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LEARNING OUTCOMES

By the end of this session the student

should be able to :

Explain the indications for a patientrequiring CVP monitoring

Identify the equipment required forcommencing CVP monitoring

Describe the nursing role, both in thecare and use of the central venousmonitoring line

Discuss the reasons for abnormalCVP readings.

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DEFINITION

Blood from the systemic veins flowsinto the right atrium.

The pressure in the right atrium is theCVP.

A catheter is passed via;

the subclavian vein or jugular vein into

the superior vena cava

to determine the venous return andintravascular volume of the rightatrium.

The normal value is 5-10cm H2O

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PURPOSE

To serve as a guide of fluid balancein critically ill patients

To estimate the circulating bloodvolume

To determine the function of the right

side of the heart

To assist in monitoring circulatoryfailure

None of these variables aremeasured directly; they must beinterpreted.

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Axillary veinCephalic vein

Median cubital vein

Basilic vein

ACCESS

External Jugular vein

Subclavian vein

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COMPLICATIONS

Carotid Artery Puncture

Pneumothorax

Air Embolism

Arrhythmia

Perforation of SVC orR. Atrium/Ventricle

Infection

Pleural Effusion

Extravasion of Infusate

Allergic reaction to catheter material

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EQUIPMENT

The equipment needed for measurement of

central venous pressure includes a sterile bag

of fluids (a) with attached fluid administration set (b),

an IV extension set (c), a manometer (d)

and a stopcock (e).

a.

b.

c.

d.

e.

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EQUIPMENT

IV extension

set to entry portof patientscentral line.

IV giving setto fluid bag.

Stopcock(Three way tap)

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DIRECTION OF FLOW

The white arrows indicate the direction of fluid flow.

Initially the white knob is turned straight up towards the manometer, allowing fluid to

flow from the fluid bag to the patient's catheter to assure the catheter is patent (a).

If fluid does not flow freely into the patient's catheter a valid CVP reading

will not be obtained.

Then the knob is turned toward the patient (b) and fluid will fill the manometer.

The manometer should not contain any air bubbles.

If air is present in the manometer or fluid line, let the fluids run, overfilling themanometer until all air is purged from the system.

Then turn the knob toward the fluids (c). The level of fluid in the manometer

will fall (the fluid is running into the patient's catheter) until the height of the

fluid column exerts a pressure equivalent to the patient's central venous pressure.

The top of the fluid column will slightly oscillate up and down as the animals'

heart beats and as the animal breathes.

a. c.b.

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POSITION OF PATIENT

3-way tap

manometer

FluidBag

Patient in supine position

CentralVenousAccess

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INTERPRETATION

An increase of above normal mayindicate weakening or failure of theright side of the heart, or excessive

intravascular volume

A pressure below 5cm H2O usuallyreflects an intravascular volume deficitor drug induced excessive vasodilation

CVP measurements must not beinterpreted on their own, but viewedalongside the patient's full clinicalpicture

(BP, Respiratory Pattern, Colour, Temperature)

Several measurements are requiredto identify a trend

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DETERMINANTS

Cardiac Competence(reduced ventricularfunction raises CVP)

Blood Volume(increased venousreturn raises CVP)

Intra Aortic &Intra Peritoneal

Pressure(raises CVP)

SystemicVascular Resistance

(raises CVP)

CVP