4. Discussion
M. pneumoniaepneumonia is a pulmonary infection caused by infection with M.
pneumoniae . The prevalence ofM.
pneumoniae pneumoniais gradually
increasing in children. Furthermore, a study involving 27,498 pediatric
patients in North China reported that 37.5% of these children hadM. pneumoniae pneumonia; during the peak of this disease, an
epidemic took place every 2–3 years (13). Almost 90% of casesoccur in
families that experience multiple cases, and immunity is not long
lasting (14). The most common symptoms at onset are fever and cough.
These symptoms tend to have a long duration and are prone to re-occur,
adversely affecting the respiratory system. Furthermore, M.
pneumoniae infection can lead to a range of complications, including
hemolysis, rash, joint pain, and swelling. In addition, the infection
can exert severe effects on the nervous and cardiovascular systems,
leading to aseptic meningitis or meningoencephalitis, arrhythmia, heart
failure, chest pain, and other severe complications(13, 15-18).
After invading the respiratory tract,M. pneumoniae localizes
between the cilia and adheres to the surface of epithelial cells via
adhesive organelles, thus preventing mucociliary clearance and
phagocytosis(19). This effect makes it very difficult for the body to
remove sputum containing M.
pneumoniae and its metabolites.Furthermore,M. pneumoniaeinfection can lead to inflammatory edema in the airways, thus causing
the tracheal wall to thicken; this
effect is exacerbated by the accumulation of sputum. These factors can
have an adverse effect on recovery time (20). Previous research also
reported that M. pneumoniae adhesion
inducesthe synthesis of hydrogen
peroxide; this endogenous form of reactive oxygen species (ROS) can
cause oxidative stress damage(21).
The accumulation of ROS,such as
peroxides, in host epithelial cells can lead to damage, including
vacuolar degeneration, mitochondrial swelling, cell dissolution, and
necrosis(22).
The clearance of sputum is driven by a combination of rhythmic waving of
the cilia and coughing; this combination of mechanismsrepresents the
body’s protective respiratory reflex to remove secretions, or foreign
bodies, from the respiratory tract through airflow and vibration(23). In
children, M. pneumoniae pneumonia weakens ciliary movements and
reduces lung function, thus making it very difficult for the body to
discharge sputum(23).Therefore, when treating children with M.
pneumoniae pneumonia, it is very important to provide sputum clearance
assistance to promote the effective clearance of sputum containing
metabolites of M. pneumoniae .This process helps to avoid the
development of further complications. A previous study highlighted that
the formation of sputum plugs in children with M. pneumoniaepneumonia results in significantly poorer chest imaging results and a
significant increase in the time required for fever remission (24).
The HFCWO systemcan simulate the
physiological process of normal coughing. This system involves
anair-pulse generatorconnected toan inflatable vest, thus causing the
patient’s chest wall to vibrate. In
a recent review of oscillating devices for airway clearance in patients
with cystic fibrosis, the HFCWO system was described as a routine form
of treatment (25). In a study of patients with cystic fibrosis combined
with exacerbation of chronic pyoobstructive bronchitis, the HFCWO system
led to a significant improvement in lung function, as compared with a
control group, both in terms of FEV1 (10.0 ± 4.6 vs 6.9 ± 3.6%
for FEV1; P = 0.04) and FVC (9.5 ± 4.8 vs 5.9 ± 3.8%; P = 0.03)
(26).The HFCWO system generates directional drainage forces and a
vibrating airflow between the lungs and the airway, thus loosening and
clearing the sputum by shear force. Furthermore, this system stimulates
cilia on the wall of the airways to help move the sputum along the air
passage, ultimately helping the patient to discharge the sputum (6).
HFCWO is widely used for treating chronic obstructive pulmonary disease
and for assisting with postoperative sputum clearance in critically ill
patients. Research has shown that HFCWO is effective and helps to
recover airway function (25). In a study of patients
undergoing single-port
video-assisted thoracoscopic surgery lobectomy, Zhu et al. found that
FEV, FVC, and PaO2, were all higher in patients treated
with HFCWO than in a control group (27). In a study of bronchiectasis,
HFCWO significantly reduced the rate of hospitalization (from 1.3±1.0 to
0.46±0.81; P<0.0001), significantly reduced the use of
antibiotics (from 2.5±0.86 to 2.1±0.92 courses/year;
P<0.0001), and reduced the decline in FEV1(from 1.85 ± 0.60 to
1.89 ± 0.60 L) (28), although the latter was not significant. Although
HFCWO has been widely used as a clinical treatment, little is known as
to how it might help children with M. pneumoniae pneumonia.
The purpose of the present study was to evaluate whether HFCWO could
improve the symptoms
of children withM.
pneumoniae pneumonia. HFCWO, which uses high-frequency chest wall
vibration to help patients to expectorate sputum, resulted in a total
effective rate that was significantly higher than that in the control
group.In addition, HFCWO obviously shortened the duration of convulsive
cough and fever. Furthermore,compared to the control group, patients
receiving HFCWO showed a significant improvement in lung function (FEV1,
FVC, and PEF, relative to predicted values). HFCWO also accelerated
improvementsin chest X-rays and reduced the length and cost of hospital
stays.
There are several limitations to this study that need to be considered.
First, because the technology has not yet been popularized, the parents
of patients were not very receptive to the technology; this inevitably
led to a small sample size. Second, as this form of treatment is still
being explored, this research study was only based in a single center.
Future research should aim to increase sample size and involve multiple
centers.