patient monitoring system with sms

7/28/2019 Patient Monitoring System With SMS

1/10

MICROCONTROLLERBASED CARDIACMONITORINGSYSYTEMWITH SMS SERVICE

Abstract

The project aims at developing a patient monitoring system. The system

contains an ECG simulator to generate ECG waveform. The ECG simulatorhas control to vary heart rate as well as to generate different types of

arrhythmias. The monitoring system keeps track of the heart rate activity.If there is any abnormality, it will send a SMS to a remote station to get

the medical assistance.

The ECG simulator is designed using an oscillator and pulse shaping circuit.

The monitoring system contains an 8-bit ADC, 8-bit microcontroller and aGSM modem. The GSM modem is serially interfaced with the

microcontroller. Standard AT command set is used to control GSM modem.

Block Diagram

A typical ECG Circuit:

A ECG Simulator module will be developed which will provide the ECG

waveform in its natural shape at the output.


2/10

The feedback from ECG module will pass through a missing pulse detector.The output of the missing pulse detector is high when the ECG continues.

Any break in ECG will trigger the missing pulse detector to go highconsequently triggering the microcontroller to generate a trigger for the

emergency.

Block Diagram:

ECG

Simulator

Micro-controller

AT89C51

LCD display

Missing

pulse

detection

Circuit

GSM

MODEM

Level

Converter


3/10

Major Components:

AT89C51 Microcontroller

GSM Modem (Serial Interface)

IC555 Timer ICCD4521

CD4017LM741 OPAMP

IC7805 Voltage regulatorsIC 7815 Voltage regulator

16x2 Lampex LCD

Rotary SwitchesBC547, BC557 NPN, PNP Transistors

1N4007 DiodesW10 Rectifier

Resistance, Capacitors etc.

ECG Background

William Einthoven developed the first electrocardiogram in 1903 using a

crude galvanometer. Technology has advanced ECG measurement, but theprinciple remains the same. The electrocardiogram is the waverepresentation of the potential difference caused by heart activity. A grasp

of the electrocardiogram has to be gained for two reasons: 1. An

understanding of the wave forms the basis for the design of the electroniccircuit to measure it; and 2. An understanding allows the concept of what

an ECG is, and how its deviation enables analysis of health. The potentialdifference is created by the flux of ions in cells, a typical cell with Sodium

and Potassium ions as shown in figure.


4/10

When the heart pumps, the cell wall offers greater permeability and an

excess of sodium is able to flow inside the cell. When the sodium flows intothe cell there is no longer a negative potential with respect to the outside.

This is known as depolarisation. Eventually after the excitation passes, the

cell repolarises, returning the potential to a negative one.


5/10

The standard for diagnostic ECG is twelve leads, however in the case ofmore portable, easy to use ECG one lead (usually Lead II) can be used.

Lead II can diagnose the more common diseases like arrhythmias. Cellsare originally polarised such that the potential inside each cell is negative

with respect to the outside. Depolarisation occurs first, making the outside

of the cell negative with respect to the inside. This imbalance causes anionic current to flow, and the Left Arm to register a positive with respect to

the right arm. This is known as the Pwave. The depolarisation then passesto the atrioventricular node. It is still relatively negative to the left ventricle

causing a current and positive voltage from the left to right arms. This is

the R-wave. The T wave is a representation of the repolarisation of thedepolarised cells. Physicians can diagnose a persons health by reading

these waves. From a signal processing perspective, the potential differencebetween left and right arms is typically 1-3mV and the frequency of the

ECG signal lies between .02 and 150Hz. The quality of an ECG sensor could

be categorised by its bandwidth. Usually sensors designed for the end ofthe market that this device was designed for only measure frequencies of

up to 30Hz. If specifications for ECG emergency care were to be met, thefrequency measured should extend to 1kHz. The problem with larger

spectrums is that a proportional amount of noise must be battled with thefrequencies that are measured.

Glossary

ARRHYTHMIA: an abnormal rhythm of the heart beat.

ASYSTOLE: a failure of the heart to beat or contract at a time whenit should have.

ATRIA: the top or collecting chambers of the heart. There are two ofthese, the right atrium and the left atrium.

AV NODE: or atrioventricular node is a special conduction centre in

the heart. It is located between the two lower chambers (ventricles)of the heart and receives the electrical impulse from the upper

chambers (atria) of the heart and passes it downward into the lower

chambers (ventricles).

BLOOD PRESSURE: the pressure of the blood against the walls of the

blood vessels. The term usually refers to arterial blood pressure. It is

determined by the force of the heart beat, the resistance to the flowof blood in the arteries, the elasticity of the vessel walls, and the


6/10

bloods thickness. The blood pressure is expressed as one numberover another, i.e., 120/80. The first number represents the systolic

pressure and the second, the diastolic pressure. Both are recorded inmillimetres of mercury. Strenuous physical activity, excitement,

nervous tension, or fright raise the systolic pressure.

BRADYCARDIA: a slow heart rate, generally under 50 beats perminute.

BUNDLE BRANCH BLOCK: a blockage of one of the specialised

conducting pathways within the lower chambers of the heart.

BUNDLE OF HIS: also called common bundle or AV bundle. A bundle

of specialised muscle fibres which conducts impulses from the AV

node to the lower chambers of the heart. Named after Wilhelm His, aGerman medical scientist.

CAPTURE: when a pacemaker impulse or discharge succeeds in

causing the ventricles of the heart to beat or contract.

CARDIAC OUTPUT: the amount of blood pumped by the heart per

minute.

CATHETERIZATION: in cardiology, the process of examining theheart by means of introducing a thin tube (catheter) into a vein or

artery and passing it into the heart. The pacemaker lead inserted

through the vein for pacing is a type of catheter.

