 in either group. However, follow-up time was
quite short and the authors conceded the possibility of bias as some of the BBT participants received unplanned telephone con-tact/support from the BBT therapist that could have influenced quality-of-life self-assessment and b
2-agonist use.
Opat et al. compared the effect of BBT taught by video with a ‘placebo’ video in adults with moderate asthma and found that BBT was associated with a significant improvement in AQOL score and a significant reduction in b
2-agonist use, but no significant
change in peak expiratory flow rate [20]. Thomas et al. examined breathing retraining by a respiratory
physiotherapist employing techniques common to standard phys-iotherapy and BBT compared with nurse-led asthma education [22]. The participants were a subgroup of asthmatic patients with dysfunctional breathing as measured by the Nijmegen question-naire [23]. The study found that AQOL improved significantly in the breathing retraining group and that two patients would need to be treated to produce clinically relevant improvement
Breathing modification (n = 13)RCT (n = 12)B&A (n = 1)
Yoga (n = 15)RCT (n = 9)B&A (n = 6)
RMT (n = 4)RCT (n = 4)
Biofeedback (n = 9)RCT (n = 5)B&A (n = 4)
Total excluded (n = 60)Reviews/comments (n = 21)No breathing training (n = 19)HVS/panic disorder (n = 7)COPD (n = 1)Multidisciplinary (n = 4)No asthma outcome measure (n = 8)Total included (n = 41)
Total citationsidentified (n = 101)
Figure 1. Summary of citations included in review.B&A: Before-and-after trial; COPD: Chronic obstructive pulmonary disease; HVS: Hyperventilation syndrome; RCT: Randomized controlled trial; RMT: Respiratory muscle training.
Table 5. Nonrandomized controlled trials of breathing modification techniques.
Study(year)
Sample Design Intervention Withdrawals Follow-up Magnitude of difference
Ref.
McHugh et al. (2006)
8 children with asthma
Before-and-after trial
BBT instruction by an accredited BBT representative
None 3 months ↓ b2-agonist use by 66%↓ ICS use by 41%↓ symptom score by 12%
[25]
↓: Decrease in; BBT: Buteyko Breathing Technique; ICS: Inhaled corticosteroid.
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in asthma-related quality-of-life questionnaire (AQLQ) for one patient in 1 month (number needed to treat: 1.96; 95% CI: not reported). There was some evidence that beneficial effects declined with time if breathing techniques were not maintained. After the end of 6 months treatment, the number needed to treat had increased from two to four. A limitation of this study was that lung function was not measured.
Cooper et al. compared BBT taught by a certified BBT practi-tioner with controled breathing (to mimic ‘pranayama’ yoga) using the ‘Pink City Lung Exerciser’ (PCLE) and a ‘placebo’ PCLE [15]. The study found significant improvement in asthma symptoms and bronchodilator use in the BBT group compared with both the PCLE and placebo groups, but no between-group difference in forced expiratory volume in 1 s (FEV
1) or provocation dose needed
to cause a 20% fall in FEV1 (PD
20) for methacholine or ICS use.
McHugh et al. examined BBT taught by an accredited represen-tative versus asthma education and relaxation in 38 subjects with asthma [16]. The groups were individually matched for asthma
severity and were followed up over 6 months. Instructor contact with the participants during follow-up was planned a priori and was the same in each group. While there was no change in lung function between groups, there was a significant reduction in ICS and b
2-agonist use in the BBT group. However, the participants
in the BBT arm might have become aware of allocation as the use of the term ‘Buteyko’ was not prohibited during instruction, possibly resulting in incomplete participant blinding.
Slader et al.’s video-based trial used hypoventilation, nasal breathing and breath holding at functional residual capacity mimicking BBT as the active intervention and a combination of nonspecific upper body exercises as the control intervention. The study found no significant change in FEV
1, FVC or airway
hyper-responsiveness (AHR) in either active or control group but significant and comparable reduction in bronchodilator and ICS use and improvement in AQLQ in both groups [17]. The conclusion was that breathing techniques may be useful in the management of patients with mild asthma symptoms who use a
Study WMD (95% CI)
-9.00 (-79.48–61.48)
31.40 (-22.03–84.83)
16.66 (-25.92–59.23)
N, mean (SD)breathing retraining
N, mean (SD)control
% weight
Bowler (1998) [12]
Holloway (2007) [19]
Overall (l-squared = 0.0%; p = 0.371)
18, 374 (115)
40, 439 (109)
19, 383 (103)
32, 408 (119)
58
-84.8 84.80
51
36.49
63.51
100.00
Favorscontrol
Favorsbreathing retraining
Figure 2. Weighted mean difference in peak expiratory flow (l/min) from breathing retraining randomized controlled trials. SD: Standard deviation; WMD: Weighted mean difference.
