Muscle Function and Muscle Ultrasound in ICU

The objective of intensive care therapists is to be able to detect as early as possible the muscle weakness acquired in intensive care, in order to implement curative strategies such as adapted nutrition and early rehabilitation. Various diagnostic tools are available for this purpose. To evaluate muscle mass, CT and MRI remain the gold standard but are difficult to implement in routine practice in ICU and are extremely expensive and can generate radiation for the patient. Functional muscle evaluation is based on different voluntary tests which are not all able to predict muscle weakness acquired in ICU. In addition, some of the voluntary tests are expensive and require expert staff for practice and interpretation of results. In addition, a muscle test such as MRC, although having an intraclass coefficient of 0.94, has little predictive value on clinical parameters such as mechanical ventilation duration and is not associated with mortality in the ward. However, it remains the test of choice to define a ICUAW with a threshold value of 48/60 points. Dynamometry is a tool for measuring muscle strength. The patient is asked to perform a short and intense maximal muscular effort against manual or instrumental resistance. The limb segments must not move, it is an isometric effort. The most common measurement in intensive care units is the dynamometric grip force, called "handgrip". In ICU, the patient may have touble with awareness, arousal or even comprehension, which will lead to biases in the evaluation of the motor force. Ultrasound is a tool available in ICU and the muscle component can be assessed qualitatively or quantitatively without the patient's participation. Several studies have also demonstrated that muscle ultrasound is capable of reliably detecting pathological changes, particularly when repeated. Muscle ultrasound could thus help identify patients at higher risk of prolonged complications. Nevertheless, this technique lacks standardization and norma