Validation of the ipsilateral nipple as the needle directional guide during right internal jugular vein catheterization: A prospective observational study

Summary Background The ipsilateral nipple has been used as a directional guide for needle advance during internal jugular vein (IJV) catheterization. We attempted to validate the utility of the ipsilateral nipple during IJV catheterization. Methods One hundred and two patients scheduled for elective surgery were enrolled. In the 15° Trendelenberg position with 30° head rotation, the apex of the triangle formed by the sternocleidomastoid muscle and the clavicle was identified. The angle formed by the line connecting the apex and the ipsilateral nipple and the actual course of the IJV was measured. The distance between the apex of the anatomical triangle and the IJV center identified were measured via ultrasound. Results The angle formed by the line connecting the apex and the ipsilateral nipple and the IJV was 16 ± 7.6° and was greater in females than males (14.8 ± 1.1 vs 17.4 ± 1.0°, P = 0.043). Regression analysis showed that height, weight, gender, and age did not affect the angle as an independent factor. The apex of the anatomical triangle was 0.5 cm medial to the IJV center and was shorter in females compared to males (0.33 ± 0.12 vs 0.6 ± 0.09 cm, P = 0.039). Conclusion Our study shows that when the needle is inserted at the apex of the anatomical triangle directed towards the ipsilateral nipple, it crosses the IJV at 16°. Since the common carotid artery is usually medial to the IJV, directing the needle towards the ipsilateral nipple seems to be a safe way to avoid the common carotid artery and successfully puncture the IJV.