Central venous pressure (CVP) is the blood pressure in the venae cavae, near the

right atrium The atrium ( la, ātrium, , entry hall) is one of two upper chambers in the heart that receives blood from the circulatory system. The blood in the atria is pumped into the heart ventricles through the atrioventricular valves. There are two at ...

of the

heart The heart is a muscular organ in most animals. This organ pumps blood through the blood vessels of the circulatory system. The pumped blood carries oxygen and nutrients to the body, while carrying metabolic waste such as carbon dioxide to t ...

. CVP reflects the amount of blood returning to the heart and the ability of the heart to pump the blood back into the

arterial An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

system. CVP is often a good approximation of right atrial pressure (RAP), although the two terms are not identical, as a pressure differential can sometimes exist between the venae cavae and the right atrium. CVP and RAP can differ when arterial tone is altered. This can be graphically depicted as changes in the slope of the

venous return Venous return is the rate of blood flow back to the heart. It normally limits cardiac output. Superposition of the cardiac function curve and venous return curve is used in one hemodynamic model. __TOC__ Physiology Venous return (VR) is the flow o ...

plotted against right atrial pressure (where central venous pressure increases, but right atrial pressure stays the same; VR = CVP − RAP). CVP has been, and often still is, used as a surrogate for preload, and changes in CVP in response to infusions of intravenous fluid have been used to predict volume-responsiveness (i.e. whether more fluid will improve cardiac output). However, there is increasing evidence that CVP, whether as an absolute value or in terms of changes in response to fluid, does not correlate with ventricular volume (i.e. preload) or volume-responsiveness, and so should not be used to guide intravenous fluid therapy. Nevertheless, CVP monitoring is a useful tool to guide hemodynamic therapy. The cardiopulmonary baroreflex responds to an increase in CVP by decreasing systemic vascular resistance while increasing

heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...

and ventricular

contractility Contractility refers to the ability for self-contraction, especially of the muscles or similar active biological tissue *Contractile ring in cytokinesis *Contractile vacuole *Muscle contraction **Myocardial contractility *See contractile cell for ...

in dogs.

Measurement

Normal CVP in patients can be measured from two points of reference: *

Sternum The sternum or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major blood vessels from injury. Sha ...

: 0–14 cm H₂O *

Midaxillary line The axillary lines are the anterior axillary line, midaxillary line and the posterior axillary line. The anterior axillary line is a coronal line on the anterior torso marked by the anterior axillary fold. It's the imaginary line that runs down ...

: 8–15 cm H₂O CVP can be measured by connecting the patient's central venous catheter to a special

infusion Infusion is the process of extracting chemical compounds or flavors from plant material in a solvent such as water, oil or alcohol, by allowing the material to remain suspended in the solvent over time (a process often called steeping). An in ...

set which is connected to a small diameter water column. If the water column is calibrated properly the height of the column indicates the CVP. In most

intensive care unit 220px, Intensive care unit An intensive care unit (ICU), also known as an intensive therapy unit or intensive treatment unit (ITU) or critical care unit (CCU), is a special department of a hospital or health care facility that provides intensi ...

s, facilities are available to measure CVP continuously. Normal values vary between 4 and 12 cmH₂O.

Factors affecting CVP

Factors that increase CVP include: *

Cardiac tamponade Cardiac tamponade, also known as pericardial tamponade (), is the buildup of fluid in the pericardium (the sac around the heart), resulting in compression of the heart. Onset may be rapid or gradual. Symptoms typically include those of obstructi ...

*Decreased cardiac output *Forced

exhalation Exhalation (or expiration) is the flow of the breath out of an organism. In animals, it is the movement of air from the lungs out of the airways, to the external environment during breathing. This happens due to elastic properties of the lungs, ...

* Heart failure *

Hypervolemia Hypervolemia, also known as fluid overload, is the medical condition where there is too much fluid in the blood. The opposite condition is hypovolemia, which is too little fluid volume in the blood. Fluid volume excess in the intravascular compa ...

* Mechanical ventilation and the application of positive end-expiratory pressure (PEEP) *

Pleural effusion A pleural effusion is accumulation of excessive fluid in the pleural space, the potential space that surrounds each lung. Under normal conditions, pleural fluid is secreted by the parietal pleural capillaries at a rate of 0.6 millilitre per k ...

Pulmonary embolism Pulmonary embolism (PE) is a blockage of an artery in the lungs by a substance that has moved from elsewhere in the body through the bloodstream ( embolism). Symptoms of a PE may include shortness of breath, chest pain particularly upon breathin ...

* Pulmonary hypertension * Tension pneumothorax Factors that decrease CVP include: *Deep inhalation * Distributive shock * Hypovolemia

References

External links

Venous function and central venous pressure: a physiologic story
- a technical discussion of the more modern understanding of central venous pressure; this may well conflict with the sources below.
Central Venous Pressure and Pulmonary Capillary Wedge Monitoring
* {{DEFAULTSORT:Central Venous Pressure Medical terminology Medical monitoring Cardiovascular physiology

Measurement

Factors affecting CVP

See also

References

External links