The placement of an intravenous (IV) line is a common procedure when treating adult patients in critical care, in the emergency room or in the operating room. This simple and minimally invasive procedure can sometimes be made difficult depending on the patient's morphology or their clinical condition. The procedure then becomes time-consuming, anxiety-provoking, painful and its success is uncertain.

The placement of intravenous (IV) lines under ultrasound by nurses is a rapidly developing alternative in intensive care, emergencies and the operating room.

The main objective is to test the hypothesis that intravenous puncture guided by an ultraportable ultrasound machine is faster than puncture guided by a conventional ultrasound machine.

Inclusion Criteria:

1. Patient aged at least 18 years old
2. Patient with an A-DIVA (Adult Difficult Intravenous Access) score > 1
3. Supported by a nurse trained in all the techniques used in the protocol
4. Patient having given free, informed and oral consent -

Exclusion Criteria:

1. Patient who has already been included in the study
2. Patient whose inclusion in the study would lead to a delay in treatment
3. Adult patient protected by law
4. Pregnant woman
5. Patient not benefiting from French Social Security system -