lungmodelproject homework bme382

8/13/2019 Lungmodelproject Homework Bme382

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BME 382 Engineering Models of Physiological Systems

Project on Lung Model with Distributed l!eoli

Note: Answers are in red

Use your SIMULINK Lung Model to answer the following questions.(An outline of SIMULINK model is attached as a figure at the end of this ro!ect descrition."

Part "# $niform Lung res%onding to different &'ygen Demands

#hen the demand for o$ygen increases from your %ody organs & in articular' during

muscular e$ercise & then your ulmonary and cardioascular systems must ad!ust to roide anddistri%ute an o$ygen suly equal to the increased demand. )our autonomic control systems

will ad!ust %oth your cardiac outut and your entilation. #e already *now that the autonomic

controls sense arterial %lood ressure and use that to control the circulation. +U, -. What

particular variable could your autonomic system sense in order to most sensitively control

ventilation?

otential aria%les that the autonomic system might %e a%le to sense include/" Mi$ed enous 01 in the %lood coming out of the main ulmonary artery.

1" Arterial 01 in the %lood running through the main arteries.

2" ercent 3emoglo%in Saturation in mi$ed enous %lood.4" ercent 3emoglo%in Saturation in arterial %lood.

It would %e useful to see how these aria%les change when you ary the o$ygen demand' %ut*ee the cardiac outut and the entilation unchanged. #hy *ee 50 and 6A fi$ed 7 ,hat

will allow you to see the ure effect of a change in o$ygen demand & which your %ody would

then use to alter 6A and 50.

Use your lung model with uniform distri%ution of %oth entilation and erfusion to fill in the data

in the following ta%le:

(es%onse of $niform Lung to )arying &'ygen Demand *

while +& and ) remain constant at +& ,-./ L0min and ) , - L0min

0$ygen 8emand

(millimoles9min"

6enous 01

(mm3g"

Arterial 01

(mm3g"

6enous 3% Sat

(ercent"

Arterial 3% Sat

(ercent"

;;..


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L0, all of these aria%les on a grah li*e the one shown %elow FF

1uestions to Discuss Based on the (esults Shown in this Plot#

A" #hich aria%le is the least sensitiveto changes in o$ygen demand7 #hich is the mostsensitive?

,he aria%le that is least sensitie is the enous Arterial 3% Saturation. ,he aria%le that

is most sensitie is the arterial 01' %ecause it has the stee deth sloe' therefore if any

change haen it will cause a sensitie reaction.

+" As you thin* a%out how your %odyGs autonomic control system might hae %eenHdesigned' which aria%le would %e the %est sensor to roide feed%ac* that will %e

used to control entilation 7 FF the one that is least sensitie or the one that is most

sensitie 7 @ELAIN your choice.

,he aria%le that would %e the %est sensor to roide feed%ac* that would %e used control

entilation is arterial 01' which is most sensitie. 6entilation is the rate at which gas isenters and leaes the lungJ thus as entilation changes the %ody must ad!ust to

counter%alance the change.

5" 8uring an oeration when you are under full anesthesia' your entilatory control system

does not wor* well. 5onsequently' the anesthesiologist monitors your entilatory state

and then ad!usts the degree of mechanical entilation he roides. ,he anesthesiologistuses an oximeteras his sensor. ,his is a deice attached to the ti of one of your fingers

that shines red light through the tissues in your finger. As the ercent saturation of


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hemoglo%in changes' 3% changes the colors it a%sor%s from this light. ()ou see this

commonly as arterial %lood haing a redder color than enous %lood." ,he

anesthesiologist uses this measure of arterial 3% saturation to control entilation foryou. 50MA@ how good a measure the anesthesiologist is using as a feed%ac* signal

that he monitors to the feed%ac* signal you suggested in art +. #ill his signal wor* as

well as the one you suggested7 If not' what might the anesthesiologist need to %e alertfor7

5omared to art + the anesthesiologist does not hae a good feed%ac* if he is using the arterial 3% saturation to control entilation. rom loo*ing at igure / grah a%oe' the

arterial 3% saturation is not as sensitie for a feed%ac* as the arterial 01. Arterial

01 is a good feed%ac* signal that monitors me during an oeration. +ecause the arterial

01 is sensitie it will alert the anesthesiologist if there is a decrease in the entilation.

8" ead a%out the carotid sinus & an organ in your %ody & and comment on how well it is

suited to its hysiological role.

