Neuromuscular electrical stimulation prevents muscle function deterioration in exacerbated COPD: A pilot study

Purpose: COPD is a condition with systemic effects of which peripheral muscle dysfunction is a prominent contributor to exercise limitation, health related quality of life (HRQoL) impairment, and is an independent predictor of morbidity and mortality. Pulmonary rehabilitation (PR) is a successful strategy to improve exercise tolerance and HRQoL through the improvement of muscle function in patients with stable COPD or early after severe exacerbations of COPD (SECOPD). However, muscle function further deteriorates during SECOPD before early PR programmes commence. We aimed to investigate the feasibility and efficacy of quadriceps neuromuscular electrical stimulation (NMES) applied during a SECOPD to prevent muscle function deterioration.

Methods: We have conducted a pilot study in eleven COPD patients (FEV1 41.3 +/- 5.6 % pred) admitted to hospital with a SECOPD. We randomly allocated one leg to receive NMES (once a day for 14 days) with the other leg as a control (non-stimulated leg). We measured the change in quadriceps maximal voluntary contraction (Delta QMVC) as the main outcome.

Results: Mean quadriceps muscle strength decreased in control legs (Delta QMVC -2.9 +/- 5.3 N, p = ns) but increased in the stimulated legs (Delta QMVC 19.2 +/- 6.1 N, p <0.01). The difference in Delta QMVC between groups was statistically significant (p <0.05). The effect of NMES was directly related to the stimulation intensity (Sigma mA) applied throughout the 14 sessions (r = 0.76, p <0.01). All patients tolerated NMES without any side effects.

Conclusions: NMES is a feasible and effective treatment to prevent quadriceps muscle strength derangement during severe exacerbations of COPD and may be used to compliment early post-exacerbation pulmonary rehabilitation.