Central Venous Pressure Monitoring
Central venous pressure is the pressure within the right atrium and in the great vein within the thorax. It represents the average blood pressure within the venous compartment. CVP represents the filling pressure of the right ventricle and it indicates the ability of the right side of the heart to manage a fluid load. Hence, essentially speaking, central venous pressure and right atrial pressure are just the same.
Any changes in the function or homeostatic mechanism of the cardiovascular system will cause alterations in the venous pressure. Thus, CVP serves as a guide to fluid replacement in seriously ill patients and is a measure of effective circulating volume. In simpler words, central venous pressure is a good indicator of the volume of blood or fluid returning to the heart from the systemic circulation.
Importance of CVP Monitoring
Measuring CVP in patients is one of the most important assessments to determine cardiovascular function due to the following reasons:
- The change in CVP correlated with the patient’s clinical status is a useful indication of adequacy of venous blood volume and alterations of cardiovascular function.
- CVP reflects the pumping ability of the right atrium and ventricle.
Cases of right ventricular failure are secondary to left ventricular failure. Thus, if CVP is elevated it may signify as a late sign of left ventricular failure. When CVP is decreased, it could indicate that a patient may be hypovolemic. Verification of the suspected case is noted when CVP rises after rapid intravenous infusion is given. If CVP rises, the case might be cause by hypervolemia or poor cardiac contractility.
When measuring CVP it is very important that the zero mark on the manometer is placed at a standard reference point which is called the phlebostatic axis. After preparing the necessary equipments explain the procedure to the patient. CVP monitoring is similar to an IV and during the procedure the patient may move in bed as desired once the CVP catheter has passed. When the CVP site is located, an ink mark is made on the chest to indicate the location and the area is surgically cleansed.
Normal Central Venous Pressure
Normal CVP is 4 to 10 cm H20.
Common Complications of CVP Monitoring
- Air embolism