Central Venous Pressure (CVP)

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EQUIPMENT
• Venous pressure tray
• Cutdown tray
• Infusion solution/infusion set with CVP manometer
• Heparin flush system/pressure bag (if transducer to be used)
• IV pole
• Arm board (for antecubital insertion)
• Sterile dressing/tape
• Gowns, masks, caps, and sterile gloves
• ECG monitoring
• Carpenter’s level (for establishing zero point)
PROCEDURE
PREPARATORY PHASE
• Assemble equipment according to manufacturer’s directions.  Evaluate patient’s PT, PTT, and CBC.
• Explain the procedure to the patient and obtain informed consent.  Procedure is similar to an IV, and the patient may move in bed as desired after passage of catheter.
 Explain to patient how to perform the Valsalva maneuver.  The Valsalva maneuver performed during catheter insertion and removal decreases chance of air emboli.
 NPO 6 hours before insertion
• Position patient appropriately.
 Provides for maximum visibility of veins.
 Place in supine position.
 Arm vein—extend arm and secure on armboard.
 Neck veins—place patient in Trendelenburg’s position. Place a small rolled towel under shoulders (subclavian approach).
 Trendelenburg’s position prevents chance of air emboli. Anatomic access and clinical status of the patient are considered in site selection.
• Flush IV infusion set and manometer (measuring device) Or, prepare heparin flush for use with transducer.
 Secure all connections to prevent air emboli and bleeding.
 Attach manometer to IV pole. The zero point of the manometer should be on a level with the patient’s right atrium.
The level of the right atrium is at the 4th intercostal space midaxillary line.
 Calibrate/zero transducer and level port with patient’s right atrium.  Mark midaxillary line with indelible ink for subsequent readings.
• Place patient on ECG monitor.
Dysrhythmias may be noted during insertion as catheter is advanced.




INSERTION PHASE (BY PHYSICIAN)
• Physician dons gown, cap, and mask.
 CVP insertion is a sterile procedure.
• The CVP site is surgically cleansed. The physician introduces the CVP catheter percutaneously or by direct venous cutdown.
Patient may be asked to perform Valsalva maneuver to protect against chance of air embolus.
• Assist patient to remain motionless during insertion.
• Monitor for dysrhythmias as catheter is threaded to great vein or right atrium.
• Connect primed IV tubing/heparin flush system to catheter and allow IV solution to flow at a minimum rate to keep vein open (25 mL maximum).  Catheter placement must be verified before hypertonic or blood products can be administered.
• The catheter should be sutured in place.
 Prevents inadvertent catheter advancement or dislodgement.
• Place a sterile occlusive dressing over site.
• Obtain a chest x-ray.
 Verify correct catheter position.
TO MEASURE THE CVP
• Place the patient in a position of comfort. This is the baseline position used for subsequent readings.
• Position the zero point of the manometer at the level of the right atrium  The zero point or baseline for the manometer should be on a level with the patient’s right atrium. The middle of the right atrium is the midaxillary line in the 4th intercostal space.
• Turn the stopcock so the IV solution flows into the manometer, filling to about the 20- to 25-cm level. Then turn stopcock so solution in manometer flows into patient.
• Observe the fall in the height of the column of fluid in manometer. Record the level at which the solution stabilizes or stops moving downward. This is the central venous pressure. Record CVP and the position of the patient.  The column of fluid will fall until it meets an equal pressure (ie, the patient’s central venous pressure). The CVP reading is reflected by the height of a column of fluid in the manometer when there is open communication between the catheter and the manometer. The fluid in the manometer will fluctuate slightly with the patient’s respirations. This confirms that the CVP line is not obstructed by clotted blood.
• The CVP catheter may be connected to a transducer and an electrical monitor with either digital or calibrated CVP wave readout.
• The CVP may range from 5 to 12 cm H2O. (Absolute numerical values have not been agreed on.) Or, 2 to 6 mm Hg.
 The change in CVP is a more useful indication of adequacy of venous blood volume and alterations of cardiovascular function. The management of the patient is not based on one reading, but on repeated serial readings in correlation with patient’s clinical status.
• Assess the patient’s clinical condition. Frequent changes in measurements (interpreted within the context of the clinical situation) will serve as a guide to detect whether the heart can handle its fluid load and whether hypovolemia or hypervolemia is present.
 CVP is interpreted by considering the patient’s entire clinical picture; hourly urine output, heart rate, blood pressure, cardiac output measurements.
 A CVP near zero indicates that the patient is hypovolemic (verified if rapid IV infusion causes patient to improve).
 A CVP above 15 to 20 cm H2O may be due to either hypervolemia or poor cardiac contractility.
• Turn the stopcock again to allow IV solution to flow from solution bottle into the patient’s veins.
 When readings are not being made, flow is from a very slow microdrip to the catheter, bypassing the manometer.
FOLLOW-UP PHASE
• Observe for complications.
 Patient’s complaints of new or different pain must be assessed closely.
From catheter insertion: pneumothorax, hemothorax, air embolism, hematoma, and cardiac tamponade , Signs/symptoms of air embolism include: severe shortness of breath hypotension, hypoxia, rumbling murmur, cardiac arrest.
 From indwelling catheter: infection, air embolism
 If air embolism is suspected, immediately place patient in left lateral Trendelenburg’s position and administer oxygen. Air bubbles will be prevented from moving into the lungs and will be absorbed in 10 to 15 minutes in the right ventricular outflow tract.
• Carry out ongoing nursing surveillance of the insertion site and maintain aseptic technique.
 Inspect entry site twice daily for signs of local inflammation/phlebitis. Remove immediately if there are any signs of infection.
 Change dressings as prescribed.
 Label to show date/time of change.
 Send the catheter tip for bacteriologic culture when it is removed.

NURSING ALERT:
• A CVP line is a potential source of septicemia.
Central Venous Pressure (CVP) Monitoring
 Refers to the measurement of right atrial pressure or the pressure of the great veins within the thorax.
• Right-sided cardiac function is assessed through the evaluation of the CVP.
• Left-sided heart function is less accurately reflected by the evaluation of CVP but may be useful in assessing chronic right and left heart failure and/or differentiating right and left ventricular infarctions.
 Requires the threading of a catheter into a large central vein (subclavian, internal/external jugular, median basilic, or femoral). The catheter tip then is positioned in the right atrium, upper portion of the superior vena cava or the inferior vena cava (femoral approach only).
 Purposes of CVP monitoring include:
• To serve as a guide for fluid replacement
• To monitor pressures in the right atrium and central veins
• To administer blood products, total parenteral nutrition, and drug therapy contraindicated for peripheral infusion
• To obtain venous access when peripheral vein sites are inadequate
• To insert a temporary pacemaker
• To obtain central venous blood samples

Central Venous Pressure (CVP)