intelligent defibrillato new
TRANSCRIPT
8/7/2019 Intelligent Defibrillato New
http://slidepdf.com/reader/full/intelligent-defibrillato-new 1/8
“PORTABLE DEFIBRILLATOR”
1Harshal Mistry
2Kanchan Gaur
1, 2 Students of AVCOE, Sangamner.
Abstract
In this modern world we strive hard to achieve the
goals we set for ourselves. But in that journey we get stressed out. The studies have shown that there is a
significant rise in the number of heart related issues
with the modern times.
The main call of the time is to provide out of
hospital facility to treat people who encounter such
heart related issues. This is a small step in providing
such a facility so that the fatalities due to cardiac
arrest can be brought down. Studies have shown that
patient who suffers from a fibrillation- arrhythmic
beating of heart, has larger chances of survival if the
process of normalizing the heartbeat begins in fewminutes of the cardiac arrest. De-Fibrillator portable
is a device which is very convenient to carry around
and use when there is any kind of emergency. The
simplicity of the device makes it usable by laymen.
There is no need of any trained person for the
operation.
The devices’ self-analytical functioning
assists to decide the amount of the electric shock
required for the patient and the time at which it is to
be delivered. this improves the chances of saving the
patient significantly.
1. Intoduction
A) What is Fibrillation?
Abnormality in the heart beats. Arrhythmic beatingof the heart is called Fibrillation.
Fibrillation is a very serious type of arrhythmia.Fibrillation occurs when the heart muscle has aquivering motion rather than normal pumping action.
This condition could affect the upper (atrial) or lower (ventricular) chambers of the heart. Ventricular fibrillation of the heart can cause death in minutes,however atrial fibrillation usually is not lifethreatening and the result of an underlying medicalcondition.
Here we will concentrate on the ventricular fibrillation as it is more life threatening compared toatrial fibrillation. There are mainly to kinds of ventricular fibrillation
• Ventricular Fibrillation
• Ventricular Tachycardia
b) Ventricular fibrillation:
In ventricular fibrillation, the ventricles merelyquiver and do not contract in a coordinated way. No blood is pumped from the heart, so ventricular fibrillation is a form of cardiac arrest. It is fatal unlesstreated immediately.
The most common cause of ventricular fibrillation is
inadequate blood flow to the heart muscle due tocoronary artery disease, as occurs during a heartattack.
8/7/2019 Intelligent Defibrillato New
http://slidepdf.com/reader/full/intelligent-defibrillato-new 2/8
Figure 2.1: Waveforms for ventricular fibrillation
An ECG strip shows the presence of ventricular fibrillation, which involves rapid contraction of theventricles. Ventricular fibrillation is indicated by anerratic rhythm in which spikes and waves cannot beidentified. A normal ECG strip is shown at the bottom for comparison.
• Ventricular fibrillation causesunconsciousness in seconds, and if thedisorder is not rapidly treated, death follows.
• Electrocardiography (ECG) helps determinethe cause of cardiac arrest.
• Cardiopulmonary resuscitation (CPR) must be started within a few minutes, and it must be followed by defibrillation (an electricalshock delivered to the chest) to restorenormal heart rhythm.
C) Ventricular Tachycardia
Ventricular tachycardia may be thought of as asequence of consecutive ventricular premature beats.Sometimes only a few such beats occur together, andthen the heart returns to a normal rhythm. Ventricular tachycardia that lasts more than 30 seconds is calledsustained ventricular tachycardia. Sustainedventricular tachycardia usually occurs in people witha structural heart disorder that has damaged theventricles. Most commonly, it occurs weeks or months after a heart attack. It is more commonamong older people. However, rarely, ventricular
tachycardia develops in young people who do nothave a structural heart disorder.
• People almost always have palpitations.• Electrocardiography (ECG) is used to make
the diagnosis.
• Drugs and procedures to destroy abnormalareas of the ventricles are usually needed, but usually an automatic defibrillator isused.
Figure 2.2: Waveforms for ventricular tachycardia
An ECG strip shows the presence of ventricular tachycardia, which is one type of a rapid heartbeat.
