Blood pressure management

1. Dr Liesl Brown
Department of Pharmacy
University of Limpopo (Medunsa Campus)
Module 2.2: Cardiovascular Pharmacy (2011)

2. Aim
How to measure blood pressure using
different sphygmomanometers:
 Aeroid (mercurial and non mercurial) and
 Anaeroid (automatic)

3. Objectives
After this practical experience, you will be able to provide
the answers to the following questions:
• WHAT is the importance of monitoring blood pressure?
• HOW do we measure blood pressure?
• HOW do we measure pulse rate?
• WHAT accounts for the variability in blood pressure measurements?
• WHAT is considered to be normal and what high blood pressure?
• WHO should have their blood pressure checked?
• HOW do your measure blood pressure using a sphygmomanometer?
• WHAT are Korotkoff sounds?
• DOES cuff size matter?
• WHAT is ‘white coat’ hypertension?
• WHICH drugs are available for the treatment of hypertension?

5. The structure of blood vessels
(Revision)
 Transparencies
The structure of blood vessels (Davies et al, 2001, p 502)

6. Changes in blood pressure as blood flows
through the circulatory system (Revision)
 Transparencies
Changes in blood pressure (Davies et al, 2001, p 501)

7. Pressure-volume relationships in
arteries and veins (Revision)
 Transparencies
Pressure-volume relationships in arteries and veins (Davies et al, 2001, p 504)

8. The relationship between heart rate and
systolic blood pressure (Revision)
 Transparencies

9. Control of blood pressure (BP)
(Revision)
• Short term control:
Baroreceptor reaction to pressure differences
• Long-term control:
• Arterial baroreceptor discharge returns to
normal, within days of chronic incr. of BP
• Kidneys – control plasma by retaining/losing
water and salt ( BP)

10. The endocrinological control of blood
pressure (Revision)
 Transparencies

11. Control of arteriolar diameter
(Revision)
(a) Neural control: (c) Endothelial and blood-based
control
• Sympathetic • Endothelial derived factors
noradrenergic
• Sympathetic cholinergic
• Prostaglandins
• Thromboxane
• Parasympathitic
• Leucotrines
cholinergic
(b) Hormonal control
• Platelet-activating factor
• Catecholamines
• Histamine
• Bradykinin
• ADH
• 5-hydroxytryptamine (5-HT)
• Angiotensin-aldosterone
• Aterial natriuretic peptide (d) Metabolic influences
• Functional hyperaemia
• Reactive hyperaemia

13. Blood pressure aka systemic arterial blood
pressure
Definition:
Blood pressure is the pressure which the circulating blood exerts
against the walls of the blood vessels in the course of circulation, and is
a good indication of the capacity of the blood vessels and of cardiac
function (Griesel, p62)
• Measured in millimetres-mercury (mmHg)

14. Blood pressure
• Resistance = pressure (Ohm’s law)
flow
Where:
resistance = total peripheral resistance
flow = cardiac output
pressure = arterial blood pressure
Thus:
arterial blood pressure =
cardiac output x total peripheral resistance
An illustration of arterial pressure waves
• Arterial wave = systolic pressure (its peak) and diastole pressure (its lowest point)
• Pulse pressure = systolic pressure minus diastolic pressure

15. Types of blood pressure
1. Normal BP
• Up to 140/90 mmHg with an average of  120/80 mmHg [ 100 to 140
mmHg systolic / 60 to 90 mmHg] in an average adult (WHO)
• Increases gradually with age – systolic more than diastolic
2. Hypertension
• Mild: 140/90 mmHg to 160/95 mmHg (WHO)
• Moderate to serious hypertension: 160/95 mmHg
• In special cases:
Diabetics -  140/90 mmHg
Pregnant women -  140/90 mmHg
Isolated systolic hypertension – systolic > 160 mmHg / diastolic < 90
mmHg
3. Hypotension
•  < 120/80 mmHg

