Clinical Trial Details
— Status: Not yet recruiting
Administrative data
| NCT number |
NCT06272773 |
| Other study ID # |
IRAS Ref: 333663 |
| Secondary ID |
|
| Status |
Not yet recruiting |
| Phase |
|
| First received |
|
| Last updated |
|
| Start date |
March 2024 |
| Est. completion date |
March 2025 |
Study information
| Verified date |
February 2024 |
| Source |
Cambridge University Hospitals NHS Foundation Trust |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Observational
|
Clinical Trial Summary
Asthma is a chronic respiratory disease characterised by airway inflammation,
bronchoconstriction, and airway hyperresponsiveness. Accurate and reliable assessment of lung
function is crucial in diagnosing and monitoring asthma. The forced oscillation technique
(FOT) is a non-invasive method that has gained attention in recent years as a valuable tool
for evaluating respiratory mechanics in asthma.
FOT involves applying small amplitude oscillations at various frequencies to the respiratory
system and measuring the resulting pressure and flow responses. These measurements provide
valuable insights into the mechanical properties of the airways, including resistance,
compliance, and reactance. FOT offers several advantages over traditional spirometry, such as
its ability to assess peripheral airway function, sensitivity to small airway abnormalities,
and ease of use, particularly in young children or individuals with severe airflow
limitation. FOT also allows for assessment of respiratory mechanics in individuals who may
struggle with performing spirometry manoeuvres.
However, it is unclear whether a change in breathing pattern in patients with obstructive
lung disease impacts the assessment of a response to treatment utilising FOT.
Several studies have demonstrated a high prevalence of Breathing Pattern Disorders (BPDs) in
individuals with asthma. These findings suggest that BPDs may be common in asthma and could
contribute to the manifestation and severity of respiratory symptoms. Evidence suggests that
BPDs can adversely affect pulmonary function in individuals with asthma. One study
demonstrated that children with asthma and dysfunctional breathing exhibited significantly
reduced forced expiratory volume in one second (FEV1) compared to asthmatics without BPD.
This suggests that abnormal breathing patterns may contribute to airflow limitation in
asthma, leading to decreased lung function.
We therefore wish to determine the impact of different breathing frequencies on parameters
measured using FOT in patients diagnosed with asthma and concomitant obstructive lung
function abnormality.
Description:
Asthma is a chronic respiratory disease characterised by airway inflammation,
bronchoconstriction, and airway hyperresponsiveness. Accurate and reliable assessment of lung
function is crucial in diagnosing and monitoring asthma. The forced oscillation technique
(FOT) is a non-invasive method that has gained attention in recent years as a valuable tool
for evaluating respiratory mechanics in asthma.
FOT involves applying small amplitude oscillations at various frequencies to the respiratory
system and measuring the resulting pressure and flow responses. These measurements provide
valuable insights into the mechanical properties of the airways, including resistance,
compliance, and reactance. FOT offers several advantages over traditional spirometry, such as
its ability to assess peripheral airway function, sensitivity to small airway abnormalities,
and ease of use, particularly in young children or individuals with severe airflow
limitation. FOT also allows for assessment of respiratory mechanics in individuals who may
struggle with performing spirometry manoeuvres.
Numerous studies have investigated the utility of FOT in diagnosing asthma. For instance,
Smith et al. (2018) conducted a study on 100 adults with suspected asthma and found that FOT
parameters, such as total respiratory resistance and respiratory system reactance,
demonstrated good diagnostic accuracy compared to spirometry. Similarly, Andersson et al.
(2020) evaluated the diagnostic performance of FOT in children with asthma and reported that
FOT parameters correlated well with markers of airway inflammation, suggesting its potential
for identifying asthmatic phenotypes.
In addition to its diagnostic value, FOT has shown promise in monitoring asthma control and
assessing treatment response. A study by Van der Wiel et al. (2019) investigated the use of
FOT in adults with mild to moderate asthma and found that changes in FOT parameters, such as
frequency dependence of resistance and reactance, were sensitive to improvements in lung
function following treatment. Similarly, Song et al. (2021) conducted a systematic review and
meta-analysis and reported that FOT parameters exhibited significant changes in response to
different asthma treatments, supporting its utility as an outcome measure in clinical trials.
However, it is unclear whether a change in breathing pattern in patients with obstructive
lung disease impacts the assessment of a response to treatment utilising FOT. Several studies
have demonstrated a high prevalence of BPDs in individuals with asthma. In a study by Thomas
et al. (2018), 54% of asthma patients exhibited abnormal breathing patterns, characterized by
upper chest breathing, reduced diaphragmatic excursion, and increased accessory muscle use.
These findings suggest that BPDs may be common in asthma and could contribute to the
manifestation and severity of respiratory symptoms. Evidence suggests that BPDs can adversely
affect pulmonary function in individuals with asthma. A study by Porges et al. (2019)
demonstrated that children with asthma and dysfunctional breathing exhibited significantly
reduced forced expiratory volume in one second (FEV1) compared to asthmatics without BPD.
This suggests that abnormal breathing patterns may contribute to airflow limitation in
asthma, leading to decreased lung function.
Howlett-Foster et al (2022) demonstrated no significant difference in FOT parameters across
multiple breathing frequencies in healthy young adults. However, in obstructive lung disease
the airway luminal size is smaller due to airway inflammation, excessive smooth muscle
contraction and mucus plugging. Based on the Hagen-Poiseuille equation halving the luminal
radius increases airways resistance 16-fold. In addition, based on the law of Bernoulli, this
smaller luminal size will increase the velocity of air through the airways, reducing airway
pressure and leading to a tendency of the airways to narrow further. Therefore, in asthmatic
patients a change in breathing frequency may lead to an increase in airway velocity, a
reduction in luminal size and hence an increase in airway resistance. A change in breathing
pattern between measurements, particularly following treatment administration, may over or
underestimate treatment response if the response is measured using FOT and may not be due to
the treatment itself.
We therefore wish to determine the impact of different breathing frequencies on parameters
measured using FOT in patients diagnosed with asthma and concomitant obstructive lung
function abnormality.
