Pragmatic Approach to Small Airways Diagnostics

• Main Author: Žugić, Vladimir
• Format: Article in Journal/Newspaper
• Language: English; srp
• Published: 2021
• Subjects: small airways; diagnostic approach; mali disajni putevi; dijagnostički pristup; Otpor; Protoka; sami
• Online Access: https://hrcak.srce.hr/264143; https://hrcak.srce.hr/file/383651; https://hrcak.srce.hr/file/383652

Small airways have an inner diameter of 2 mm or less. They are characterized by lack of cartilage in their wall, sudden increase in total cross-section area, and by an abrupt switch from turbulent to laminar air flow, all of which cause minimal airflow resistance in healthy persons. Conversely, in patients with obstructive lung diseases, small airways are the primary site of airflow limitation. Small airways tests are numerous and they vary considerably in their diagnostic significance, complexity and availability. Currently, none of the existing tests represents the diagnostic “gold standard”, and none offer precise cut-off values to distinguish between small airway disease, healthy persons, and individuals with concomitant pathophysiological disorder. Negative results of these tests have significant negative predictive values, i.e. ruling out small airways as the cause of the clinical issue, while positive results of these tests should always be crosschecked to confirm the presence of small airways disorder by other methods. Results of small airways diagnostic tests do not mean much as isolated findings unless they are combined with other diagnostic methods (history, clinical findings, imaging, etc.) to elucidate any specific clinical case. On the other hand, if results are strongly suggestive of the presence of a small airways disease, that can have significant clinical implications, such as application of fine particle aerosols. The suggested diagnostic algorithm is based primarily on tests availability. It should not be implemented uncritically, but rather adapted to the healthcare system at hand. Mali disajni putevi se definišu kao disajni putevi promera 2 mm ili manjeg. Odlikuju se odsustvom hrskavice u svom zidu, naglim povećanjem ukupnog poprečnog preseka i prelaskom turbulentnog toka vazduha u laminarni, tako da je kod zdravih ljudi u njima minimalan otpor protoku vazduha. Za razliku od toga, u opstruktivnim bolestima pluća mali disajni putevi predstavljaju glavno mesto ograničenja protoka vazduha. Testovi koji se koriste u dijagnostici promena u malim disajnim putevima su brojni i oni značajno variraju u svojoj dijagnostičkoj vrednosti, složenosti i dostupnosti. Trenutno ne postoji test koji predstavlja zlatni standard u dijagnostici bolesti malih disajnih puteva, niti test sa jasnim graničnim vrednostima pomoću kojih bi se mogle razlikovati osobe sa poremećajem funkcije malih disajnih puteva i „zdrave“ osobe, odnosno osobe s pridruženim patofiziološkim poremećajima. Negativni rezultati ovih testova mogu sa velikom sigurnošću ukazati na to da mali disajni putevi ne igraju ulogu u datom kliničkom problemu, dok bi pozitivne rezultate pojedinačnih testova trebalo uvek proveriti različitim metodama da bi se potvrdilo prisustvo poremećaja u malim disajnim putevima. Rezultati dijagnostičkih testova za male disajne puteve sami po sebi ne znače mnogo ako se ne kombinuju s drugim metodama i ne uklope u dati klinički problem (anamnestički podaci, klinička slika, vizualizacioni metodi i drugo). S druge strane, ako rezultati ovih testova definitivno ukažu na problem u malim disajnim putevima, to može imati značajne kliničke implikacije, na primer, primenu aerosola sa finim česticama u lečenju. Predloženi algoritam kao osnovni kriterijum uzima dostupnost dijagnostičkih testova. Ovaj algoritam ne treba smatrati definitivnim rešenjem, već ga uvek treba prilagoditi postojećem zdravstvenom sistemu.