title: Neural versus pneumatic control of pressure support in patients with chronic obstructive pulmonary diseases at different levels of positive end expiratory pressure: a physiological study.
abstract: BACKGROUND
  Intrinsic positive end-expiratory pressure (PEEPi) is a "threshold" load that must be overcome to trigger conventional pneumatically-controlled pressure support (PSP) in chronic obstructive pulmonary disease (COPD). Application of extrinsic PEEP (PEEPe) reduces trigger delays and mechanical inspiratory efforts. Using the diaphragm electrical activity (EAdi), neurally controlled pressure support (PSN) could hypothetically eliminate asynchrony and reduce mechanical inspiratory effort, hence substituting the need for PEEPe. The primary objective of this study was to show that PSN can reduce the need for PEEPe to improve patient-ventilator interaction and to reduce both the "pre-trigger" and "total inspiratory" neural and mechanical efforts in COPD patients with PEEPi. A secondary objective was to evaluate the impact of applying PSN on breathing pattern.
  
  
  METHODS
  Twelve intubated and mechanically ventilated COPD patients with PEEPi ≥ 5 cm H2O underwent comparisons of PSP and PSN at different levels of PEEPe (at 0 %, 40 %, 80 %, and 120 % of static PEEPi, for 12 minutes at each level on average), at matching peak airway pressure. We measured flow, airway pressure, esophageal pressure, and EAdi, and analyzed neural and mechanical efforts for triggering and total inspiration. Patient-ventilator interaction was analyzed with the NeuroSync index.
  
  
  RESULTS
  Mean airway pressure and PEEPe were comparable for PSP and PSN at same target levels. During PSP, the NeuroSync index was 29 % at zero PEEPe and improved to 21 % at optimal PEEPe (P < 0.05). During PSN, the NeuroSync index was lower (<7 %, P < 0.05) regardless of PEEPe. Both pre-trigger (P < 0.05) and total inspiratory mechanical efforts (P < 0.05) were consistently higher during PSP compared to PSN at same PEEPe. The change in total mechanical efforts between PSP at PEEPe0% and PSN at PEEPe0% was not different from the change between PSP at PEEPe0% and PSP at PEEPe80%.
  
  
  CONCLUSIONS
  PSN abolishes the need for PEEPe in COPD patients, improves patient-ventilator interaction, and reduces the inspiratory mechanical effort to breathe.
  
  
  BACKGROUND
  Clinicaltrials.gov NCT02114567 . Registered 04 November 2013.
authors.affiliation: Department of Critical Care Medicine, Nanjing Zhongda Hospital, Southeast University, School of Medicine, 87 Dingjiaqiao Street, Nanjing, 210009, China. liulingdoctor@126.com.
authors.forename: Ling
authors.initials: L
authors.lastname: Liu
authors.affiliation: Department of Critical Care Medicine, Nanjing Zhongda Hospital, Southeast University, School of Medicine, 87 Dingjiaqiao Street, Nanjing, 210009, China. peachab@126.com.
authors.forename: Feiping
authors.initials: F
authors.lastname: Xia
authors.affiliation: Department of Critical Care Medicine, Nanjing Zhongda Hospital, Southeast University, School of Medicine, 87 Dingjiaqiao Street, Nanjing, 210009, China. yiyiyang2004@126.com.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Critical Care Medicine, Nanjing Zhongda Hospital, Southeast University, School of Medicine, 87 Dingjiaqiao Street, Nanjing, 210009, China. federico.longhini@gmail.com.|Department of Translational Medicine, Eastern Piedmont University "A. Avogadro", Novara, Italy. federico.longhini@gmail.com.
authors.forename: Federico
authors.initials: F
authors.lastname: Longhini
authors.affiliation: Department of Translational Medicine, Eastern Piedmont University "A. Avogadro", Novara, Italy. pnavalesi@gmail.com.|Anaesthesia and Intensive Care, Sant'Andrea Hospital, ASL VC, Vercelli, Italy. pnavalesi@gmail.com.|CRRF Mons. L. Novarese, Moncrivello, VC, Italy. pnavalesi@gmail.com.
authors.forename: Paolo
authors.initials: P
authors.lastname: Navalesi
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Canada. jennifer.beck@rogers.com.|Department of Pediatrics, University of Toronto, Toronto, Ontario, M5G 1X8, Canada. jennifer.beck@rogers.com.|Institute for Biomedical Engineering and Science Technology (iBEST) at Ryerson University and St-Michael's Hospital, Toronto, Canada. jennifer.beck@rogers.com.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Beck
authors.affiliation: Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Canada. sinderby@rogers.com.|Department of Medicine, University of Toronto, Toronto, Ontario, Canada. sinderby@rogers.com.|Institute for Biomedical Engineering and Science Technology (iBEST) at Ryerson University and St-Michael's Hospital, Toronto, Canada. sinderby@rogers.com.
authors.forename: Christer
authors.initials: C
authors.lastname: Sinderby
authors.affiliation: Department of Critical Care Medicine, Nanjing Zhongda Hospital, Southeast University, School of Medicine, 87 Dingjiaqiao Street, Nanjing, 210009, China. haiboq2000@126.com.
authors.forename: Haibo
authors.initials: H
authors.lastname: Qiu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D026741:Physical Therapy Modalities; D011175:Positive-Pressure Respiration / Q000379:methods* / Q000592:standards; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy*; D012121:Respiration, Artificial / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology*; D012138:Respiratory Therapy / Q000379:methods*