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Cardiac Output AndHemodynamic Measurements

Iskander Al-Githmi, MD, FRCSC,

FCC Asst! ro"essor o" Sur#ery

$in# A%dula&i& 'ni(ersity

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Adol" )u#en Fick * + . / +.0+1

http://www.answers.com/main/Record2?a=NR&url=http%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FImage%3AAdolf+Fick.png

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Historical erspecti(e

2 Adol" Fick3 + .- +.0+2 4orn in Sep! + ., in $assel, Germany

2 )arned MD in + 5+2 + 55- Introduced a la6 o" di""usion called

Fick la6 o" di""usion

2 + 70- 8as the "irst one to de(elop atechni9ue "or measurin# cardiac output

2 Fick 6as died in Au#! +.0+

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Cardiac Cycle

2 hase +3 Atrial contraction2 hase 3 Iso(olum contraction2 hase :3 Rapid e;ection2

hase 3 Rapid "illin#2 hase 73 Reduced "illin#

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Cardiac output

2 ?olume o" %lood e;ected "rom le"t (entriclein one minute

2It is the determinant o" #lo%al o=y#entransport "rom the heart to the %ody

2 It re"lects the e""iciency o" cardio(ascularsystem

2 @here no a%solute (alue "or cardiac outputmeasurement

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Cardiac output in"luencin# "actors

?entricular reload- ?olume o" %lood in the (entricle at the end o"

diastole- Any chan#es in the (entricular preload 6ill a""ect

the (entricular stroke (olume

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Cardiac output in"luencin# "actors

?entricular reload

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Frank- Starlin# Mechanism

2 @he a%ility o" the heart to chan#e its "orceo" contraction and there"ore stroke (olumein response to chan#es in (enous return

I!) * the #reater the diastolic (olume or "i%erstretch at the end o" diastole the stron#er

the "orce o" contraction at systole2 @he "orce o" contraction 6ill decline once

this physiolo#ical limit has reached

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Frank-Starlin# s Mechanism

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Cardiac output in"luencin# "actors

reload assessment2 It has %een (ery di""icult to measure the "i%er

len#th or (olume at the %edside2 It is clinically accepta%le to measure preload as

a pressure!2 C? is used to e(aluate ri#ht (entricular preload

2 ulmonary artery diastolic pressure or C8are used to e(aluate the le"t (entricular preload

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Cardiac output in"luencin# "actors

Contractility2 Increased contractility, 6ill shi"t Starlin# s cur(e

to the le"t2 Decreased contractility 6ill shi"t Starlin# s cur(e

to the ri#ht

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Cardiac output in"luencin# "actors

Assessment o" contractility

2Stroke (olume *S?1 S? B )D? - )S?

2 Stroke (olume inde= *S?I1

S?I B CI HR2 e"t (entricular stroke 6ork inde= ?S8I B MA / C8 = S?I = *0!0+:>1

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Cardiac output in"luencin# "actors

A"terload2 Related to (entricular 6all stress

aplace a63 @ension *@1B r t2 A"terload per se does not

Alter preload

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Clinical Measurement o" A"terload

2 Ri#ht (entricular a"terload- ulmonary (ascular resistance * ?R1- ?R B M A - A8 CO = 0

- Eormal3 50 dynes sec cm -5

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Clinical Measurement o" A"terload

2 e"t (entricular a"terload-Systemic (ascular resistance *S?R1-S?R B MA - RA CO = 0

Eormal3 00 / + 00 dynes sec cm -5

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?entricular compliance

Compliance B ?

2 Gi(en a chan#e in the pressure cause a chan#ein the (olume

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);ection Fraction2 Is a "raction o" %lood e;ected %y the (entricle

relati(e to its end-diastolic (olume

)FB S? )D?! +00

2 );ection "raction is used as a clinical inde= toe(aluate the inotropic status o" the heart

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Methods o" calculatin# and measurin#cardiac output

Simple method32 CO B S? = HR2 S? B ml = pulse pressure2 CO B ml = pulse pressure = HR

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Methods o" calculatin# and measurin#cardiac output

Fick rinciple3 #old standardJ CO B ?O O art / O (en

Arterial O B H% = +!:< = O sat!?enous O B Mi=ed (enous %lood

?O B O=y#en consumption

2 Fick rinciple relies on the total uptake o" a su%stances %yperipheral tissue is e9ual to the product o" %lood "lo6 to theperipheral tissue and arterial / (enous concentration di""erence o"the su%stances

2 Fick cardiac outputs are in"re9uently used %ecause di""iculties incollectin# and analy&in# e=haled #as conc! In critically ill patients%ecause may not ha(e normal ?O (alue

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Methods o" calculatin# and measurin#cardiac output

@hermodilution Method2 4ased on ho6 "ast the "lo6in# %lood can dilute

the su%stances introduced into the circulation

2 Ste6art-Hamilton )9uation3 CO B I = >0 cm = t = + k

2 Area under the cur(e is in(ersely proportion tothe rate o" %lood "lo6! @his "lo6 is e9ui(alent tocardiac output in the a%sence o" shunt

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Methods o" calculatin# and measurin#cardiac output

@hermodilution Cur(e

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@hermal dilution method

imitations2 A""ected %y the phase o" respiration and should

%e measured at the same point o" respiratorycycle

2 ?ariations in the speed o" cold 6ater in;ectioncan result in altered measurement

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Eon In(asi(e Methods

Doppler Method2 4ased on measurin# the len#th o" %lood "lo6-

(elocity in the ascendin# aorta in unit time!Multiplied %y the cross- sectional area o" theaorta to #i(e stroke (olume! Multiplied to heartrate to #i(e cardiac output!

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Methods o" calculatin# and measurin#cardiac output

Impedance plethysmo#raphy

2 @his techni9ue 6as de(eloped %y EASA!

Cardiac output can %e measured acrosse=ternally electrodes! It measures a chan#in#impedance in the chest *%lood (olume1! @he rateo" chan#e o" impedance is a re"lection o" cardiac

output!

CO B Art! 4 total peripheral (asc! resistance

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Kuestions

Kuestion +Durin# a cardiac output readin# the thermistor o"

the AC measures the temperature o" the3a! 4lood%! In;ectatec! ulmonary artery %lood

d! Mi=in# o" %lood and in;ectate

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Kuestions

2 Kuestion 8hich o" the "ollo6in# statements is correct

As it relates to cardiac output cur(e La! @he lar#er the cur(e, the lar#er the output%! @he smaller the cur(e, the smaller the outputc! @he lar#er the cur(e, the smaller the output

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Kuestions

2 Kuestion :8hen patients take a spontaneous %reath,?enous return and cardiac output3

a! Increase%! Decrease

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Kuestions

Kuestion < A 50- year-old male 6ith myocardial ischemia presents 6ith

the "ollo6in#3

2 HR + 4 M2 CO >! min2 MA mmH#2 S?O 5+2 C? > mmH#

2 A8 +>2 SaO .