79 Central venous pressure.
Central venous pressure (CVP) is the blood pressure in the large veins close to the heart (the superior vena cava), and it closely approximates the pressure in the right atrium. It reflects the balance between the volume of blood returning to the heart, the tone of the veins and the ability of the right ventricle to pump this blood on. CVP was long used as a guide to a patient's filling (preload) and fluid needs. Research has shown, however, that CVP alone predicts poorly whether more fluid will increase cardiac output.
How CVP is measured
CVP is measured invasively with a catheter whose tip lies in the superior vena cava, connected to a pressure transducer levelled at the right atrium (mid-axillary line, fourth intercostal space). It is read at the end of expiration. At the bedside, the height of the pulsation in the internal jugular vein (jugular venous pressure) gives an estimate.
Causes of changes
Low CVP
Hypovolaemia (bleeding, dehydration), vasodilation (sepsis, anaphylaxis, spinal anaesthesia), deep inspiration.
High CVP
Right heart failure, fluid overload, tricuspid valve disease, pulmonary hypertension, pulmonary embolism, cardiac tamponade, tension pneumothorax, constrictive pericarditis, mechanical ventilation with PEEP, forced expiration.
Limitations
A meta-analysis of 43 studies found that CVP, either as a single value or as its change after fluid, did not reliably predict fluid responsiveness. CVP is therefore no longer recommended as the sole guide for fluid therapy, but a high or rising CVP remains a useful warning of right heart failure, tamponade or fluid overload, and a high CVP impairs blood flow out of organs such as the kidneys and liver.
for sudden breathlessness with distended neck veins, chest pain, low blood pressure or fainting.
References
- Marik PE, Cavallazzi R. Does the central venous pressure predict fluid responsiveness? An updated meta-analysis and a plea for some common sense. Crit Care Med. 2013;41(7):1774–1781.
This article is for general information and does not replace a consultation with a doctor. Measurements must be interpreted by a physician together with symptoms and other tests.
Published on 1 May 2024