Kwon MY, Lee EK, Kang HJ, et al. The effects of the Trendelenburg position and intrathoracic pressure on the subclavian cross-sectional area and distance from the subclavian vein to pleura in anesthetized patients. Anesth Analg. 2013;117(1):114–118.
Full-text for Emory users.
“We evaluated the effects of increased intrathoracic pressure (20 cm H2O) or Trendelenburg position on the CSA and DSCV-pleura during SCV catheterization and general anesthesia, and determined whether their changes were clinically relevant (defined as [DELTA]CSA and [DELTA]DSCV-pleura >=15% vs S-0). Applying positive intrathoracic pressure alone or Trendelenburg position alone provided a statistically increased CSA of the SCV, but this increase did not meet our defined threshold for a relevant degree ([DELTA]CSA of >=15%). Only the combined application of these 2 maneuvers yielded a relevant increase in the CSA ([DELTA]CSA 23.2% vs S-0). No maneuvers provided a relevant change of DSCV-pleura ([DELTA]DSCV-pleura >=15%) despite their statistically significant changes in some conditions.” (Kwon, 2013, p. 116)