- Slides: 21
Venous Pressure l Venous Pressure generally refers to the average pressure within venous compartment of circulation l 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 ? ? v Direct: by catheter introduced into large thoracic veins v Indirect: pressure Is estimated from Jugular venous
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. l Pressure changes transmitted from right atrium l The right internal jugular is the best neck vein to inspect l Provides information about hemodynamic changes in right atrium & ventricle l
Anatomy Of IJV
Cont…. The internal jugular vein is lateral to carotid artery & deep to sternomastoid muscle. External jugular is superficial to sternomastoid
Cont…. l l l 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 l Prominent ‘a’ wave : Right atrial and right ventricular hypertrophy (due to P. HTN or P. stenosis) Tricuspid stenosis. l Cannon wave: Large ‘a’ wave produce when Rt atrium contract against closed tricuspid valve. This seen in complete heart block
Cont… l 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 l Change in posture ? l Change in respiration ? l Pulsation pattern ? l Palpation ? l Occlusion ?
The JVP and carotid pulse can be differentiated several ways l 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. l 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 from above. l l 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. l 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 v CONFIRM v. MEASURE v
Method l Position 45 degree l Rest the pt head on pillow to ensure neck muscle relax, and slightly tilted toward the left side. l look acorss the neck from the Rt side of the pt. l Identify the Jugular vein l Confirm the pulse.
Cont. . l Identify the upper limit of venous pulsation l JVP is measured by two pencils method l Place one pencil at sternal angle vertical to ground & other pencil at upper limit of venous pulsation horizontal to the ground l Measure length of the verticbal pencil in cm btw the sternal angle & where it is crossed by the horizontal pencil. l Normal JVP up to 3 cm
Causes of raised JVP Right heart failure Constrictive pericarditis Superior vena cava obstruction Pericardial effusion Cardiac tamponade Tricuspid valve disease
Cardiac tamponade l l l 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 pressure 2. hypotension 3. diminished heart sounds