PERPUSTAKAAN UTHM

*30000001957492*

PSZ 19:16 (Pind. 1/97) UNIVERSITITEKNOLOGI MALAYSIA

BORANG PENGESAHAN STATUS TESIS*

JUDUL: DEVELOPMENT OF A PC INTERFACED BLOOD PRESSURE METER

(e-BPMS)

SESIPENGAJIAN: 2005/2006

Say a IDA LAILA BINTI AHMAD

(HURUF BESAR)

mengaku membenarkan tesis (PSM/Sar jana/Doktor Fnlsofah)* ini dis impan di Perpustakaan Universiti Teknologi Malaysia dcngan syarat-syarat kegunaan seperti berikut:

1. Tesis adalah hakmilik Universiti Teknologi Malaysia. 2. Perpustakaan Universiti Teknologi Malaysia dibenarkan membuat salinan untuk tujuan

pengajian sahaja. 3. Peipustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara

institusi pengaj ian tinggi. 4. * * Sila tandakan ( S )

• SULIT (Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam A K T A R A H S I A R A S M I 1972)

• T E R H A D (Mengandungi maklumat T E R H A D yang telah ditentukan oleh organisasi/badan di mana penyelidikan di ja lankan)

IZI T I D A K T E R H A D

(T-ANDATANGAN PENULIS)

Alamat tetap:

146, TAMAN SRI INDAH

JALAN LENCONG BARAT,

05050 KEDAH DARUL AMAN

(TANDAJ^fGANVEN^ELIA)

PROF. DR RUZAIRI ABDUL RAHIM

Nama Penyelia

Tarikh: MEI 2006 Tarikh: M E I 2006

C A T A T A N : * Potong yang tidak berkenaan. ** Jika tesis ini SULIT atau T E R H A D , sila lampirkan surat daripada pihak

berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT atau T E R H A D .

• Tesis dimaksudkan sebagai tesis bagi I jazah Doktor Falsafah dan Sarjana secara penyelidikan, atau disertasi bagi pengajian secara kerja kursus dan penyelidikan, atau Laporan Projek Sarjana Muda (PSM).

" I / W e * h e r e b y dec la re that I /we* h a v e read th rough this p ro jec t r epor t and in

m y / e e r * op in ion this p ro jec t repor t is su f f i c i en t in t e rms of s c o p e and qua l i t y f o r the

a w a r d of the d e g r e e of M a s t e r of E n g i n e e r i n g (E lec t r i ca l -E lec t ron ics &

T e l e c o m m u n i c a t i o n s ) "

* Delete as necessaiy

D E V E L O P M E N T O F A PC I N T E R F A C E D B L O O D P R E S S U R E METIER

( e - B P M S )

IDA L A I L A BINTI A H M A D

A project report submi t ted in partial fu l f i lmen t of the

r equ i r emen t s f o r the award of the degree of

M a s t e r of Eng inee r ing (Elec t r ica l -Elec t ronics & T e l e c o m m u n i c a t i o n s )

Facu l ty of Electr ical Eng inee r ing

Univers i t i Tekno log i Malays ia

M A Y 2006

ii

I declare that my project report entitled "Development of a PC Based Blood Pressure

Meter (e-BPMS)" is the resu l t of m y o w n r e sea r ch excep t as ci ted in r e f e r e n c e s . T h e

p ro j ec t r epor t has not b e e n accep ted f o r a n y d e g r e e and is not c o n c u r r e n t l y s u b m i t t e d

in c a n d i d a t u r e of a n y o the r degree .

S igna tu re

N a m e

D a t e

Ida La i la b in t i A h m a d

M a y 2 0 0 6

Ill

To my BeCovedparents; TnciH Ahmad "Bin Shapii andTuan JAsfinah Masran,

thanks for encouragement and never ending support.

My dearest sisters; Ida Liyani and Ida Jarhana JAfiqah credits go to Both of

you for ad the joyous moments.

JAndfor my great hearted fiance; Hedzuan Shah "Bin \jussoff my deepest

appreciation for your great advise, constant sacrifice and endCess

understanding.

May JAffah (swt) shower his Bfessings upon ad of you

i v

A C K N O W L E D G E M E N T

A l h a m d u l i l l a h , in comple t i on of this p ro jec t r epor t I w o u l d l ike to e x p r e s s m y

credi t to all pe r sons w h o invo lved e i ther di rect ly or ind i rec t ly in g iv ing u s e f u l inpu t s

to m e .

