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[Effect of airway pressure and Trendelenburg position on the cross-sectional area of the internal jugular vein in anesthetized patients].

BACKGROUND
Several maneuvers such as, Trendelenburg position or breath holding, are proposed to increase success rate and decrease complications during internal jugular vein cannulation. We investigated the relationship between the cross-sectional area of the right internal jugular vein (RIJV) and several maneuvers in anesthetized patients.


METHODS
We studied 18 adult patients (10 males, 8 females) undergoing RIJV cannulation after anesthetic induction and endotracheal intubation. We measured cross-sectional area of the RIJV at the level of the cricoid cartilage using ultrasound imaging and standardized by dividing it with body weight. Measurements were taken at supine position (S), supine plus 20 cmH2O breath hold (SH), 10 degrees Trendelenburg position (T-position) (T), and 10 degrees T-position plus 20 cmH2O breath hold (TH). We also measured blood volume (BV) with pulse dye-densitometry.


RESULTS
The standardized cross-sectional areas of the RIJV during S, SH, T and TH maneuvers were 1.92 +/- 1.5, 2.82 +/- 1.8, 2.71 +/- 1.5, 3.51 +/- 1.6 mm2 x kg(-1), respectively. Every maneuver increased significantly the cross-sectional area compared to that of supine position (P < 0.05). The effects of the maneuvers tended to be larger when the BV was smaller.


CONCLUSIONS
Breath holding at 20 cmH2O and 10 degrees T-position showed almost the same dilatation effects on RIJV (164%, 159%). Simultaneous performance of the both maneuvers was most effective (222%) in dilating cross-sectional area of RIJV in anesthetized patients.