A carotid sinus is at the origin of the internal carotid artery located in the human nec*.,he carotid sinus is well suited to its hysiological role %ecause it contains numerous

%arorecetors (sensor located in the %lood essel that detects the ressure of %lood

flowing". H,he sensor can send a message to the central nerous system (5NS" toincrease or decrease total eriheral resistance and cardiac outut (Wikipedia". ,his

shows how the sinus is needed to human surial.

Part 2# (es%onse of a uniform lung to breathing at high altitude

At /1'>>> feet' which is a common altitude for hi*ers in the oc*y Mountains' the artial

ressure of o$ygen in the insired air has declined to />> mm3g. ,o see how a healthy' uniformlung will resond to this challenge' fill in the data in the following ta%le %y using your

SIMULINK model:

01 insired air

mm3g

6entilation

L9min

5ardiac 0utut

L9min

Arterial 01

mm3g

Arterial 3% Sat

ercent

/ < > < > /> > < //.1 24.42 ?1.2

1uestions to answer in your discussion#

/" 5omment on how well increasing entilation counteracts the challenge of high altitude

ersus how well increasing cardiac outut does.

As the entilation increases and the cardiac outut remains the same' thus the arterial

01 increases. ,he reason why is %ecause since there is an increase in air flow thus'


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arterial 01 will counteract the more inta*e of 01 into the %lood. #hen cardiac outut'

which is %lood flow increases the arterial 01 will remain close to arterial 01 that has a

lower insired air.

1" +ased on your understanding of gas e$change in the lung' @ELAIN why one

comensation (increasing 50 or 6A" wor*s %etter than the other. (3IN,: recall thematerial %alance equation that we used to calculate the flu$ of 01 deliered %y an

aleolus."

)+F 5A"B lu$ (moles of 01 deliered er minute" B (5a F 5"

,he comensation that wor*s %est according to the equation is 6A' %ecause 6A is the

concentration of air flow it will increase as the concentration of insired air decreases.

Part 3# a 4&4 5$46&(M L$47 55 (e%onse to a Pulmonary Embolism

Use your SIMULINK model to study the effect of a %lood clot that may trael from where itformed in a systemic ein (often in a leg" through the right heart and into the ulmonary arteries.

,he %lood clot cannot ass along as the ulmonary arteries %ranch and narrow' so eentually it%ecomes lodged in a smaller ulmonary artery. ,he clot then %loc*s all %lood flow downstream

to aleoli that would normally hae %een fed from the %loc*ed artery.

,o simulate this in your model' alter the distri%ution of erfusion in your distri%uted Lung

SIMULINK model. Ma*e ,#0 of the aleoli receie only a >.>>>>/ fraction of the total

cardiac outut (". Since the total of all the distri%utions must B /' ad!ust the other fractional

distri%utions too.

#ith the lung in this simulated N0NFUNI0M state' use your SIMULINK model to determine

the data in the ,a%le on the ne$t age:

4&45$46&(M L$47

with a %ulmonary embolism blocing blood flow to 9:; of al!eoli

Situation 6entilation

L9min

5ardiac 0utut

L9min

Arterial 01

mm3g

Arterial 3% Sat

ercent

UNI0MLUN

<


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,he method of 4> em%olism D increased 6A showed an increase in arterial 01 %ac* to almost

uniform lung. ,he reason why is %ecause as entilation increases' thus the arterial 01 increases.

6A and arterial 01 are directly roortional to each other. ,he %lood clot will cause 4> of thealeoli to %e %loc*edJ this is shown %y changing . as goes from high concentration to low

concentration' so ressure will reach equili%rium' %y increase 6A.

Part 9# a 4&4 5$46&(M L$47 55 (e%onse to a Broncho5S%asm5hronic o%structie ulmonary disease (508" is one of the main causes of limited lifeF

style and een death. In some cases' the disease is not uniform and only arts of the lung are

affected. ,he ro%lem reoles around a constriction of airways %y inflammation or actie

contraction of the smooth muscle surrounding the airways.

)ou will model this in your SIMULINK model %y altering the distri%ution of entilationin your model. Ma*e ,#0 of the aleoli receie only a >.>>>>/ fraction of the total

entilation (6A". Since the total of all the distri%utions must B /' ad!ust the other fractional

distri%utions too. @M@M+@ to reset the distri%ution of erfusion to N0MAL (i.e.' undo

the changes you made for art 2."

#ith the lung in this simulated N0NFUNI0M state' use your SIMULINK model to determinethe data in the ,a%le %elow:

4&45$46&(M L$47

with a broncho5s%asm blocing !entilation to 9:; of al!eoli

Situation Insired

01

6entilation

L9min

5ardiac 0utut

L9min

Arterial 01

mm3g

Arterial 3%

Sat

UNI0M LUN / <


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