{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,4]],"date-time":"2026-04-04T01:41:51Z","timestamp":1775266911438,"version":"3.50.1"},"reference-count":41,"publisher":"Wiley","issue":"5","license":[{"start":{"date-parts":[[2023,4,10]],"date-time":"2023-04-10T00:00:00Z","timestamp":1681084800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"funder":[{"DOI":"10.13039\/501100003593","name":"Conselho Nacional de Desenvolvimento Cient\u00edfico e Tecnol\u00f3gico","doi-asserted-by":"publisher","award":["304061\/2019\u20100"],"award-info":[{"award-number":["304061\/2019\u20100"]}],"id":[{"id":"10.13039\/501100003593","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Clin Physio Funct Imaging"],"published-print":{"date-parts":[[2023,9]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Background<\/jats:title><jats:p>Dysfunctional breathing (DB) is a common, but largely underappreciated, cause of chronic dyspnoea. Under visual inspection, most subjects with DB present with larger sequential changes in ventilation (V\u0307E) and breathing pattern (tidal volume (VT) and breathing frequency (<jats:italic>f<\/jats:italic>)) before and\/or during incremental cardiopulmonary exercise testing (CPET). Currently, however, there are no objective criteria to indicate increased ventilatory variability in these subjects.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>Twenty chronically dyspnoeic subjects with DB and 10 age\u2010 and sex\u2010matched controls performed CPET on a cycle ergometer. Cut\u2010offs to indicate increased V\u0307E, VT, <jats:italic>f<\/jats:italic>, and <jats:italic>f<\/jats:italic>\/VT ratio variability (\u0394\u2009=\u2009highest\u2010lowest 20\u2009s arithmetic mean) over the last resting minute (<jats:sub>rest<\/jats:sub>), the 2<jats:sup>sd<\/jats:sup> min of unloaded exercise (<jats:sub>unload<\/jats:sub>), and the 3rd min of loaded exercise (<jats:sub>load<\/jats:sub>) were established by ROC curve analyses.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>Subjects with DB presented with increased V\u0307E, higher ventilatory variability, higher dyspnoea burden, and lower exercise capacity compared to controls (<jats:italic>p<\/jats:italic>\u2009&lt;\u20090.05). \u0394V\u0307E<jats:sub>load<\/jats:sub> (&gt;4.1\u2009L\/min), \u0394<jats:italic>f<\/jats:italic><jats:sub>rest<\/jats:sub> (&gt;5 breaths\/min; bpm), \u0394<jats:italic>f<\/jats:italic><jats:sub>unload<\/jats:sub> (&gt;4\u2009bpm), \u0394<jats:italic>f<\/jats:italic><jats:sub>load<\/jats:sub> (&gt;5\u2009bpm), \u0394<jats:italic>f<\/jats:italic>\/VT<jats:sub>rest<\/jats:sub> (&gt;4.9\u2009bpm\/L), and \u0394<jats:italic>f<\/jats:italic>\/VT<jats:sub>load<\/jats:sub> (&gt;1.3\u2009bpm\/L) differentiated DB from a normal pattern (areas under the curve ranging from 0.729 to 0.845). High \u0394<jats:italic>f<\/jats:italic>, in particular, was associated with DB across all CPET phases.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>This study provides objective criteria to indicate increased ventilatory variability during incremental CPET in dyspnoeic subjects with DB. Large variability in breathing frequency seems particularly useful in this context, a finding that should be prospectively confirmed in larger studies.<\/jats:p><\/jats:sec>","DOI":"10.1111\/cpf.12820","type":"journal-article","created":{"date-parts":[[2023,3,31]],"date-time":"2023-03-31T04:38:25Z","timestamp":1680237505000},"page":"305-312","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Cardiopulmonary exercise testing to indicate increased ventilatory variability in subjects with dysfunctional breathing"],"prefix":"10.1111","volume":"43","author":[{"given":"Nathalia B. S.","family":"Mendes","sequence":"first","affiliation":[{"name":"Hospital de Cl\u00ednicas de Porto Alegre; Rio Grande do Sul Universidade Federal do Rio Grande do Sul Porto Alegre Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Franciele","family":"Plachi","sequence":"additional","affiliation":[{"name":"Hospital de Cl\u00ednicas de Porto Alegre; Rio Grande do Sul Universidade Federal do Rio Grande do Sul Porto Alegre Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Amanda","family":"Guimar\u00e3es","sequence":"additional","affiliation":[{"name":"Hospital de Cl\u00ednicas de Porto Alegre; Rio Grande do Sul Universidade Federal do Rio Grande do Sul Porto Alegre Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Talmir","family":"Nolasco","sequence":"additional","affiliation":[{"name":"Hospital de Cl\u00ednicas de Porto Alegre; Rio Grande do Sul Universidade Federal do Rio Grande do Sul Porto Alegre Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ricardo","family":"Gass","sequence":"additional","affiliation":[{"name":"Hospital de Cl\u00ednicas de Porto Alegre; Rio Grande do Sul Universidade Federal do Rio Grande do Sul Porto Alegre Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marcelo","family":"Nogueira","sequence":"additional","affiliation":[{"name":"Santa Casa de Porto Alegre Universidade Federal de Ci\u00eancias da Sa\u00fade de Porto Alegre Porto Alegre Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Paulo J. 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