Purpose: To facilitate electrocardiography (ECG)-guided central venous catheter placement by observing the shape and size of the P wave at specific locations of a central venous catheter (CVC) tip.
Methods: We evaluated 54 patients for whom central venous catheterization was planned as part of routine care for their elective surgery. The junction of the superior vena cava (SVC) and the right atrium (RA) was defined as the superior border of the crista terminalis by transesophageal echocardiography. The RA ECGs were recorded while withdrawing the CVC into the SVC or advancing it into the RA at 1-cm intervals. Saline was used as an electrical conductor via the distal lumen of the CVC.
Results: The tallest peaked and biphasic P waves [median (interquartile range)] were observed when the CVC tip was located at positions 0.0 cm (-1.0 to 0.0) and -4.0 cm (-5.0 to -3.0) below the SVC/RA junction, respectively. The P wave returned to a normal shape and size at 4.0 cm (3.0 to 4.0) above the SVC/RA junction. Overshoot P waves were observed at - 4.0 cm (-5.0 to -3.0) below the SVC/RA junction in 22 patients, when the CVC tip appeared to be contacting or in close proximity to the RA wall.
Conclusions: During ECG-guided central venous catheterization, the tallest peaked P wave may be used to place the CVC tip at the SVC/RA junction, the normally-shaped P wave identifies the mid to upper SVC, and biphasic P waves identify RA localization.