BME 320 final

A more accurate way of measuring the mean electrical axis would be to

add the QRS potentials for the two leads, instead of only the R wave

Einthoven's triangle

allow us to determine the mean electrical axis of the heard, this electrical axis can be thought of as a dipole

The lungs operate in this network of functions by

allowing us to inhale a volume of air.

Filters can be

analog or digital

A first order filter is a type of linear time - invariant system that

attenuates or amplifies different frequency components of a signal.

As sound wave propagates through a medium, it

attenuates, or loses intensity, but maintains its frequency. If the waves hit a stationary object, part of the signal waves reflect back and is used in sonography images. moving objects reflect a different frequency which depends on the velocity of the target.

Ultrasounds

behaves like sound waves but has a shorter wave length, meaning it can reflect off very small surfaces

Senor / Actuators

examples of transducers sensors senses a signal actuator actuates or moves

Ficks method

is a minimally invasive method which measures the cardiac output. This is an indirect method of flow measurement, not vey accurate. involve taking blood samples from main artery and pulmonary artery using a catheter and uses a spirometer.

Wheatsone bridge

is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit. provides extremely accurate measurements

Ultrasound blood flow measurement is widely used in

medical diagnostics, such as assessing the blood flow in arteries and veins, detecting abnormalities like blockages or narrowing, and evaluatung the fuctions of the heart.

Analog filters consists of

multiple stages of resistor, capacitor, and incuctors such as RC,RL, or RLC circuits

Cardiac electrical activity

muscular organ composed of differentchambers (atria and ventricles) that contract and relax to pump blood through the body.These contractions are initiated and coordinated by electrical signals generated byspecialized cardiac cells.

pulse pressure =

sysolic - diastolic

Mean Arterial Pressure (MAP)

1/3(systolic) + 2/3(diastolic)

Common mode gain

(R1*R4 - R2*R3)/R1(R2+R4)

Typical amplitudes are aaround

1mV for top of Q 0.2-0.3mV for T 0.1-0.3mV for P

CMRR =

20log(diff gain / common gain)

Gain

= Output/input

what principle is ficks method based on

It is based on the principle of mass conservation. with a unit of L/min

QRS Complex

Reflects ventricular depolarization and atrial repolarization. The QRScomplex is larger and more complex due to the larger mass of ventricular tissues.

ECG contains

a baseline wander, contaminated with 60 Hz noise. ECG frequency is much lower than 60Hz muscular twich and impact the ECG

Resistance of flow in blood vessels = 8PL/pi*r^4

a blockage where r = r/2 will increase the resistance by a factor of 16.

Digital filters

High degree of flexibility achieve precise and consistent filtering characterostic, not affected by component tolerances or aging Digital filter designs and settings can be stored and reproduced Can be adaptive(parameters are easily adjustable) well-suited for more complexx signal processing such as spectral analysis, time-frequency analysis, and feature extraction, makingthem versatile for advanced biomedical data analysis

Accuracy

How true a value is

Standard lim leads :

Lead 1 : right arm (-) to left arm (+) Lead 2: right arm(-) to left leg(-) lead 3: right arm (-) to left leg(+)

Lead II =

Lead I + Lead III

Given RA,LA,LL whats are the leads

Lead I = LA-RA Lead II = LL-RA Lead III = LL - LA

Path of Data Acquisition

Physiological signal> Amp >Filter > A/D > Discrete Filtering > memory/display

The basic equation for ficks methos is Q =(V*O2)/(Ca-Cv) can you define the terms

Q is the cardiac output V*O2 is the rate of oxygen consumption Ca is the oxygen content in arterial blood Cv is the oxygen content in the venous blood

P wave

Represents atrial depolarization as the electrical impulse spreads from the SA node to the atria.

Common causes of hypertension:

Resistance of artery wall increase.

The primary components of the hearts electrical eyetem are:

SA node ( natural pacemakers, generates electrical impulses that initiate heartbeats) AV node(acts as a relay station, delaying the electrical signal before transmitting it to the ventricles) Bundle of his and Purkinje Fibers(These structures distribute the electrical impulses throughout the ventricles,causing their contraction)

T wave

Signifies ventricular repolarization, the recovery of electrical charges in theventricles.

pros and cons of BP methods

Stethiscope, indirect and non invasive, requires ear training and subjective Oscillatory method, automated process invasive is the most reliable, requires catheter to be inserted to the blood stream or heart.

What is the main goal of the cardiac cycle

The main goal of the cardiac cylce is to deliver oxygen and nutrients to the body.

Forced Vital Capacity (FVC)

This evaluation monitors the amount of air a person can move in and out of their lungs.

what does it mean when the absorption coefficient is proportional to frequency?

This implies that lower frequency has lower absorption, meaning for deeper penetration of the wave in the body, lower frequency must be used

Doppler untrasound is an

Ultrasound blood flow measurement, which is non-invasive technique to assess blood flow in the human body.

Differential Gain

Vout / (V2-V1)

vital signs

a pressure is exerted on the walls of the arteries by the blood is the pulsatile pressure

Filters and Amplifiers

are among the most timportant components of data acquisition and processing units.

What type of blood do arteries and veins carry

arteries carry oxygenated blood veins carry deoxygenated blood

pressure represents the force exerted by the fluid on the walls of the container or vessel, what does it mean in the circulatory system

blood pressure is the force exerted by the blood against the walls of the blood vessels

Bifircation

branching, observed in nature to optimal delivery of resources

ECG records the heart's electrical activity

by measuring the voltage differences on the skins surfacese that result from the collective depolarization and repolarization of cardiaccells.

