Page 30 - Škrgat, Sabina, ed. 2023. Severe Asthma Forum - Monitoring and Treatable Traits in Severe Asthma. Koper: University of Primorska Press. Severe Asthma Forum, 2
P. 30
The BPAT includes assessment of abdominal latory response) and prolong BHT to 40 or
or apical breathing, inspiratory and expira- 50s.42 A short BHT (<30s) after normal ex-
severe asthma forum 2: severe asthma - monitoring and treatable traits in severe asthma tory flow, inspiration and expiration through piration at functional residual capacity is con-
mouth or nose, air hunger, breathing rate and sidered to be related to DB. A physician Kon-
rhythm.17 Recently, it appeared to be a useful stantin Buteyko, M.D., Ph.D., that developed
screening tool for identifying DB in patients breathing technics to reduce HVS claimed
with difficult-to-treat and severe asthma (with that BHT can detect chronic h yperventila-
score ≥4 as a cut-off for diagnosing DB was tion and that BHT predicts alveolar CO2
confirmed with sensitivity 95% and specifici- (PaCO2) according to his patented mathe-
ty 78%).37 Similarly, it is useful in evaluating matical formula.41,43
DB in long COVID (12 weeks after confirmed
or presumed pneumonia caused by SARS- Finally, to objectively evaluate breath-
CoV2 virus). Using the established cut-off, it ing patterns in various clinical and outpa-
showed a sensitivity of 89.5% and specificity tient settings, an ideal system should tend to
of 78.3%.3 fulfill the following characteristics: (1) Accu-
rate calculation of volume changes without
The Hyperventilation Provocation Test using a mouthpiece that may alter the normal
(HVPT) requires voluntary h yperventilation breathing pattern; (2) Need of a simple, sta-
for several minutes and is considered positive ble and repeatable calibration; (3) Possibility
if symptoms of HVS are recognized by the of use in non-collaborating subjects (during
examinee. Earlier, the test was a gold stand- sleep, or in unconscious patients); (4) Per-
ard for diagnosing HVS and the symptoms mitting the analysis in different postures; (5)
of HVS were largely attributable to hypocap- Permitting the analysis under dynamic con-
nia (low end-tidal carbon dioxide). Howev- ditions such as walking or cycling; (6) Allow-
er, a high percentage of false-positive results ing high frequency response in order to accu-
during the HVPT has been found in stud- rately describe rapid phenomena (i.e. electric
ies with a control condition of stressful men- or magnetic stimulation of phrenic nerves);
tal load.38,39 What is more, when limiting (6) Allowing the analysis of movements and
symptoms to hypocapnia, a study in the Lan- volume changing of the upper thorax, low-
cet found a high rate of false positives (66%) er thorax, and abdomen; (7) Allowing the
in patients where end-tidal pCO2 was main- analysis of movements and volume chang-
tained at baseline value by manual titration of ing of the hemi thoraces; (8) Being non-inva-
carbon dioxide from the cylinder into the in- sive and safe for the patient.44 Different tech-
spired air.40 niques with various limitations are available
for measuring natural breathing at rest - tid-
The end-tidal carbon dioxide measure- al breathing patterns, as well as exercise-in-
ment (ET-CO2) is measured using capnogra- duced changes in breathing. A less frequently
phy with an expected low ET-CO2 in h yper- used techniques include pneumotachography,
ventilation.41 respiratory induction plethysmography opto-
electronic plethysmography and structured
The Breath Hold Test or Breath Hold- light plethysmography. These vary in the
ing Time (BHT) is an indicator of a person’s source of the signal and the type of param-
ventilatory response to biochemical (sensitivi- eters that are generated, such as thoraco-ab-
ty to hypoxia and hypercapnia), biomechani- dominal asynchrony.45–47 Only structured
cal (lung volumes), non-chemical factors, and light plethysmography does not necessitate
psychologic factors, as well as training, exer- direct contact with patient’s body and is less
cise and altitude, etc. For example, divers may dependent on patient’s cooperation.47 How-
