Background: Muscle mass loss has been a contributing factor to intensive care unit acquired weakness (ICUAW), a common complication in critically ill patients. Although research evidence supports neuromuscular electrical stimulation (NMES) as a means of early mobilization, there are not any data on the effects of different protocols on muscle mass loss. This study aimed to explore the effects of different ΝΜΕS protocols on muscle mass in ICU patients. Methods and findings: This was a prospective, randomized study conducted in a multidisciplinary ICU. Twenty-one patients were randomized into two intervention NMES groups; these were the medium frequency (MF) group (45 Hz, 400 μsec, 12/6 sec on/off 45 min) and the high frequency (HF) group (75 Hz, 400 μsec, 5/21 sec on/off, 45 min). NMES was applied daily, from admission on vastus lateralis, vastus medialis and peroneus longus of both lower extremities. The contraction strength of the stimulated muscles was evaluated with a scale ranging from 0 (no contraction) to 4 (full extension). Alterations of muscle mass were evaluated with ultrasound measurements, performed on admission and at 10th day after, to quantify the muscle layer thickness of the quadriceps muscle (rectus femoris and vastus intermedius). Values are reported as mean ± SD. Eight patients of the MF group and 4 patients in the HF group were finally evaluated. No difference (p>0.05) between MF and HF groups (respectively) was observed for age (56 ± 16 vs. 65 ± 20 yrs), gender (4/4 vs. 3/1 male/ female), SOFA score (8 ± 3 vs. 7 ± 3), APACHE II score (17 ± 6 vs. 10 ± 5) and SAPS III score (65 ± 11 vs. 53 ± 13) at ICU admission. In relation to right quadriceps, muscle layer thickness decreased in the MF (from 2.7 ± 0.9 to 2.4 ± 0.7 mm, 9.5 ± 7.2%, p=0.04) and the HF (from 2.7 ± 0.6 to 2.5 ± 0.5 mm, 6.7 ± 3.7%, p=0.05) group. In concern to left quadriceps, thickness was also decreased in the MF (from 2.7 ± 0.8 to 2.2 ± 0.6 mm, 20.2 ± 6.2%, p=0.03) and the HF (from 2.7 ± 0.6 to 2.4 ± 0.7 mm, 15.7 ± 10.5%, p=0.06). For right and left legs (respectively), no significant between group differences were found for either absolute (p=0.58 and 0.41) or percentage (p=0.50 and 0.41) decrease. No significant differences between the MF and HF groups (respectively) were also observed for number (8.0 ± 1.1 vs. 7.8 ± 1.3 sessions, p=0.73) and percentage (93 ± 8% vs. 97 ± 6%, p=0.46) of NMES sessions completed and strength of contraction (2.5 ± 0.9 vs. 3.5 ± 0.6, p=0.11). Conclusions: Different NMES protocols applied in critically ill patients resulted in similar effects on muscle layer thickness of the quadriceps. Further studies are needed for the optimal protocol to be established.
Katsogianni A, Vasileiadis I, Petrocheilou G, Patsaki E, Sidiras G, Nanas S, Stranjalis G, Routsi C and Karatzanos E