Favorscontrol
Favorsbreathing retraining
Study WMD (95% CI)
0.00 (-12.20–12.20)
3.96 (-3.37–11.29)
2.27 (-2.03–6.57)
N, mean (SD)breathing retraining
N, mean (SD)control
% weight
Bowler (1998) [12]
Cowie (2008) [21]
Grammatopoulou (2011) [18]
Overall (l-squared = 0.0%; p = 0.830)
18, 72 (22)
56, 82.9 (19.2)
19, 72 (15)
63, 79 (21.6)
94
-12.2 12.20
102
12.43
34.41
1.70 (-4.20–7.60) 20, 86.3 (8.21) 20, 84.0 (10.7) 53.17
100.00
Figure 3. Weighted mean difference in forced expiratory volume in 1 s (% predicted) from breathing retraining randomized controlled trials. SD: Standard deviation; WMD: Weighted mean difference.
Systematic review of the effectiveness of breathing retraining in asthma management
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Review
Expert Rev. Respir. Med. 5(6), (2011)
reliever frequently, but there is no evidence to favor shallow nasal breathing over nonspecific upper body exercises.
Cowie et al. compared BBT taught by an accredited practitioner with breathing exercises taught by a physiotherapist and found significant and comparable improvement in asthma control and
quality-of-life scores in both groups but no difference in FEV1%
predicted between the groups [21]. The improvement in medi-cation use and AQLQ score in both arms in these two studies suggested a common mechanism or that improvement was due to nonspecific effects.
Study WMD (95% CI)
-0.13 (-0.68–0.42)
0.10 (-0.25–0.45)
-0.01 (-0.15–0.14)
N, mean (SD)breathing retraining
N, mean (SD)control
% weight
Fluge (1994) [59]
Holloway (2007) [19]
Meuret (2007) [13]
Overall (l-squared = 0.0%; p = 0.781)
12, 2.33 (0.67)
40, 2.8 (0.7)
9, 2.46 (0.62)
32, 2.7 (0.80)
209
-685 6850
207
6.86
17.05
-0.21 (-0.68–0.26) 8, 2.32 (0.33) 4, 2.53 (0.42) 9.53
0.14 (-0.17–0.45)
-0.02 (-0.28–0.24)
Cowie (2008) [21]
Thomas (2009) [14]
Grammatopoulou (2011) [18]
56, 2.72 (0.934)
73, 2.95 (0.83)
63, 2.58 (0.803)
79, 2.97 (0.78)
21.30
32.08
-0.13 (-0.53–0.27) 20, 2.33 (0.67) 20, 2.46 (0.62) 13.19
100.00
Favorscontrol
Favorsbreathing retraining
Study SMD (95% CI)
1.19 (0.44–1.94)
0.35 (0.00–0.70)
N, mean (SD)breathing retraining
N, mean (SD)control
% weight
Bowler (1998) [12]
Holloway (2007) [19]
Overall (l-squared = 65.4%; p = 0.021)
18, 1.2 (0.9) 15, 0.4 (0.13)
220
-1.94 1.940
227
13.05
0.13 (-0.33–0.60) 32, -15.2 (10.9) 40, -16.7 (11.6) 20.61
-0.09 (-0.45–0.27)
0.37 (0.08–0.67)
Cowie (2007) [21]
Thomas (2009) [14]
Grammatopoulou (2011) [18]
56, 5.6 (1.17)
94, 5.41 (1.23)
63, 5.7 (1)
89, 4.94 (1.29)
24.17
26.50
0.60 (-0.04–1.23) 20, 52.3 (5.4) 20, 48.8 (6.31) 15.67
100.00
Favorscontrol
Favorsbreathing retraining
Figure 4. Weighted mean difference in forced expiratory volume in 1 s (l) from breathing retraining randomized controlled trials. SD: Standard deviation; WMD: Weighted mean difference.
Figure 5. Standardized mean difference in asthma-related quality-of-life score from breathing retraining randomized controlled trials. Asthma-related quality-of-life scores from the Holloway study (lower score is better) were attributed negative values to be consistent with other studies (higher score is better). Weights are from random effects analysis. SD: Standard deviation; SMD: Standardized mean difference.
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Holloway et al. examined a physiotherapist-taught breathing technique (Papworth method) plus usual care versus usual care only in a cohort with mild or well-controlled asthma from a semirural general practice [19]. At both 6- and 12-month follow-up, there was significant improvement in St George Respiratory Questionnaire symptom score, hospital anxiety and depression (HAD) questionnaire anxiety and depression scores and Nijmegen questionnaire score but no between-group difference in lung
function. The study was limited by the absence of a control inter-vention. Thomas et al. also examined physiotherapist-led breath-ing training versus nurse-led asthma education in a larger cohort of subjects with reduced asthma-related quality-of-life (AQOL) recruited from general practice [14]. At 6-month follow-up, sig-nificant improvements in AQLQ score, Nijmegen questionnaire score and HAD questionnaire anxiety and depression scores in the breathing training group compared with the control group were
Study WMD (95% CI)
2.30 (0.37–4.23)
1.65 (0.31–2.99)
N, mean (SD)breathing retraining
N, mean (SD)control
% weight
Bowler (1998) [12]
Meuret (2007) [13]
Overall (l-squared = 41.3%; p = 0.146)
18, 35.3 (3) 19, 33 (3)
159
-8.75 8.750
154
24.60
3.20 (-2.35–8.75) 8, 38.5 (5.8) 4, 35.3 (3.9) 5.23
-0.10 (-2.43–2.23)
0.60 (-1.19–2.39)
Holloway (2007) [19]
Thomas (2009) [14]
Grammatopoulou (2011) [18]
40, 39.2 (3.4)
73, 33 (5.48)
32, 39.3 (6)
79, 32.4 (5.78)
19.97
26.55
3.30 (1.29–5.31) 20, 37.9 (3.54) 20, 34.6 (2.91) 23.65
100.00
Favorscontrol
Favorsbreathing retraining
Figure 6. Weighted mean difference in end tidal CO2 (mmHg) from breathing retraining randomized controlled trials.Weights are from random effects analysis. SD: Standard deviation; WMD: Weighted mean difference.
