ICU acquired muscle weakness (IAMW) is a common disease that is associated with high morbidity and mortality. Patients with septic shock are particularly at risk.

The diagnosis of IAMW is clinical and based on the rating of the Medical Research Council score (MRC score). A MRC score lower than 48 defines the IAMW. But this evaluation is only usable in sufficiently awaken patients.

Several studies have highlighted the role of microRNAs in regulating physiological processes and diseases related to the skeletal muscles. To date, no study was interested in IAMW.

The aim of this study is to compare the microRNA detection kinetics on the appearance of IAMW.

In septic shock patients, the kinetics of nine microRNAs will be compared between two groups: those with IAMW (IAMW + group) and those without IAMW (IAMW - group).

MicroRNAs (miR-1, miR-21, miR-133, miR-155, miR-206, miR-208a, miR-208b, miR-486, miR-499) will be measured at day 1, day 2, day 5 and day 7 after septic shock onset.

Inclusion Criteria:

Patients with septic shock criteria:

• At least two of the following criteria: temperature < 36 ° C or > 38 ° C, heart rate > 90 beats / minute, respiratory rate> 20 breaths / minute or PaCO2 < 32mmHg, leukocytes > 12,000 / mm3 or < 4000 / mm3
• Refractory Hypotension (blood pressure < 90mmHg or need norepinephrine) or lactate ≥ 4 mmol / L

Exclusion Criteria:

• Age<18years
• Patients with preexisting neuromuscular disease
• Pregnancy
• Moribund patients with early therapeutic limitation
• Patients who had a seizure in the last 6 months

septic shock patients admitted into ICU.