IntroductionCritically ill patients are characterized by increased loss of muscle mass, partially attributed to sepsis and multiple organ failure, as well as immobilization. Recent studies have shown that electrical muscle stimulation (EMS) may be an alternative to active exercise in chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF) patients with myopathy. The aim of our study was to investigate the EMS effects on muscle mass preservation of critically ill patients with the use of ultrasonography (US).MethodsForty-nine critically ill patients (age: 59 ± 21 years) with an APACHE II admission score ≥13 were randomly assigned after stratification upon admission to receive daily EMS sessions of both lower extremities (EMS-group) or to the control group (control group). Muscle mass was evaluated with US, by measuring the cross sectional diameter (CSD) of the vastus intermedius and the rectus femoris of the quadriceps muscle.ResultsTwenty-six patients were finally evaluated. Right rectus femoris and right vastus intermedius CSD decreased in both groups (EMS group: from 1.42 ± 0.48 to 1.31 ± 0.45 cm, P = 0.001 control group: from 1.59 ± 0.53 to 1.37 ± 0.5 cm, P = 0.002; EMS group: from 0.91 ± 0.39 to 0.81 ± 0.38 cm, P = 0.001 control group: from 1.40 ± 0.64 to 1.11 ± 0.56 cm, P = 0.004, respectively). However, the CSD of the right rectus femoris decreased significantly less in the EMS group (-0.11 ± 0.06 cm, -8 ± 3.9%) as compared to the control group (-0.21 ± 0.10 cm, -13.9 ± 6.4%; P < 0.05) and the CSD of the right vastus intermedius decreased significantly less in the EMS group (-0.10 ± 0.05 cm, -12.5 ± 7.4%) as compared to the control group (-0.29 ± 0.28 cm, -21.5 ± 15.3%; P < 0.05).ConclusionsEMS is well tolerated and seems to preserve the muscle mass of critically ill patients. The potential use of EMS as a preventive and rehabilitation tool in ICU patients with polyneuromyopathy needs to be further investigated.Trial Registrationclinicaltrials.gov: NCT00882830

The relationship between the electromyographic (EMG) power spectrum and muscle conduction velocity was investigated during both fatiguing and nonfatiguing contractions of the adductor pollicis muscle. Changes in the EMG power spectrum were measured by Fourier transform analysis and by comparing the power in the high (130-238 Hz) and low (20--40 Hz) frequency bands. Changes in conduction velocity were measured during voluntary activity from changes in the muscle mass action potential evoked by periodic maximal shocks to the nerve. This was varied independently either by maintaining a 60-s fatiguing maximal voluntary contraction involving 30--50% loss of force or by changing muscle temperature in the absence of fatigue. Both procedures resulted in similar changes in the power spectrum. However, the change in conduction velocity required to generate equal changes in the EMG was about 10 times greater in the absence of fatigue than those observed during a 60-s maximum contraction initiated at any initial muscle temperature. This suggests that during fatigue of maximal voluntary contractions, factors other than changes in the wave form of individual muscle fiber action potentials must contribute to the observed shift in the total surface EMG frequency components.

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