Study WMD (95% CI)
72.00 (40.03–103.97)
29.54 (-3.76–62.84)
N, mean (SD)yoga
N, mean (SD)control
% weight
Nagarantha (1985) [28]
Singh (1990) [29]
Overall (l-squared = 46.0%; p = 0.116)
44, 363 (108) 50, 291 (12.2)
97
-105 1050
108
31.64
14.00 (-49.07–77.07) 18, 475 (99) 18, 461 (94) 17.17
15.00 (-41.92–71.92)
4.00 (-58.39–66.39)
Vedanthan (1998: am results) [32]
Vedanthan (1998: pm results) [32]
Manocha (2002) [33]
7, 412 (60)
7, 406 (62)
7, 397 (48)
7, 402 (57)
19.38
17.40
5.21 (-66.98–77.40) 21, 370 (140) 26, 365 (105) 14.41
100.00
Favorscontrol
Favorsyoga
Figure 7. Weighted mean difference in peak expiratory flow (l/min) from yoga randomized controlled trials. Weights are from random effects analysis. SD: Standard deviation; WMD: Weighted mean difference.
Systematic review of the effectiveness of breathing retraining in asthma management
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Expert Rev. Respir. Med. 5(6), (2011)
found. However, there was no improvement in lung function in either group. More recently, Grammatopoulou et al. examined the effect of physiotherapist-led breathing training plus usual treat-ment in 40 adults with mild/moderate asthma recruited from a hospital asthma clinic [18]. They found significant improvement in airway control test (ACT) score, Short Form-36 version 2 Health Survey (SF-36v2) physical component score, increased end tidal CO
2 and reduced respiratory rate in the intervention group com-
pared with controls who continued with usual treatment only. While there was no between-group change in lung function, there was a significant improvement in FEV
1% predicted within the
intervention group at 3 months follow-up compared with baseline.Meunert et al. conducted a pilot study in 12 asthma subjects
recruited by advertisement [13]. The intervention was initial edu-cation in breathing patterns in asthma followed by capnometry- assisted breathing training and home breathing exercises over a 4-week period, plus usual treatment (n = 8). The control group (n = 4) continued with usual treatment for the 4-week period
and were then offered the intervention, taken up by only two participants. At 8-week follow-up normocapnia (end-tidal pCO
2
40 mmHg), an improvement in asthma control, asthma symp-toms and a reduction in PEF variability with no change in FEV
1
were found in the intervention group. Follow-up was not done in the control group. The small number in the study together with the absence of useful data from the control group limits the usefulness of the findings.
Chiang et al. examined the effect of breathing/relaxation instruction in addition to a clinic-planned asthma self-man-agement program compared with self-management only in 48 Taiwanese children with moderate to severe asthma recruited from an asthma clinic [24]. PEF, asthma symptoms and medica-tion use improved in both groups with no between-group differ-ences. There was a significant reduction in anxiety scores in the experimental group only. The adequacy of blinding in the study was in doubt in that the breathing/relaxation instruction was given by a ‘researcher’.
Study WMD (95% CI)
8.79 (0.37–17.22)
N, mean (SD)yoga
N, mean (SD)control
% weight
Vempati (2009) [31]
Manocha (2002) [33]
Overall (l-squared = 65.2%; p = 0.056) 109
-27.8 27.80
112
18.00 (8.28–27.72) 28, 77.9 (17.2) 26, 59.9 (19.1) 30.72
2.13 (-11.57–15.83) 21, 76.6 (21.8) 26, 74.4 (26.1) 21.88
5.90 (2.26–9.54)Sodhi (2009) [30] 60, 83.2 (10.5) 60, 77.3 (9.86) 47.39
100.00
Favorscontrol
Favorsyoga
Study WMD (95% CI)
-359.68 (-1270.49–551.13)
N, mean (SD)yoga
N, mean (SD)control
% weight
Singh (1990) [29]
Overall (l-squared = 66.9%; p = 0.082) 27
-1804 18040
26
40.00 (-515.48–595.48) 18, 3460 (870) 18, 3420 (830) 57.48
-900.00 (-1803.55–3.55)Vedanthan (1998) [32] 9, 3290 (820) 8, 4190 (1050) 42.52
100.00
Favorscontrol
Favorsyoga
Figure 9. Weighted mean difference in forced expiratory volume in 1 s (% predicted) from yoga randomized controlled trials. Weights are from random effects analysis. SD: Standard deviation; WMD: Weighted mean difference.
Figure 8. Weighted mean difference in forced expiratory volume in 1 s (ml) from yoga randomized controlled trials. Weights are from random effects analysis. SD: Standard deviation; WMD: Weighted mean difference.