Voltage of the ECG signal can vary depending on the location of the electrods

closer to the heart the potentials can be as high as 5 mV

OP Amp

configured so that the negative and positive imput voltages of the opamp are kept equal by the net currents produced by theinput and output voltages flowing through the external resistors. 2. The operational amplifier has a high gain. 3. The operational amplifier has a high input impedance and zero outputimpedance. Therefore, there is no current entering the input terminals of theamplifier

Transducer

converts one energy to another

power of the ultrasound

decays exponentially

The doppler equation relates the

frequency shift, velocity of the blood cells, and the ffrequency of the transmitted ultrasound waves

ECG or EKG

fundamental diagostic tool which analyzes the electrical activity of the hear

aliasing

high frequency components can fold back into the desired frequency range.

A sphygomomanoter(blood pressure cuff)

is an indirect and noninvasive, which are easy to prevent death due to hypertension

Flow = volume/time(L/min)

is hard to measure

Pressure is not a DC signal,

it is a time varying signal

Digital filters are

just a computer algorithm that works on discrete data, such as FIR filters

A stethoscope is used to listen to the

korotkft sounds

First order filters are implemented as

low-pass or high-pass filters. The key characteristic of first order filter is its frequency response.

A good amplifier should

make a desired potential difference larger, and reduce the artificat or noise

Ficks mothod assumes steady-state

meaning that the oxygen consumption and blood flow rates remain relatively constant during the measurement.

is the measurement of flow or blood pressure more challenging

measurement of flow

In a balanced bridge, there is

no current throught the middle terminals bc the voltages are equal

Can the stroke volume be measured without a catheter

no, it needs a catheter inserted in the left ventricle.

High blood pressure(hypertension)

occurs when systolic is above 140 and diasytolic is above 90

blood pressure is depended

on the area of where it is being measured.

The doppler effect is a

phenomemon where the frequency of a wave appears to change when observed from a moving source or bobserver.

how is the pulmonary circuits of blood an exception

pulmonary artery carry deoxygenated blood to the lungs and pulmonary veins return oxygenated blood from lungs

Ventilation

refers to the moving air in and out of the lungs.

When ultrasound waves encounter moving blood cells, the waves are

reflected back with a frequency shift. This shift is proportional to the velocity of the blood cells

first order high pass filters

remove low frequencies, employed to eliminate baseline wonderor slow variations in a signal, making it easier to analyze rapid physiologicalchanges.

first order Low pass filters

removes high frequency noises from physiologicalsignals or for smoothing data to remove high-frequency fluctuations.

PQ interval

represents time between artial contraction and beginning of ventricular contraction around 0.16sec

QT interval

represents time between ventricular conraction and ventricular repolarization 0.35s

ultrasonic vibration

requires an elastic medium such as liquid or solid

Polarization and depolarization

rest(polarized) during activation(depolarized) The depolarization wave representsthe electrical activity associated with the contraction of the heart chambers repolarization refers to the restoration of the resting state.

High blood pressure has been correlated with an increased

risk for man y diseases like stroke, heart attack, cardiovascular disease, and kidney failure.

An ideal voltmeter

should have an infinite resistance

An ideal ammeter

should have no internal resistance

Blood flow in the body

starts at the heart and is pumped from the left ventricles through the aorta to the tissues, comes back to heart through the viens, to the right atrim to the right ventricle to the pulmonary arteries in the lungs where gas exchange occures, and to the pulmonary viens to the left atrium to the left ventricle

CO can be found by using

stroke volume * Heart rate

Normal ranges of blood pressure

systolic : 120-130 mmHg diastolic: 80 - 85 mmHg

Blood pressure consists of 2 numbers

systolic and diastolic pressures

What does the law of conservation of mass state

the amount of a substance in a closed system remains constant over time if there is no addition or removal of the substance.

Common location of measireing the blood pressure is

the brachiel artery because it is the same level of the heart.

Change in pressure = flow*resistence

the change in pressure causes a flow

The alveoli in the lungs are responsible for

the transfer of oxygen to the blood stream and carbon dioxide out of the blood stream.

As the heart beats and forces blood into the systematic vessels

they expand to accommodate the pulse of blood during systolic pressure and contract during diastolic pressure to supply the body with a constant blood flow

Purpose of filters

to shape and improve the quality of a phisological signal.

Blood pressure is analougous

to the pressure of a fluid in a closed system

Respiration consists of

ventilation, gas transfer and transport, and the control of breathing

tidal volume

volume of air that enters or leaves the lungs during a single breath.

Stroke volume is the

volume of blood ejected from the left ventricle in one contraction

Cardiac Output-CO

volume of blood pumped by the heart per unit of time.

if R1*R4 = R2*R3

vout = (R3/R1)(V2-V1)

The equation of the doppler shift is Δf = 2f0 * (v*cos(θ)/c) can you explain what each term is:

Δf is the doppler shift f0 is the frequency transmitted v is the velocity of the blood cells θ is the angke between the direction of blood flow and the ultrasound beam c is the speed of sound in the medium

equation for an ultrasound is λ=C/f

C is the velocity of the sound and f is the frequency

Analog Filters characteristics

Can process in real time, advantageous for certain applications where low latency is critical, important in feeback systems No aliasing straightforward to implement. more power efficient, essential for battery powered medical devices

What can decrease the elastic property of the lungs making it harder to fill them with air

Cigarette smoking and lung cancer

ideal filter

Fpass = Fstop