Blood pressure Prepared by : Christian Raveina

Definition Blood pressure is the force exerted by the blood against the wall of blood vessel

Two measurements:• Systolic blood pressure : is force exerted by arterial walls during systole. It is the maximum pressure during ventricle contraction • Diastolic blood pressure : is the force exerted by blood against arterial wall during diastole. It is the maximum pressure when the ventricles are relaxed

• Unit of measuring blood pressure is (mmHg) millimeters of mercury

• Normal blood pressure is 120/80 mm of Hg

• Here , systolic pressure is 120 mmHg & diastolic pressure is 80 mmHg

• Pulse pressure is the difference between systolic & diastolic pressure

• Normally, The pulse pressure is 40 mmHg

Physiology of blood pressure

Cardiac output : It is the amount of blood ejected by heart in 1 minute

Stroke volume : It is the amount of blood ejected by heart in 1 cycle. Normally heart eject 70-80 ml blood in 1 cycle

Cardiac output = stroke volume Χ heart rate

Peripheral vascular resistance : It is the resistance to the blood flow determined by the tone of vascular muscle’s & the diameter of blood vessels ,smaller the lumen greater the resistance ,ultimately blood pressure raises. That is why vasoconstriction leads to elevation of blood pressure

Blood volume : as soon as the blood volume increases, pressure exerted against arterial wall also increases. That is why giving intravenous fluid in hypotension increases the blood pressure .with hemorrhage & bleeding , blood volume decreases & automatically Blood pressure falls

Blood pressure basically depends upon cardiac output & the peripheral vascular resistance

Blood pressure = cardiac output + peripheral vascular resistance

Here cardiac output is stroke volume × heart rate

So If client has 72 heart rate , then cardiac out put is 70 × 72 = 5040ml

Blood pressure may increase with increase in blood volume in blood vessel as well as by increase in heart rate

Factors affecting the blood pressure

Age : blood pressure varies throughout the age. As age increases, BP also raises. Infant blood pressure: 65-115/42-80 mm Hg 7 year child : 87-177/48-64 mmHg Normal adult : 120/80 mmHg Older people, systolic pressure rises with

decreased elasticity Body size/obesity : It is observed that as the

body size increases, BP also fluctuates. Heavier & taller child have higher BP than the smaller child of same age

Emotions/stress : anxiety , fear , pain , stress, sympathetic nervous system get activated, causing vasoconstriction , increases heart contraction & ultimately raises blood pressure

Gender : After puberty , male have higher blood pressure than females. But after menopause , women tend to have high BP than male of same age

Ethnicity : African – Americans have higher incidence of high blood pressure than European- Americans

Diet : people taking diet rich in salt & unsaturated fatty acids, having higher blood pressure. Cocaine use also increases blood pressure. Caffeine intake also increases blood pressure.

Smoking : due to nicotine blood pressure increases

Exercise : Regular exercise, decreases the blood pressure. Helps in keeping BP normal

Diurinal variations : usually, person have low BP in early morning & gradually rises & peaks in evening

Medications : medications such as opioid analgesics, antihypertensive drugs have greater effect on BP

Chemicals : such as epinephrine , ADH , Angiotensin II cause vasoconstriction , thus elevating BP. Histamine,kinens cause vasodilation , thus decrease BP.

Regulation of blood pressure Vasomotor centers has main role in

regulating blood pressure Chemo receptors & baro receptors located

throughout the arterial system are sensitive to the blood volume & its chemical composition

These receptors send impulses to vasomotor center which may cause vasodilation or vasoconstriction to keep BP in normal limits

Alteration in blood pressure Hypertension : Elevated systolic

pressure or diastolic pressure at least for 3 consecutive visits . Ex: 190/140 mmHg

Hypotension : BP falls below normal limits of client. Generally,systolic pressure falls to 90 mmHg or below

Orthostatic hypotension /postural hypotension : suddenly BP fall of normotensive client while rising to upright position

Blood pressure monitoring

Measured by : Invasively ( Direct method ) : insertion

of catheter inside the artery Non-invasively (Indirect method ) :

palpation & auscultation It is best for nurse to measure blood

pressure by auscultation

Articles required : Sphygmomanometer Stethoscope Bowl with alcohol swab , paper bag Pen , record form

Preliminary assessment Collect the patient’s data about factors

posing client at risk for BP changes. It includes medical history ( cardiac problem , renal problem , diabetic , blood transfusion , surgery , exercise , coffee intake , smoking, medication , emotions , pain .

Avoid exercise , coffee , smoking at least 30 minutes before checking BP

Assess symptoms of hypertension like headache , furnishing of face nasal bleeding , weakness , fatigue

Assess symptoms of hypotension like dizziness , mental confusion , pale , restlessness , cyanoted skin , cool extremities

Procedure

Collect all the articles Wash hands Explain procedure to the client. Ex:

you are going to monitor his BP Provide comfortable position. Ex :

sitting , supine while keeping his upper arm at heart level ,palm up

Ensure that mercury level of sphygmomanometer is at zero

Ensure cuff width against client’s arm

Ensure mercury meniscus is at your eye level

Palpate brachial artery pulse Ensure no air in the cuff & wrap it

evenly around client’s arm centering arrow over brachial artery

Place lower edge of cuff about 1 inch above antecubital fossa

Tuck the end of wrap under cuff

Ensure that connecting tubings are free of each other. Estimate systolic pressure by palpating the artery with finger tips of one hand while inflating cuff, rapidly to pressure 30 mmHg above point when pulse reappears. Deflate cuff fully & wait for 30 secs

Place earpiece of stethoscope in ears & bell/diaphragm on brachial artery

Close valve of pressure bulb clockwise until tight

Rapidly inflate cuff to 30mmHg above palpated systolic pressure

Slowly release the pressure bulb valve & allow the mercury to fall at rate of 2-3 mmHg/sec

Listen & watch mercury level drop. when first clear :”tap tap” (karot koff)

Sound is heard , note the systolic blood pressure

Continue to deflate the bulb & when sound disappears , note the diastolic blood pressure

Listen for 10-20 mmHg after the last sound & then escape air quickly

Remove cuff Inform client of his BP reading as

needed Reposition client comfortably Record reading immediately

Replace articles : Clean earpiece & bell/diaphragm of

stethoscope with alcohol swab Discard used alcohol swabs Place articles to their correct place

Wash hands

Recording vital signs As record is a legal document, It protects the

hospital as well as client. Nurse must document the reading of vital signs & any deviations

While documenting vital signs, she should follow organizations policies procedure

Vital sign can be documented on graphic sheet notes in case of abnormality detected. Such as elevated temp, tachycardia, shortness of breath. Also document the actions taken for identified problems

Vital signs are documented on vital chart as well as graphic sheet.