Page 77 - Škrgat, Sabina, ed. 2022. Severe Asthma - Basic and Clinical Views. Koper: University of Primorska Press. Severe Asthma Forum, 1
P. 77
ung Function Tests to be Used in Severe 4.1
Asthma: Spirometry and Bronchodilator Test,
Diffusion Capacity for CO, Induced Sputum,
Body Plethysmography, Electronic PEF
Measurements
Matjaž Fležar1,2
Abstract 3 University Clinic
Lung function tests are the cornerstone for asthma diagnostic procedure and patient follow-up of Respiratory and Allergic
and is complementary to other phenotyping tools used later for precision diagnosis. Spirome- Diseases Golnik, Slovenia
try and bronchodilator tests are used to define degree and reversibility of airway disease, dif-
fusion capacity of the lung for CO is used as exclusion tool for comorbid diseases (particularly 2 Faculty of Medicine,
COPD), Body plethysmograph is used in small airway asthma to determine the degree of air University of Ljubljana,
trapping and hyperinflation, electronic PEF monitoring is used for work-related asthma char- Ljubljana, Slovenia
acterization and targeted sputum examinations (induced sputum protocol) are used in im-
mune phenotyping process. In hands of pulmonologist these tests (not all of them routinely
used) are necessary to separate uncontrolled asthma from severe asthma phenotype.
Keywords: lung function tests, severe asthma, work related asthma, asthma phenotyping
Introduction histamine vs. allergen test) BHR can be used
Asthma from lung function perspective is a to determine inducible airway constriction,
disease detected by smooth muscle hyperres- seen in asthma, COPD, some normal persons,
ponsiveness and airway obstruction, which is in children after childhood bronchiolitis, in
variable and reversible. All these physiological smokers and in a course of acute bronchitis.
hallmarks of the disease can be appropriate- The presence of BHR is linked to respiratory
ly tested, although the results may vary over symptoms such as chronic cough, nocturnal
the course and intensity of the disease. If cho- cough, wheeze, dyspnea on exertion, period-
sen in context of a clinical picture of a patient, ic dyspnea at rest, inhalational allergy-related
they can provide most definite diagnostic con- lower respiratory symptoms, etc.
firmation of the disease6.
In diagnostic procedure of asthma, as-
Clinically used Tests and Physiological sessment of BHR is in place if pre-test proba-
Background bility of asthma is at least 30% and not more
than 70%. It is also not necessary if the patient
Smooth Muscle Hyperresponsiveness present with completely reversible airway ob-
In case of normal spirometry (no obstruction) struction (normalization of flows, volumes
and pretest probability of asthma between 30 and resolution of obstruction – norma-
and 70%, a surrogate test to detect airway hy- lization of FEV1/VC ratio) after 400mcg
per responsiveness in non-specific or specific of inhaled short acting bronchodilator drug
bronchial provocation test (methacholine or (e.g., salbutamol). Proper timing of the test
https://doi.org/10.26 493/978 -961-293 -157-5.77-81
Asthma: Spirometry and Bronchodilator Test,
Diffusion Capacity for CO, Induced Sputum,
Body Plethysmography, Electronic PEF
Measurements
Matjaž Fležar1,2
Abstract 3 University Clinic
Lung function tests are the cornerstone for asthma diagnostic procedure and patient follow-up of Respiratory and Allergic
and is complementary to other phenotyping tools used later for precision diagnosis. Spirome- Diseases Golnik, Slovenia
try and bronchodilator tests are used to define degree and reversibility of airway disease, dif-
fusion capacity of the lung for CO is used as exclusion tool for comorbid diseases (particularly 2 Faculty of Medicine,
COPD), Body plethysmograph is used in small airway asthma to determine the degree of air University of Ljubljana,
trapping and hyperinflation, electronic PEF monitoring is used for work-related asthma char- Ljubljana, Slovenia
acterization and targeted sputum examinations (induced sputum protocol) are used in im-
mune phenotyping process. In hands of pulmonologist these tests (not all of them routinely
used) are necessary to separate uncontrolled asthma from severe asthma phenotype.
Keywords: lung function tests, severe asthma, work related asthma, asthma phenotyping
Introduction histamine vs. allergen test) BHR can be used
Asthma from lung function perspective is a to determine inducible airway constriction,
disease detected by smooth muscle hyperres- seen in asthma, COPD, some normal persons,
ponsiveness and airway obstruction, which is in children after childhood bronchiolitis, in
variable and reversible. All these physiological smokers and in a course of acute bronchitis.
hallmarks of the disease can be appropriate- The presence of BHR is linked to respiratory
ly tested, although the results may vary over symptoms such as chronic cough, nocturnal
the course and intensity of the disease. If cho- cough, wheeze, dyspnea on exertion, period-
sen in context of a clinical picture of a patient, ic dyspnea at rest, inhalational allergy-related
they can provide most definite diagnostic con- lower respiratory symptoms, etc.
firmation of the disease6.
In diagnostic procedure of asthma, as-
Clinically used Tests and Physiological sessment of BHR is in place if pre-test proba-
Background bility of asthma is at least 30% and not more
than 70%. It is also not necessary if the patient
Smooth Muscle Hyperresponsiveness present with completely reversible airway ob-
In case of normal spirometry (no obstruction) struction (normalization of flows, volumes
and pretest probability of asthma between 30 and resolution of obstruction – norma-
and 70%, a surrogate test to detect airway hy- lization of FEV1/VC ratio) after 400mcg
per responsiveness in non-specific or specific of inhaled short acting bronchodilator drug
bronchial provocation test (methacholine or (e.g., salbutamol). Proper timing of the test
https://doi.org/10.26 493/978 -961-293 -157-5.77-81
