Keywords
Mouth Breathing - muscle strength - evaluation studies
Introduction
The child who chronically breathes through the mouth might also have difficulties
with functional capacity, compromised respiratory system, damaging lung ventilation
with lower thoracic expansibility and, consequently, may develop a weakness of the
respiratory muscles.[1]
[2]
[3]
[4]
[5]
Currently researchers and clinicians are increasingly seeking methods of instrumental
evaluation, especially with the goal to gather data complementary to clinical evaluations
because it is necessary to evaluate the breathing muscles and consequences of those
respiratory changes in the Mouth Breathing child.[6]
Because the literature points to a physiologic relationship between Mouth Breathing
standard and respiratory muscle strength and because there are few studies that evaluate
the respiratory muscle strength in mouth breathers, the present study had the objective
to develop a review to investigate studies that used the methods of evaluation of
muscle strength in mouth breathers. The review was made in order to gather the clinical
evidence available in the literature to answer the clinical question.
Methods
First, the research question was formulated, considering the goal of the review in
this study: What are the evaluation methods of respiratory muscle strength in mouth
breathers?
Next, a systematic search was made in Medline databases via PubMed, Latin American
Literature in the Health Sciences (LILACS), and Scientific Electronic Library Online
(SciELO), between November 2011 and October 2012, and included papers and dissertations
covering the evaluation methods of RMS in inspiration and expiration during Mouth
Breathing defining the eligibility criteria.
The keywords used for search followed the description of DeCS/MeSH terms, being: muscle strength, Mouth Breathing, evaluation studies. A search was also performed with the same keywords in Portuguese. The combinations
between those words were made in each database mentioned above, using the Boolean
operator AND, without language restriction ([Table 1]).
Table 1
Levels of evidence-based medicine[a]
|
Levels
|
|
|
1
|
Systemic revision and random clinical trials with or without meta-analysis
|
|
2
|
Randomized controlled trials
|
|
3
|
Noncontrolled random clinical trials
|
|
4
|
Cohort study; case–control study; cross-sectional and quasirandomized studies
|
|
5
|
Case–control studies, case series
|
|
6
|
Expert opinions
|
Note: Table adapted from Oxford Centre for Evidence Based Medicine—Levels of Evidence.[7]
a Studies with the major strength of evidence are in the first position in the classification.
As for the level of scientific evidence, studies with the major strength of evidence
are in the first position in the classification with a score of 1 and the lower strength
with a score of 8.[7] Due to the lack of studies with evidence level 1, 2, 3, and 6, publications with
evidence level 4 and 5 were selected for this review ([Table 1]).
The abstracts of publications identified were evaluated according to the previously
mentioned eligibility criteria. The ones selected according to the inclusion criteria
had their methodologic quality evaluated by the following classification: random allocation,
“blind” subjects, “blind” therapists, control groups, statistical analysis, and statistical
comparison between the selected study groups ([Table 2]). The selected studies had their methodologic quality evaluated by two independent
reviewers (R.A. and D.C.) and the differences were discussed with a third reviewer
(H.J.).
Table 2
Methodological classification of selected studies
|
Okuro et al, 2011[9]
|
Banzatto, 2009[11]
|
Barbiero et al, 2007[10]
|
|
Specified inclusion criteria
|
Yes
|
Yes
|
Yes
|
|
Random allocation
|
No
|
No
|
No
|
|
“Blind” subjects
|
No
|
No
|
No
|
|
“Blind” therapists
|
Yes
|
No
|
No
|
|
Control group
|
Yes
|
No
|
No
|
|
Statistical analysis
|
Yes
|
Yes
|
Yes
|
|
Statistical comparison between groups
|
Yes
|
Yes
|
No
|
Currently, there are still few systematic reviews with meta-analysis available in
physiotherapy and other health fields. The reasons that hamper the execution of this
kind of study include the use of different research protocols and variations in methodologic
quality.[8]
Results
In principle, all studies were identified by the electronic search in the computer
screen. Then, the studies were subsequently analyzed and the publications that addressed
the evaluation methods of respiratory muscle strength in mouth breathers were included
in the revision (one case–control study and two case studies).
