INTRODUCTION Central venous catheterization (CVC) is procedure used in hospital settings for patient monitoring, diagnostic, and therapeutic means. The right internal jugular vein (RIJV) is the first choice recommended, with ultrasound (US)-guided as the gold standard. This method is not always available, especially in rural settings or developing countries, and complications are still frequent even under expert hands. The head-down tilt (Trendelenburg) position involves elevation of the lower limbs to favor venous return and increase neck veins regurgitation. Evidence is scarce and contradicting regarding the safety of degree of inclination and head rotation. The objective of this study was to determine the effects of different degrees of Trendelenburg and head rotation on the RIJV and right common carotid artery (RCCA). METHODS An experimental, longitudinal, prospective, analytical study was performed. Healthy adults of both sexes were recruited to voluntarily participate. INCLUSION CRITERIA adults between 18 and 29 years of age, with normal vital signs, and a BMI ≤24.9. Those with RIJV pathology, anatomical variations, neck surgeries, COVID, or metabolic diseases were excluded. Neck US-imaging was performed, obtaining cross-sectional area (CSA) measurements of RIJV and RCCA, and their relationship, at the inferior level of the thyroid cartilage. Randomization at Trendelenburg positions of 0°, 5°, 10° and 15° and left head-rotation of 0°, 45° and 90° in each inclination were performed. Vital signs and oxygen saturation were monitored between each position, as well questioning for discomfort symptoms. RESULTS Measurement of the RIJV and RCCA area was performed in 54 healthy participants (30 men), age range 21-32. RIJV basal CSA was 1.0±0.5mm2 in a supine position (0°) without head rotation (0°). Trendelenburg angle and head-rotation increased the CSA of the RIJV in a statistically significant way, obtaining the greatest area in a 15° Trendelenburg position and maximum rotation (Table 1). This, in turn, had no statistically significant difference with 10° Trendelenburg and 45° rotation (Table 2). CONCLUSIONS A 5º, 10º, or 15º Trendelenburg position and contralateral head rotation increase RIJV CSA. Head rotation also changes the location of the vein anterior to the RCCA at maximum rotation, but not significantly at 45º. Although the greatest area obtained is achieved at the 15º Trendelenburg position with 90º head rotation, this position is uncomfortable and does not have statistical difference with 10º Trendelenburg position with 45 to 90º head rotation, which represents an increase of the initial diameter of 60% of CSA, making it a feasible position. Although Ultrasound-guided catheterization is the gold-standard, Trendelenburg position and 45º head rotation help increase RIJV diameter, to create a safer procedure. SIGNIFICANCE AND IMPLICATIONS This study provides anatomical evidence of RIJV changes with Trendelenburg and head rotation. Most international guidelines focus on CVC approach, and fail to mention patient positioning. The publishing of this data will aid with future versions of CVC guidelines.
Anatomical changes of the internal jugular vein with Trendelenburg position and head rotation. Evidence for a safer catheterization.