Central venous pressure
Encyclopedia
Central venous pressure (also known as: right atrial pressure; RAP) describes the pressure of blood in the thoracic vena cava, near the right atrium
Right atrium
The right atrium is one of four chambers in the hearts of mammals and archosaurs...

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

It is a good approximation of right atrial pressure, which is a major determinant of right ventricular end diastolic volume. 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
Cardiac output
Cardiac output is the volume of blood being pumped by the heart, in particular by a left or right ventricle in the time interval of one minute. CO may be measured in many ways, for example dm3/min...

). 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.

Measurement

Normal CVP can be measured from two points of reference:
  • Sternum: 0–14 cm H2O
    Centimetre of water
    A centimetre of water is a less commonly used unit of pressure derived from pressure head calculations using metrology...

  • Midaxillary line
    Midaxillary line
    The midaxillary line is a coronal line on the torso between the anterior axillary line and the posterior axillary line.It is a landmark used in thoracentesis.-External links:* http://www.meddean.luc.edu/Lumen/MedEd/MEDICINE/PULMONAR/apd/lines.htm...

    : 8–15 cm H2O


CVP can be measured by connecting the patient's central venous catheter
Central venous catheter
In medicine, a central venous catheter is a catheter placed into a large vein in the neck , chest or groin...

 to a special infusion
Infusion pump
An infusion pump infuses fluids, medication or nutrients into a patient's circulatory system. It is generally used intravenously, although subcutaneous, arterial and epidural infusions are occasionally used....

 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 progressive intensive care unit
Intensive Care Unit
thumb|220px|ICU roomAn intensive-care unit , critical-care unit , intensive-therapy unit/intensive-treatment unit is a specialized department in a hospital that provides intensive-care medicine...

s in the U.S., specialized monitors are available to continuously measure CVP as well as other hemodynamic values.

Normal values are 2–8 mmHg

Factors affecting CVP

Factors that increase CVP include:
  • Hypervolemia
    Hypervolemia
    Hypervolemia, or 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.-Causes:Excessive sodium or fluid intake:* IV therapy...

  • forced exhalation
    Exhalation
    Exhalation is the movement of air out of the bronchial tubes, through the airways, to the external environment during breathing....

  • Tension pneumothorax
  • Heart failure
  • Pleural effusion
    Pleural effusion
    Pleural effusion is excess fluid that accumulates between the two pleural layers, the fluid-filled space that surrounds the lungs. Excessive amounts of such fluid can impair breathing by limiting the expansion of the lungs during ventilation.-Pathophysiology:...

  • Decreased cardiac output
    Cardiac output
    Cardiac output is the volume of blood being pumped by the heart, in particular by a left or right ventricle in the time interval of one minute. CO may be measured in many ways, for example dm3/min...

  • Cardiac tamponade
    Cardiac tamponade
    Cardiac tamponade, also known as pericardial tamponade, is an emergency condition in which fluid accumulates in the pericardium ....

  • Mechanical ventilation
    Mechanical ventilation
    In medicine, mechanical ventilation is a method to mechanically assist or replace spontaneous breathing. This may involve a machine called a ventilator or the breathing may be assisted by a physician, respiratory therapist or other suitable person compressing a bag or set of bellows...

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


Factors that decrease CVP include:
  • Hypovolemia
    Hypovolemia
    In physiology and medicine, hypovolemia is a state of decreased blood volume; more specifically, decrease in volume of blood plasma...

  • Deep inhalation
  • Distributive shock
    Distributive shock
    Distributive shock is defined by hypotension and generalized tissular hypoxia. This form of relative hypovolemia is the result of blood vessel dilation...


External links


See also

Pulmonary Capillary Wedge Pressure
Pulmonary capillary wedge pressure
The pulmonary capillary wedge pressure or PCWP is the pressure measured by wedging a pulmonary catheter with an inflated balloon into a small pulmonary arterial branch.Physiologically, distinctions can be drawn among pulmonary venous pressure, pulmonary artery pressure, pulmonary...

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