title: Seated and semi-recumbent positioning of the ventilated intensive care patient - effect on gas exchange, respiratory mechanics and hemodynamics.
abstract: OBJECTIVE
  To compare the effect of semi-recumbent and sitting positions on gas exchange, respiratory mechanics and hemodynamics in patients weaning from mechanical ventilation.
  
  
  BACKGROUND
  Upright positions are encouraged during rehabilitation of the critically ill but there effects have not been well described.
  
  
  METHODS
  A prospective, randomized, cross-over trial was conducted. Subjects were passively mobilized from supine into a seated position (out of bed) and from supine to a semi-recumbent position (>45° backrest elevation in bed). Arterial blood gas (PaO2/FiO2, PaO2, SaO2, PaCO2 and A-a gradient), respiratory mechanics (VE,VT, RR, Cdyn, RR/VT) and hemodynamic measurements (HR, MABP) were collected in supine and at 5 min and 30 min after re-positioning.
  
  
  RESULTS
  Thirty-four intubated and ventilated subjects were enrolled. The angle of backrest inclination in sitting (67 ± 5°) was greater than gained with semi-recumbent positioning (50 ± 5°, p < 0.001). There were no clinically important changes in arterial blood gas, respiratory mechanic or hemodynamic values due to either position.
  
  
  CONCLUSIONS
  Neither position resulted in significant changes in respiratory and hemodynamic parameters. Both positions can be applied safely in patients being weaned from ventilation.
authors.affiliation: Department of Physiotherapy, Royal Brisbane and Women's Hospital, Brisbane, Australia. Electronic address: PeterJ_Thomas@health.qld.gov.au.
authors.forename: Peter
authors.initials: P
authors.lastname: Thomas
authors.affiliation: Burns Trauma and Critical Care Research Centre, University of Queensland, Brisbane, Australia.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Paratz
authors.affiliation: Burns Trauma and Critical Care Research Centre, University of Queensland, Brisbane, Australia; Department of Intensive Care Medicine, Royal Brisbane and Women's Hospital, Brisbane, Australia.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Lipman
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001784:Blood Gas Analysis; D003422:Critical Care; D018592:Cross-Over Studies; D005260:Female; D006439:Hemodynamics; D006801:Humans; D057194:Intention to Treat Analysis; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D056888:Patient Positioning; D011187:Posture / Q000502:physiology*; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012121:Respiration, Artificial / Q000379:methods*; D015656:Respiratory Mechanics; D055815:Young Adult
keywords: Intensive care; Posture; Respiratory mechanics; Semi-recumbent; Weaning