title: Ventilation distribution measured with EIT at varying levels of pressure support and Neurally Adjusted Ventilatory Assist in patients with ALI.
abstract: OBJECTIVE
  The purpose of this study was to compare the effect of varying levels of assist during pressure support (PSV) and Neurally Adjusted Ventilatory Assist (NAVA) on the aeration of the dependent and non-dependent lung regions by means of Electrical Impedance Tomography (EIT).
  
  
  METHODS
  We studied ten mechanically ventilated patients with Acute Lung Injury (ALI). Positive-End Expiratory Pressure (PEEP) and PSV levels were both 10 cm H₂O during the initial PSV step. Thereafter, we changed the inspiratory pressure to 15 and 5 cm H₂O during PSV. The electrical activity of the diaphragm (EAdi) during pressure support ten was used to define the initial NAVA gain (100 %). Thereafter, we changed NAVA gain to 150 and 50 %, respectively. After each step the assist level was switched back to PSV 10 cm H₂O or NAVA 100 % to get a new baseline. The EIT registration was performed continuously.
  
  
  RESULTS
  Tidal impedance variation significantly decreased during descending PSV levels within patients, whereas not during NAVA. The dorsal-to-ventral impedance distribution, expressed according to the center of gravity index, was lower during PSV compared to NAVA. Ventilation contribution of the dependent lung region was equally in balance with the non-dependent lung region during PSV 5 cm H₂O, NAVA 50 and 100 %.
  
  
  CONCLUSIONS
  Neurally Adjusted Ventilatory Assist ventilation had a beneficial effect on the ventilation of the dependent lung region and showed less over-assistance compared to PSV in patients with ALI.
authors.affiliation: Department of Intensive Care Adults, Erasmus MC Rotterdam, Room H623, 's Gravendijkwal 230, 3015 CE Rotterdam, The Netherlands. paul.blankman@gmail.com
authors.forename: Paul
authors.initials: P
authors.lastname: Blankman
authors.forename: Djo
authors.initials: D
authors.lastname: Hasan
authors.forename: Martijn S
authors.initials: MS
authors.lastname: van Mourik
authors.forename: Diederik
authors.initials: D
authors.lastname: Gommers
mesh_terms: D055371:Acute Lung Injury / Q000628:therapy*; D017097:Electric Impedance; D006801:Humans; D007362:Intensive Care Units; D059725:Interactive Ventilatory Support / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D015656:Respiratory Mechanics; D014054:Tomography / Q000379:methods*
references.citation: Crit Care. 2011 Aug 11;15(4):R193
references.pmid: 21834953
references.citation: Chest. 2007 Mar;131(3):711-717
references.pmid: 17356084
references.citation: Intensive Care Med. 2011 Nov;37(11):1826-32
references.pmid: 21946913
references.citation: Crit Care Med. 2010 Sep;38(9):1830-7
references.pmid: 20639752
references.citation: Anesthesiology. 1994 Apr;80(4):751-60
references.pmid: 8024128
references.citation: Chest. 2009 Mar;135(3):695-703
references.pmid: 19017889
references.citation: Anaesthesia. 1998 Nov;53(11):1054-61
references.pmid: 10023273
references.citation: Intensive Care Med. 2012 Feb;38(2):230-9
references.pmid: 22127483
references.citation: Anesthesiology. 1974 Sep;41(3):242-55
references.pmid: 4604401
references.citation: N Engl J Med. 2001 Jun 28;344(26):1986-96
references.pmid: 11430329
references.citation: Am J Respir Crit Care Med. 1999 Apr;159(4 Pt 1):1241-8
references.pmid: 10194172
references.citation: Respir Physiol Neurobiol. 2009 Apr 30;166(2):117-24
references.pmid: 19429528
references.citation: Minerva Anestesiol. 2010 Dec;76(12):1024-35
references.pmid: 21178912
references.citation: Pediatr Res. 2007 Mar;61(3):289-94
references.pmid: 17314685
references.citation: Intensive Care Med. 2012 May;38(5):838-46
references.pmid: 22481227
references.citation: Crit Care Med. 2010 Feb;38(2):518-26
references.pmid: 20083921
references.citation: Intensive Care Med. 2009 Jun;35(6):1132-7
references.pmid: 19255741
references.citation: Intensive Care Med. 2008 Nov;34(11):2010-8
references.pmid: 18629471
references.citation: Crit Care. 2010;14(3):R100
references.pmid: 20509966
references.citation: Crit Care Med. 2006 Dec;34(12):2997-3004
references.pmid: 16957635
references.citation: Intensive Care Med. 2011 Feb;37(2):263-71
references.pmid: 20871978