Firs t ly , m y h ighes t g ra t i tude to m y supe rv i so r P ro f . Dr . Ruza i r i B in A b d u l

R a h i m f o r h i s bene f i c i a l ideas , w o n d e r f u l g u i d a n c e and e n c o u r a g e m e n t . W i t h o u t

h i m , this p ro j ec t w o u l d not b e a success .

S e c o n d l y , I t ook this oppo r tun i t y to t hanks m y s p o n s o r J aba t an P e r k h i d m a t a n

A w a m ( J P A ) and K o l e j Univers i t i T e k n o l o g i T u n H u s s e i n O n n ( K U i T T H O ) f o r

f u n d i n g m e to f u r t h e r m y s tudies .

Las t ly , to all m y co l l eagues , c o u r s e m a t e s and o the r g r a d u a t e s tuden ts , t h a n k s

f o r all the mora l suppor t and e n c o u r a g e m e n t t h r o u g h o u t m y ent i re s t udy in U T M .

XIV

A B S T R A C T

B l o o d p re s su re me te r is an essent ia l i n s t rumen t to d e t e r m i n e ou r b l o o d

p r e s s u r e s ta tus . N o w a d a y s , there are va r ious types of b l o o d p re s su re m e t e r ava i l ab l e

m a n u f a c t u r e d f r o m va r ious c o m p a n i e s . In o rde r to m e e t the d e m a n d on t e l e m e d i c i n e

and t e c h n o l o g y a d v a n c e m e n t , a n e w f o r m of b l o o d p r e s s u r e m e t e r is des i r ab le . T h i s

p r o t o t y p e of b l o o d p re s su re m e t e r is i n t e r faced wi th a p e r s o n a l c o m p u t e r ( P C ) w h i c h

ab le to s i m u l a t e the m e a s u r e m e n t p r o c e s s in real t ime . T h e p r o p o s e d s y s t e m w a s

n a m e d e - B P M S (E lec t ron ic B l o o d P res su re M e a s u r e m e n t S y s t e m ) s u g g e s t s the u s a g e

of bo th h a r d w a r e and s o f t w a r e in d e t e r m i n i n g b l o o d p re s su re r ead ing . H a r d w a r e

e l e m e n t s ope ra t e on osc i l lomet r i c p r inc ip le w h i c h g ives the resu l t s in t e r m s of

sys to l ic , d ias to l ic and M A P ( M e a n Arter ia l P ressure ) . F u r t h e r m o r e , these resu l t s wi l l

b e p r e sen t ed and s imu la t ed on the s o f t w a r e end . e - B P M S graph ica l u s e r i n t e r f a c e

( G U I ) w a s d e v e l o p e d b y us ing Visua l Bas ic 6 .0 ( V B 6 ) l a n g u a g e w h i c h h igh l igh t s the

u se r f r i e n d l y a t t r ibutes . M o r e o v e r , the s imula ted w a v e f o r m wil l e v a l u a t e the b l o o d

p r e s s u r e and g ives bene f i c i a l adv ises in t e rm of con t ro l l ing b l o o d p r e s s u r e to b e

op t ima l . Th i s app l ica t ion s h o w s s ign i f i can t i m p r o v e m e n t on the overa l l p e r f o r m a n c e

and g ives re l i ab le resul t s . T h e f r a m e w o r k used to des ign e - B P M S is e a sy to

u n d e r s t a n d and it can b e e x t e n d e d fu r the r to endo r se n e w app l ica t ion area .

v i

ABSTRAK

Ala t m e n g u k u r t ekanan da rah ada l ah pen t ing un tuk m e m b e r i k a n s ta tus

kes iha tan t ekanan da rah s e s e o r a n g ind iv idu . Kini , t e rdapa t p e l b a g a i j e n i s alat

m e n g u k u r t ekanan da rah y a n g be rope ras i m e n g g u n a k a n t ekn ik - t ekn ik y a n g be r l a inan

d ik i l angkan oleh pe lbaga i p e n g e l u a r . . K e p e s a t a n p e r k e m b a n g a n t ekno log i p a d a

m a s a ini u n t u k m e n c a p a i apl ikas i T e l e - P e r u b a t a n m e n y e b a b k a n k e p e r l u a n u n t u k

m e n c i p t a satu alat m e n g u k u r t ekanan d a r a h y a n g ba ru m e n i n g k a t . P r o j e k ini

