Background Airway inflammation is considered
to be the hallmark of asthma and is also playing a role in COPD and
other lung diseases [1,2]. Its assessment by non-invasive methods
has proven useful in asthma management [3], but no easy and
affordable methods to this end are available in everyday practice.
We have developed a device to measure the temperature of the
exhaled breath (exhaled breath temperature, EBT) as a surrogate
marker of the inflammation in the intrathoracic airways [4]. The
high level of precision of the instrument allows picking the signal
attributable to the input from the airway wall to the overall
temperature of the exhaled air. Most studies on EBT so
far have been done in asthmatic patients and have suggested the
utility of this approach to assess non-invasively changes in the
degree of airway inflammation [5-9]. Our portable device makes this
method much more applicable in everyday clinical practice as it
makes possible individual measurements possible in the home of
those suffering. The option with the newest third generation
devices to have a succession of measurements accessible to the
treating physicians could make decision making about treatment
modalities more objective. We have demonstrated the association
between the daily course of EBT, PEF and symptoms [10].
The method holds particular promise in pediatric practices, as
children at the age of 3 and above are able to cope with the
requirements of the measurement. Actually, most of the initial work
to prove the feasibility of the method was done by Giorgio
Piacentini and co-workers in children [6, 8, 9]. In a recent study
the team of Nikos Papadopoulos found an association between viral
exacerbations of asthma and EBT in paediatric patients [11].
EBT measurements appear to hold promise also in other lung
diseases. There are reports that EBT is shifting downwards in
patients with chronic obstructive pulmonary disease, in whom
airways and pertaining vasculature are reduced [12, 13]. We have
preliminary yet unpublished data of increased EBT (but not axillary
temperature) in cases with viral infections, tuberculosis and
bronchopneumonia. Advantages
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Simplicity of use. |
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Few consumables. |
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Immediate results. |
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Possibility to use X-halo at the patient’s home. |
Areas of application
1. |
Research: |
|
a. |
Field epidemiological studies. |
|
b. |
Clinical trials comparing anti-inflammatory drugs. |
|
c. |
Pilot studies in areas beyond asthma and COPD. |
|
d. |
Pilot studies in areas beyond pulmonary medicine. |
|
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2. |
Patient care: |
|
a. |
To assess asthma / COPD control on subsequent visits in the physician’s office. |
|
b. |
Day-to-day assessment of asthma / control at the patients’ homes (like PEF-meter). |
|
c. |
To predict onset of respiratory viral infections in patients at risk. |
Limitations
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At this point of development of the device it is
not possible to use it to discriminate asthmatics from non
asthmatics on the basis of one time measurement of EBT.
|
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No reference values in relation to age, gender,
height, weight and ethnicity are available thus far.
|
EBT and Nitric Oxide measurement (FeNO)
FeNO has been established as a non-invasive marker of airway
inflammation in eosinophilic asthma [14]. It has been demonstrated
useful in monitoring asthma control [15] and in assessing the
anti-inflammatory effect of inhaled corticosteroids [16]. Most of
the intital work has been done with sophisticated NO-analyzers
using the principle of chemiluminescence. Recently, a handheld
device (NIOX MINO; Aerocrine) using electrochemical sensors for NO
assessment has been introduced to the market [17, 18] which is more
affordable for use in physicians’ offices. However, the
initial and maintenance costs of this portable NO device still
limit its use. There are also issues related to the repeatability
of the results [19, 20]. Correlations have been found between FeNo
and EBT [6, 8, 9]. EBT ranges fall within a narrower band, but
their repeatability is quite high. Measuring EBT also captures the
signal of non-eosinophilic inflammation. T. Popov
References
1. |
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2. |
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4. |
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6. |
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7. |
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11. |
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14. |
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15. |
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16. |
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19. |
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