{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T10:49:12Z","timestamp":1777891752743,"version":"3.51.4"},"reference-count":18,"publisher":"SAGE Publications","issue":"10","license":[{"start":{"date-parts":[[2014,4,29]],"date-time":"2014-04-29T00:00:00Z","timestamp":1398729600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["Respir Care"],"published-print":{"date-parts":[[2014,10]]},"abstract":"<jats:sec>\n                    <jats:title>BACKGROUND:<\/jats:title>\n                    <jats:p>\n                      Unidirectional breathing (UB), nose-in mouth-out (NMB) or vice versa, is thought to create PEEP, stabilize small airways, and increase expiratory flow and exhaled tidal volume (V\n                      <jats:sub>T<\/jats:sub>\n                      ) in patients with expiratory obstructive disorders. However, the exact mechanism providing the benefits of UB remains unknown. Our hypothesis was that the benefits of UB are achieved mainly through reduction of upper airway dead space.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>METHODS:<\/jats:title>\n                    <jats:p>\n                      Sixteen stable COPD patients requiring oxygen use at home were enrolled in this prospective study at a tertiary health care center. A nasal mask and a mouthpiece were used, each having a removable one-way valve to direct the breathing pattern. Four experimentally defined patterns of spontaneous breathing, NMB, mouth-in nose-out (MNB), nose-in nose-out (NNB), and mouth-in mouth-out (MMB), were compared. Each breathing pattern lasted 5 min followed by a 5-min rest period. A NICO device continuously monitored respiratory parameters. The functional anatomical dead space volume (V\n                      <jats:sub>D<\/jats:sub>\n                      ) and expired V\n                      <jats:sub>T<\/jats:sub>\n                      values were determined. Breathing efficiency (BE) was calculated as alveolar V\n                      <jats:sub>T<\/jats:sub>\n                      divided by expired volume.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>RESULTS:<\/jats:title>\n                    <jats:p>\n                      Functional anatomical V\n                      <jats:sub>D<\/jats:sub>\n                      was higher in bidirectional breathing (BB) (overall: 207.4 \u00b1 7.9 mL; MMB: 232.5 \u00b1 72.7 mL; NNB: 182.2 \u00b1 75 mL) compared to UB (overall: 178.1 \u00b1 87.2 mL; NMB: 176.9 \u00b1 91.3 mL; MNB: 179.3 \u00b1 83.2 mL) (\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      &lt; .001). BE achieved with UB (overall: 76.2 \u00b1 6.5%; NMB: 76.8 \u00b1 6.8%; MNB: 75.6 \u00b1 6.3%) was higher than that with BB (overall: 66.2 \u00b1 0.09%; MMB: 64.3 \u00b1 0.10%; NNB: 68.1 \u00b1 0.08%) (\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      &lt; .001). The difference in BE between UB and BB was more pronounced with small V\n                      <jats:sub>T<\/jats:sub>\n                      values (UB: 73.8 \u00b1 0.08; BB: 49.4 \u00b1 0.09) than with large V\n                      <jats:sub>T<\/jats:sub>\n                      values (UB: 77.3 \u00b1 0.06; BB: 63.0 \u00b1 0.07) (\n                      <jats:italic toggle=\"yes\">P<\/jats:italic>\n                      &lt; .001).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>CONCLUSIONS:<\/jats:title>\n                    <jats:p>\n                      Our data suggest that a reduction in functional anatomic V\n                      <jats:sub>D<\/jats:sub>\n                      may be the underlying mechanism for the benefits associated with UB in COPD patients. (ClinicalTrials.gov registration NCT00784004.)\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.4187\/respcare.02899","type":"journal-article","created":{"date-parts":[[2014,4,30]],"date-time":"2014-04-30T00:53:43Z","timestamp":1398819223000},"page":"1487-1493","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":3,"title":["A Unidirectional Breathing Pattern Improves Breathing Efficiency in Subjects With Severe COPD"],"prefix":"10.1177","volume":"59","author":[{"given":"Demet S","family":"Sulemanji","sequence":"first","affiliation":[{"name":"Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Fangping","family":"Bao","sequence":"additional","affiliation":[{"name":"Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts."