title: High-flow nasal cannula: impact on oxygenation and ventilation in an acute lung injury model.
abstract: BACKGROUND
  High-flow nasal cannula therapy (HFNC) has been shown to be more effective than continuous positive airway pressure (CPAP) in reducing intubations and ventilator days. HFNC likely provides mechanisms to support respiratory efficiency beyond application of distending pressure. We reason that HFNC washout of nasopharyngeal dead space impacts CO(2) removal along with oxygenation. The aim of this study was to demonstrate the flow dependence of CO(2) reduction and improved oxygenation during HFNC and the dependence on leak around the nasal prongs.
  
  
  METHODS
  Neonatal piglets (n=13; 2-6 kg) were injured with IV oleic acid and supported with HFNC at 2 through 8 L/min. High and low leak around the nasal prongs was accomplished by using single and double prong cannulae, respectively. Measurement of hemodynamic, respiratory and blood gas parameters were made at each setting following 10 min for physiologic equilibration. Tracheal pressures were recorded by transmural catheters.
  
  
  RESULTS
  With HFNC, CO(2) trended downward in a flow-dependent manner independent of leak. Oxygenation and tracheal pressures increased in a flow-dependent manner with the greatest effect during double prong. At 8 L/min, tracheal pressures did not exceed 6 ± 1 cmH(2) O.
  
  
  CONCLUSIONS
  HFNC improves gas exchange in a flow-dependent manner; double prong had greater impact on O(2;) single prong had greater impact on CO(2) elimination.
authors.affiliation: Nemours Children's Clinic of Wilmington, The Nemours Foundation, Alfred I. duPont Children's Hospital, Primary Research Institution, Wilmington, Delaware 19803, USA. mfrizzol@nemours.org
authors.forename: Meg
authors.initials: M
authors.lastname: Frizzola
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Miller
authors.forename: Maria Elena
authors.initials: ME
authors.lastname: Rodriguez
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhu
authors.forename: Jorge
authors.initials: J
authors.lastname: Rojas
authors.forename: Anne
authors.initials: A
authors.lastname: Hesek
authors.forename: Angela
authors.initials: A
authors.lastname: Stump
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Shaffer
authors.forename: Kevin
authors.initials: K
authors.lastname: Dysart
mesh_terms: D055371:Acute Lung Injury / Q000097:blood / Q000139:chemically induced / Q000628:therapy*; D000818:Animals; D000831:Animals, Newborn; D001784:Blood Gas Analysis; D004195:Disease Models, Animal; D019301:Oleic Acid / Q000633:toxicity; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D011659:Pulmonary Gas Exchange; D013552:Swine; D014132:Trachea / Q000502:physiology
chemical_list: D019301:Oleic Acid