Venous Pressure

Venous Pressure

Venous Pressure generally refers to the average pressure within venous compartment of circulation

Blood from all the systemic veins flows into the right atrium of the heart, therefore the pressure in the Rt atrium called Central Venous pressure

Factor affecting CVP

Cardiac output Respiratory Activity Contraction of Skeletal muscles (leg &

abdominal muscles). Sympathetic Vasoconstrictor tone Gravity

All these affect CVP by either changing venous blood volume or venous compliance

How to measure the CVP??

Direct: by catheter introduced into large thoracic veins

Indirect: Is estimated from Jugular venous pressure

Jugular Venous Pulse (JVP)

There is no valves between the Rt atrium and the Internal Jugular Vein . So the degree of distension of this vein is detected by the Rt atrium pressure.

Pressure changes transmitted from right atriumThe right internal jugular is the best neck vein to

inspect Provides information about hemodynamic

changes in right atrium & ventricle

Anatomy Of IJV

Cont.…

The internal jugular vein is lateral to carotid artery & deep to sternomastoid muscle.

External jugular is superficial to sternomastoid

JVP waves

Cont.…

A a positive wave due to atrial contraction. C a positive deflection due closure of tricuspid

(carotid pulsation) X a negative deflection due to atrial relaxation V a positive deflection due to filling of the right

atrium against the closed tricuspid valve during ventricular contraction (venous return)

Y a negative deflection due to emptying of the right atrium upon ventricular relaxation

Abnormalities of wave

Prominent ‘a’ wave :

Right atrial and right ventricular hypertrophy (due to P.HTN or P.stenosis)

Tricuspid stenosis.Cannon wave:

Large ‘a’ wave produce when Rt atrium contract against closed tricuspid valve. This seen in complete heart block

Cont…

Kussmaul sign:

A paradoxical rise of JVP on inspiration. Causes:

Constrictive pericarditis

Cardiac tamponade

Sever Rt ventricular failure

Difference between arterial and venous pulsation in neck

Change in posture ?Change in respiration ?Abdomino-jugular reflux ?Pulsation pattern ?Palpation ?Occlusion ?

How measure JVP?

LOOK

CONFIRM

MEASURE

Method

Position 45 degreeRest the pt head on pillow to ensure neck

muscle relax, and slightly tilted toward the left side.

look acorss the neck from the Rt side of the pt.

Identify the Jugular veinConfirm the pulse.

Cont..

Identify the upper limit of venous pulsationJVP is measured by two pencils methodPlace one pencil at sternal angle vertical to

ground & other pencil at upper limit of venous pulsation horizontal to the ground

Measure length of the vertical pencil in cm btw the sternal angle & where it is crossed by the horizontal pencil.

Normal JVP up to 3 cm

raised JVP

Causes of raised JVP

Right heart failure

Constrictive pericarditis

Superior vena cava obstruction

Pericardial effusion

Cardiac tamponade

Tricuspid valve disease

Cardiac tamponade

Cardiac tamponade: the accumulation of fluid in the pericardium in an amount sufficient to cause serious obstruction to the inflow of blood to ventricle results in cardiac tamponade.

The three principal features of tamponade are: 1.elevation of intracardiac pressures 2.limitation of ventricular fillng 3.reduction of cardiac output

Beck triad:

1.increased jugular venous pressure2.Hypotension3.diminished heart sounds

Thank you