The goal of placing a central venous catheter is to place the tip just above the junction of the superior vena cava (SVC) and right atrium (RA). A catheter tip in the right atrium can rarely perforate the thin atrial wall, resulting in hemopericardium.
Connecting the ECG pads (Gebhard et al):
(1) 3 ECG pads are placed:
(1a) one on left shoulder in anterior axillary line at the level of the left clavicle
(1b) one below the heart in the left anterior axillary line
(1c) one on the right shoulder in the anterior axillary lines
(2) An electric switch is placed on the wire to the pad in the right anterior axillary line. This connects to a guidewire in the central venous catheter. Some authors do not use the guidewire but rather inject normal saline through the catheter.
(3) The ECG is monitored while advancing the catheter.Changes in the P wave are identified and then the catheter is withdrawn until they disappear.
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Change in the P Wave of the ECG
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Location of Tip
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tallest, peaked
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at the junction of the SVC and RA
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biphasic P wave
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within the right atrium
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normal P wave
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someplace in the superior vena cava
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where:
• Schummer noticed that use of the ECG to place the tip of a left-sided CVC often resulted in tip abutting against the wall of the SVC. They believe that a peak in the P wave identifies the pericardial reflection rather than the SVC-RA junction.
The use of the ECG to guide catheter tip placement avoids the need for a chest X-ray. Many patients who need a central venous catheter are exposed to a high cumulative amount of radiation.
