Method of locating the tip of a central venous catheter

A method of locating a tip of a central venous catheter, the central venous catheter having a portion disposed within the superior vena cava, a distal pair of electrodes, and a proximal pair of electrodes spaced longitudinally from the distal pair of electrodes, the method comprising:

• obtaining a distal electrical signal from the distal pair of electrodes;
• generating a first P wave from the distal electrical signal;
• determining a first deflection value of the first P wave;
• obtaining a proximal electrical signal from the proximal pair of electrodes;
• generating a second P wave from the proximal electrical signal;
• determining a second deflection value of the second P wave;
• calculating a first ratio from the first and second deflection values;
• obtaining a SVC deflection value;
• calculating a second ratio of one of the first and second deflection values to the SVC deflection value;
• and
• determining a location of the tip of the central venous catheter based on the first ratio and the second ratio.