Ventricular tachycardia is indicated by a series of repeating wide uncoordinated spikes. A normal ECGstrip is shown at the bottom for comparison.
d) Is there a solution?
Once the victim experiences the ventricular fibrillation then the best way to treat the person is togive a CPR (Cardio Pulmonary Resuscitation). Eventhen if the patient doesn’t recover then it is the timeto provide some sort of De-Fibrillation.
De-Fibrillation is the process of giving short
electrical shocks to the patients on and around their heart in order to regularize the heart beating. Studieshave shown that a calculated amount of electricalshock given to the patient at the time of fibrillationcan again regularize the beating of the heart.
E) What is De-Fibrillation?
8/7/2019 Intelligent Defibrillato New
http://slidepdf.com/reader/full/intelligent-defibrillato-new 3/8
De-Fibrillation is the process in which an electronicdevice gives an electric shock to the heart. This helpsreestablish normal contraction rhythms in a hearthaving dangerous arrhythmia or in cardiac arrest. Inrecent years small portable defibrillators have become available. These are called AutomatedExternal De-Fibrillator (AED).
2. Main body of the paper 2.1 Manual External De-Fibrillator
The units are in conjunction with (or more often haveinbuilt) electrocardiogram readers, which thehealthcare providers use to diagnose a cardiaccondition (most often fibrillation or tachycardiaalthough there are some other rhythms which can be
treated by different shocks). The healthcare provider will then decide what charge (in joules) to use, basedon proven guidelines and experience, and will deliver the shock through paddles or pads on the patient’schest. as they require detailed medical knowledge,these units are generally only found in the hospitalsand on some ambulances.
2.2Automated External De-Fibrillator (AED)
An automated external defibrillator or AED is a portable electronic device that automaticallydiagnoses the potentially life threatening cardiacarrhythmias of ventricular fibrillation and ventricular tachycardia in a patient, and is able to treat themthrough defibrillation, the application of electricaltherapy which stops the arrhythmia, allowing theheart to reestablish an effective rhythm.
AEDs are designed to be simple to use for thelayman, and the use of AEDs is taught in many first
aid, first responder and basic life support (BLS) levelCPR classes.
Photograph 2.1( Portable Difibrillator)
Photograph 2.2( Portable Difibrillator by Philips)
2.3 Block digram of Portable Difibrillator.
Figure 2.3: Block dig of defibrillator
8/7/2019 Intelligent Defibrillato New
http://slidepdf.com/reader/full/intelligent-defibrillato-new 4/8
Micro-controller
It is the brain of this system. The entire decisionmaking is done by the microcontroller. Let us see thefunctions that are performed by the controller.
• Generate PWM output for the inverter sothat the voltage that comes from a battery can bestepped up.
• It keeps check on the capacitor charge levelusing feedback and an ADC and controls theCapacitor Charging PWM accordingly.
• It also controls the output PWM which inturn controls the energy that is released during anelectric shock. The functions above are for chargingand discharging the capacitor during the de-
fibrillation process. But it also has to check for theappropriate time for discharging the charge so thatde-fibrillation occurs.
• Controller measures the peak of the wave
received from the patient using an ADC. Theduration of the wave is calculated using a timer. Thisinformation helps to calculate the fibrillation timeand hence type.
• Depending on the type of fibrillation the
controller decides the time of de-fibrillation. Thecontroller controllers the selections of the channel between capacitor charge feedback and R-wave.
High voltage capacitor charger
This module consists of three blocks. They allcombined performs the task of charging the capacitor so that it can be discharged as and when required.
• Inverter
Basically, DC to AC inverter work by using controlcircuit to generate electric pulse at high power (typically at hundred to thousand watts) and then thishigh power pulse is connected to step up transformer to get high voltage, i.e. 220 volt. By using a timer,the generated pulse can be formed in modified sinewave by using pulse width modulation technique. Inthis circuit, microcontroller will generate pulse that isused for MOSFET IRFZ 44 driving. This MOSFETis switched ON and OFF which in turn controls DC
current to low side. The high voltage is generated atthe other side that can turn on the lamp. To get ahigher power, we can add more MOSFETs in parallelconnection.