16. -Hypertension (HT)
Definition:
Hypertension is defined as a sustained increase in
the systolic and/or diastolic arterial pressure
above the normal (Griesel, p63)

17. Classification of hypertension
• Primary (essential, idiopathic) hypertension
• Secondary hypertension
• Other types of hypertension:
• Malignant hypertension (MH)
Definition:
MH is a sudden, acute condition which develops in primary hypertensive
patients
• Pre-eclampsia (Pregnancy associated hypertension) (PE)
Definition:
PE is a condition characterised by hypertension with a degree of renal
limitation which suddenly develops during the second half of pregnancy?

18. --Causes of hypertension
• Complication of renal disease/failure
• Causes:
• Secretion of abnormal large amounts of renin + in
ability to excrete adequate amounts of salt & H2O
• E.g. during early renal failure: the kidney
experiences ischaemia and secretes renin 
angioTS I conversion to angioTS II resulting in
vasoconstriction + aldosterone (salt + H2O
retaining)

19. -Hypotension (low blood
pressure)
Definition:
Hypotension is defined as a decrease in systolic
and diastolic arterial pressure below the
normal

20. -Chronic low blood pressure
Sufferers presents with:
• Tiredness
• Lack of energy
• Periods of vertigo

21. -Orthostatic hypotension
Definition:
BP that falls > 20 mmHg on standing from
a sitting or recumbent position
• Seen more in the elderly
• Causes:
• Reduction of compliance of arteries is a normal part of aging
• inadequate heart rate response owing to a decline in
autonomic control
• Certain HT drugs (give drugs at night)

22. -Syncope (fainting)
Caused by a sudden lowering of blood pressure with
resultant cerebral anoxia and loss of consciousness
• Causes:
• E.g. When a person stands for a long period of time –
blood accumulates in the lower limbs leading to the
draining of blood from the brain
• Neurogenic factors (e.g. sudden pain, bad news)
• Can turn into a shock condition, esp. when if accompanied by
other causes e.g. trauma, serious infection

23. -Shock
Condition of acute circulatory failure which
characteristic hypotension and decrease in µ-
circulation leading to hypoxia of the vital organs
• Factors leading to shock:
• Heart pump failure
• Blood volume decrease
• Peripheral circulatory failure due as a result of vasodilatation so that
the blood accumulates in non-essential areas

25. Arterial pressure measurement
• Direct measurement:
• most precise measure
• direct connection to major artery to a transductor via a
catheter
• Indirect measurement:
• Method developed by Riva-Rocci
• Use a sphygmanometer
• Auscultatory method (hear)
• Palpatory method (feel)

26. -The ausculatatory method
• Involves listening to Korotkoff sounds using a stethoscope placed
over the brachial artery in antecubital fossa of the elbow
• When:
• Pressure (exerted by the cuff ) much bigger that the pressure of
the systolic pressure there is no blood flow, hence no sound
• Pressure much lower that the systolic pressure this leads to
blood forcing its way under the cuff for short periods at the
beginning of the systole when the pressure is highest
• Blood flow sound are turbulent, and move in a high velocity .
This causes the sharp tapping (1st Korotkoff sound) that can
be heard (systolic pressure)
• Pressure in cuff falls lower and lower the sound (lub-dup)
becomes louder, then diminishes (you hear the change in sound
from a tapping to a muffeld sound and then thereafter to silence
(this is the diastolic pressure / 5th Korotkoff sound)

27.  Transparencies

28. -The palpatory method
• Taking the radial pulse while inflating the cuff
• The systolic pressure is the pressure where the cuff pressure cuts
off the pulse, hence no pulse can be felt
• Limitations:
• Cannot measure diastolic pressure
• Advantage:
• Provides a wise instrument in a patient suspected of HT (silent
period with Korotkoff sounds)

