title: Additive effects of non-invasive ventilation to hyperoxia on cerebral oxygenation in COPD patients with exercise-related O2 desaturation.
abstract: BACKGROUND
  It is currently unknown whether potential haemodynamic improvements induced by non-invasive ventilation (NIV) would positively impact upon cerebral oxygenation (COx) in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD).
  
  
  OBJECTIVE
  To investigate the effects of NIV on exercise COx in COPD patients presenting with exercise-related O(2) desaturation.
  
  
  METHODS
  On a double-blind trial, 13 males (FEV1 = 48·8 ± 15·1% predicted) were randomly assigned to NIV (16 cmH(2)O IPS and 5 cmH(2)O PEEP) plus HOx (FiO(2) = 0·4) or sham NIV (7 cmH(2)O IPS and 5 cmH(2)O PEEP to overcome breathing circuit resistance) plus HOx during ramp-incremental exercise performed on different days. Near-infrared spectroscopy and impedance cardiography assessed changes (Δ) in COx and cardiac output (Q(T)), respectively.
  
  
  RESULTS
  There were no significant between-intervention differences in peak work rate, ventilation and reported symptoms (P>0·05). Peripheral oxyhaemoglobin saturation remained above 98% throughout the tests. NIV + HOx was associated with larger increases in Δ COx, Δ Q(T) and Δ stroke volume at maximal and submaximal exercise (P<0·05). Increases in the area under the curve (to an iso-work rate) of Δ COx under NIV + HOx were significantly (P<0·01) correlated with improvements in Δ Q(T) (r = 0·82) and Δ stroke volume (r = 0·87). There was, however, no significant correlation between enhancement in these physiological responses with changes in peak work rate with NIV + HOx (P>0·05).
  
  
  CONCLUSIONS
  NIV added benefit to HOx in improving central haemodynamics and COx in O(2) 'desaturators' with COPD. The clinical relevance of such beneficial effects on exercise tolerance, however, remains to be demonstrated.
authors.affiliation: Pulmonary Function and Clinical Exercise Physiology Unit, Department of Medicine, Division of Respiratory Diseases, Federal University of Sao Paulo (UNIFESP), Sao Paulo, Brazil.
authors.forename: Miguel K
authors.initials: MK
authors.lastname: Rodrigues
authors.forename: Mayron F
authors.initials: MF
authors.lastname: Oliveira
authors.forename: Aline
authors.initials: A
authors.lastname: Soares
authors.forename: Erika
authors.initials: E
authors.lastname: Treptow
authors.forename: J Alberto
authors.initials: JA
authors.lastname: Neder
mesh_terms: D000368:Aged; D001938:Brazil; D002302:Cardiac Output; D002307:Cardiography, Impedance; D002560:Cerebrovascular Circulation; D004311:Double-Blind Method; D015444:Exercise; D017079:Exercise Tolerance; D005541:Forced Expiratory Volume; D006801:Humans; D000860:Hypoxia / Q000097:blood* / Q000503:physiopathology; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D063087:Noninvasive Ventilation / Q000379:methods; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption; D011175:Positive-Pressure Respiration; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D019265:Spectroscopy, Near-Infrared; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D010100:Oxygen