Dysfunctions radial arterial catheter are frequent. This was a prospective, randomized observational study monocentric in ICU in France. Patients are randomized in 2 groups : One to less than 4 four centimeters to the wrist joint (Group A) and the other, to more than four centimeters to the wrist joint. (Group B). The primary outcome was the incidence of catheter dysfunction (defined by the impossibility of taking blood from the catheter and / or the impossibility having a reliable blood pressure curve). Investigators compared also the incidence of infection, satisfaction of doctors and nurses, the numbers of days with catheter and the cause of withdrawal.

Inclusion Criteria:

• all patients admitted in ICU, older than 18 years and who required an arterial catheter are include