},{"name":"Department of Anesthesia, Zhejiang University, Hangzhou, China."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yandong","family":"Jiang","sequence":"additional","affiliation":[{"name":"Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts."}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Robert M","family":"Kacmarek","sequence":"additional","affiliation":[{"name":"Department of Anesthesia, Critical Care and Pain Medicine, Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts."},{"name":"Respiratory Care Services Department, Massachusetts General Hospital, Boston, Massachusetts."}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"179","published-online":{"date-parts":[[2014,4,29]]},"reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0272-5231(21)00454-8"},{"key":"e_1_3_2_3_2","first-page":"564","article-title":"The effect of air flow and oral pressure on the mechanics of breathing in patients with asthma and emphysema","volume":"90","author":"Schmidt RW","year":"1964","unstructured":"Schmidt RW, , Wasserman K, , Lillington GA. The effect of air flow and oral pressure on the mechanics of breathing in patients with asthma and emphysema. Am Rev Respir Dis, 1964; 90:564\u2013571.","journal-title":"Am Rev Respir Dis"},{"key":"e_1_3_2_4_2","doi-asserted-by":"publisher","DOI":"10.1126\/science.169.3950.1102"},{"key":"e_1_3_2_5_2","doi-asserted-by":"publisher","DOI":"10.1378\/chest.125.2.459"},{"key":"e_1_3_2_6_2","doi-asserted-by":"publisher","DOI":"10.1378\/chest.128.2.640"},{"key":"e_1_3_2_7_2","doi-asserted-by":"publisher","DOI":"10.1034\/j.1399-6576.2001.450917.x"},{"key":"e_1_3_2_8_2","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1959.14.2.174"},{"key":"e_1_3_2_9_2","doi-asserted-by":"publisher","DOI":"10.1152\/japplphysiol.90599.2008"},{"issue":"1","key":"e_1_3_2_10_2","first-page":"100","article-title":"The efficacy of pursed-lips breathing in patients with chronic obstructive pulmonary disease","volume":"93","author":"Thoman RL","year":"1966","unstructured":"Thoman RL, , Stoker GL, , Ross JC. The efficacy of pursed-lips breathing in patients with chronic obstructive pulmonary disease. Am Rev Respir Dis, 1966; 93(1):100\u2013106.","journal-title":"Am Rev Respir Dis"},{"key":"e_1_3_2_11_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(87)92225-2"},{"key":"e_1_3_2_12_2","doi-asserted-by":"publisher","DOI":"10.1097\/00044067-200105000-00004"},{"key":"e_1_3_2_13_2","doi-asserted-by":"publisher","DOI":"10.1097\/01.HCR.0000281770.82652.cb"},{"issue":"3","key":"e_1_3_2_14_2","first-page":"381","article-title":"Effect of pursed lips expiration on the pulmonary pressure-flow relationship in obstructive lung disease","volume":"96","author":"Ingram RH","year":"1967","unstructured":"Ingram RHJr, , Schilder DP. Effect of pursed lips expiration on the pulmonary pressure-flow relationship in obstructive lung disease. Am Rev Respir Dis, 1967; 96(3):381\u2013388.","journal-title":"Am Rev Respir Dis"},{"key":"e_1_3_2_15_2","doi-asserted-by":"publisher","DOI":"10.1053\/mr.2000.3790"},{"key":"e_1_3_2_16_2","doi-asserted-by":"publisher","DOI":"10.1186\/cc2461"},{"key":"e_1_3_2_17_2","doi-asserted-by":"publisher","DOI":"10.1152\/jappl.1964.19.1.92"},{"key":"e_1_3_2_18_2","doi-asserted-by":"publisher","DOI":"10.1177\/000313480507100206"},{"key":"e_1_3_2_19_2","doi-asserted-by":"publisher","DOI":"10.1007\/s00134-002-1545-6"}],"container-title":["Respiratory Care"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/full-xml\/10.4187\/respcare.02899","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.4187\/respcare.02899","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.4187\/respcare.02899","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T06:09:51Z","timestamp":1777615791000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/10.4187\/respcare.02899"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2014,4,29]]},"references-count":18,"journal-issue":{"issue":"10","published-print":{"date-parts":[[2014,10]]}},"alternative-id":["10.4187\/respcare.02899"],"URL":"https:\/\/doi.org\/10.4187\/respcare.02899","relation":{},"ISSN":["0020-1324"],"issn-type":[{"value":"0020-1324","type":"print"}],"subject":[],"published":{"date-parts":[[2014,4,29]]}}}