Impact of inspiratory muscle training combined with functional electrical stimulation of lower limbs in patients with decompensated heart failure
S Elsalhy, M Ibrahim Mohamed, Y Ahmed Abd Elhadi Ahmed, S Hassan Mohammed MehaniAbstract
Background
Inspiratory muscle weakness affects up to 70% of patients hospitalised with acute decompensated heart failure (ADHF) and limits exercise tolerance. Functional electrical stimulation (FES) of the lower limbs is a feasible adjunct that can be initiated early during hospitalisation, yet few studies examined combining inspiratory muscle training (IMT) with FES in this population.
Purpose
To compare the effects of combined IMT + FES VS IMT alone VS usual medical care on respiratory muscle strength, functional capacity, quality of life (QOL), and hospital length of stay (LOS) in patients with ADHF.
Methods
135 patients with ADHF (mean age 53 ± 6 years; left ventricular ejection fraction ≤ 40%) were randomly assigned to three equal groups (n = 45each). Group A received standard medical treatment plus IMT (30% of maximal inspiratory pressure [MIP], 30 min/session, 4–5 days/week), lower-limb FES (quadriceps and gastrocnemius; 10 Hz, 150 µs, 20 s on/20 s off, up to 70 mA) combined with low-intensity cycling; Group B received medical treatment plus IMT; Group C received medical treatment only. Interventions lasted 4 weeks. Primary outcomes were MIP, 6-minute walk distance (6MWD), and Duke Activity Status Index (DASI) with estimated peak oxygen uptake (VO₂peak). Secondary outcomes included QOL (Minnesota Living with Heart Failure Questionnaire [MLHFQ]), dyspnoea severity (modified Medical Research Council [mMRC] scale), handgrip strength, and LOS.
Results
Baseline characteristics were comparable across groups (all p > 0.05). MIP increased more in Group A (+19.1 cmH₂O, +46.3%) than in Group B (+9.8 cmH₂O, +23.0%) and Group C (+3.4 cmH₂O, +7.7%; F = 196.36, p < 0.001, partial η² = 0.856). The 6MWD improved by +86.4 m in Group A versus +50.4 m in Group B and +21.3 m in Group C (F = 42.43, p < 0.001, η² = 0.563). Estimated VO₂peak rose by +4.85 mL/kg/min in Group A versus +3.09 in Group B and +0.79 in Group C (F = 70.19, p < 0.001, η² = 0.680). MLHFQ scores decreased by 23.1 points in Group A versus 15.6 in Group B and 4.6 in Group C (F = 57.16, p < 0.001). Median mMRC grade fell from 2 to 0 in Groups A and B and to 1 in Group C (Kruskal–Wallis H= 28.71, p < 0.001). Handgrip strength improved more in Group A (3.61 kg +18.02%) than Group B (+2.42 kg, +11.38%) and group C (+1.12 kg, +5.37%) F=39.345, p < 0.001. Hospital LOS was shorter in Group A (7.4 ±3.0 days) compared with Group B (9.9 ±2.7 days; p=0.004) and Group C (10.8 ±2.9 days; p < 0.001; F=8.81, η²=0.211). LVEF did not change significantly in any group.
Conclusion
In patients with ADHF, combining IMT with lower-limb FES and low-intensity cycling during hospitalisation produces greater improvements in inspiratory muscle strength, functional capacity, QOL, and dyspnoea than IMT alone or usual care, and is associated with shorter hospital stay. Adding FES to IMT may represent a feasible strategy to enhance early in-hospital cardiac rehabilitation in this population.IMT_AND_FES_IN_DECOMPENSATED_HFprimary_and_secondary_outcomes_between_groups