Supine With Moderate Frog Leg Positioning Optimizes Femoral Vein Exposure and May Reduce Arterial Injury Risk During Femoral Venipuncture

The overlap between the femoral vein (FV) and femoral artery (FA) complicates FV cannulation. This study used ultrasonography to evaluate the combined effects of body position and passive knee bending on FV size and exposure. In 103 healthy participants, femoral vessels were imaged and compared at three positions regarding inguinal crease in either supine or Reverse Trendelenburg positions with 4 different postures of leg bending. Although most difference were not significant, the results showed the highest FV/FA ratio, but the lowest FV overlap degree can be detected in the supine position with right heel resting against the medial aspect of the left knee. This was especially true at the level of the inguinal crease. This specific body site, position, and posture may provide the best FV cannulation accessibility and lowest risk of arterial injury. More study is needed for confirmation.