TY - JOUR T1 - Reductions in dead space ventilation with Nasal High Flow depend on physiologic dead space volume - Metabolic hood measurements during sleep in patients with COPD and controls JF - European Respiratory Journal JO - Eur Respir J DO - 10.1183/13993003.02251-2017 SP - 1702251 AU - Paolo Biselli AU - Kathrin Fricke AU - Ludger Grote AU - Andrew T Braun AU - Jason Kirkness AU - Philip Smith AU - Alan Schwartz AU - Hartmut Schneider Y1 - 2018/01/01 UR - http://erj.ersjournals.com/content/early/2018/04/12/13993003.02251-2017.abstract N2 - Background: Nasal high flow (NHF) reduces minute ventilation and ventilatory loads during sleep but mechanisms are not clear. We hypothesized NHF reduces ventilation in proportion of the physiologic but not anatomic dead space. Methods: 11 subjects (5 Controls and 6 COPD) underwent a polysomnography with transcutaneous CO2 (tcCO2) monitoring under a metabolic hood. During stable NREM 2 sleep, subjects received NHF (20 L/min) intermittently for periods of 5–10 min. We measured CO2 production and calculated dead space ventilation. Results: Controls and patients with COPD responded similarly to NHF. NHF reduced minute ventilation (5.6±0.4 L/min to 4.8±0.4 L/min, p<0.05) and tidal volume (0.34±0.03 to 0.3±0.03 L, p<0.05) without a change in energy expenditure, tcCO2 or alveolar ventilation. There was a significant decrease in dead space ventilation (2.5±0.4 L/min to 1.6±0.4 L/min, p<0.05) but not respiratory rate. The reduction in dead space ventilation correlated with baseline physiologic dead space fraction (r2=0.36, p<0.05) but not respiratory rate or anatomic dead space volume. Conclusion: During sleep, NHF decreases minute ventilation due to an overall reduction in dead space ventilation in proportion to the extent of baseline physiologic dead space fraction.Nasal High Flow decreases dead space ventilation in both controls and patients with COPD during sleepFootnotesThis manuscript has recently been accepted for publication in the European Respiratory Journal. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article.Conflict of interest: Dr. Biselli reports grants from NIH Grant: HL105546, grants from FAPESP, grants from CNPq, during the conduct of the study.Conflict of interest: Dr. Fricke reports grants from NIH Grant: HL105546, during the conduct of the study.Conflict of interest: Dr. Grote reports grants from Resmed Foundation, grants from Philips Foundation, grants, personal fees and non-financial support from Resmed, personal fees from Philips, personal fees from Itamar, personal fees from Weinmann, outside the submitted work.Conflict of interest: Dr. Braun reports grants from NIH Grant: HL105546, during the conduct of the study.Conflict of interest: Dr. Kirkness reports grants from NIH Grant: HL105546, other from Fisher & Paykel Healthcare, during the conduct and publication of the study.Conflict of interest: Dr. smith reports grants from NIH Grant: HL105546, during the conduct of the study.Conflict of interest: Dr. Schwartz reports grants from NIH Grant: HL105546, during the conduct of the study.Conflict of interest: Dr. Schneider reports grants from NIH Grant: HL105546, personal fees and non-financial support from Fisher & Paykel HC, grants from Resmed, personal fees from TNI Medical, during the conduct of the study; personal fees from Fisher & Paykel HC, personal fees from TNI Medical, outside the submitted work; In addition, Dr. Schneider has a patent United States Patent 7,080,645 issued to TNI Medical. ER -