The purpose of this study is to compare the distance between femoral artery and vein in frog position, abduction-exorotation position and anatomical position.

The incidence of unintentional arterial puncture during cannulation of femoral vein was high(20-50%). The addition of knee flexion to abcudtion-exorotation position (frog position) have been shown to increase the cross sectional area of femoral vein. The purpose of this study is to compare the distance between femoral artery and vein in frog position, abduction-exorotation position and anatomical position.

This study is an analytical observational study with cross sectional design within one grup with repeated measurement. The distance between artery and vein was measured in three position. The measurement was taken twice for each position. First picture was taken by one operator and one ultrasonography for all patient. Then another operator measured the distances with caliper feature on the ultrasonograph.

Inclusion Criteria:

1. Malay race adult 18-60 years old
2. Agree to participate in the study and undergoing femoral vein cannulation
3. Normal weight with IMT 19-25 kg/m2

Exclusion Criteria:

1. Previous cannulation on the same vein
2. Femoral vein catheter has been placed
3. Anatomical variation (artery-venous malformation, venous or artery branch at 2 cm inferior to inguinal ligament)
4. Abdominal distention
5. Femoral vein thrombosis
6. Hypotension (Mean Arterial Pressure <65 mmHg, or using vasopressor or inotrope)

Drop out Criteria:

1. Anatomical abnormalities of femoral vein or artery visualized using ultrasonography examination
2. Fail to visualize femoral vein or artery using ultrasonography for two minutes, operated by trained personnel and declared competent by cardiovascular anesthesiologist consultant
3. Patient not cooperative during procedure, hence, unable to maintain limb position for more than 2 minutes in any position examined
4. Patients with right femur fracture

All Malay race adult seeking for medication in Ciptomangunkusumo Hospital who agree to participate in the study