b e r t u j u a n u n t u k m e n c a d a n g k a n satu alat m e n g u k u r t ekanan da rah y a n g ba ru

m e n g g u n a k a n pr ins ip o s i l ome t r i k di m a n a i anya d i h u b u n g k a n d e n g a n k o m p u t e r

per ibad i dan b o l e h m a m a p a r k a n s imu la s i b a g a i m a n a t ekanan da rah s e s e o r a n g

d i t en tukan . P ro to ta ip alat m e n g u k u r t e k a n a n da rah ini d i n a m a k a n e - B P M S iai tu

s ingka tan u n t u k " S i s t e m m e n g u k u r t e k a n a n da rah e l ek t ron ik" . S i s t e m ini b o l e h

d i b a h a g i k a n k e p a d a dua e l e m e n iai tu " h a r d w a r e " dan j u g a " s o f t w a r e " . " H a r d w a r e "

akan m e m b e r i k a n k e p u t u s a n anal is i s d a l a m b e n t u k b a c a a n s is tol ik , d ias to l ik dan j u g a

pura ta t ekanan arteri . S e t e r u s n y a b a c a a n ini akan d i p a p a r k a n o leh " s o f t w a r e " y a n g

telah d i p r o g r a m k a n m e n g g u n a k a n b a h a s a p e n g a t u r c a r a a n "Vi sua l Bas i c 6 . 0 " ( V B 6 )

p a d a k o m p u t e r . Has i l p ro to ta ip ini b e r j a y a m e m b e r i k e p u t u s a n y a n g tepat dan

b e r j a y a m e m e n u h i ob jek t i f p r o j e k ini dan i anya bo leh d iperba ik i lagi di m a s a akan

da tang .

TABLE OF CONTENTS

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF SYMBOLS / ABBREVIATIONS xv

LIST OF APPENDICES xvii

1 INTRODUCTION

1.1 B a c k g r o u n d

1.2 T h e o r y

1.2.1 B lood P re s su re

1.2.2 Fac to r s con t r ibu t ing to b l o o d

p ressu re d i seases

1.2.3 B l o o d P re s su re I n s t r u m e n t s

1.3 B lood P res su re M e a s u r e m e n t s M e t h o d s

1.3.1 A u s c u l t a t o r y T e c h n i u q e

1.3.2 A u t o m a t e d A u s c u l t a t o r y t echn ique

1.3.3 Osc i l l ome t r i c t e c h n i q u e

1

2

2

3

5

6

6

7

7

v i i i

1.3.4 I n f r a s o u n d and u l t r a sound 8

t echn ique

1.3.5 T o n o m e t r y t e c h n i q u e 9

1.3.6 A m b u l a t o r y b l o o d p r e s s u r e 9

m o n i t o r i n g t e c h n i q u e ( A B P M )

