Central venous pressure ( CVP ) is the blood pressure in the cavae vein, near the right atrium of the heart. CVP reflects the amount of blood that returns to the heart and the heart's ability to pump blood back into the arterial system. CVP is often a good approximation of right atrial pressure (RAP), although the two terms are not identical, since pressure differences can sometimes occur between the vena cavae and the right atrium. CVP and RAP can be different when the artery tone is changed. This can be graphically represented as a change in the slope of the return of the vein plotted against right atrial pressure (where central venous pressure increases, but the right atrial pressure remains the same; VR = CVP - RAP).
CVP has, and is often still, used as a substitute for preload, and CVP changes in response to intravenous fluid infusion have been used to predict the volume response (ie whether more fluid will increase cardiac output). However, there is increasing evidence that CVP, whether as an absolute value or in terms of changes in response to fluid, is not correlated with ventricular volume (ie preload) or volume response, so it should not be used to guide intravenous fluid therapy.. However, CVP monitoring is a useful tool for guiding hemodynamic therapy. Baroreflex cardiopulmonary responds to increased CVP by decreasing systemic vascular resistance while increasing heart rate and ventricular contractility in dogs.
Video Central venous pressure
Measurement
Normal CVP in patients can be measured from two reference points:
- Sternum: 0-14 cmÃ, H 2 O
- Midaxillary line: 8-15 cm H 2 O
CVP can be measured by connecting the patient's central venous catheter to a special infusion set that is connected to a small diameter water column. If the water column is well calibrated the height of the column shows the CVP.
In most intensive care units, facilities are available to measure CVP on an ongoing basis.
Normal values ​​vary between 4 and 12 cmH 2 O.
Maps Central venous pressure
Factors that affect CVP
Factors that improve the CVP include:
- Heart Tamponade
- Decrease in cardiac output
- forced to breathe
- Heart failure
- Hypervolemia
- Mechanical ventilation and positive expiratory end expression (PEEP) application
- Pleural effusions
- Pulmonal Emboli
- Lung Hypertension
- Tension pneumothorax
Factors that decrease CVP include:
- Breathe deep
- Distributive Shock
- Hypovolaemia
See also
- Jugular venous pressure
- Pulmonary capillary wedge pressure
References
External links
- Venous function and central venous pressure: physiological stories - technical discussions about understanding central venous pressure more modern; this may conflict with the source below.
- Central Vein Pressure Monitor
- Concept of Cardiovascular Physiology
- Central Vein Pressure Monitor and Dozens of Lung Capillaries
- Cardiovascular Physiology
- Central Vein Pressure at National Library of Medicine's Medical Subject Headings (MeSH)
Source of the article : Wikipedia
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