alterations in oxygenation 3

8/8/2019 Alterations in Oxygenation 3

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Alterations in OxygenationAlterations in Oxygenation

NeonateNeonate


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A. Congenital Heart Diseases andA. Congenital Heart Diseases and

DefectsDefectsNeonateNeonate

Third week gestation, a functionalThird week gestation, a functionalcardiovascular system was developed tocardiovascular system was developed to

support further development of the embryosupport further development of the embryo

Seventh week gestation, partitioning of theSeventh week gestation, partitioning of theheart, is completedheart, is completed


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Congenital Heart Diseases and DefectsCongenital Heart Diseases and Defects Congenital Heart DefectsCongenital Heart Defects

-- are anatomical abnormalities in the heart that areare anatomical abnormalities in the heart that arepresent at birth.present at birth.

-- the incidence of CHD is approximately 1% of birthsthe incidence of CHD is approximately 1% of birthsand it is the second major cause of death in the first year ofand it is the second major cause of death in the first year oflifelife

-- the causes of congenital heart defects are unknown,the causes of congenital heart defects are unknown,but both genetic and environmental factors influence thebut both genetic and environmental factors influence thedevelopment of CHDsdevelopment of CHDs

-- other factors linked to CHDs include maternalother factors linked to CHDs include maternalalcoholism, maternal rubella infection, maternal diabetesalcoholism, maternal rubella infection, maternal diabetes

mellitus, maternal use of certain medications, includingmellitus, maternal use of certain medications, includinganticonvulsants, Warfarin (Coumadin), Isotretinoinanticonvulsants, Warfarin (Coumadin), Isotretinoin(Accutane) and exposure to X(Accutane) and exposure to X--rays.rays.

-- prematurity, low birth weight, and congenitalprematurity, low birth weight, and congenitalinfections can also increase the risk for congenital heartinfections can also increase the risk for congenital heartdefectsdefects


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Two Classifications of Congenital HeartTwo Classifications of Congenital Heart

DefectsDefects1. Acyanotic heart disease1. Acyanotic heart disease

-- involves heart or circulatory anomaliesinvolves heart or circulatory anomalies

that involve either a stricture to the flow ofthat involve either a stricture to the flow ofblood or shunt that moves blood from theblood or shunt that moves blood from thearterial to the venous system (oxygenatedarterial to the venous system (oxygenatedto the unoxygenated blood or left to rightto the unoxygenated blood or left to right

shunts)shunts)-- these disorders cause the heart tothese disorders cause the heart to

function as an ineffective pump and makefunction as an ineffective pump and makethe child prone to heart failurethe child prone to heart failure


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2. Cyanotic heart disease2. Cyanotic heart disease

-- occurs when blood is shunted from theoccurs when blood is shunted from thevenous to the arterial system as a result ofvenous to the arterial system as a result of

abnormal communication between the twoabnormal communication between the two

chambers or vessels of the heartchambers or vessels of the heart

(deoxygenated blood to oxygenated blood;(deoxygenated blood to oxygenated blood;right to left shunts)right to left shunts)

This type classification although helpful is notThis type classification although helpful is not

accurate because children with acyanotic heartaccurate because children with acyanotic heart

disease can develop cyanosis and childrendisease can develop cyanosis and children

with cyanotic heart disease may not exhibitwith cyanotic heart disease may not exhibit

cyanosis until they are seriously ill.cyanosis until they are seriously ill.


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Four Classifications of CongenitalFour Classifications of Congenital

Heart DefectsHeart Defects-- this set of classifications for congenital heartthis set of classifications for congenital heartdefects addresses the hemodynamic anddefects addresses the hemodynamic andblood flow patterns of the defects; andblood flow patterns of the defects; and

allowing a more predictable set of signs andallowing a more predictable set of signs andsymptomssymptoms

1. Defects with Increased Pulmonary Blood flow1. Defects with Increased Pulmonary Blood flow

2. Defects with Obstruction to Blood Flow2. Defects with Obstruction to Blood Flow3. Defects with Mixed Blood Flow3. Defects with Mixed Blood Flow

4. Defects with Decreased Pulmonary Blood4. Defects with Decreased Pulmonary BloodF

lowF

low


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Fetal CirculationFetal Circulation


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1. Defects with Increased Pulmonary1. Defects with Increased Pulmonary

