Affiliations: Katholieke Universiteit Leuven, Leuven, Belgium,
Correspondence to: Martijn A. Spruit, PT, MSc, Onderwijs & Navorsing, Laboratorium Pneumologie, B-3000 Leuven, Belgium; e-mail: firstname.lastname@example.org
To the Editor:
We have read with great interest the article of Zanotti and coworkers1 on the effects of peripheral muscle strength training in bed-bound patients with COPD receiving mechanical ventilation (July 2003). As compared with active limb mobilization, active limb mobilization with electrical stimulation resulted in significantly greater improvements in muscle strength and decreased the number of days needed to transfer from bed to chair. We would like to make four comments:
(1) The authors reported two articles2–3 as the two only trials that studied the effects of peripheral muscle strength training in patients with COPD. In 2002 alone, two other articles4–5 on peripheral strength training in COPD were published.
(2) Muscle weakness is expected to occur after long periods of inactivity accompanied with inflammation, malnutrition, and oxidative stress. Indeed, we found a significant decrease in quadriceps peak torque already after 3 days of hospital stay due to an acute exacerbation of COPD.6 Therefore, starting peripheral muscle strength training early appears to be of great value to prevent the loss of muscle function. Why did the authors choose to start their interventions only after a minimum of 30 days of bed confinement?
(3) Why did the authors exclude patients who had been treated with systemic corticosteroids for > 5 days while they were in the ICU? Indeed, corticosteroids were shown to have detrimental effects on peripheral muscle strength in patients with COPD.7 Hence, the latter patients may benefit even more from peripheral muscle strength training than the patients with COPD studied by Zanotti and coworkers.1
(4) Although significant improvements in peripheral muscle strength and function (eg, transfer bed to chair) were found, patients only reached mean scores of 3.08 and 3.83 on the subjective Medical Research Scale after active limb movement without and with electrical stimulation, respectively.1 Therefore, we believe that it is very important to stress the necessity of continuing exercise training after discharge from the hospital in patients with COPD. Along these lines, Neder and coworkers8 also suggested that electrical stimulation of peripheral muscles can be used as a treatment to prepare patients with COPD for active exercise training programs.
We are honored by the interest of Spruit and colleagues in our article, and we will try to answer their comments. The choice to start the intervention of limb mobilization after 30 days was principally due to the fact that our Unit is not an “acute” unit, but we receive patients from other hospitals, where they stay for a variable and unpredictable period. The phrase “patients… had been confined to bed for at least 30 days” means that the shortest time spent in the ICU was 30 days.
We know that corticosteroids may have a detrimental effect on peripheral muscle strength in patients with COPD. The choice to exclude them from this study was once again due to the different provenance of our patients: it was not always possible to know the exact therapy our patients underwent while in the ICU, so we wanted to avoid any possible pharmacologic interference; in other words, we tried to obtain the most possible homogeneous population regarding the reason of peripheral muscle atrophy.
We completely agree with Spruit and colleagues that electrical stimulation of peripheral muscles is particularly indicated in those patients with peripheral muscle atrophy further worsened by the use of corticosteroids, and it is surely true that it is very important to continue exercise training after hospital discharge. Indeed, we explain to our patients and their relatives why physical activity is useful and how it is important and effective. Furthermore, we recommend any sort of physical activity at hospital discharge, but how many patients are available to do that?
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