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

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 dictated by the Rt atrium pressure.

Pressure changes transmitted from right atrium

The 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

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 pericarditisCardiac tamponadeSever Rt ventricular failure

Difference between arterial and venous pulsation in neck

Change in posture ?Change in respiration ?Pulsation pattern ?Palpation ?Occlusion ?

The JVP and carotid pulse can be differentiated several ways multiphasic - the JVP "beats" twice (in quick succession) in the cardiac cycle. In other

words, there are two waves in the JVP for each contraction-relaxation cycle by the heart. The first beat represents that atrial contraction (termed a) and second beat represents venous filling of the right atrium against a closed tricuspid valve (termed v) . The carotid artery only has one beat in the cardiac cycle.

non-palpable - the JVP cannot be palpated. If one feels a pulse in the neck, it is generally the common carotid artery.

occludable - the JVP can be stopped by occluding the internal jugular vein by lightly pressing against the neck. It will fill from above.

If a person is standing, his JVP appears to be lower on the neck (or may not be seen at all because it is below the sternal angle). The carotid pulse's location does not vary with standing.

varies with respiration - the JVP usually decreases with deep inspiration. Physiologically, inspiration decreases the thoracic pressure and increases blood movement into the heart (venous return), which a healthy heart moves into the pulmonary circulation.

How measure JVP?

LOOK CONFIRMMEASURE

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 verticbal pencil in cm btw the sternal angle & where it is crossed by the horizontal pencil.

Normal JVP up to 3 cmJVP + 5 cm = CVP

Causes of raised JVP

Right heart failureConstrictive pericarditisSuperior vena cava obstructionPericardial effusionCardiac tamponadeTricuspid 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