What is Central Venous Pressure (CVP)?

From the Guidelines

CVP, or Central Venous Pressure, is a measurement of the pressure within the thoracic vena cava near the right atrium of the heart, which reflects the pressure of blood returning to the heart and indicates how well the right side of the heart is functioning. CVP is typically measured using a central venous catheter placed in a large vein such as the internal jugular, subclavian, or femoral vein. Normal CVP values range from 2-6 mmHg or 5-10 cmH2O. This measurement is particularly useful in critically ill patients to assess volume status, cardiac function, and guide fluid management.

Key Points to Consider

• Elevated CVP may indicate right heart failure, cardiac tamponade, or fluid overload, while low CVP often suggests hypovolemia or vasodilation 1.
• Healthcare providers use CVP alongside other hemodynamic parameters to make clinical decisions about fluid administration or diuretic therapy.
• The use of CVP alone to guide fluid resuscitation can no longer be justified because the ability to predict a response to a fluid challenge when the CVP is within a relatively normal range (8–12 mm Hg) is limited 1.
• Dynamic measures of assessing whether a patient requires additional fluid have been proposed in an effort to improve fluid management and have demonstrated better diagnostic accuracy at predicting those patients who are likely to respond to a fluid challenge by increasing stroke volume 1.

Clinical Application

• CVP measurement works based on the principle that pressure in the venous system reflects the balance between blood volume, venous tone, and cardiac function.
• In clinical practice, CVP is used in conjunction with other parameters such as mean arterial pressure (MAP) to guide fluid management and ensure adequate tissue perfusion 1.

From the Research

Definition of CVP

• Central venous pressure (CVP) is an estimate of right atrial pressure, used to assess cardiac preload and volume status in critically ill patients 2.
• CVP is determined by the interaction between cardiac function and venous return 2.

Clinical Use of CVP

• CVP is commonly used to guide fluid resuscitation in critically ill patients 3, 4.
• It is also used to assist in the diagnosis of right-sided heart failure and to evaluate haemodynamic instability 2, 3.
• However, the use of CVP has been challenged in many studies, which have reported it to be a poor predictor of haemodynamic responsiveness 3, 5.

Measurement and Interpretation of CVP

• CVP measurements are relatively easy to obtain, but may be difficult to interpret due to the complex relationship between CVP, cardiac output, and the vascular system 2.
• The interpretation of CVP needs to be considered in conjunction with an assessment of cardiac output 5.
• A CVP of > 10 mm Hg should be considered high, and the probability of an increase in cardiac output with volume infusion is low 5.
• The correct measurement of CVP is pivotal to its proper clinical application, and aligning pressure transducers to the phlebostatic axis is crucial 6.