Management of the musculoskeletal system has not always been the priority of intensivists. However, for several years now, we have known that Intensive Care Unit Acquired Weakness (ICUAW) can have an considerable impact on the vital and functional prognosis of patients. Early rehabilitation dedicated teams are often in place to prevent and treat peripheral muscle deficits. Nevertheless, the diaphragm is often neglected in this support.
Boris Jung and his team have focused on diaphragm weakness during ventilation weaning and its impact on the outcome of extubation . Over a six month period, they screened all patients admitted to the 16-bed medical and surgical ICU with an ICUAW (Medical Research Council score <48), mechanically ventilated for at least 48 hours and undergoing a spontaneous breathing trial. Diaphragmatic function was then assessed in 3 ways (magnetic stimulation of the phrenic nerves, maximal inspiratory pressure and ultrasound). Of the 185 consecutive admitted patients, 40 (22%) presenting a MRC score of 31 [20-36] were included. Diaphragm dysfunction was observed in 32 patients (80%). The phrenic magnetic stimulation seemed to be the best method of evaluation because it did not involve patient participation. 50% of patients with ICUAW failed extubation, with a mortality rate of 50%. The diaphragmatic dysfunction was not statistically significant between the two populations, but a trend was found (p = 0.08). However, correlation between severity of ICUAW, the MRC score and the diaphragmatic dysfunction was not fully demonstrated.
In another study , about half (44%) of patients mechanically ventilated for at least 36 hours showed a reduction in the thickness and contractility of the diaphragm. Weakness severity was more significant in patients ventilated in controlled mode (p = 0.02) and with a high driving pressure (p = 0.01). The first treatment to prevent dysfunction would be engaging this muscle by forcing its contraction and assisting him with moderate support. For patients already severely affected, in the same way that the peripheral muscles are rehabilitated, treatments exist. A meta-analysis published in 2013  showed that specific respiratory muscle training allowed to increase the strength of these muscles, and reduced the number of ventilator days.
Diaphragmatic dysfunction of mechanically ventilated patients is often overlooked. Although its evaluation is not yet easy, this dysfunction should not be neglected. Nowadays, early rehabilitation of peripheral muscles plays an increasingly important role in ICU. Prevention and rehabilitation of diaphragmatic dysfunction must return to our practices to optimise ventilator weaning of our patients.
Article review prepared and submitted by physiotherapist and ESICM member Matthieu Reffienna on behalf of the N&AHP.
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