Am. J. Respir. Crit. Care Med., Vol 153, No. 3, 03 1996, 1105-1109.
Stroke volume during exercise in cystic fibrosis
P Pianosi and A Pelech
Department of Pediatrics and Child Health, Children's Hospital of Winnipeg, Manitoba, Canada.
Previous studies comparing cardiac output (Q) and stroke volume (SV)
between cystic fibrosis (CF) patients and control subjects have shown
conflicting results: some found lower SV in CF patients with severe airflow
limitation, and others showed no difference between CF and control
subjects. Methodologic problems could explain these discrepant findings.
The aim of this study was to better characterize Q and SV with exercise in
CF patients with mild as well as severe airflow obstruction. Subjects
included 18 CF patients with FEV1 ranging from 28 to 80% of predicted
without pulmonary hypertension, and 16 matched control subjects. Cardiac
output was measured at three levels of upright cycle exercise using the
indirect Fick (CO2) method with blood gas sampling. Q on exercise was
similar among control and CF subjects. SV was lower in CF patients,
particularly those with FEV1 < or = 55% predicted, than in control
subjects. Stepwise regression of SV on height, percent ideal body weight,
and FEV1 showed a significant effect of relative underweight on SV. Despite
this, well-nourished patients with FEV1 56 to 80% of predicted also had
lower SV. As these findings were consistent across the range of severity of
lung disease and age, even in the absence of malnutrition, they imply that
another mechanism accounts for SV limitation during exercise in CF.
