title: A comparative study of landmark-based topographic method versus the formula method for estimating depth of insertion of right subclavian central venous catheters.
abstract: OBJECTIVE
  Subclavian central venous catheterisation (CVC) is employed in critically ill patients requiring long-term central venous access. There is no gold standard for estimating their depth of insertion. In this study, we compared the landmark topographic method with the formula technique for estimating depth of insertion of right subclavian CVCs.
  
  
  METHODS
  Two hundred and sixty patients admitted to Intensive Care Unit requiring subclavian CVC were randomly assigned to either topographic method or formula method (130 in each group). Catheter tip position in relation to the carina was measured on a post-procedure chest X-ray. The primary endpoint was the need for catheter repositioning. Mann-Whitney test and Chi-square test was performed for statistical analysis using SPSS for windows version 18.0 (Armonk, NY: IBM Corp).
  
  
  RESULTS
  Nearly, half the catheters positioned by both the methods were situated >1 cm below the carina and required repositioning.
  
  
  CONCLUSIONS
  Both the techniques were not effective in estimating the approximate depth of insertion of right subclavian CVCs.
authors: Department of Anaesthesiology, MS Ramaiah Medical College, Bengaluru, Karnataka, India.
authors: Tejesh C
authors: TC
authors: Anandaswamy
authors: Department of Anaesthesiology, Bangalore Medical College and Research Institute, Bengaluru, Karnataka, India.
authors: Vinay
authors: V
authors: Marulasiddappa
keywords: Central venous catheter tip; formula method; topographic method