Objective: Does the electrocardiographic method for central venous catheter positioning distinguish between a correct intravasal and a malpositioned extravasal position?
Methods: 24 cardiac surgical patients were enrolled in this prospective observational study. In 18 patients the left, in another 6 patients the right internal jugular vein was cannulated. Using a J-wire within a triple-lumen catheter the amplitude of the P-wave was measured at 3 different intravasal sites: Intra-1: (intravasal baseline electrocardiogram), i. e. 10 cm marking of the catheter on skin level; Intra-2: clear rise of the P-wave amplitude upon further insertion of the catheter; Intra-3: maximum P-wave amplitude. At this position the control of the catheter tip was achieved by means of transoesophageal echocardiography (TOE). Intraoperatively, another J-wire within a triple-lumen catheter was placed by the heart surgeon on 3 extravasal sites and the ECG was recorded: Extra-1: extravasal at the left innominate vein above the pericardial reflection; Extra-2: extravasal on the superior vena cava below the pericardial reflection; Extra-A: extravasal on ascending aorta below the pericardial reflection. The catheter was suture fixed with its tip in position Intra-3. Post surgery a chest radiograph was taken.
Results: All catheter tips were visualised at the basis of the Crista terminals (border between right atrium and superior vena cava) by TOE control. The rise of the P wave amplitude at Intra-2, Extra-2 and Extra-A was highly significant compared to the base line at Intra-1 (Intra-1/Intra-2, Intra-1/Extra-2, Intra-1/Extra-A: p in each case < 0.001). The P wave amplitudes of the corresponding intra- and extravasal positions of the left innominate vein (Intra-1/Extra-1, n = 18, p = 0.096)) as well as those of the superior vena cava (Intra-2/Extra-2, n = 24, p = 0.859) did not differ.
Conclusion: The electrocardiographic method can not differentiate between intra- and extravasal position of a central venous catheter, and thus, presumably fails to identify malpositioning as a result of vascular perforation.