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McHugh et al. examined breathing retraining using BBT on eight asthmatic children using a before-and-after (B&A) design (Table 5) [25]. At 3-month follow-up, the main findings were a decrease in b
2-agonist and ICS use, a reduction in missed school
days and oral steroid courses and an improved asthma symptom score compared with baseline. However, confidence intervals and tests of significance were not reported and lung function was not examined. The authors conceded that self-selection of the partici-pants and the small number in the study precluded meaningful interpretation of the results.
It was not possible to include data from all studies in a meta-analysis of breathing retraining owing to differences in outcome reporting. However, where such analyses could be done, no effect of breathing retraining on lung function could be demonstrated (Figures 2–4) but a favorable effect of breathing retraining on AQOL and on end-tidal CO
2 was shown (Figures 5 & 6).
Yoga Randomized controlled trial studiesA total of 14 studies examined yoga in asthma management and nine used an RCT design (Table 2). In six out of the nine studies [26–31] it was not clear whether true randomization had been car-ried out and in seven studies [26–32] double blinding was either not clear or not done. Follow-up times in these studies varied from immediate to 54 months and study numbers ranged from 16–120. Two studies found a significant between-group difference in lung function or AQOL [27,31].
The longest study in terms of follow-up [28], found significant benefit from integrated yoga exercises as well as usual treatment with increased PEFR, decreased medication use and a decrease in attack severity. However, the study participants were from a yoga clinic, with the associated risk of selection bias, and while both active and control groups continued with usual prescribed bronchodilator medication, the control group did not receive a ‘placebo’ intervention. There was a high attrition rate (47%) as only ‘frequent’ practitioners (>16 days per month) in the
intervention arm were included in the final analysis, which was not intention-to-treat.
Singh et al. utilized pranayama by enforcing the 1:2 inspiratory:expiratory ratio with the PCLE device (a disk with a one-way valve that imposes a 1:2 ratio) compared with an other-wise identical (non-pranayama) device in a case-crossover study of 22 adults with mild asthma [29]. There was a significant increase in the doubling dose for PD
20 for histamine with the active com-
pared with the control device but no significant difference in lung function parameters between the devices.
Although their research question addressed exercise training rather than yoga in asthma management, Ceugniet et al. incor-porated a pranayama technique into their study of exercise train-ing in children with severe asthma [26]. They reported a trend towards better FEV
1 but no significant effect on FEV
1/FVC ratio
following exercise training with pranayama. No change was found in lung function in the control group following similar exercise training without pranayama. In a later study on a similar par-ticipant group, the same authors [27] found that the same inter-vention significantly reduced respiratory frequency, dead space/tidal volume ratio and increased tidal volume in the group using exercise with pranayama. However, postexercise oxygen satura-tion in the intervention group was reduced from pretest values by a clinically important amount, whereas it did not change in the control group.
Vedanthan et al. found that 16 weeks of integrated yoga com-pared with usual treatment had no effect on lung function as mea-sured at 4 and 6 weeks after study commencement [32]. Manocha et al. examined Sahaja yoga compared with relaxation, discussion and cognitive behavior training [33]. They found an improvement in AHR, AQOL mood subscale and the profile of mood states score at the end of the 4-month study period in the intervention group only but no significant between-group differences in any measure 2 months later. Sabina et al. trialed 16 weeks of integrated yoga versus stretching exercises and found no between-group dif-ference in FEV
1, rescue inhaler use and AQOL at 16 weeks [34].
Study SMD (95% CI)
-0.61 (-1.01– -0.21)
N, mean (SD)yoga
N, mean (SD)control
% weight
Vempati (2009) [31]
Overall (l-squared = 0.0%; p = 0.499) 50
-1.27 1.270
52
-0.73 (-1.27– -0.19) 29, -5.46 (1.1) 28, -0.45 (1.5) 54.99
-0.46 (-1.05–0.14)Manocha (2002) [33] 21, 0.66 (0.42) 24, 0.91 (0.64) 45.01
100.00
Favorscontrol
Favorsyoga
Figure 10. Standardized mean difference in asthma-related quality-of-life score from yoga randomized controlled trials. Asthma-related quality-of-life score from Vempati study (lower score is better) were attributed negative values to be consistent with Manocha study (higher score is better). SD: Standard deviation; SMD: Standardized mean difference.
Systematic review of the effectiveness of breathing retraining in asthma management
802
Review
Expert Rev. Respir. Med. 5(6), (2011)
Sodhi et al. examined yoga breathing exer-cises in addition to usual treatment versus usual treatment only in a cohort of asthma subjects recruited from a hospital clinic and yoga camps [30]. They reported significant improvement in all lung function parameters compared with baseline in the intervention group but no between-group comparisons were carried out.
Vempati et al. randomized 60 partici-pants from a hospital-based ‘Integral Health Clinic’ to either an intensive yoga instruc-tion program or to usual care and found sig-nificant improvement in lung function and exercise-induced bronchoconstriction in the intervention group compared with the con-trol group and improvement in AQOL in both groups [31]. However, the study popula-tion was biased towards yoga devotees, ther-apist-related effects were uneven between the groups and the follow-up period was short.