CIRCUITRY: the electrical portion of your pacemaker designed to

pace the heart at a pre-established rate, and with a demandpacemaker, to sense your own underlying rhythm.

CORONARY ARTERIES: the arteries that supply blood to the heart

muscle itself.

CARDIAC INSUFFICIENCY: inability of the heart to pump adequately.Causes shortness of breath, fluid retention, etc.

DEMAND: a type of pacemaker that fires only when necessary; i.e.,when the hearts own intrinsic rate becomes slower than the rate at

which the pacemaker is programmed to operate.

DEPOLARIZATION: electrical activity spreading through the heart,causing it to contract or beat.


7/10

DIASTOLE: relaxation of the heart between contractions.

ECTOPIC: electrical stimulation of cardiac contractions beginning at a

point other than the sinoatrial (SA) node.

ELECTROCARDIOGRAM: often called EKG or ECG. It is a graphicrecord of the electric currents produced by the heart.

ELECTRODE: the wire connecting the pacemaker (pulse generator) to

the heart. It is responsible for carrying the electrical discharge to theheart and the sensed electrical activity of the heart back to the

pacemaker.

ENDOCARDIAL: refers to the inside layer of the heart. An endocardialelectrode is one that is inserted via a vein, and the tip contacts the

internal surface of the heart.

EPICARDIAL: the outer layer of the heart. An epicardial electrode isone that is attached directly to the hearts outer surface.

FIBRILLATION: rapid uncoordinated contractions of the heart muscle

occurring when the individual muscle fibres take up independentirregular contractions.

FIBROSIS: scarring of the heart or other organs of the body. Withinthe electrical portion of the heart this scarring may cause heart block

or other rhythm disturbances.

HEART BLOCK: a condition where the transmission of electricaldischarges from the upper chambers of the heart to the lower

chambers are partially or completely blocked, resulting in the

chambers NOT working in a synchronised way.

HYPERTENSION: an unstable or persistent elevation of blood

pressure above the normal range. May eventually lead to an

enlarged heart and kidney damage.

HERMETIC SEAL: a process where the battery and circuitry of thepulse generator are sealed within a metal container that cannot bepenetrated by body fluids.

INTRINSIC RATE: patients own natural heart rate.


8/10

MYOCARDIAL INFARCTION: the damage or death of areas of theheart muscle (myocardium) resulting from a reduction in the blood

supply reaching that area.

NITROGLYCERIN: a medication used to relax the muscles in the

blood vessels. Often used to relieve attacks of angina pectoris andspasm of coronary arteries. It is vasodilator.

PACE: a condition in which a heart beat is initiated by a pacemaker.

PAC: premature atrial contraction, a heart beat which has originated

early in the upper chambers of the heart (atria). It is consideredectopic since it is not in the usual conduction pathway.

PROGRAMMABLE PACEMAKER: a type of pacemaker which can be

adjusted from the outside of the body using a specific instrument(programmer). The programmer can be used to vary the rate of

pacing as well as the electrical output of the pacemaker. This does

NOT require surgery.

PULSE: a rhythm in the arteries caused by the contractions of the

heart.

PULSE GENERATOR: referring to the entire pacemaker; that is thecircuitry and batteries together, which produce the periodic electrical

impulse to the heart.

PURKINJE FIBRES: specialised muscular fibres forming a network inthe walls of the hearts lower chambers. Believed to be involved in

conducting electrical impulses to the muscular walls of the ventricles.These impulses are responsible for the contractions of the ventricles.

PVC: premature ventricular contraction. Similar to PAC but occurring

within the lower chambers of the heart.

RATE RESPONSE: a function that allows the pacemaker to increasethe heart rate during exercise.

REED SWITCH: a component of the circuitry of a demand pacemakerthat is activated by placing a magnet over the unit. This causes a

demand pacemaker to become a fixed-rate unit by bypassing the

sensing circuitry.

RHYTHM: a regular and repetitive recurrence of a beat.


9/10

SA NODE: sinoatrial node, the special nerve centre in the upper rightchamber of the heart that in most instances initiates each beat.

SENSE: the ability of a pacemaker to recognise the electrical impulse

of a heart beat.

SEPTUM: a thick muscular wall dividing the heart into right and left.

SINUS RHYTHM: a normal type of rhythm initiated from the upper

chambers of the heart with the electrical impulse passing normallyinto the lower chambers.

STIMULUS: an electrical discharge by the pacemaker to the heart.

STOKES / ADAMS ATTACKS: fainting spells associated with atemporary lack of perfusion of the blood to the brain generally

associated with complete heart block.

SYSTOLE: the contraction of the heart which forces blood throughthe arteries.

SYNCOPE: fainting.

TACHYCARDIA: a rapid heart rate usually over 120 beats per minute.

THRESHOLD: the lowest amount of electrical energy from a

pacemaker stimulus necessary to cause the heart to contract.

TITANIUM: a type of metal used to make the outer case of the

pacemaker.

TRANSVENOUS: a type of electrode which is generally endocardial. It

is inserted through a vein and passed to the heart, with the tip of the

electrode placed in the endocardiumin.

TRANSTHORACIC SURGERY: when an opening is made between the

ribs so that epicardial electrodes can be sewn directly to the outer

wall of the left ventricle.

VENTRICLES: the lower chambers of the heart. There are two, the

right and left ventricles. The right ventricle pumps blood to the lungsand the left ventricle pumps blood throughout the body.


10/10

Conclusion:

The proposed project is a real demonstration of the working of a

demand type pacemaker, which can take action in real time in the

absence of feedback from heart. The pacemaker device is completely

programmable which can provide varying output controllable byuser.

The project is proposed to be developed by using low costcomponents and thus it is economical and compact.

patient monitoring system with sms

Documents