accommodate to the absence of respiratory
movements (non-chemical factors for venti-
or apical breathing, inspiratory and expira- 50s.42 A short BHT (<30s) after normal ex-
severe asthma forum 2: severe asthma - monitoring and treatable traits in severe asthma tory flow, inspiration and expiration through piration at functional residual capacity is con-
mouth or nose, air hunger, breathing rate and sidered to be related to DB. A physician Kon-
rhythm.17 Recently, it appeared to be a useful stantin Buteyko, M.D., Ph.D., that developed
screening tool for identifying DB in patients breathing technics to reduce HVS claimed
with difficult-to-treat and severe asthma (with that BHT can detect chronic h yperventila-
score ≥4 as a cut-off for diagnosing DB was tion and that BHT predicts alveolar CO2
confirmed with sensitivity 95% and specifici- (PaCO2) according to his patented mathe-
ty 78%).37 Similarly, it is useful in evaluating matical formula.41,43
DB in long COVID (12 weeks after confirmed
or presumed pneumonia caused by SARS- Finally, to objectively evaluate breath-
CoV2 virus). Using the established cut-off, it ing patterns in various clinical and outpa-
showed a sensitivity of 89.5% and specificity tient settings, an ideal system should tend to
of 78.3%.3 fulfill the following characteristics: (1) Accu-
rate calculation of volume changes without
The Hyperventilation Provocation Test using a mouthpiece that may alter the normal
(HVPT) requires voluntary h yperventilation breathing pattern; (2) Need of a simple, sta-
for several minutes and is considered positive ble and repeatable calibration; (3) Possibility
if symptoms of HVS are recognized by the of use in non-collaborating subjects (during
examinee. Earlier, the test was a gold stand- sleep, or in unconscious patients); (4) Per-
ard for diagnosing HVS and the symptoms mitting the analysis in different postures; (5)
of HVS were largely attributable to hypocap- Permitting the analysis under dynamic con-
nia (low end-tidal carbon dioxide). Howev- ditions such as walking or cycling; (6) Allow-
er, a high percentage of false-positive results ing high frequency response in order to accu-
during the HVPT has been found in stud- rately describe rapid phenomena (i.e. electric
ies with a control condition of stressful men- or magnetic stimulation of phrenic nerves);
tal load.38,39 What is more, when limiting (6) Allowing the analysis of movements and
symptoms to hypocapnia, a study in the Lan- volume changing of the upper thorax, low-
cet found a high rate of false positives (66%) er thorax, and abdomen; (7) Allowing the
in patients where end-tidal pCO2 was main- analysis of movements and volume chang-
tained at baseline value by manual titration of ing of the hemi thoraces; (8) Being non-inva-
carbon dioxide from the cylinder into the in- sive and safe for the patient.44 Different tech-
spired air.40 niques with various limitations are available
for measuring natural breathing at rest - tid-
The end-tidal carbon dioxide measure- al breathing patterns, as well as exercise-in-
ment (ET-CO2) is measured using capnogra- duced changes in breathing. A less frequently
phy with an expected low ET-CO2 in h yper- used techniques include pneumotachography,
ventilation.41 respiratory induction plethysmography opto-
electronic plethysmography and structured
The Breath Hold Test or Breath Hold- light plethysmography. These vary in the
ing Time (BHT) is an indicator of a person’s source of the signal and the type of param-
ventilatory response to biochemical (sensitivi- eters that are generated, such as thoraco-ab-
ty to hypoxia and hypercapnia), biomechani- dominal asynchrony.45–47 Only structured
cal (lung volumes), non-chemical factors, and light plethysmography does not necessitate
psychologic factors, as well as training, exer- direct contact with patient’s body and is less
cise and altitude, etc. For example, divers may dependent on patient’s cooperation.47 How-
accommodate to the absence of respiratory
movements (non-chemical factors for venti-
