29/02/2024
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India's Nursing Experts
Central Venous Pressure (CVP), also known as mean venous pressure (MVP) is the pressure of blood in the thoracic vena cava, near the right atrium of the heart.
Measurement
Normal CVP can be measured from two points of reference:
Sternum: 0β14 cm H2O
Midaxillary line: 8β15 cm H2O
CVP can be measured by connecting the patientβs central venous catheter to a special infusion 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 units, facilities are available to measure CVP continuously.
Normal values vary between 4 and 12 cmH2Oγ
SITE NORMAL PRESSURE RANGE (in mmHg)
CENTRAL VENOUS PRESSURE 3 β 8
RIGHT VENTRICULAR PRESSURE Systolic 15 β 30
Diastolic 3 β 8
PULMONARY ARTERY PRESSURE Systolic 15 β 30
Diastolic 4 β 12
PULMONARY VEIN / PULMONARY WEDGE PRESSURE 2 β 15
LEFT VENTRICULAR PRESSURE Systolic 100 β 140
Diastolic 3 β 12
Factors Affecting CVP
Factors that increase CVP include:
Hypervolemia
forced exhalation
Tension pneumothorax
Heart failure
Pleural effusion
Decreased cardiac output
Cardiac tamponade
Mechanical ventilation and the application of positive end-expiratory pressure (PEEP)
Pulmonary Hypertension
Pulmonary Embolism
Factors that decrease CVP include:
Hypovolemia
Deep inhalation
Distributive shock
Insertion Sites
Internal jugular veins This site is chosen frequently
Subclavian veins This site is often chosen as there are more recognizable anatomical landmarks,
Femoral veins This site provides rapid central access during an emergency such as a cardiac arrest.
Potential Complications
Haemorrhage β from the catheter site β if it becomes disconnected from the infusion. Patients who have coagulation problems such as those on warfarin or those will clotting disorders are at risk. Catheter occlusion β by a blood clot or kinked tube β regular flushing of the CVC line and a well secured dressing should help to avoid this.
Infection β redness, pain, swelling around the catheter insertion site may all indicate infection. Careful asepsis is needed when touching a CVC site. Swabs for MC&S should be taken if infection is suspected.
Air embolus β if the infusion or monitoring lines become disconnected there is a risk that air can enter the venous system. All lines and connections should be checked at the start of every shift to minimize the risk of this occurring.
Catheter displacement β if the CVC moves into the chambers of the heart then cardiac arrhythmias may be noted, and should be reported. If the CVC is no longer in the correct position, CVP readings and medication administration will be affected.
CVP Recording
Nursing and medical staff must be familiar with the equipment being used to ensure accurate readings and provide patients with appropriate care. CVP is usually recorded at the mid-axillary line where the manometer arm or transducer is level with the phlebostatic axis. This is where the fourth intercostal space and mid-axillary line cross each other allowing the measurement to be as close to the right atrium as possible.
Using A Manometer
Explain the procedure to the patient to gain informed consent.
If IV fluid is not running, ensure that the CVC is patent by flushing the catheter.
Place the patient flat in a supine position if possible. Alternatively, measurements can be taken with the patient in a semi-recumbent position. The position should remain the same for each measurement taken to ensure an accurate comparable result
G K Pawar.....βοΈ