29. How to measure systemic arterial
• Let the patient be seated or lie down
(document this) blood pressure
• Using the left arm of the patient, determine the
radial pulse
• Wrap the cuff around the left arm, above elbow
at the level of the heart
• Inflate the cuff, keeping track of the radial
pulse
• When the radial pulse cannot be felt anymore,
you have an estimate of what the systolic BP is
• Place the stethoscope in your ears
• Deflate the cuff and pump the cuff 20 mmHg
higher than the systolic blood pressure
• Slowly deflate the cuff again
• Listen to the beginning of the throbbing sound
(systolic blood pressure) and the end of the
throbbing sound (diastolic pressure)
• Repeat the procedure three times and
determine a mean BP
• Readings are influenced if:
• The cuff is too small ( leads to the pressure
not adequately transmitted to artery)
• Cuff is not wrapped around the arm

30. Correct determination of arterial blood
pressure
• Points of importance during BP measurements:
• The patient
• Instruments
• The person taking the reading
• Environmental factors
• Interpretation

31. Significance of blood pressure
readings
• BP varies over a 24 hour period
• Influenced by factors such as:
• Physical activity
• Emotional status of patient
• Pain
• Temperature of the environment
• Use of tobacco
• Use of caffeine
• Certain drugs
• Physiological factors e.g. gender
build
posture
emotions
physical exertion
age (BP increases with age)

32. An illustration of blood pressure
differences with age
 Transparencies

33. The effect of sleep on blood pressure
• While sleeping there is a decrease in sympathetic tone
leading to a fall in BP
• Arterial CO2 tension also rises + together with cyclic BP
changes this leads to an increase cerebral blood flow

35. • Antiadrenergic agents:
• Agents acting on the
• Centerally acting: arteriolar smooth
• Resperpine muscle:
• Methyl dopa • Diazoxide
• Clonidine • Hydralazine
• Minoxidil
• Peripherally acting: • Na-nitroprusside
• -adrenoceptor
blocking agents
•Prazosin • Calcium channel
•Doxazosin blockers:
•Urapidil • Verapamil
•Indoramin
• Nifedipine
•Urapidil
• Amlopidine
• Diltiazem
• Felodipine
•  + -adrenoceptor
• Istradipine
blocking agents:
• Labetalol • Lacidipine
• Carvedilol • Nimodipine

36. • Diuretics:
• Low ceiling diuretics
• Hydrochlorothiazide
• Cyclopenthiazide
• Chlortalidone
• Indapamide
• Metolazone
• Agents acting on renin-
•
angiotensin system: High ceiling diuretics
• ACE-I • Furosemide
• Captopril • Bumetanide
• Benzapril • Piretanide
• Cilazapril
• Ramipril • K+-sparing diuretics
• Trandolapril
• Spironolactone
• ACE-I and diuretic combos
• Amiloride
• Captopril/diuretic • Triamterene
• Enalapril/diuretic
• Lisinopril/diuretic
• Quinapril/diuretic

37. Drugs that affect blood pressure
Drugs that increase BP/affect antihypertensive therapy:
• Sympathomimetics in cold and flu medication e.g. ephedrine,
phenylephedrine, phenylpropanolamine
• Most appetite suppressants
• NSAIDs
• MOA-I should it be used with foods that contain tyramine /
dopamine e.g. cheese and wine
• Methylphenidate (Ritalin®)
• Oral contraceptives
• Carbenoxolone
• Corticosteroids
• Antihypertensive medication – should they be withdrawn
suddenly

38. Drugs that affect blood pressure
Drugs that tend to decrease BP or to potentiate therapy for
hypertension:
• Cardiac antidysrhythmic drugs e.g. amiodarone, bretylium
• BDZs e.g. diazepam
• Bromocryptine
• Droperidol
• Levo-dopa
• Meprobamate
• Phenothiazines
• Phenothiazines
• TCAs e.g. imipramine

40. Part V: Practical Exercise: Measuring blood
pressure using different types of
sphygmomanometers