Anatomical changes of the internal jugular vein with Trendelenburg position: A systematic review and meta‐analysis

Abstract

Introduction The anatomy of the internal jugular vein (IJV) may be influenced by the position of the patient. A head-down-tilt or Trendelenburg position could potentially increase the size and diameter of the IJV, however, its use in clinical scenarios, such as cathetherization (a frequent procedure), is debatable. Small venous cross-section could make cannulation difficult, even while guided by ultrasound, increasing the risk of complications. The objective of this study was to systematically review all studies that analyze parameters of IJV size variations due to Trendelenburg position evaluated by ultrasound. Methods Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, all cross-sectional studies comparing the effect of Trendelenburg position were included. Any degree of head-down tilt with a supine position on the cross-sectional area (CSA) and anteroposterior (AP) diameter of the right internal jugular vein (RIJV) in healthy adults were eligible. Measurements and outcomes had to be with ultrasonography. An experienced librarian designed and conducted the search strategy in Ovid MEDLINE, EMBASE, Web of Science, Scopus, and Cochrane. Four independent reviewers, working in duplicate, assessed for eligibility of studies. Cross-sectional area (CSA) and anteroposterior (AP) diameter of the RIJV were collected and pooled using fixed-effects meta-analyses. Effect sizes are presented as mean difference (MD) and 95% confidence interval (CI). Heterogeneity between studies was assessed using the X2 test and I2 statistic. Data syntheses were conducted using Review Manager Version 5.3. Results A total of 22 articles (613 study subjects) were included. The overall risk of bias was moderate. In healthy adults, exposure to any degree of the Trendelenburg position significantly increased the CSA (MD:0.38cm²; [95% CI:0.35-0.41]; P<0.00001; I²=0%) and AP diameter (MD:1.87 mm; [95% CI:1.51-2.23]; P<0.00001; I²=0%) of the RIJV. No significant changes were exhibited when comparing the results of studies performed with the head rotated (MD:0.35cm²; [95% CI:0.29-0.42]; P<0.00001; I²=0%) with those using a neutral position of the head (MD:0.38 cm²; [95% CI:0.35-0.41]; P<0.00001; I²=0%) No significant increase of the AP diameter of the RIJV was identified from the 10° Trendelenburg position to both 15° and 20° inclinations. Conclusions The available published evidence favors Trendelenburg position, with a >5° statistically increasing RIJV CSA and AP diameter. Further inclination from 10° does not statistically benefit IJV size. This position should be recommended by international guidelines for CVC placement, when patient conditions allow it, as most guidelines fail to mention patient positioning.