1.3.7 Pu l se d y n a m i c t e c h n i q u e 10

1.3.8 P l e t h y s m o g r a p h y t e c h n i q u e 10

1.3.9 F inge r cu f f t e c h n i q u e 10

1.4 S t a t emen t of the p r o b l e m 11

1.5 Pro jec t Ob jec t i ve s 11

1.6 S i g n i f i c a n c e of p ro jec t 12

2 LITERATURE REVIEW

2.1 R e v i e w of re la ted l i te ra ture 13

3 METHODOLOGY

3.1 M e t h o d chosen 25

3 .2 In s t rumen t s 26

3.2.1 H a r d w a r e 27

3 .2 .2 S o f t w a r e 29

3 .2 .3 S y s t e m In tegra t ion 31

4 HARDWARE DEVELOPMENT

4 .1 H a r d w a r e D e s i g n 32

4 .2 H a r d w a r e Par ts 33

4 .2 .1 P res su re senso r ( M X 5 0 5 0 G P ) 33

4 .2 .2 Opera t iona l a m p l i f i e r ( L M 3 2 4 N ) 35

4 .2 .3 Di f fe ren t i a l a m p l i f i e r 3 6

4 .2 .4 T w o po les h igh pa s s res i s tance- 37

capac i t ance ( R C ) f i l te r

4 .2 .5 P I C 16F877 3 8

4 .2 .6 M A X 2 3 2 41

4 .2 .7 R S 2 3 2 Ser ia l in te r face 4 3

4 . 3 H a n d s h a k i n g in Ser ia l C o m m u n i c a t i o n 4 6

i x

4.3.1 S o f t w a r e H a n d s h a k i n g 4 7

4 .3 .2 H a r d w a r e H a n d s h a k i n g 4 8

4 . 4 Ful l c i rcui t ope ra t ion 4 8

4 .5 H a r d w a r e T e s t i n g 4 9

4 .5 .1 A l p h a Tes t i ng 4 9

4 .5 .2 S y s t e m Tes t i ng 4 9

5 SOFTWARE DEVELOPMENT

5.1 S o f t w a r e D e s i g n 5 0

5 .2 Graph ica l U s e r In t e r f ace D e s i g n 5 0

5.2.1 F l a sh Sc reen 51

5 .2 .2 M a i n Screen 51

5 .2 .3 e - B P M S Fi le M e n u 5 3

5 .2 .4 e - B P M S V i e w M e n u 55

5 .2 .5 M e a s u r e m e n t In t e r f ace 5 6

5 .2 .6 E r r o r Ind ica t ion 5 8

5 .3 P IC P r o g r a m m i n g 5 8

5 .4 W a v e f o r m R e c o n s t r u c t i o n A l g o r i t h m 6 3

6 RESULTS AND DISCUSSIONS

6.1 H a r d w a r e E x p e r i m e n t s 6 4

6.1.1 P re s su re sensor 6 4

6 .1 .2 D i f f e r en t i a l A m p l i f i e r 6 6

6 .1 .3 T w o po l e s h igh pa s s R C f i l te r 67

6 .1 .4 P I C 16F877 m i c r o c o n t r o l l e r 69

6 .1 .5 M A X 2 3 2 - R S 2 3 2 in t e r f ace 7 0

6 .1 .6 e - B P M s ou tpu t (b lood p r e s s u r e 71

r e a d i n g de t e rmina t i on )

