Evaluation of a Cardiopulmonary Exercise Testing System

Abstract

To assess the utility of the ERGOCID-AT Plus system for the analysis of expired gases during the stress test, there were studied 691 subjects, 141 healthy subjects, 320 with different forms of ischemic heart disease and the rest with other cardiovascular diseases. The values obtained for the ventilatory variables measured are in physiological ranges and agree to those described in the literature for different pathologies.

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Abstract— To assess the utility of the ERGOCID-AT Plus
system for the analysis of expired gases during the stress test,
there were studied 691 subjects, 141 healthy subjects, 320 with
different forms of ischemic heart disease and the rest with
other cardiovascular diseases. The values obtained for the
ventilatory variables measured are in physiological ranges
and agree to those described in the literature for different
pathologies.
I. HEADINGS
In the last three decades, Cardiopulmonary exercise
testing (CPX) has proved its value and has consequently
gained worldwide acceptance to be considered as the gold
standard for the evaluation of functional capacity in athletes,
healthy and sick subjects, and to perform prognostic
stratification in patients with cardiovascular disease and
with other conditions, in stable clinical conditions, even
with left ventricular dysfunction or with heart failure [1].
ERGOCID-AT Plus is a computer-based medical
equipment designed to evaluate the physiologic exercise
capability of patients and healthy subjects analyzing the
ECG and the concentration and flow of the inspired and
exhaled gases (O2 and CO2) [2]. The main objective of this
work is to assess the utility of the ERGOCID-AT Plus
system for the analysis of expired gases during the stress
test.
II.MATERIALS AND METHODS
A total of 691 subjects of both sexes between 15 and 79
years of age, 141 healthy subjects, 320 with different forms
of ischemic heart disease and the rest with other
cardiovascular diseases were studied consecutively at the
Rehabilitation Center of Institute of Cardiology and
Cardiovascular Surgery of Havana. Maximal or symptom-
limited exercise testing were performed using ERGOCID-
AT Plus system with a treadmill and a ramp protocol for the
stress.
Exhaled gases were continuously acquired during rest,
exercise and recovery by the breath-to-breath method, as
well as the electrocardiogram was continuously monitored
and automated blood pressure was recorded every two
minutes throughout the test. At the end, the data were
preprocessed to eliminate artifacts and averaged the values
at 10 s intervals. The anaerobic threshold (AT) was
estimated using the V slope and ventilatory equivalent
methods simultaneously. Maximum oxygen consumption
(VO2max) was defined as the highest oxygen consumption
(VO2) reached during the exercise, accepting the highest
value obtained from this parameter when a physiological
* Research supported by Ministry of Science and Environment of the
Republic of Cuba.
N. Gómez López is with the Digital Medical Technology, Street 202
#1704, CP 11600 Havana, Cuba (phone: 537-271-5054; fax: 537-273-6387
e-mail: nglopez@icid.cu).
E. Rivas Estany is with Rehabilitation Center of Institute of Cardiology
and Cardiovascular Surgery of Havana (e-mail: crehab@infomed.sld.cu).
plateau, also called a peak VO2, was not reached. The slopes
of the regression lines for the calculation of the ventilatory
equivalent for oxygen and carbon dioxide were calculated
with an interval of 1 min after the start of the exercise and 1
min before its end. Cardiac output was estimated by non-
invasive methods using the formula presented by Stringer,
Hansen and Wasserman in 1997 [3].
III. RESULTS
The healthy subjects showed a VO2max of 23.7±9
ml/kg/min and a maximum cardiac output of 11.4±4 l/min,
unlike cases with ischemic heart disease (19.6±6 ml/kg/min,
9±3 l/min) and left ventricular dysfunction (17.3±6 and
8.1±4), which had significantly lower values (p= .00).
Patients with heart failure and dilated cardiomyopathy
showed the lowest values, as well as the highest ventilatory
index (VE/VCO2) in the AT (31.8±7) (p = .00), reflecting
increased dead space during the exercise. The highest values
were observed in the high-performance athletes studied:
54.8±9 ml/kg/min and 26.5±8 l/min (p = .00) as a
consequence of better cardiac function and functional
capacity.
The values of the ventilatory variables measured in AT or
in maximal exercise are in physiological ranges and agree to
those described in the literature for different pathologies [1,
3, 4]. The main limitation of this investigation are the small
samples of cases of each group.
CONCLUSIONS
The results obtained from the evaluation and the use of
ERGOCID-AT Plus demonstrate the utility of this system
for the analysis of exhaled gases during the effort in the
accurate and objective functional evaluation of healthy
subjects and with cardiovascular diseases.
REFERENCES
[1] Guazzi M, Arena R, Halle M, Piepoli MF, et al, “2016 focused update:
clinical recommendations for cardiopulmonary exercise testing data
assessment in specific patient populations“, European Heart Journal,
DOI: 10.1093/eurheartj/ehw180, May 2016.
[2] Gómez N, Rodríguez J, Pérez R, et al, “Diseño de un sistema para
pruebas de esfuerzo”, Bioingeniería y Física Médica Cubana, vol. 7,
pp. 4-10, Enero-Abril 2006.
[3] Stringer WW, Hansen JE, Wasserman K, “Cardiac output estimated
noninvasively from oxygen uptake during exercise”. J Appl Physio,
vol. 3, pp. 908-912, 1997.
[4] Balady GJ, Arena R, Sietsema K, et al, “Clinician’s guide to
cardiopulmonary exercise testing in adults. A scientific statement
from the American Heart Association”, Circulation. vol. 122, pp. 191-
225, 2010.
Evaluation of a Cardiopulmonary Exercise Testing System
N. Gómez López, E. Rivas Estany