Pulmonary function at peak exercise in patients with chronic heart failure.
BACKGROUND
Various respiratory abnormalities are associated with chronic heart failure (CHF). However, changes in inspiratory capacity (IC) and breathing pattern from rest to exercise in patients with CHF have not been thoroughly investigated in these patients.


METHODS
Seventy seven (66 male/11 female) patients with clinical stable CHF (age: 52+/-11 years) were studied. All the patients underwent pulmonary function tests, including measurements of IC and maximal inspiratory pressure (Pimax) at rest and then a maximal cardiopulmonary exercise testing (CPET) on a treadmill. During the CPET, IC was measured every 2 min. Pimax was measured again after the end of CPET.


RESULTS
Percent predicted forced expiratory volume in 1 s (FEV1) was 91+/-12, %predicted forced vital capacity (FVC) was 92+/-13, %FEV1/FVC was 81+/-4, and %predicted IC was 85+/-18. Peak exercise IC was lower than resting (2.4+/-0.6 vs. 2.6+/-0.6 l, p<0.001). Analysis of variance between Weber's groups revealed statistically significant differences in peak exercise IC (p<0.001), VE/VCO2slope (p<0.001), resting Pimax (p=0.005) and post-exercise Pimax (p<0.001). At rest, there was a statistically significant difference in end-tidal CO2 (P(ETCO2)) (p=0.002), in breathing frequency (p=0.004), in inspiratory time (Ti) (p=0.04) and in total respiratory time (T(Tot)) (p=0.004) among Weber's groups. At peak exercise there was a statistically significant decrease in minute ventilation (VE) (p<0.001), tidal volume (VT) (p<0.001), respiratory cycle (VT/TI) (p<0.001) and P(ETCO2) (p<0.001). Peak IC was correlated with peak VO2 (r=0.72, p<0.001), anaerobic threshold (r=0.71, p<0.001), VO2/t slope (r=0.54, p<0.0001), and post-exercise Pimax (r=0.62, p<0.001).


CONCLUSIONS
In patients with CHF, peak exercise IC is reduced in parallel with disease severity, which is probably due to respiratory muscle dysfunction.
Papazachou
Ourania
O
Pulmonary and Critical Care Medicine Department, Cardiopulmonary Exercise Testing Laboratory and Rehabilitation Center, National and Kapodestrian University of Athens, Evgenidio Hospital, 20, Papadiamantopoulou str, Athens 115 28, Greece.
Anastasiou-Nana
Maria
M
Sakellariou
Dimitrios
D
Tassiou
Antonia
A
Dimopoulos
Stavros
S
Venetsanakos
John
J
Maroulidis
George
G
Drakos
Stavros
S
Roussos
Charis
C
Nanas
Serafim
S
D015308:Anaerobic Threshold; D000704:Analysis of Variance; D002908:Chronic Disease; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D005541:Forced Expiratory Volume; D006333:Heart Failure / Q000503:physiopathology*; D006801:Humans; D007320:Inspiratory Capacity; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011237:Predictive Value of Tests; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics; D014797:Vital Capacity