6 .2 S o f t w a r e S imu la t i on 7 3

6.2.1 W a v e f o r m R e c o n s t r u c t i o n 7 3

6 .2 .2 C o m p a r i s o n of Resu l t s 7 4

6 .3 P e r f o r m a n c e M e a s u r e s 7 5

XIV

7 CONCLUSIONS AND RECOMMENDATIONS

7.1 C o n c l u s i o n s 77

7 .2 L imi t a t i ons of e - B P M S 78

7 .3 Fu tu re r e c o m m e n d a t i o n 79

REFERENCES 81

APPENDICES 85

xi

LIST OF TABLES

TABLE TITLE PAGE

1.1 B l o o d p ressu re c l a s s i f i ca t ion f o r adul t s g iven 3

by A H A

5.1 B a u d Ra tes fo r A s y n c h r o n o u s M o d e ( B R G H = 1) 6 0

LIST OF FIGURES

xi i

FIGURE TITLE PAGE

1.1 S p h y g m o m a n o m e t e r 5

1.2 De t e rmina t i on of b l o o d p re s su re u s i n g 8

osc i l lomet r ic t e c h n i q u e

2.1 O M R O N b l o o d p re s su re m e t e r 19

2 .2 C I T I Z E N b l o o d p re s su re m e t e r 2 0

2 .3 B I P I T O N E b l o o d p re s su re m e t e r 2 0

2 .4 H E A L T H - O - M E T E R b l o o d p re s su re m e t e r 21

2 .5 L U M I S C O P E b l o o d p re s su re m e t e r 22

2 .6 F O R E C A R E b l o o d p re s su re me te r 2 3

3.1 Bas ic p r inc ip le in osc i l lomet r i c m e t h o d 2 6

3 .2 B l o c k d i a g r a m fo r e - B P M S 27

3.3 H a r d w a r e f l o w c h a r t 2 8

3 .4 S o f t w a r e f l o w c h a r t 3 0

4.1 M P X 5 0 5 0 G P p res su re senso r 33

4 .2 Expec ted ou tpu t of p re s su re senso r 3 4

4 .3 P o w e r supp ly d e c o u p l i n g and f i l t e r ing c i rcui t 3 4

4 .4 L M 3 2 4 N opera t iona l amp l i f i e r 35

4 .5 Di f fe ren t ia l amp l i f i e r c i rcui t 37

4 .6 Expec t ed osci l la t ion s ignal g iven b y 37

d i f ferent ia l ampl i f i e r

4 .7 Expec ted filter f r e q u e n c y r e sponse 38

4 .8 Basic mic rocon t ro l l e r b l o c k d i ag ram and 39

P I C 1 6 F 8 7 7 pin a s s i g n m e n t s

xiii

4 .9 Tes t set up for M A X 2 3 2 4 2

4 .10 Expec t ed ou tpu t f r o m M A X 2 3 2 4 2

4.11 M A X 2 3 2 ch ip con f igu ra t i on and its 4 3

internal ou t look

4 . 1 2 Bi -d i rec t iona l R S - 2 3 2 in te r face 4 4

4 .13 H a n d s h a k i n g t iming d i a g r a m 4 7

5.1 F lash screen 51

5 .2 e - B P M S main screen 52

5 .3 T e x t d o c u m e n t of " I n f o " bu t ton 5 2

5 .4 e - B P M S w a v e f o r m d i sp lay sc reen 5 3

5.5 e - B P M S file m e n u 5 4

5 .6 E x a m p l e of resul t to be pr in ted 5 4

5 .7 e - B P M S " a b o u t " s c r eensho t 55

5 .8 e - B P M S da t abase s c r eensho t 5 6

5 .9 e - B P M S pat ien t b l o o d p r e s s u r e s ta tus d i sp lay 57

5 .10 S a m p l e of w a v e f o r m r econs t ruc t ed b y e - B P M S 57

5 .11 e - B P M S er ror ind ica t ion 5 8

5 .12 In i t ia l iza t ion of reg is te r A D C O N 1 and 5 9

all por ts u sed

5 .13 Se t t ing of t r ansmiss ion m o d e and b a u d rate 6 0

5 .14 P C de tec t ion of S T A R T / S T O P da ta t r ans fe r 61

5 .15 Star t ing the Ana log - to -Dig i t a l C o n v e r s i o n 61

O p e r a t i o n

5 .16 A D R E S L and A D R E S H set t ing fo r da ta t r ans fe r 62

5 .17 De tec t the end of C a p t u r e Dura t i on 62

5 .18 R o u t i n e fo r r econs t ruc t ion of w a v e f o r m 63

6.1 Di f f e ren t i a l p re s su re ob t a ined f r o m senso r 65

6 .2 D i f f e r en t i a l amp l i f i e r c i rcui t 67

6.3 Fi l ter f r e q u e n c y r e s p o n s e 68

6.4 Inpu t / ou tpu t of ana log to digi tal conve r t e r ( A D C ) 69

6.5 Ou tpu t of bo th pin T2EN and T 2 0 U T 71

6 .6 E x a m p l e of b lood p re s su re w a v e f o r m obta ined 7 2

6.7 B lood p ressu re osc i l la t ions e n v e l o p e 73

6.8 W a v e f o r m recons t ruc t ion poin ts 7 4

XIV

6.9 C o m p a r i s o n on w a v e f o r m s ob ta ined f r o m e - B P M S 75

6 .10 P e r f o r m a n c e m e a s u r e s of e - B P M S 7 6

7 .1 U n w a n t e d no tch and j i t t e rs cap tu red 7 8

7 .2 Incons i s ten t r ead ing w h e n p ressu re 7 9

> I S O m m H g is app l ied

LIST OF SYMBOLS/ ABBREVIATIONS

A/D Analog-Dig i t a l

AAMI Assoc ia t ion of A d v a n c e m e n t M e d i c a l I n s t r u m e n t a t i o n

ABPM A m b u l a t o r y B l o o d P r e s s u r e M o n i t o r i n g

ADC A n a l o g to digi ta l C o n v e r t e r

AHA A m e r i c a n Hea l th A s s o c i a t i o n

Ap Attenua t ion

ASCII A m e r i c a n S t a n d a r d C o d e f o r I n f o r m a t i o n I n t e r c h a n g e

atm A t m o s p h e r i c un i t (p re s su re m e a s u r e m e n t )

CMOS C o m p l e m e n t a r y M O S F E T

COM C o m p o n e n t O b j e c t M o d e l

CP C u f f P res su re s igna l

CPU Centra l P r o c e s s i n g U n i t

CTS Clear T o S e n d

DIY D o It Yourse l f

DSR Data Set R e a d y

DTR Data T e r m i n a l R e a d y

e-BPMS Elec t ron ic B l o o d P r e s s u r e M e a s u r e m e n t S y s t e m

EIA/TIA-232E Serial C o m m u n i c a t i o n S t anda rd

EMI Elec t romagne t i c I n d u c e d V o l t a g e

FET Field E f f e c t T rans i s to r

GND G r o u n d

GPIB Genera l P u r p o s e In t e r f ace B u s

GUI Graphica l U s e r In t e r f ace

Hz Her tz (unit of f r e q u e n c y )