The meta-analyses of RCTs of yoga on lung function showed no effect on PEF or absolute values of FEV
1 (Figures 7 & 8).
However, there was a favorable effect of yoga on FEV
1% predicted (Figure 9) and a favorable
effect of yoga on AQOL (Figure 10).
Nonrandomized controlled trial studiesFive such studies were found (Table 6) and all used the B&A method [35–39]. Two studies had substantial loss to follow-up [35,36]. Study numbers ranged from 9 to 570 and follow-up times from immediate to 54 months with all studies reporting improvement in lung func-tion, AQOL or AHR for the intervention compared to the control group.
Respiratory muscle training A total of four RCTs [40–43] investigated the effect of respiratory muscle training on asthma (Table 3). Participant numbers ranged from 22 to 92 with follow-up times vary-ing between 4 and 6 months; all studies employed muscle strengthening techniques. All studies found significant improvement in lung function, b
2-agonist use or symptoms in
the active intervention group compared with controls.
Girodo et al. employed a then novel method of deep diaphragmatic breathing training that did not involve the use of a corset. Over a 16-week training period, this technique lessened attack intensity and decreased total medication use by 50%, Ta
ble
6. N
on
ran
do
miz
ed c
on
tro
lled
tri
als
of
yog
a te
chn
iqu
es.
Stu
dy
(yea
r)Sa
mp
leD
esig
nIn
terv
enti
on
Wit
hd
raw
als/
dro
p o
uts
Fo
llow
-up
Mag
nit
ud
e o
f d
iffe
ren
ce
Ref
.
Nag
endr
a et
al.
(198
6)
570
yoga
sch
ool
part
icip
ants
Befo
re-a
nd-
afte
r tr
ial
2 w
eeks
of
2.5
h/d
ayor
4 w
eeks
of
1.5
h/d
ay o
f as
anas
, pra
naya
mas
, lec
ture
s
Non
e3
–54
mon
ths
↓ at
tack
s/w
eek:
2.6
; ↓ s
ever
ity:
0.4
5↓
bron
chod
ilato
r do
ses/
wee
k: 5
.81
↓ co
rtis
one
dose
s/ye
ar: 8
7.45
↑ PE
FR: 5
3.9
l/m
in
[38]
Jain
et
al.
(199
1)46
ast
hmat
ic c
hild
ren,
re
crui
tmen
t un
know
nBe
fore
-and
-af
ter
tria
l4
0 w
eeks
of
inpa
tient
yog
a tr
aini
ng. 2
.5 h
/day
of
kriy
as,
asan
as a
nd p
rana
yam
as
20 lo
st t
o fo
llow
-up
2 ye
ars
↑ FE
V1:
11.
8% p
redi
cted
; ↑PE
FR: 8
.3 l/
min
↓
exer
cise
labi
lity
inde
x: 1
1.3%
↑ re
stin
g Pa
O2:
7.1
mm
Hg
↑ po
stex
erci
se P
aO2:
6.4
mm
Hg
↓ po
stex
erci
se P
aCO
2: 2
mm
Hg
[35]
Jain
et
al. (
1993
)42
adu
lt re
spira
tory
ou
tpat
ient
sBe
fore
-and
-af
ter
tria
l4
0 da
ys in
patie
nt y
oga
trai
ning
th
en m
onth
ly o
utpa
tient
vis
its
for
1 ye
ar
11 lo
st t
o fo
llow
-up
1 ye
ar↑
FEV
1: 7
.9%
pre
dict
ed↑
MV
V: 1
4.9
l/m
in; ↑
MM
FR: 2
6.5
l/m
in↑
12-m
in w
alk
dist
ance
: 19.
1m↑
phys
ical
fitn
ess
inde
x: 4
.7
↑ ex
erci
se la
bilit
y in
dex:
4.3
%
[36]
Kha
nam
et
al.
(199
6)
9 re
spira
tory
ou
tpat
ient
sBe
fore
-and
-af
ter
tria
l7
days
of
yoga
cam
p 2
h/d
ay o
f as
anas
, pra
naya
mas
, le
ctur
es
Non
eN
one
↑ br
eath
hol
ding
tim
e: 1
0 s
↑ pe
ak in
spira
tory
flow
rat
e: 2
l/m
in↑
ches
t ex
pans
ion:
3.5
6 cm
/min
[37]
Sath
ypra
bha
et a
l.(2
001
)37
adu
lts,
rec
ruitm
ent
unkn
own
Befo
re-a
nd-
afte
r tr
ial
21 d
ays
inpa
tient
yog
a th
erap
y,
diet
and
‘nat
ure
cure
tre
atm
ent’
Non
eN
one
↑ V
C: 1
.06l
; ↑FV
C: 1
.1l
↑ FE
V1:
1.4
l↑
FEV
1/FV
C: 1
4.02
%↑
MV
V: 1
8.2
l/m
in
[39]
↑: In
crea
se in
; ↓: D
ecre
ase
in; F
EV1:
For
ced
expi
rato
ry v
olum
e in
1 s
; MM
FR: M
axim
al m
id-e
xpira
tory
flow
rat
e; M
VV
: Max
imum
vol
unta
ry v
entil
atio
n; P
EFR
: Pea
k ex
pira
tory
flow
rat
e; V
C: V
ital
cap
acit
y.