• AC to DC converter
This is simple full wave rectifier circuit, which willgenerate DC voltage for capacitor charging.
• Charging controller
This DC voltage will not be going directly tocapacitor; MOSFET will be used in between.Microcontroller will check capacitor voltage throughcharger feedback and control MOSFET accordingly.
• Capacitor charger feedback
This circuit will step down the capacitor voltage tovery low voltage say 3V. Then it will be bufferedusing Op-amp and given to ADC to check capacitor charging level. Once the level has reached thesatisfactory level the controller will stop charging the
capacitor. The discharging of the capacitor doesn’ttake place until the capacitor charge level reaches theappropriate value even if the discharge switch is pressed.
• High voltage capacitor discharge
Capacitor discharge will be done through MOSFET.If we are using PWM discharge method so we canuse transformer isolation between high voltage
capacitor circuit and our control circuit. MultipleMOSFET can be used for different levels of energy,in another words we can control discharge current.This decision is taken by the micro-controller. Andthus the appropriate amount of charge is dischargedso that we get the best possible outcome.
8/7/2019 Intelligent Defibrillato New
http://slidepdf.com/reader/full/intelligent-defibrillato-new 5/8
• R-point detector and timing measurement
ADC will be used to measure voltage level fromelectrocardiogram simulator. Microcontroller willcheck the spike voltage during R-wave. Period will be measured using timer. According to this data thedecision will be made which type of fibrillation hasoccurred.
• LCD screen
This screen gives the status of the de-fibrillator andthe messages for the person who is using it. Thismakes it user friendly as it gives the instruction what
is to be done.
2.4 Mechanism of Operation
An AED is external because the operator applies theelectrode pads to the bare chest of the victim, asopposed to internal defibrillators, which haveelectrodes surgically implanted inside the body of a patient.
Automatic refers to the unit's ability to autonomously
analyze the patient's condition and to assist this, thevast majority of units have spoken prompts, and somemay also have visual displays to instruct the user.
When turned on or opened, the AED will instruct theuser to connect the electrodes (pads) to the patient.Once the pads are attached, everyone should avoidtouching the patient so as to avoid false readings bythe unit. The pads allow the AED to examine theelectrical output from the heart and determine if the patient is in a shock able rhythm (either ventricular fibrillation or ventricular tachycardia). If the devicedetermines that a shock is warranted, it will use the
battery to charge its internal capacitor in preparationto deliver the shock. This system is not only safer (charging only when required), but also allows for afaster delivery of the electrical current.
When charged, the device instructs the user to ensureno one is touching the patient and then to press a button to deliver the shock; human intervention isusually required to deliver the shock to the patient in
order to avoid the possibility of accidental injury toanother person (which can result from a responder or bystander touching the patient at the time of theshock). Depending on the manufacturer and particular model, after the shock is delivered mostdevices will analyze the patient and either instructCPR to be given, or administer another shock.
Many AED units have an 'event memory' which storethe ECG of the patient along with details of the timethe unit was activated and the number and strength of any shocks delivered. Some units also have voicerecording abilities to monitor the actions taken by the personnel in order to ascertain if these had anyimpact on the survival outcome. All this recordeddata can be either downloaded to a computer or printed out so that the providing organization or responsible body is able to see the effectiveness of both CPR and defibrillation. Some AED units even provide feedback on the quality of the compressions provided by the rescuer.
The first commercially available AEDs were all of amonophasic type, which gave a high-energy shock,up to 360 to 400 joules depending on the model. Thiscaused increased cardiac injury and in some casessecond and third-degree burns around the shock padsites. Newer AEDs (manufactured after late 2003)have tended to utilize biphasic algorithms which givetwo sequential lower-energy shocks of 120 - 200 joules, with each shock moving in an opposite polarity between the pads. This lower-energywaveform has proven more effective in clinical tests,as well as offering a reduced rate of complicationsand reduced recovery time.
