Arterial Blood Arterial Blood PressurePressure

Definition.Definition.Factor affecting blood Factor affecting blood pressure .pressure .Causes .Causes .Classification .Classification .Type of blood pressure Type of blood pressure apparatuses .apparatuses .How to measure .How to measure .Treatment .Treatment .

Arterial Blood Pressure Arterial Blood Pressure (BP)(BP)

Is a measure of the force that the circulating blood exerts against the arterial wall

OR

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

It tells us how hard the heart is working.

Too high means the heart is working extra hard and this could be very dangerous!

Blood pressure almost always is measured in millimeters of mercury (mmHg).

Occasionally pressure is measured in centimeters of water ( cm H2O)

1 mmHg = 1.36 cm H2O

Factors affecting BPFactors affecting BP 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.

(BP)

Factors determining BPFactors determining BP

(CO)Flow

Blood Pressure = Cardiac Output X Peripheral Resistance

(PR)Diameter

of arterioles

BP depends on:

1. Cardiac output. 2. Peripheral resistance. 3. Blood volume.

Cardiac Output Cardiac Output Is the volume of blood being pumped by the heart, in particular by a Left or Right ventricle in the Time interval of one minuteCardiac Output (Q) = SV × HR

Peripheral ResistancePeripheral ResistanceThe sum of resistance to flow that must be overcome to push blood through the circulatory system

Stroke VolumeStroke VolumeIs the volume of blood pumped from one ventricle of the heart with each beat

Causes Of HypertensionCauses Of HypertensionEssential hypertension 95%Secondary hypertension 5%

RenalEndocrinePregnancyDrugsCoartation of aortaOthers

Blood PressureBlood Pressure

Pulse pressure Systolic BP – Diastolic BP

The most important determinant of pulse pressure is STROKE VOLUME.

Mean arterial pressure Diastolic BP + 1/3 Pulse pressure

Is a term used in medicine to describe an average blood pressure in an individual

NOTENOTE !!! !!!

HypertensionHypertension

Sustained raised in BP which require medical interventions.

Classification of blood pressure for adults

Category Systolic mmHg Diastolic mmHg

Hypotension < 90 < 60

Normal 90 – 120 60 – 80

Prehypertension 121 – 139 81 – 89

Stage 1 Hypertension 140 – 159 90 – 99

Stage 2 Hypertension ≥ 160 ≥ 100

How is Blood Pressure How is Blood Pressure Taken?Taken?

Invasi

ve

Non-I

nvasi

ve

Blood Pressure

Palpatory Method

Auscultatory Method

Ultrasonic MethodOscillometric Method

Tonometry

Extravascular Sensor

Intravascular Sensor

Types Of BP ApparatusesTypes Of BP ApparatusesMercury Type Aneroid Type

Digital Type

A- Palpatory MethodA- Palpatory MethodFeel the radial pulse.An occlusive cuff is placed on arm and

inflated above the level at which the pulse become impalpable.

Gradually deflate it.The level at which the pulse become

palpable again is taken as systolic pressure.

1- The blood pressure can be measured in noisy environment too

ADVANTAGES

2- Technique does not require much equipment

1- Only the systolic pressure can be measured (not DP)

DISADVANTAGES

2- The technique does not give accurate results for infants and hypotensive patients

B- B- Auscultatory MethodAuscultatory MethodApply the cuff one inch above the elbowPalpate the brachial arteryPlace the stethoscope lightly over itInflate the cuff above the systolic level

determined by the palpatory methodLower the pressure in the cuff The level at which Korotkoff sound are

heard is the Systolic pressure.The level at which sound disappear is

diastolic pressure.

1- Auscultatory technique is simple and does not require much equipment

ADVANTAGES

DISADVANTAGES1- Auscultatory tecnique cannot be used in noisy

environment2- The observations differ from observer to

another3- A mechanical error might be introduced into the

system e.g. mercury leakage, air leakage, obstruction in the cuff etc.

4- The technique does not give accurate results for infants and hypotensive patients

1. The first Korotkoff sound is Clear tapping, repetitive sounds for at least two consecutive beats is considered the systolic pressure.

2. The second sounds are the murmurs heard for most of the area between the systolic and diastolic pressures.

3. The third = A loud, crisp tapping sound.4. The fourth sound, at pressures within 10

mmHg above the diastolic blood pressure, were described as “muffling" and "muting".

5. The fifth Korotkoff sound is silence as the cuff pressure drops below the diastolic blood pressure. The disappearance of sound is considered diastolic blood pressure .

Korotkoff soundKorotkoff sound

Common problem in BP Common problem in BP measurementmeasurementWrong cuff sizeExcess pressure of stethoscopePatient arm at the wrong levelWhite coat effectAuscultatory Gap (silent gap)

Auscultatory GapAuscultatory GapIn some hypertensive patients the

Krotokoff sound disappear for some time between systolic and diastolic pressure.

So there is a risk of either recording a low systolic or high diastolic .

Avoid it by using palpatory method before the Auscultatory method.

Treatment Treatment Treatment goal <140/85 mmHg

(130/80 mmHg in diabetic)

Lifestyle changes include :Stop smokingLow fat dietLow salt intakeExerciseReduce wt

Drugs:

ACE inhibitorB-blockerCa channel blockerDiurtics

Postural HypotensionPostural HypotensionDrop in systolic BP>20 mmHg OR

diastolic BP>10 mmHg after standing for 3 minutes.

Causes:HypovolemiaAntipsychoticsAddison‘s diseasehypopituitarism

Apply Your KnowledgeApply Your KnowledgeNormal Blood Pressure in Adults (18 or older)

is ??What can cause sounds to be heard down to

zero mmHg??A cuff with a bladder too small for the

patients arm will result in ?? If the cuff is applied too loosely, the pressure

reading will be ?? How you can avoid incorrectly assessing the

systolic blood pressure due to the auscultatory gap??

Thank youThank you