Burgess, Ekanayake, Lowe, Dunt, Thien & Dharmage
www.expert-reviews.com 803
Review
although for many participants, persistence with the exercise program was short-lived [40].
Weiner et al., in three separate RCTs, found that specific inspiratory muscle training using either an externally weighted device or a purpose-designed threshold inspiratory muscle trainer (HealthScan; NJ, USA) compared with ‘sham’ muscle training significantly increased inspiratory muscle strength as measured by maximal inspiratory mouth pressure at residual volume (PI
max
at residual volume). With 4–6 months training, subjects with the active intervention improved FEV
1, FVC, symptoms and Borg
dyspnea score and decreased bronchodilator use. The most recent of these studies that compared female to male asthmatics [43] found that using the same training method to allow females to attain a PI
max equal to that of males resulted in a significant and
highly correlated decrease in both dyspnea score and medication use in the active intervention group only.
A meta-analysis (Figure 11) showed a favorable effect of respiratory muscle training on b
2-agonist use.
Biofeedback training A total of seven RCTs [44–50] and five B&A studies [51–55] were identified (Tables 4 & 7). Six RCTs [44–49] and two B&A studies [52,53] found significant improvement in lung function, medication use or asthma symptoms. Participant numbers were generally small and follow-up times were short.
Kahn et al. trained 20 children with asthma attending an allergy clinic to induce bronchoconstriction using inhalation, suggestion or medication methods previously known to induce bronchoconstriction [46]. Bronchodilatation via FEV
1 biofeedback
reinforcement was then taught weekly to the intervention group (n = 10). Compared to ten controls who received weekly FEV
1
measurement but no biofeedback reinforcement, the intervention group experienced significant reductions in medication use, num-ber of emergency room visits and asthma attacks over the 1-year follow-up period. Lung function was not reported. However, when Khan et al. repeated the study in 80 similar children over a 12-month period, these findings could not be replicated [45].
A limitation in these studies was the use of a forced expiratory maneuver as the biofeedback instrument. Any improvement could not necessarily be attributed to genuine operant conditioning as the maneuver is partly dependent on motivation and effort, which might vary between individuals.
Mussell et al. in a study of trachea–bronchial noise reduction as the biofeedback instrument to reverse induced bronchospasm, found that trachea–bronchial noise reduction as the biofeedback instrument was modestly and nonsignificantly more effective than no intervention [50]. Janson-Bjerklie et al. trialed contingent bio-feedback versus random feedback and found that total respiratory resistance (TRR) across five training sessions was greater in their intervention group than the control group [44]. Lehrer et al. found that respiratory sinus arrhythmia as a feedback tool compared with electromyography biofeedback plus incentive inspirometry or self-relaxation reduced respiratory impedance by 23% in a small group of adults with asthma but the authors did not report results of any statistical tests [47]. Two later studies by Lehrer et al. found that heart rate variability biofeedback plus breathing training or heart rate variability biofeedback alone significantly reduced controller medication use and improved airway resistance, inde-pendent of increasing age in asthmatic adults but produced no change in lung function [48,49].
One uncontrolled study [52] showed a significant improvement in mid-expiratory flow rate and TRR compared with baseline using an auditory signal reflecting TRR as the biofeedback tool while another [53] found improvement in FEV
1 and FEF
50 in 17 out
of 20 asthmatic children taught to use respiratory sinus arrhyth-mia feedback to prolong expiration. On the other hand, Erskine-Millis et al. found no benefit for TRR from either short-term or more intensive biofeedback training compared with baseline and even a deterioration in FEV
1 after more intensive training. It was
concluded that no benefit was to be had from biofeedback training in adults with moderate/severe chronic asthma [51].
Steptoe et al. showed that nonasthmatic subjects were able to decrease airways resistance significantly and consistently over biofeedback training sessions, but asthmatic subjects’ airways
Study WMD (95% CI)
-1.19 (-2.15– -0.24)
N, mean (SD)RMT
N, mean (SD)control
% weight
Weiner (2000) [42]
Overall (l-squared = 0.0%; p = 0.716) 21
-2.75 2.750
20
-1.30 (-2.41– -0.19) 11, 1.6 (1.33) 11, 2.9 (1.33) 73.45
-0.90 (-2.75–0.95)Weiner (2002) [43] 10, 2.1 (1.58) 9, 3 (2.4) 26.55
100.00
Favorscontrol
FavorsRMT
Figure 11. Weighted mean difference in b2-agonist use from respiratory muscle training randomized controlled trials.RMT: Respiratory muscle training; SD: Standard deviation; WMD: Weighted mean difference.
Systematic review of the effectiveness of breathing retraining in asthma management
804
Review
Expert Rev. Respir. Med. 5(6), (2011)
resistance was more variable, with only a trend towards a decrease (p = 0.059) [55]. Finally, Mass et al. found no change in lung function, dyspnea score or reliever medica-tion use over a 4-week trial period of bio-feedback to reduce respiratory resistance in a cohort of 15 asthmatics [54].