2.5. Analysis
A defibrillator analyzer is basically meant tomeasure the energy content in the discharge pulse. Itworks on the principle that the energy contained in a pulse of arbitrary shape and time duration is given by
E=∫0T e (t) i (t) dt -------------------- (1)
Where E=energy in watt-secs
E (t) = voltage as a function of time,
I (t) = current as a function of time,
T=time duration of pulse
8/7/2019 Intelligent Defibrillato New
http://slidepdf.com/reader/full/intelligent-defibrillato-new 6/8
When the exists across a fixed resistance, the energydissipated in the resistance is given by
E = 1/R∫0T [e(t)]2 dt --------------(2)
Where R is the resistance of the load
Second equation shows that defibrillator analyzer circuit should consist of blocks shown in dig. Thedefibrillating pulse is applied a standard 50Ω loadand the voltage developed across it is given to asquaring ckt. The squaring consists of a four quadrantmultiplier followed by an operational amplifier. Theoutput of this device is a current which is proportional to the product of two inputs. In thesquaring mode, the two inputs are connected together so that the output is a square of input voltage. Theoperational amplifier acts as a current to voltageconverter producing an output voltage which is proportional to the output current, from the
multiplier.
Figure2.4: Basic Block of Defibrillator energy meter
Meter
Besides these basic blocks the defibrillator analyzer contains other ckts for controlling the measurementoperation. For ex, the pulse integrator ckt integratesthe squared function pulse during the time that a pulse is present. During the reminder of display time,it acts as an analog storage element. The voltagestored in the pulse integrator is read on the energymeter calibrated in watt-sec.
Besides determining the value of delivered energyfrom a Lown or trapezoidal defibrillator, it is often
necessary to have a display of energy waveform. Thiscan be done by storing the waveform in digitalmemory and getting it out with a time expansionthrough a digital to analog converter for convenientrecording on a standard ECG machine.
Input wave forms to defibrillator unit
1) For slower heart rate:
Graph 2.1: waveforms for slower heartrate
2) For faster heart rate:
Graph 2.2:waveforms for faster heartrate
Table No. 1: Result Table
Cases Heart
rate
(per min)
Energy
( volts)
Energy
(joules)
1.Normal 65 -
8/7/2019 Intelligent Defibrillato New
http://slidepdf.com/reader/full/intelligent-defibrillato-new 7/8
1.Bradycardia 33 32.Tachycardia 100 63.Atrialfibrillation
118 11
4.Ventricular fibrillation
140 19
E=1/2 CV2 ----------------------------- (3)
C =16 µF, V= Applied voltage in Volts
E = Energy in Joule
Graph No. 2.3: heart rate Vs different conditions
3. Conclusions
3.1 Conclusion
In the modern times we have gained the pace to reachour goals but in the journey we have also closed onthe many life threatening diseases. The rise of heartattack fatalities has also gone up alarmingly.
We have just seen a device that will help treat a patient who has just suffered from ventricular fibrillation or ventricular tachycardia within fewminutes of the mishap. This increases the chances of the patient to survive the fatality.
We have studied the block diagram and operation of Automated External De-Fibrillation (AED).
3.2. Future Scope
• GSM interface for notification on usage
One can give a GSM interface so that it indicationwhen the device is used, to
Pre-fed numbers. The voice would be a prerecordedvoice message which would give the location of thedevice so that the emergency service can reach theexact location of the fatality.
This will help the person on the site other than the patient. The helper doesn’t have to think of calling anambulance. This is done automatically. The systemalso informs the closed ones of the patient if thedevice is used at home.
3.3 Applications
1. Fitness Center and Health clubs.
2. Ambulance, Fire fighting crew.3. Government offices, corporate offices.
4. Restaurants, Airport, Hotels.
5. Shopping Centers, Sports Stadiums.
6. Schools, Universities, Community Centers.
7. Fitness Center and Health clubs.
4. Bibliography
1.Handbook of biomedical instrumentation by R.S.
khandpur (pn 714-727)
2. Healthy heart handbook for women by Marian
8/7/2019 Intelligent Defibrillato New
http://slidepdf.com/reader/full/intelligent-defibrillato-new 8/8
Sandmaier.
3. State of heart by Larry W.Stephenson
4. The heart by Matthias Rath
5. Understanding heart diseases by Arthur Selzer