title: Cerebral oxygenation during exercise in patients with terminal lung disease.
abstract: OBJECTIVE
  In patients with terminal lung disease who were exercising, we assessed whether improved arterial O2 saturation with an increased fraction of inspired oxygen (FIO2) affects cerebral oxygenation.
  
  
  METHODS
  Randomized, crossover.
  
  
  METHODS
  The cerebral changes in oxyhemoglobin (DeltaHbO2) and changes in deoxyhemoglobin (DeltaHb) levels were evaluated using near-infrared spectrophotometry and the middle cerebral artery (MCA) mean velocity (V(mean)) was determined by transcranial Doppler ultrasonography in 13 patients with terminal lung disease (New York Heart Association class III-IV). Patients were allocated to an FIO2 of either 0.21 or 0.35 during incremental exercise with 15 min between trials.
  
  
  RESULTS
  Peak exercise intensity (mean [+/- SE], 26 +/- 4 W) reduced the arterial O2 pressure (at rest, 64 +/- 3 mm Hg; during exercise, 56 +/- 3 mm Hg) and the arterial oxygen saturation (SaO2) [at rest, 92 +/- 2%; 87 +/- 2%; p < 0.05], while the arterial CO2 pressure was not significantly affected. The MCA V(mean) increased from 49 +/- 5 to 63 +/- 7 cm/s (p < 0.05) as did the DeltaHb, while the DeltaHbO2 remained unaffected by exercise. With an elevated FIO2, the SaO2 level (at rest, 95.8 +/- 0.7%; during exercise, 96.0 +/- 1.0%) and arterial O2 pressure (at rest, 102 +/- 11 mm Hg; during exercise, 100 +/- 8 mm Hg) were not significantly affected by exercise, and the levels of blood oxygenation remained higher than the values established at normoxia (p < 0.05). The MCA V(mean) increased to a level similar to that achieved during control exercise (ie, to 70 +/- 11 cm/s). In contrast to control exercise, DeltaHb decreased while DeltaHbO2 increased during exercise with 35% O2 (p < 0.05).
  
  
  CONCLUSIONS
  An O2-enriched atmosphere enabled patients with terminal lung disease to maintain arterial O2 saturation during exercise. An exercise-induced increase in cerebral perfusion was not affected by hyperoxia, whereby the enhanced availability of oxygenated hemoglobin increases cerebral oxygenation. The clinical implication of the study is that during physical activity patients with terminal lung disease are recommended to use an elevated FIO2 to protect cerebral oxygenation.
authors.affiliation: Department of Anesthesia, Copenhagen Muscle Research Center, Copenhagen, Denmark.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Jensen
authors.forename: Henning Bay
authors.initials: HB
authors.lastname: Nielsen
authors.forename: Kojiro
authors.initials: K
authors.lastname: Ide
authors.forename: Per Lav
authors.initials: PL
authors.lastname: Madsen
authors.forename: Lars Bo
authors.initials: LB
authors.lastname: Svendsen
authors.forename: Ulrik Gerner
authors.initials: UG
authors.lastname: Svendsen
authors.forename: Niels Henry
authors.initials: NH
authors.lastname: Secher
mesh_terms: D000328:Adult; D001921:Brain / Q000378:metabolism*; D002560:Cerebrovascular Circulation; D018592:Cross-Over Studies; D015444:Exercise; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D010108:Oxyhemoglobins / Q000378:metabolism; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging / Q000503:physiopathology*; D016037:Single-Blind Method; D017585:Ultrasonography, Doppler, Transcranial
chemical_list: D006454:Hemoglobins; D010108:Oxyhemoglobins; C100003:deoxyhemoglobin