Effects of Supplemental O sub(2) Inhalation on Cerebral Oxygenation During Exercise in Patients With Left Ventricular Dysfunction

• Published in: Circulation journal : official journal of the Japanese Circulation Society Vol. 71; no. 9; pp. 1418 - 1423
• Main Authors: Koike, Akira, Nagayama, Osamu, Goda, Ayumi, Hoshimoto, Masayo, Yamaguchi, Kaori, Tajima, Akihiko, Uejima, Tokuhisa, Itoh, Haruki, Aizawa, Tadanori
• Format: Journal Article
• Language: English
• Published: 01-01-2007
• ISSN: 1346-9843; 1347-4820
• DOI: 10.1253/circj.71.1418

Background It has been recently reported that cerebral oxyhemoglobin (O sub(2)Hb) decreases during exercise in nearly 50% of patients with dilated cardiomyopathy. The present study evaluated whether the inhalation of supplemental O sub(2) diminishes the decrease in cerebral O sub(2)Hb during exercise. Methods and Results ten patients with a left ventricular ejection fraction -50% and a clearly observable decrease in cerebral O sub(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 sub(2). In the latter test, the switch from room air to 50% O sub(2) was performed, on average, at 43.0+/-14.2 W. Cerebral O sub(2)Hb was continuously monitored during exercise using near-infrared spectroscopy. In the control exercise test, cerebral O sub(2)Hb gradually decreased as the work rate increased in all the subjects. When the subjects breathed 50% O sub(2), this decrease in cerebral O sub(2)Hb was diminished. The change in cerebral O sub(2)Hb from rest to peak exercise during the test under 50% O sub(2) was significantly higher than that during the control test (-0.23 +/-1.89 vs -2.47+/-1.57 mu mol/L, p=0.002). Similarly, the change in the cerebral tissue oxygenation index was significantly higher in the test under 50% O sub(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 sub(2).