Every patient need venous access for surgery under anesthesia. It is the most frequently performed invasive procedure in medicine in the whole world. In expert groups, ultrasonographically guided vascular access (UGVA) appears to be a significantly better method, but studies on larger groups of patients are lacking.

Prospective randomized 2-arm study which is comparing success rate of ultrasound guided a palpation inserted cannulas in patients undergoing primary hip or knee arthroplasty.

The project will be managed according to the protocol of principles of Good Clinical Practice and valid regulations.

More than 2 billion peripheral vascular cannulas (PVCs) are introduced globally each year. Each patient needs venous access for surgery under anesthesia. It is the most frequently performed invasive procedure in medicine in the whole world. Nevertheless, investigators still do not know how to fix them adequately, to work reliably for at least 72 hours.

Then there is a group of patients with difficult intravenous access (DIVA). These patients often have to undergo repeated painful punctures through the skin when introducing PVC. Many times well trained healthcare worker in the ultrasound-guided vascular access is needed to introduce PVC in DIVA patients. Up to one third of adult patients are DIVA. In overweight orthopedic patients, this subpopulation can reach up to 50% . Up to 64% PVC fails within 72 hours.

Several studies have shown that PVC introduced at the site of limb flexion (elbow, wrist), repeated punctures increase the risk of thrombosis, infection and phlebitis. In expert groups, ultrasonographically guided vascular access (UGVA) appears to be a significantly better method, but studies on larger groups of patients are lacking.

Investigators hypothesise that UGVA is superior in many parameters. The aim of our study is to compare two types of cannula insertion methods and their benefits and risks for patients. Ultrasound guided insertion and palpation guided insertion. To have evidence robust enough and after statistical analysis investigators decided for sample of 500 patients.

Investigators will evaluate data after 100, 250 and 500 patients. After statistical analysis will be calculate benefit/risk ratio for patients and take steps towards patient safety and satisfaction.

The project will be managed according to the protocol of principles of Good Clinical Practice and valid regulations.

Patients are divided in two groups. Group A (insertion by palpation of vein): standard cannula (name brand "vasofix" BBraun) insertion through vein palpation and insertion in block room.

- prior insertion medical staff will fill in study protocol form A

Group B (UGVA): DIVA score calculation, Ultrasound-guided (name brand "deep access introcan" BBraun) cannula insertion

- prior insertion medical staff will fill in study protocol form B

In primary outcome investigators hypothesised that UGVA need less attempts to successful cannulation in comparison with vein cannulation by palpation. Investigators also think that deep vein cannula secured by UGVA will have lower failure rates by any means. In general there are several benefits in UGVA. On the other hand all above is applicable only in hands of well trained medical staff.

Inclusion Criteria:

• Primary hip or knee arthroplasty
• BMI over 25

Exclusion Criteria:

• reoperation of endoprosthesis
• mental disorder
• age under 18
• sepsis
• protocol non-compliance
• gravidity
• patient refusal or no informed consent or both