Among the 13 publications initially selected in databases, 10 were excluded. Among
the excluded ones, eight papers had no relation with the main subject according to
their title and abstract and two were repeated ([Fig. 1]).
Fig. 1 Search and selection of studies for revision according to PRISMA (Preferred Reporting
Items for Systematic Reviews and Meta-Analyses).[24] Abbreviation: LILACS, Latin American Literature in the Health Sciences.
To have a better presentation of results, the following were considered in the selected
publications: author/year, country, sample, age average in years, methods, and equipments
for evaluation of the respiratory muscle strength and results ([Table 3]).
Table 3
Studies evaluating the evaluation methods of respiratory muscle strength in children
with mouth breathing
|
Author/year
|
Country
|
Sample
|
Average age (y)
|
Methods and evaluation equipments of respiratory muscle strength
|
Results
|
|
Okuro et al, 2011[9]
|
Brazil
|
92 children, from both sexes: 30 had clinical otorhinolaryngologic diagnosis of MB
and 62 had NB
|
8–12
|
All participants submitted to PImax and PEmax evaluation; averages of PImax and PEmax
obtained with an analog manovacuometer MV-120 (Ger-Ar Medical Equipment Ltd., São
Paulo/SP, Brazil)
|
In MB group, there were no differences in averages of PImax and PEmax. The PImax and
PEmax values were lower in MB group than in NB. MB negatively affected the respiratory
biomechanics and exercise capacity.
|
|
Banzatto, 2009[11]
|
Brazil
|
32 children from both sexes, with MB and enlarged tonsils pre- and post-adenotonsillectomy
|
6–13
|
Averages of PImax and PEmax obtained with an analog manovacuometer MV-120 (Ger-Ar
Medical Equipment Ltd., São Paulo/SP, Brazil) pre and post adenotonsillectomy
|
PImax was lower in children with enlarged tonsils preoperatively. There was significant
increase of PImax 3–6 months postoperatively, denoting a gain in breathing muscle
strength. PEmax increased postoperatively; however, this increase was not significant.
|
|
Barbiero et al, 2007[10]
|
Brazil
|
20 children with functional MB, being 60% male and 40% female
|
Average 9.4 ± 1.1
|
Measurements of maximum static breathing pressures obtained with a digital manovacuometer
MVD300 (Globalmed - Suport of Therapeutic Material Ltd., Porto Alegre/RS, Brazil),
performed before and after RB utilization
|
The comparisons among maximum static breathing pressures did not show statistic significant
differences in PEmax between the previous and subsequent values to the treatment with
RB associated to the quiet breathing standard. There were significant differences
related to PImax after the treatment. This increased PImax seems to show that the
children started to better use their diaphragmatic muscles, reeducating their function
and directly influencing the inspiratory muscle strength.
|
Abbreviations: MB, mouth breathing; NB, nasal breathing; PEmax, maximum expiratory
pressure; PImax, maximum inspiratory pressure; RB, respiratory biofeedback.
The three included studies had as population children between 6 and 13 years of age
with and without Mouth Breathing.[9]
[10]
[11] The studies evaluated the respiratory muscle strength in Mouth Breathing children
through the measurements of maximum static respiratory pressures (inspiratory and
expiratory) by a manovacuometer. Analog and digital manovacuometers were used.
Those studies included 144 children of both sexes: 82 with Mouth Breathing and 62
with nasal breathing (control group). A control group was included only in the study
of Okuro et al.[9] Of them, 32 children were evaluated pre- and post-adenotonsillectomy because they
had enlarged tonsils, 20 were evaluated pre- and posttreatment using biofeedback,
and 92 had postural assessment and exercise ([Table 3]).
Regarding the methodologic quality, all studies had the inclusion criteria and statistical
analysis, but no one had random allocation and “blind” subjects. From the three publications,
only the Okuro et al study had “blind” therapists and a control group.[9] The three studies made a statistical comparison between the mouth breathers subgroups
([Table 2]).
One fact is that the authors were unanimous with relation to the manovacuometry method
as a means to evaluate the breathing pressures pre- and posttreatment and pre- and
postsurgery used to evaluate respiratory muscle strength in children with Mouth Breathing.
Two of them used an analog and a digital manovacuometer. The studies were not analyzed
for efficacy of both method and equipment used in Mouth Breathing children ([Table 3]).