DiscussionThe BBT has been the most widely pub-licized among the CAM techniques used in asthma management. Individual stud-ies using BBT consistently demonstrated a reduction in asthma medication use, and together with respiratory physiotherapy studies, often showed an improvement in AQOL and the subjective experience of asthma symptoms. However, there was no significant improvement in lung function in any of the BBT studies to account for the positive results. This was supported by the results of meta-analyses, which failed to show an effect of these techniques using pooled estimates. While it is possible that the deep inspiration required for lung function testing might induce bronchoconstriction [56] and override any beneficial effect from BBT, it is also possible that the studies were inadequately powered to detect changes in lung function parameters. Larger studies might reveal an effect. A meta-analysis of the studies that explored the postulated underly-ing mechanism proposed in BBT showed a significant increase in end-tidal CO
2 in the
active intervention arm. Critics of BBT argue that medication
reduction could be due to the therapist’s influence and it is difficult to evaluate that possibility. On the other hand, there was no evidence of a detrimental effect on asthma control with reduction in medication usage and to some extent, there might have been an improvement in symptoms. Longer fol-low-up is needed to show that improvement in asthma control as measured by medica-tion usage is sustained for a duration that is clinically meaningful, and that BBT has no adverse effects. Despite the lack of evidence for physiological change to account for the observed benefits, a decrease in medication use could be useful considering the possible systemic effects of ICS use [57,58].
Respiratory muscle training studies were few in number but three out of four such studies found positive results in terms of Ta
ble
7. N
on
ran
do
miz
ed c
on
tro
lled
tri
als
of
bio
feed
bac
k tr
ain
ing
.
Stu
dy
(yea
r)
Sam
ple
Des
ign
Inte
rven
tio
nW
ith
dra
wal
s/d
rop
ou
tsFo
llow
-up
Mag
nit
ud
e o
f d
iffe
ren
ce
Ref
.
Feld
man
(1
976
)4
inpa
tient
chi
ldre
n w
ith s
ever
e as
thm
aBe
fore
-and
-aft
er t
rial
Biof
eedb
ack
trai
ning
with
an
audi
tory
si
gnal
refl
ectin
g TR
R as
fee
dbac
k to
ol
Non
eN
one
↑ M
MEF
: 7.8
% (p
< 0
.05)
↓
TRR
: 64.
5% (p
< 0
.01)
[52]
Step
toe
et a
l. (1
981)
8 as
thm
atic
hos
pita
l st
aff
16 n
onas
thm
atic
st
uden
ts
Befo
re-a
nd-a
fter
tria
l (p
lann
ed b
ut n
ot
com
plet
ed a
s a
cont
rolle
d st
udy)
Four
ses
sion
of
four
tria
ls o
ffe
edba
ck u
sing
vis
ual a
nd a
udito
ry s
igna
ls
to r
eflec
t TR
R
Non
eN
one
No
cons
iste
nt c
hang
e in
TRR
in
asth
mat
ic g
roup
mem
bers
[55]
Ersk
ine-
Mill
is
et a
l. (1
987)
Stud
y 1:
9 a
dult
s St
udy
2: 1
0 ad
ults
(a
sthm
a w
ith a
n em
otio
nal t
rigge
r)
Befo
re-a
nd-a
fter
tria
lSt
udy
1: 4
wee
ks b
iofe
edba
ck t
rain
ing
usin
g vi
sual
dis
play
to
indi
cate
TRR
Stud
y 2:
one
pro
long
ed s
essi
on o
f bi
ofee
dbac
k tr
aini
ng (1
h w
ith r
ests
) usi
ng
visu
al d
ispl
ay t
o in
dica
te T
RR
Non
eS1
: 4 w
eeks
S2: n
one
Stud
y 1:
no
chan
ge in
TTR
Stud
y 2:
no
chan
ge in
TTR
↓ FE
V1
(by
21%
; p <
0.0
1)
[51]
Mas
s et
al.
(199
3)
15 o
utpa
tient
s w
ith
asth
ma
Befo
re-a
nd-a
fter
tria
lTh
ree
sess
ions
ove
r 4
wee
ks o
f fe
edba
ck
trai
ning
req
uirin
g pa
rtic
ipan
t to
mai
ntai
n re
spira
tory
res
ista
nce
with
in a
tar
get
rang
e us
ing
a vi
sual
ana
log
14
wee
ksN
o ch
ange
in F
EV1,
br
eath
less
ness
, phy
sica
l act
ivit
y or
rel
ieve
r m
edic
atio
n us
e
[54]
Lehr
er e
t al
. (2
00
0)
20 c
hild
ren
with
clin
ical
di
agno
sis
of a
sthm
aBe
fore
-and
-aft
er t
rial
Dai
ly s
essi
ons
of R
SA b
iofe
edba
ck t
o in
duce
pro
long
ed e
xpira
tion
5 da
ys/w
eek
for
13–1
5 se
ssio
ns
Non
e 3
wee
ks↑
FEV
1 an
d ↑
FEF 50
at
stud
y en
d in
17
out
of 2
0 ch
ildre
n [53]
↑: In
crea
se in
; ↓: D
ecre
ase
in; F
EV1:
For
ced
expi
rato
ry v
olum
e in
1 s
; FEF
50: F
orce
d ex
pira
tory
flow
at
50%
of
forc
ed v
ital
cap
acit
y; M
MEF
: Max
imal
mid
-exp
irato
ry fl
ow; R
SA: R
espi
rato
ry s
inus
arr
hyth
mia
; TRR
: Tot
al
resp
irato
ry r
esis
tanc
e.
