title: The semi-seated position slightly reduces the effort to breathe during difficult weaning.
abstract: OBJECTIVE
  The influence of posture on breathing effort in patients with difficult weaning is unknown. We hypothesized that posture could modulate the breathing effort in difficult-to-wean patients.
  
  
  METHODS
  A prospective, crossover, physiologic study was performed in 24 intubated patients breathing with pressure support who had already failed a spontaneous breathing trial or an extubation episode. Their median duration of mechanical ventilation before measurements was 25 days. Breathing pattern, occlusion pressure (P (0.1)), intrinsic PEEP (PEEP(i)), and inspiratory muscle effort evaluated by the pressure-time product of the respiratory muscles and the work of breathing were measured during three postures: the seated position in bed (90°LD), simulating the position in a chair, the semi-seated (45°), and the supine (0°) positions consecutively applied in a random order. A comfort score was obtained in 17 cooperative patients. The influence of position on chest wall compliance was measured in another group of 11 sedated patients.
  
  
  RESULTS
  The 45° position was associated with the lowest levels of effort (p ≤ 0.01) and occlusion pressure (p < 0.05), and tended to be more often comfortable. Respiratory effort was the lowest at 45° in 18/24 patients. PEEP(i) and PEEP(i)-related work were slightly higher in the supine position (p ≤ 0.01), whereas respiratory effort, heart rate, and P (0.1) values were increased in the seated position (p < 0.05).
  
  
  CONCLUSIONS
  A 45° position helps to unload the respiratory muscles, moderately reduces PEEP(i), and is often considered as comfortable. The semi-seated position may help the weaning process in ventilator-dependent patients.
authors.affiliation: Medical Intensive Care Unit (ICU), Henri Mondor University Hospital, AP-HP, Créteil, France. nicolas.deye@lrb.aphp.fr
authors.forename: N
authors.initials: N
authors.lastname: Deye
authors.forename: F
authors.initials: F
authors.lastname: Lellouche
authors.forename: S M
authors.initials: SM
authors.lastname: Maggiore
authors.forename: S
authors.initials: S
authors.lastname: Taillé
authors.forename: A
authors.initials: A
authors.lastname: Demoule
authors.forename: E
authors.initials: E
authors.lastname: L'Her
authors.forename: F
authors.initials: F
authors.lastname: Galia
authors.forename: A
authors.initials: A
authors.lastname: Harf
authors.forename: J
authors.initials: J
authors.lastname: Mancebo
authors.forename: L
authors.initials: L
authors.lastname: Brochard
mesh_terms: D000368:Aged; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008170:Lung Compliance / Q000502:physiology; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration; D011187:Posture; D011446:Prospective Studies; D012119:Respiration; D015300:Ventilator Weaning / Q000379:methods*