Arterial and venous blood pressures

Arterial Blood Pressure (BP)

= The lateral pressure force generated by the pumping action of the heart on the wall of aorta & arterial blood vessels per unit area.

OR = Pressure inside big arteries (aorta & big vessels).

■ Measured in (mmHg), & sometimes in (cmH2O), where 1 mmHg = 1.36 cmH2O.

■ Of 2 components: systolic … (= max press reached) diastolic … (= min press reached)

Arterial Blood Pressure (continued)

■ Diastolic pressure is more important, because diastolic period is longer than the systolic period in the cardiac

cycle.

■ Pulse pressure = Systolic BP – Diastolic BP.

■ Mean arterial pressure = Diastolic BP + 1/3 Pulse press.

In normal adult 120/80 mmHg.

Factors affecting ABP:

■ Sex … M > F …due to hormones/ equal at menopause. ■ Age … Elderly > children …due to atherosclerosis. ■ Emotions … due to secretion of adrenaline &

noradrenaline. ■ Exercise … due to venous return.■ Hormones … (e.g. Adrenaline, noradrenaline, thyroid H). ■ Gravity … Lower limbs > upper limbs.■ Race … Orientals > Westerns … ? dietry factors, or

weather. ■ Sleep … due to venous return. ■ Pregnancy … due to metabolism.

Factors determining ABP:

Blood Pressure = Cardiac Output X Peripheral Resistance

(BP) (CO)Flow

(PR)Diameter

of arterioles

■ BP depends on:

1. Cardiac output CO = SV X HR. 2. Peripheral resistance. 3. Blood volume.

Total peripheral resistance = TPR

-- combined resistance of all vessels -- vasodilation resistance decreases -- vasoconstriction resistance increases

Classification of Blood Pressure

JNC (Joint National Committee ) 7 Guidelines (2003)

Category SBP DBP Normal < 120 or < 80 Prehypertension 120-139 or 80-89 Stage 1 140-159or 90-99 Stage 2 ≥ 160 or ≥ 100

Definitions and Classification of BP Levels (mmHg)

CategorySystolicDiastolic

Optimal<120and<80

Normal120-129and/or80-84

High Normal130-139and/or85-89

Grade 1

Hypertension140-159and/or90-99

Grade 2Hypertension

160-179and/or100-109

Grade 3

Hypertension≥ 180and/or≥ 110

Isolated Systolic

Hypertension

≥ 140and <90

Journal of Hypertension 2007;25:1105-1187 European Society of Hypertension, European Society of Cardiology

Hypertension with no known cause (primary, formerly, essential hypertension) is most common.

Hypertension with an identified cause (secondary

hypertension) is usually due to a renal disorder.

Usually, no symptoms develop unless hypertension is severe or long-standing.

Measurement

Arterial pressure is most commonly measured via a sphygmomanometer.

Invasive measurement Noninvasive measurement

Invasive measurement

Arterial blood pressure (BP) is most accurately measured invasively through an arterial line.

Invasive arterial pressure measurement with intravascular cannulae involves direct measurement of arterial pressure by placing a cannula needle in an artery (usually radial, femoral, dorsalis pedis or brachial(

Noninvasive measurement

Palpation method Auscultatory method

Is your patient ready? If your patient has finished a cigarette or an alcoholic

beverage within the last 15 minutes the readings will be altered.

If they haven’t sat quietly for at least 5 minutes or are talking during the procedure, the readings will be altered.

Systolic and diastolic BP's in hypertensive and normotensive patients increase with talking

And if you have placed the cuff over a shirt sleeve the readings will not be reliable.

Brachial artery is the most common measurement site

Close to heartConvenient measurement

1. Use appropriate size BP cuff Is the cuff you are using sized for the patient? A cuff too

large can cause reading to be lower than actual and a cuff too small can cause reading to be higher than actual.

Cuff sizes are:Small Adult 17-25cm/Standard Adult 23-33cm/Large Adult 31-40cm/Thigh 38-50cm.

2. Position patient Patient should be seated with back and arms

supported, feet on floor, and legs uncrossed with upper arm at heart level

3.Measure baseline BP bilaterally

Cuff applied 1 inch above crease at elbow Locate brachial artery Palpate radial pulse Inflate cuff until pulse disappears

Palpation method

The blood pressure can be measured in noisy environment

Only the systolic pressure can be measured (not DP) The technique does not give accurate results for infants

and hypotensive patients

Auscultatory method

Pulse waves that propagate through the brachial artery, generate Korotkoff sounds.

There are 5 distinct phases in the Korotkoff sounds, which define SP and DP

The Korotkoff sounds are ausculted with a stethoscope

Korotkoff sounds

First Phase A clear tapping sound; onset of the sound for two

consecutive beats is considered systolic Second Phase

The tapping sound followed by a murmur Third Phase

A loud crisp tapping sound

Fourth Phase Abrupt, distinct muffling of sound, gradually

decreasing in intensity Fifth Phase

The disappearance of sound, is considered diastolic blood pressure- two points below the last sound heard

3

RECOMMENDED BLOOD PRESSURERECOMMENDED BLOOD PRESSUREMEASUREMENT TECHNIQUEMEASUREMENT TECHNIQUE

2.• The cuff must be level with heart.

• If arm circumference exceeds 33 cm,a large cuff must be used.

• Place stethoscope diaphragm overbrachia l artery.

2.2.•• The cuff must be level with heart.The cuff must be level with heart.

•• If arm circumference exceeds 33 cm,If arm circumference exceeds 33 cm,a large cuff must be used.a large cuff must be used.

•• Place stethoscope diaphragm overPlace stethoscope diaphragm overbrachia l artery.brachia l artery.

1.• The patient should

be relaxed and thearm must besupported.

• Ensure no tightclothing constrictsthe arm.

1.1.•• The patient shouldThe patient should

be relaxed and thebe relaxed and thearm must bearm must besupported.supported.

•• Ensure no tightEnsure no tightclothing constrictsclothing constrictsthe arm.the arm.

3.• The column of

mercury must bevertical .

• Infla te to occlude thepulse. Deflate at 2 to3 mm/s. Measuresystolic (first sound)and diastolic(disappearance) tonearest 2 mm Hg.

3.3.•• The column ofThe column of

mercury must bemercury must bevertical .vertical .

•• Infla te to occlude theInfla te to occlude thepulse. Deflate at 2 topulse. Deflate at 2 to3 mm/s. Measure3 mm/s. Measuresystolic (first sound)systolic (first sound)and diastolicand diastolic(disappearance) to(disappearance) tonearest 2 mm Hg.nearest 2 mm Hg.

StethoscopeStethoscope

MercuryMercurymachinemachine

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

(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 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 cm

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