Proper Head Position For Right Subclavian Catheterization

Objective1. The study used ultrasonography to observe in three head positions how the flow velocities and diameters of three veins and also the angles composed of right subclavian vein, internal jugular vein and brachiocephalic vein changed. So as to speculate proper head position for safe subclavian catheterization.2. We then conducted a follow-up clinical trial to confirm these findings.Methods1. Ultrasonography was performed for 60 adult volunteers at three head positions: left (45°), neutral and right (30°). Angles composed of right subclavian vein, internal jugular vein and brachiocephalic vein and also the flow velocities and diameters of three veins were measured.2. The incidence of placing the catheter tip in the ipsilateral internal jugular vein during the right subclavian approach was compared between the left (45°) and right (45°) head positions in 80 patients.Results1. In the ultrasonography study, the mean angles between right subclavian vein and internal jugular vein in the left, neutral and right positions were 117.33±12.33°, 105.90±10.51°and 95.59±9.60°, respectively. Angles increased with head turning left (left> neutral> right; P< 0.05). Angles between right subclavian vein and brachiocephalic vein did not differ among the three head positions (P> 0.05).2. The diameters of the internal jugular vein in the left, neutral and right positions were 1.19±0.20 cm, 1.14±0.18 cm and 1.20±0.16 cm, respectively. The diameters increased with head turning to left or right (left> neutral, right> neutral; P< 0.05). The diameters of the subclavian vein or brachiocephalic vein did not differ among the three head positions (P> 0.05).3. The flow velocities of the internal jugular vein in the left, neutral and right positions were 25.20±1.88 cm/s, 18.35±2.45 cm/s and 24.88±1.80 cm/s, respectively. The flow velocities increased with head turning to left or right (left> neutral, right> neutral; P< 0.05). The flow velocities of the subclavian vein in the left, neutral and right positions were 14.79±2.71 cm/s, 19.44±2.24 cm/s and 19.01±2.21 cm/s, respectively. The flow velocities decreased with head turning to left (P< 0.05), and there was no statistical difference between right and neutral position (P> 0.05). The flow velocities of the brachiocephalic vein in the left, neutral and right positions were 29.46±2.20 cm/s, 46.40±1.69 cm/s and 45.73±1.43 cm/s, respectively. The flow velocities decreased with head turning to left or right (left< neutral, right< neutral; P< 0.05).4. In the prospective randomized clinical trial, the incidences of placing the catheter tip in the ipsilateral internal jugular vein during the right subclavian approach in the left-turning group and right-turning group were 7.32% and 4.76%, respectively. There was no statistical difference between left-turning group and right-turning group (P=0.599).Conclusions1. The changes of head position may affect anatomy relationships among subclavian vein, internal jugular vein and brachiocephalic vein. Proper head position for safe right subclavian catheterization may be turning right moderately.2. Though the incidences are different, there was no statistical difference between two groups. To confirm these findings, we may need a much bigger sample size.