Overshoot phenomena of respiratory gas variables during exercise recovery in cardiac patients.
BACKGROUND
Transient increases (overshoot) in respiratory gas variables have been observed during exercise recovery, but their clinical significance is not clearly understood. Our group evaluated the relationship between the presence of overshoot of respiratory gas variables and the parameters obtained from cardiopulmonary exercise testing (CPX).


RESULTS
In total, 227 patients with various cardiac diseases underwent CPX. The overshoot phenomena of O₂ uptake (·VO₂), ·VO₂/heart rate (O₂-pulse), and CO₂ output (·VCO₂) were analyzed by respiratory gas analysis during recovery after maximal exercise. The overshoot of ·VO₂, O₂-pulse, and ·VCO₂ were recognized in 11 (5%), 43 (19%), and 12 (5%) patients, respectively. Compared with the patients without a ·VO₂ overshoot, those with a ·VO₂ overshoot had a significantly lower peak ·VO₂ (12.3±3.7 vs. 17.9±6.2ml·min⁻¹·kg⁻¹, P=0.003), lower anaerobic threshold (9.4±1.7 vs. 12.4±3.3 ml·min⁻¹·kg⁻¹, P=0.001), higher ·VE-·VCO₂ slope (38.0±5.2 vs. 33.2±9.6, P=0.013), and lower left ventricular ejection fraction (LVEF) (39.9±22.8 vs. 55.8±16.8%, P=0.003). Similar findings were obtained for the patients with an O₂-pulse overshoot and those with a ·VCO₂ overshoot.


CONCLUSIONS
The overshoot phenomena of respiratory gas variables during recovery after maximal exercise are correlated with impaired cardiopulmonary function during exercise in cardiac patients.
Department of Cardiovascular Medicine, Toho University Omori Medical Center.
Takeya
T
Suzuki
Akira
A
Koike
Osamu
O
Nagayama
Koji
K
Sakurada
Hidekazu
H
Tsuneoka
Jo
J
Kato
Takeshi
T
Yamashita
Junichi
J
Yamazaki
D000368:Aged; D015308:Anaerobic Threshold; D001794:Blood Pressure; D001944:Breath Tests; D002245:Carbon Dioxide / Q000378:metabolism*; D015444:Exercise; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006331:Heart Diseases / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology*; D006339:Heart Rate; D006801:Humans; D007564:Japan; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D020127:Recovery of Function; D012119:Respiration; D013318:Stroke Volume; D013997:Time Factors; D016277:Ventricular Function, Left
D002245:Carbon Dioxide; D010100:Oxygen