www.jcrpjournal.com Inspiratory Muscle Training in CHF Patients / 1
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■ PURPOSE: Inspiratory muscle training (IMT) improves exercise capacity
and ventilatory responses to exercise in patients with chronic heart
failure (CHF) with inspiratory muscle weakness (IMW). We analyzed
the effects of IMT on the oxygen uptake efficiency slope (OUES) in
this patient population.
■ METHODS: Thirty-two CHF patients with IMW (maximal inspiratory pres-
sure [PImax] 70% of predicted) were randomly assigned to either a
12-week program of IMT (IMT, n = 16) or placebo-IMT (P-IMT,
n = 16). PImax and OUES were obtained before and after the inter-
vention.
■ RESULTS: Inspiratory muscle training resulted in 115% increment in
PImax (5.9 0.9 vs 12.7 0.9 kPa; P .001) and in significant
improvement in OUES (1,554 617 to 2,037 747 mL
-1
min
-1
O
2
/L min
-1
of minute ventilation; P = .001). There were no signifi-
cant changes in the P-IMT group. There was a significant association
between the changes in PImax and OUES (r = 0.82, P .01).
■ CONCLUSION: In CHF patients with IMW, IMT results in a significant
increase in OUES.
Inspiratory Muscle Training
Improves Oxygen Uptake Efficiency
Slope in Patients With Chronic
Heart Failure
Ricardo Stein, MD, ScD, Gaspar R. Chiappa, ScD, PT, Henrique Güths, MSc, PT, Pedro Dall’Ago, ScD, PT,
and Jorge P. Ribeiro, MD, ScD
Author Affiliations: Exercise
Pathophysiology Research Laboratory
and Cardiology Division, Hospital de
Clinicas de Porto Alegre (Drs Stein,
Chiappa, and Ribeiro), School of
Physical Therapy, UNILASALLE,
Canoas (Mr Güths and Dr Dall’Ago),
Department of Physiological Sciences,
Fundação Faculdade Federal de
Ciências Médicas de Porto Alegre,
Porto Alegre (Dr Dall’Ago), and
Department of Medicine, Federal
University of Rio Grande do Sul, Porto
Alegre (Dr Ribeiro), Brazil.
Corresponding Author: Ricardo Stein,
MD, ScD, Exercise Pathophysiology
Research Laboratory, Hospital de
Clinicas de Porto Alegre, Rua Ramiro
Barcelos 2350, 90035-007 Porto
Alegre, Rio Grande do Sul, Brazil
(ristein@pq.cnpq.br).
K E Y W O R D S
chronic heart failure
inspiratory muscle training
oxygen uptake efficiency
Oxygen uptake efficiency slope (OUES) has been
proposed as a measure of cardiorespiratory function-
al reserve, a submaximal parameter that has prog-
nostic implications and can be used in the evaluation
of exercise capacity in patients with chronic heart
failure (CHF).
1–3
It translates the relationship between
the responses of oxygen uptake (
˙
VO
2
) and minute
ventilation (
˙
V
E
) during incremental exercise via a log-
arithmic transformation of ventilation and represents
how effectively the lungs extract the oxygen and how
it is used in the periphery.
Some CHF patients show reduced maximal inspi-
ratory pressure (PImax) and limited endurance of
inspiratory muscles, which are currently recognized