Siting Central Venous Catheters Precisely While Performing the Access Procedure

Overview

For central venous catheters (CVC) to function properly, optimal tip location is of utmost importance. One technique to verify CVC position is the ECG method. Nowadays, the ECG method is applied using the maximum P-wave amplitude (P-max). The hypothesis is that a method believed to be precise in assessing CVC position can provide the same results for CVC tip positions regardless of their respective insertion sites. Can the ECG method (at P-max) provide the same results for the position of CVC tips regardless of their insertion site?

Only critically ill patients with multiple organ dysfunction are eligible for the study. Another condition is a prerequisite for reliable illustration of the results, i.e. at least two central venous lines has to be in place. All catheters are to be placed using the ECG method with the CVC tip at P-max. In all patients, a chest X-ray has to be performed within 24 hours of line insertion to assess the CVC positions. The University's Institutional Review Board (IRB) registered and approved the study protocol (1518-03/05). The requirement for written informed consent was waived by the IRB. Central venous catheters (CVC) play an important role in the management of critically ill patients by allowing measurement of haemodynamic variables that cannot be measured accurately by non-invasive means and by allowing delivery of medications and nutritional support that cannot be given safely through peripheral venous catheters. Unfortunately, these catheters are not without potential for harm. The insertion procedure in particular carries the risk of serious mechanical complications, though ultrasound imaging may dramatically reduce this risk. For the catheter to function properly, tip location is of utmost importance. Inserting the tip too far into the right atrium raises serious risks of arrhythmias or even pericardial tamponade. Inserting it too shallowly - in the innominate vein or the upper third of the superior vena cava - poses the risk of intimal damage and consequently venous thrombosis, fibrin sleeve formation, and persistent withdrawal occlusion. Even with correct initial positioning, these catheters are prone to tip migration. However, the risk of erosion and even perforation of the vein wall also should not, in the light of their intensity, be ignored. The ECG method of siting CVC tips has undergone marked development over recent decades. At present, the ECG method with its new interpretation - CVC tip at the maximum P-wave amplitude (P-max) - is a stable and reliable bedside method for positioning CVC tips exactly at the transition of the right atrium (RA) and superior vena cava (SVC) in patients in sinus rhythm. This is the only method that directly enables the operator to assess the correct CVC position during insertion. This study investigates the hypothesis that a method believed to be a precise approach to assessing CVC position can provide the same results for the position of two CVC tips regardless of respective insertion sites.