Ultrasound evaluation of central veinsin the intensive care unit:effects of dynamic manoeuvres.

Objective: To determine: (1) the proportion of small (<5 mm) or thrombosed internal jugular veins (IJV) and femoral veins (FV) in which catheter placement would be difficult without ultrasound guidance; (2) which position increases central vein sizes and may facilitate cannulation of these vessels.

Design: Prospective study.

Setting: Twelve-bed adult medical intensive care unit.

Patients And Participants: Sixty patients (62 +/- 19 years, SAPS II score 36 +/- 17).

Interventions: Ultrasound examinations of the IJV and FV in supine, Trendelenburg (T) and reverse Trendelenburg (Ti) positions.

Measurements And Results: Maximum diameter and cross-sectional area (CSA) were measured. Venous catheter placement would have been difficult (diameter < 5 mm) or even impossible (thrombosis) for 22% of right IJV, 13% of left IJV, 2% of left and 2% of right FV. In the T position, the CSA of the IJV increased (right IJV: 1.7 +/- 1.4 to 2.01 +/- 1.34 cm2, left IJV: 1.18 +/- 0.81 to 1.34 +/- 0.85 cm2; p < 0.05) and theCSA of the FV decreased (right FV: 1.42 +/- 0.61 to 1.22 +/- 0.58 cm2, left FV: 1.51 +/- 0.62 to 1.26 +/- 0.58 cm2; p < 0.05). In the Ti position, the CSA of the IJV decreased (right IJV: 1.7 +/- 1.4 to 1.35 +/- 1.35 cm2, left IJV: 1.18 +/- 0.81 to 0.87 +/- 0.62 cm2; p < 0.05) and the CSA of the FV increased (right FV: 1.42 +/- 0.61 to 1.66 +/- 0.65 cm2, left FV: 1.51 +/- 0.62 to 1.65 +/- 0.68 cm2; p < 0.05). In two-thirds of patients, the right IJV was significantly larger than the left IJV.

Conclusions: Ultrasonography should be performed before at least central venous catheter placement to detect the presence of deep vein thrombosis or vessels less than 5 mm in diameter. Some positions increase veins' diameter at least internally, T position increasing IJV size and Ti position increasing FV size.