Burgess, Ekanayake, Lowe, Dunt, Thien & Dharmage
www.expert-reviews.com 805
Review
improved lung function and quality of life, and a meta-analysis showed a significant reduction in medication use, warranting further examination of this technique.
Methods in yoga were highly heterogeneous, ranging from comprehensive inpatient programs to short-term outpatient training. Comparing RCTs to non-RCTs, we found that non-RCTs involving yoga training tended to yield higher therapeutic effects than RCTs. Studies that isolated a component of yoga found some benefit, whereas the only RCT of integrated yoga that yielded significant improvement was limited by a high and selective drop-out rate. Nonetheless, a meta-analysis showed a favorable effect of yoga on AQOL and a similar, although limited, effect was seen on one measure of lung function. We attempted to perform sensitivity analyses by incorporating non-RCTs of yoga in some of the meta-analyses. However this was not possible owing to unavailability of data from non-RCTs in a form suitable for inclusion in a meta-ana lysis.
Biofeedback training was limited by heterogeneity in meth-odology and often limited by small sample sizes. The need for specialized equipment in patient training limits the more general use of this technique among asthma patients.
Nearly all systematic reviews are restricted to RCTs and the inclusion of B&A trials in this review is novel. In a B&A trial, it is difficult to link improvements in outcome measures to the intervention as the outcome may have multiple determinants and it is difficult to know what proportion of a given outcome is determined by the intervention and what is due to patient-related factors. With that limitation, it is notable that the B&A trials of yoga techniques tended to show improvement in outcomes such as medication use and lung function parameters, which were sometimes statistically significant. It would be of interest to see the results of an adequately powered, well-designed RCT of a clearly defined yoga intervention in asthma management.
Owing to differences in study design, sample size, participant retention and adequacy of follow-up it was difficult to draw firm conclusions about the benefits of these treatments.
ConclusionThe BBT and similar breathing retraining techniques, yoga and respiratory muscle training all showed some benefit as alternative
treatments for asthma. However, there were too few well-designed studies with adequate power and length of follow-up to allow defi-nite conclusions to be drawn. On the existing evidence, and pro-vided that prescribed medications were continued, it would be rea-sonable for clinicians to offer qualified support to asthma patients intending to undertake such techniques under the supervision of a qualified instructor.
Given the rising popularity of complementary and alternative medicine in asthma, further studies of breathing retraining are warranted so that clinicians and patients alike can make informed treatment decisions.
Expert commentaryAsthma management can be difficult. As is often the case in chronic disease for which a cure cannot always be offered, patients with asthma will turn to CAMs in an attempt to self-help. The literature on CAMs in asthma management is not extensive and that which exists may report findings that are not always based on robust study design. However, clinicians would do well not to prejudge complementary methods but evaluate the empirical evidence for the benefits and risks of these methods, and if such evidence is lacking, take the lead in implementing adequately powered trials that employ the scientific method that might provide the evidence.
There is evidence indicating possible benefit from several tech-niques, the BBT, yoga and respiratory muscle retraining. All are readily available, not difficult to learn and may be cost-effective. These techniques will not replace asthma medication or a care-fully designed asthma plan, but their use should not be dismissed out of hand. Further well-designed trials of these techniques are needed to properly evaluate their place in asthma management.
Five-year viewPatient-driven asthma self-help will not lessen in the near future and clinicians should take the lead in setting up scientific tri-als of self-help methods, particularly breathing retraining. Consequently, we anticipate that the body of evidence for breath-ing retraining in asthma management will grow over the next few years and result in the establishment of clear guidelines as to whether and when such techniques should be employed.
Key issues
• Despite their popularity among asthma patients, breathing retraining techniques are controversially regarded by clinicians.
• The Buteyko breathing technique (BBT), physiotherapist-led breathing retraining, respiratory muscle retraining, yoga and biofeedback have been trialed in asthma management.
• In pooled estimates, asthma-related quality of life was significantly improved by BBT or physiotherapist-led breathing retraining and by yoga. No evidence was found for improvement in lung function from BBT or physiotherapist-led breathing retraining. However, there is limited evidence for improvement in lung function from yoga and for the reduction in b2-agonist use from respiratory muscle retraining.
• On current evidence, it is reasonable for clinicians to offer qualified support to patients intending to use BBT, physiotherapist-led breathing retraining, yoga or respiratory muscle retraining, provided there is supervision by a qualified instructor, usual prescribed medication is continued and limitations of the interventions are understood.
• Biofeedback is unlikely to be of practical use in asthma management.
• Further well-designed, adequately powered randomized controlled trials of breathing retraining techniques in asthma management are warranted.
Systematic review of the effectiveness of breathing retraining in asthma management
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Expert Rev. Respir. Med. 5(6), (2011)
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No writing assistance was utilized in the production of this manuscript.
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Systematic review of the effectiveness of breathing retraining in asthma management
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