title: Effects of supplemental O2 inhalation on cerebral oxygenation during exercise in patients with left ventricular dysfunction.
abstract: BACKGROUND
  It has been recently reported that cerebral oxyhemoglobin (O(2)Hb) decreases during exercise in nearly 50% of patients with dilated cardiomyopathy. The present study evaluated whether the inhalation of supplemental O(2) diminishes the decrease in cerebral O(2)Hb during exercise.
  
  
  RESULTS
  Ten patients with a left ventricular ejection fraction <50% and a clearly observable decrease in cerebral O(2)Hb during preliminary exercise testing underwent 2 additional symptom-limited incremental exercise tests: 1 while breathing room air (control) and the other while breathing 50% O(2). In the latter test, the switch from room air to 50% O(2) was performed, on average, at 43.0+/-14.2 W. Cerebral O(2)Hb was continuously monitored during exercise using near-infrared spectroscopy. In the control exercise test, cerebral O(2)Hb gradually decreased as the work rate increased in all the subjects. When the subjects breathed 50% O(2), this decrease in cerebral O(2)Hb was diminished. The change in cerebral O(2)Hb from rest to peak exercise during the test under 50% O(2) was significantly higher than that during the control test (-0.23 +/-1.89 vs -2.47+/-1.57 micromol/L, p=0.002). Similarly, the change in the cerebral tissue oxygenation index was significantly higher in the test under 50% O(2) (0.45 +/-4.46 vs -3.33+/-3.06%, p=0.023).
  
  
  CONCLUSIONS
  Impaired cerebral oxygenation during moderate to heavy intensity exercise in patients with left ventricular dysfunction can be offset by breathing supplemental O(2).
authors.affiliation: The Cardiovascular Institute, Tokyo, Japan. koike@cvi.or.jp
authors.forename: Akira
authors.initials: A
authors.lastname: Koike
authors.forename: Osamu
authors.initials: O
authors.lastname: Nagayama
authors.forename: Ayumi
authors.initials: A
authors.lastname: Goda
authors.forename: Masayo
authors.initials: M
authors.lastname: Hoshimoto
authors.forename: Kaori
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Akihiko
authors.initials: A
authors.lastname: Tajima
authors.forename: Tokuhisa
authors.initials: T
authors.lastname: Uejima
authors.forename: Haruki
authors.initials: H
authors.lastname: Itoh
authors.forename: Tadanori
authors.initials: T
authors.lastname: Aizawa
mesh_terms: D000368:Aged; D002560:Cerebrovascular Circulation; D054022:Cerebrum / Q000098:blood supply / Q000378:metabolism / Q000503:physiopathology*; D015444:Exercise; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000008:administration & dosage / Q000378:metabolism*; D010101:Oxygen Consumption; D010108:Oxyhemoglobins / Q000378:metabolism; D010807:Physical Endurance; D013318:Stroke Volume; D018487:Ventricular Dysfunction, Left / Q000378:metabolism / Q000503:physiopathology*
chemical_list: D010108:Oxyhemoglobins; D010100:Oxygen