Evaluation of central venous catheter position with two different mathematical formulas

Objective: It is important for the anaesthesiologists to ensure optimal placement of central venous catheter. Using mathematical formulas for the optimal placement is quite popular because it is easy, inexpensive, and safe. The aim of this study was to determine which one of the two different formulas that have been used to determine the depth of central venous catheter would provide a better determination of the positioning of the catheter tip. Materials and Methods: After obtaining approval from Ethics Committee for Non-invasive Research of Dokuz Eylul University Faculty of Medicine, the study was conducted with patients undergoing open heart surgery in the hospital of Dokuz Eylul University Faculty of Medicine between April and August 2013. Depths of the catheter of the patients in which catheter placement in the right internal jugular vein was performed with intra-atrial ECG method, were compared with the formulas calculated using patients' height, namely Peres' (L = length/10 cm) and Prerana N.Shah' (L = [(length/15)+2]±1.58 cm). The location of the catheter relative to the carina and the distance of the catheter tip to the carina were evaluated with a postoperative PA chest x-ray. Results: Of the 35 patients, the mean depth of the catheter was 14.77 ± 2.53 cm. The catheter tip was seen under the carina in 23 (65.7%) patients, and above the carina in 12 (34.3%) patients. The average depth of the catheters calculated using the formula of Prerana was 14.75 ± 0.10 cm when 1.58cm was added, whereas 11.59 ± 0.61 cm when 1.58 was substracted. The average depth of the catheters calculated using the formula of Peres was found to be 16.75 ± 0.92 cm. Discussion and Conclusion: Anthropometric characteristics may show differences between populations, therefore the formulas are generally modified according to that population before use. The comparison of the two different formulas in the literature, which are for the optimum placement of a central venous catheter tip through insertion from right internal jugular vein, revealed that the formula proposed by Prerana was more appropriate to our patient population, compared to the formula of Peres. Keywords: central venous catheter, internal jugular vein, intra-atrial ECG.