Discussion
Currently, the evaluation methods of respiratory muscle strength are becoming more
important because the three studies included were made from 2007, which evaluated
the breathing muscles in mouth breathers in order to detect or not the improvement
before and after some intervention. This clinical importance of evaluating the breathing
muscles was proposed in previous publications.[12]
[13]
It is observed that Brazil was predominant in the three included studies because they
were the only one that focused in the theme of this revision, due to the search by
keywords and the inclusion criteria. This discovery may be explained because the manovacuometer
equipment is made in Brazil and is standardized and certified by the National Institute
of Metrology, Standardization and Industrial Quality, besides its commercialization,
acquisition, and maintenance being more easily accomplished in Brazilian territory.
From this, the Brazilian scientists started doing several researches about Mouth Breathing,
respiratory muscle strength, posture, and their relationships. However, there is still
a lack of studies correlating Mouth Breathing and respiratory muscle strength.
Some studies[14]
[15]
[16]
[17] found in previous searches focused on changes of body posture or on association
with the respiratory function in individuals with Mouth Breathing, given that musculoskeletal
changes are the more easily identified signals. Thus, respiratory muscle strength
was not usually evaluated.
Another relevant factor was the sample size. It was identified as a prevalent variation
between 20 and 32 children with Mouth Breathing (9–11), and this compromises the reproducibility
of those findings for the general population because of the reduced number of individuals
present on studies.
In the publications selected for this review, the age of analyzed subjects was between
7 and 13 years, and according to the World Health Organization,[18] the age group from 7 to 12 years old is defined as prepubertal and was established
because this period is considered of transition in breathing system development and
marks the end of rapid growth and structural changes of the periphery breathing units.[19]
There was clinical homogeneity among the studies favoring the reliable evaluation
of breathing pressures in the population set by the authors by manovacuometry. This
measurement technique used by the included studies is widely found in the literature
because there is a consensus in relation to the ideal method of manovacuometry to
evaluate this maximum respiratory pressures (PImax and PEmax).[12]
These pressures are measured in the mouth using a manovacuometer. The higher values
exclude significantly clinical weakness of the breathing muscles.[12] Measurements are useful for differentiation between a neuromuscular weakness of
abdominal muscles and a specific weakness of the diaphragm or others inspiratory muscles.[20]
[21]
[22]
Furthermore, it is necessary to evaluate the respiratory muscles and the consequences
of this respiratory change in the Mouth Breathing child.[6] The child that chronically breathes through the mouth may develop changes in the
respiratory system,[1]
[2] impairing lung ventilation,[22] demanding less strength from the breathing muscles, which would lead to muscle weakness
and lower chest expansion, sagging, and abdominal protrusion.[3]
[23]
Moreover, it is possible to say that when there is a treatment with attention focused
on respiratory muscle strength, there is significant increase in PEmax and PImax values,
improving this strength and all respiratory mechanics in the Mouth Breathing. The
three studies show the evaluation of pressures before and/or after a clinical evaluation.
Given the few studies found for this review, it is noted that the lack of the evaluation
of the respiratory muscle strength interferes in the diagnosis of some of this strength
deficit, as well as in the definition of the treatment and in the revaluation process
of respiratory strength to evidence if this treatment is effective or not. In clinical
practice, the delay to detect the diagnosis of Mouth Breathing and the unimportance
of this clinical condition may lead to few scientific studies focused on respiratory
muscle strength of the mouth breather being performed.
Thus, it is expected that further studies aimed at the methods used to evaluate respiratory
muscle strength in Mouth Breathing will be performed, as studies correlating results
of manovacuometry with data collected from other instruments for this evaluation,
because there are many gaps to be filled in correlation studies of diagnoses in Mouth
Breathing.
Conclusion
Despite manovacuometry being used in clinical practice to evaluate the respiratory
muscle strength in individuals with and without Mouth Breathing, it was found in this
review that there is not yet enough evidence to support the recommendation of this
technique. The low methodological rigor of the available studies hinders a truthful
and reliable result to support or refute the use of manovacuometry.
Finally, it was observed that there are few studies evaluating respiratory muscle
strength in Mouth Breathing people, through manovacuometry, suggesting that new research
needs to be performed.