LCD Liqu id Crys ta l D i s p l a y

MAP M e a n Arterial P ressure

mmHg Uni t mi l l ime te r m e r c u r y

MOSFET M e t a l O x i d e S e m i c o n d u c t o r F E T

MS Chart M i c r o s o f t Char t ( A c t i v e X f u n c t i o n )

MS Comm. M i c r o s o f t C o m m u n i c a t i o n ( A c t i v e X f u n c t i o n )

MSC M u l t i m e d i a Supe r C o r r i d o r

NIBP N o n Invas ive B lood P r e s s u r e

Pa Pasca l unit (p ressure m e a s u r e m e n t )

PC Per sona l C o m p u t e r

PIC Per iphera l In te r face Con t ro l l e r

RC Res i s to r -Capac i to r

RS-232 Ser ia l C o m m u n i c a t i o n P ro toco l

RTS R e q u e s t to Send

RXD R e c e i v e d da ta

SI In te rna t iona l S y s t e m (uni t of m e a s u r e m e n t )

SPBRG B a u d ra te gene ra to r

TTL Trans i s to r -Trans i s to r L o g i c

TXD T r a n s m i t da ta

UART Unive r sa l A s y n c h r o n o u s R e c e i v e r / T r a n s m i t t e r

V V o l t (unit of vo l tage)

VB6 Visua l Bas ic 6 .0

V D C Direc t cur ren t V o l t a g e

Van, V o l t a g e ou tpu t

Vs V o l t a g e S u p p l y

WHO W o r l d Hea l th Organ iza t i on

x v i i

LIST OF APPENDICES

APPENDIX TITLE PAGE

A P I C P r o g r a m m i n g 85

B V B P r o g r a m m i n g 88

C e - B P M S Circui t D i a g r a m 92

D S tanda rd B l o o d P re s su re T a b l e 9 3

E D a t a Shee t 9 4

CHAPTER 1

INTRODUCTION

1.1 Background

B l o o d p re s su re is o n e of m o s t impor t an t m e a s u r e m e n t s w h i c h ind ica t e p e r s o n ' s

hea l th cond i t ion . A b n o r m a l b l o o d p re s su re r e a d i n g m a y lead to va r ious d i s ea se s w h i c h

c a n b e p r e v e n t e d b y t r ea tment . B l o o d p re s su re re la ted d i seases are u s u a l l y b e i n g

r e fe r red as "s i len t k i l le r" . T h e c o n s e q u e n c e p r o m o t e d can b e e i ther ca rd i ac d i s o r d e r or

the m a l f u n c t i o n s of ou r b o d y s y s t e m s . C o n s i d e r i n g these h u g e e f f e c t s m a y b e too

h a r m f u l f o r h u m a n b o d y , thus p r even t i ve ac t ion needs to b e taken . H i g h b l o o d p r e s s u r e

is an e p i d e m i c d i sease w h i c h a l w a y s a m a j o r c o n c e r n s in d e v e l o p e d coun t r i e s . S ta t i s t ic

s h o w s the grea t n u m b e r of cases f o r the pas t decades , w h i c h t r iggers the ins igh t to

p r e v e n t and cont ro l this d i sease r a the r than cure it. N o w a d a y s , the n e e d f o r a r e l i ab le

m e d i c a l t e chno log ie s and analys is is des i rable , s ince the users p r e f e r to e x p e r i e n c e the i r

m e d i c a l d i agnos i s t hemse lves . H o m e m o n i t o r i n g p r o v i d e s an accu ra t e r e co rd of

m e a s u r e m e n t s ove r t ime he lps in p l ann ing an overa l l p e r s o n a l hea l th r e g i m e n .

F u r t h e r m o r e , b l o o d p re s su re m a n a g e m e n t is a s tep t o w a r d s a hea l th ie r l i fes ty le .

