No effect of Valsalva maneuver or Trendelenburg angle on axillary vein size.

Background: A new technique for establishing ultrasound-guided central access involves the use of the axillary vein, the distal projection of the subclavian vein, via the lateral chest.

Objective: To examine the effects of Valsalva maneuver and Trendelenburg positioning on axillary vein cross-sectional area (CSA).

Methods: Using a group-sequential design, we enrolled stable emergency patients and measured their axillary veins sonographically.