Neuromuscular Electrical Stimulation for the prevention of respiratory muscle weakness in critically ill patients and its association with myokine's change

To evaluate the effects of NMES on myokine concentrations, peripheral and respiratory muscle function, and structure in mechanically ventilated ICU patients. 

This exploratory randomized controlled trial compared NMES applied twice daily for three days with standard care. Blood samples were taken at baseline, immediately after NMES, and at two and six hours post-treatment (T2 and T6). This was repeated on days one and three. The control group (CG) had blood drawn at baseline and T6. Myokines measured included IL-6, BDNF, Myostatin, and Decorin. Ultrasound assessed quadriceps muscle layer thickness (MLT) and diaphragmatic thickening fraction (TFdi), while diaphragm function was measured via tracheal tube pressure from phrenic nerve stimulation (Ptr,tw). Measurements were taken on days one and three. 

Eleven patients were randomized (six CG, five NMES). No significant baseline differences were seen. The CG showed a 27% quadriceps MLT reduction from day one to day three [1.78 cm (1.3-2.7) to 1.3 cm (1.1-2.4), p 0.01]. In the NMES group, MLT decreased by 13% [1.7 cm (1.3-2.3) to 1.5 cm (1.1-2.3), p = 0.06]. TFdi showed no significant changes: NMES slightly increased from 19.5% to 22%, while CG decreased from 25.2% to 15% (p = 0.06 and 0.31, respectively). For Ptr,tw, CG showed a median decrease of 1.73 cmH2O (p = 0.03), while the NMES group showed no significant change (p = 0.19). 

There were no significant differences between groups for MLT (p = 0.66 and 0.83 on days one and three), TFdi (p = 0.52 both days), or Ptr,tw (p = 0.25 and 0.9). Myokine levels also showed no significant differences between groups or within either group. For Decorin, p = 0.92 for NMES and 0.62 for CG; Myostatin, 0.92 for NMES and 0.41 for CG; IL-6, 0.71 for NMES and 0.92 for CG; and BDNF, 0.33 for NMES and 0.13 for CG. 

NMES may help preserve peripheral muscle mass, as shown by the slower quadriceps MLT reduction, and may improve diaphragm function, as indicated by Ptr,tw in the NMES group. However, no significant changes were seen in myokine concentrations. Larger studies are needed to confirm these findings.

This study highlights the potential of NMES to mitigate muscle atrophy and improve respiratory muscle function in ICU patients, suggesting a possible role for NMES in enhancing recovery and reducing MV time in critical care.