721

1.2 Theory

1.2.1 Blood pressure

B l o o d p re s su re is de f ined as the p r e s su re of the b lood aga ins t the wa l l s of the

ar ter ies . It is the resu l t an t of t w o fo rces . O n e is c rea ted b y the hear t as it p u m p s b l o o d

in to the ar ter ies and th rough the c i r cu la to ry s y s t e m . T h e o the r is the f o r c e of the ar ter ies

as they res is t the b l o o d f l ow . B l o o d p r e s s u r e is m e a s u r e d in mi l l ime te r s of m e r c u r y

( m m H g ) and r e c o r d e d as two n u m b e r s sys to l ic p r e s su re "over" d ias to l ic p ressure . F o r

e x a m p l e , the doc to r m i g h t say "130 o v e r 80" 130 /80 m m H g as a b l o o d p r e s s u r e r ead ing .

T h e m e a s u r e m e n t is t aken w h e n the d o c t o r pu t s the cu f f a round p a t i e n t ' s a r m and p u m p s

it up .

T h e p r e s s u r e exer ted b y the cu f f wi l l b l o c k the b l o o d f l o w in the vesse l . A s the

p re s su re is r e l eased s lowly , b l o o d s tar ts to f l o w aga in and the doc to r can hea r the f l o w

us ing a s t e thoscope . T h e n u m b e r at w h i c h b l o o d starts f l o w i n g aga in is r e c o r d e d as

m a x i m u m o u t p u t of p re s su re of the hea r t (sys tol ic) . T h e n , the d o c t o r wi l l c o n t i n u e

r e l eas ing the p r e s s u r e of the cu f f and l i s tens unt i l there is no sound . T h e n u m b e r (80)

ind ica tes the p r e s s u r e in the sy s t em w h e n the hea r t is r e l axed (diastol ic) .

A c c o r d i n g to A m e r i c a n H e a r t A s s o c i a t i o n ( A H A ) , op t ima l b l o o d p re s su re wi th

respec t to c a r d i o v a s c u l a r risk is less than 120/80 m m H g . H o w e v e r , u n u s u a l l y l ow

r ead ings shou ld b e eva lua ted to ru le ou t m e d i c a l causes . If the pa t i en t exh ib i t s l ow

read ings eve ry m e a s u r e m e n t s , the re is a po ten t ia l of h a v i n g l ow b l o o d p re s su re

(hypo tens ion) . T h e sys to l ic p re s su re of 120 to 139 m m H g or d ias to l ic p r e s s u r e of 80 to

3

89 m m H g is c o n s i d e r e d as at r i sk of h a v i n g h igh b lood p re s su re (pre h y p e r t e n s i o n ) .

F u r t h e r m o r e , b l o o d p re s su re r ead ing of 140/90 m m H g is cons ide red e l eva ted h igh

(hype r t ens ion ) . T h e r a n g e of b l o o d pressure r e c o m m e n d e d by A H A is s u m m a r i z e d in

the T a b l e 1.1 b e l o w .

T a b l e 1.1: B l o o d p re s su re c lass i f ica t ion f o r adul t s g iven b y A H A

C a t e g o r y Sys to l i c ( m m H g ) Dias to l ic ( m m H g )

N o r m a l < 130 < 8 5

H i g h N o r m a l 130-139 85-89

H y p e r t e n s i o n

S t a g e 1 (mi ld ) 140-159 9 0 - 9 9

S tage 2 ( m o d e r a t e ) 160-179 100-109

S tage 3 ( severe ) 108-209 110-119

S t a g e 4 (very severe ) > 2 1 0 > 1 2 0

B l o o d p r e s s u r e r e a d i n g is k n o w n to b e var ied b e t w e e n one p e o p l e to ano the r . It

is r e c o m m e n d e d b y A H A that ideal ly , b lood p re s su re m u s t b e c h e c k e d at leas t t w i c e a

yea r and it shou ld b e m o r e o f t e n if it is h igh . S o m e of the f ac to r s a f f e c t i n g b l o o d

p re s su re can b e c l a s s i f i ed in to severa l ca tegor ies c o n c e r n i n g phys io log i ca l , gende r ,

l i f es ty les and m a n y o thers . T h e e labora t ion of these f ac to r s wi l l b e in f o l l o w i n g sec t ion .

1.2.2 Factors contributing to blood pressure diseases

Firs t ly is the e las t ic i ty of b l o o d vesse l de t e rmines the a m o u n t of b l o o d f l o w at

one t ime. T h e na tu re of b l o o d vesse l changes as w e age, as the vesse l ge t s th icker , t he