Effect of the lateral tilt position on femoral vein cross-sectional area in anesthetized adults

ABSTRACT

BACKGROUND: A lateral tilt position can affect the size of the femoral vein (FV) due to increased venous blood volume in the dependent side of the body. METHODS: Forty-two patients, aged 20–60 years, were enrolled in this study. The crosssectional area (CSA), anteroposterior, and transverse diameters of the FV were measured 1 cm below the left inguinal line using ultrasound. The value of each parameter was recorded in the following four positions (1) supine, (2) supine + 10° left-lateral tilt (LLT), (3) 10° reverse Trendelenburg (RT), and (4) RT + LLT. RESULTS: CSAs of the left FV in the supine, supine + LLT, RT, RT + LLT positions were 0.93 ± 0.22, 1.11 ± 0.29, 1.17 ± 0.29, and 1.31 ± 0.32 cm2, respectively. Compared to the supine position, there was a significant increase in CSA and anteroposterior diameter according to the three changed positions. The transverse diameter of the left FV was significantly increased in supine + LLT, RT, RT + LLT positions compared to that in the supine position (P = 0.010, P = 0.043, P = 0.001, respectively). There was no significant difference in the transverse diameter of the left FV between the supine + LLT and RT positions (P = 1.000). CONCLUSIONS: Adding LLT to the supine and RT positions increased the CSA of the unilateral FV significantly.