BloodF

lowBloodF

low-- congenital heart disease associated withcongenital heart disease associated withincreased pulmonary blood flow involves bloodincreased pulmonary blood flow involves bloodflow from the left side of the heart, which is underflow from the left side of the heart, which is undergreater pressure, to the right side of the heart,greater pressure, to the right side of the heart,which is under less pressure, through abnormalwhich is under less pressure, through abnormalopenings between the two systems or the greatopenings between the two systems or the greatarteries.arteries.

a. Patent Ductus Arteriosusa. Patent Ductus Arteriosusb. Atrial Septal Defectb. Atrial Septal Defect

c. Atrioventricular Canal Defectc. Atrioventricular Canal Defect

d. Ventricular Septal Defectd. Ventricular Septal Defect


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a. Patent Ductus Arteriosusa. Patent Ductus Arteriosus

Ductus ArteriosusDuctus Arteriosus

-- is an accessory fetal structure that connectsis an accessory fetal structure that connectsthe pulmonary artery to the aorta.the pulmonary artery to the aorta.

-- it is necessary for survival of the fetusit is necessary for survival of the fetusintrauterineintrauterine

-- for preterm infant, it is a common findingfor preterm infant, it is a common findingsimply because of developmental immaturitysimply because of developmental immaturity

-- for term newborn, the ductus arteriosusfor term newborn, the ductus arteriosusbegins to close within twelve hours and should bebegins to close within twelve hours and should becompletely closed by 2completely closed by 2--3 weeks to 3 months of3 weeks to 3 months ofage.age.


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Patent Ductus ArteriosusPatent Ductus Arteriosus

-- a ductus arteriosus that remains open, in aa ductus arteriosus that remains open, in afull term baby after several weeks of life or until 3full term baby after several weeks of life or until 3months of agemonths of age

-- the ductus remains open, blood will shuntthe ductus remains open, blood will shunt

from the aorta into the pulmonary artery due to thefrom the aorta into the pulmonary artery due to thedecrease in pulmonary vascular resistancedecrease in pulmonary vascular resistance

-- LeftLeft--toto--right shunting of blood caused byright shunting of blood caused bypatency of the ductus arteriosus results inpatency of the ductus arteriosus results in

increased pulmonary artery blood flow as well asincreased pulmonary artery blood flow as well asleft atrial and left ventricular overloadleft atrial and left ventricular overload


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-- in this condition, blood will shunt from thein this condition, blood will shunt from the

aorta (oxygenated blood) to the pulmonaryaorta (oxygenated blood) to the pulmonary

artery (deoxygenated blood) because ofartery (deoxygenated blood) because of

increased pressure in the aorta; the shuntedincreased pressure in the aorta; the shunted

blood returns to the left atrium of the heart, outblood returns to the left atrium of the heart, out

to the aorta and again to the pulmonary arteryto the aorta and again to the pulmonary artery-- the degree of shunting depends on thethe degree of shunting depends on the

size of the patent ductus arteriosus as well assize of the patent ductus arteriosus as well as

the pulmonary vascular resistancethe pulmonary vascular resistance

-- this causes right ventricular hypertrophythis causes right ventricular hypertrophy

and increased pressure in the pulmonaryand increased pressure in the pulmonary

circulation from the extra shunted bloodcirculation from the extra shunted blood


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Altered HemodynamicsAltered Hemodynamics

-- the hemodynamic consequences ofthe hemodynamic consequences of

PDA depends on the size of the ductusPDA depends on the size of the ductus

arteriosus and pulmonary vasculararteriosus and pulmonary vascularresistanceresistance

-- a small ductus offers high resistance toa small ductus offers high resistance to

flow, limiting the volume of the shuntedflow, limiting the volume of the shunted

bloodblood


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-- at birth the resistance in the pulmonary andat birth the resistance in the pulmonary and

systemic circulations is almost similar, equalizingsystemic circulations is almost similar, equalizing

the resistance within the aorta and pulmonarythe resistance within the aorta and pulmonary

artery. However, as the pulmonary resistance falls,artery. However, as the pulmonary resistance falls,

blood is then shunted from the aorta to theblood is then shunted from the aorta to the

pulmonary arterypulmonary artery

-- the additional blood is recirculated throughthe additional blood is recirculated through

the lungs and returned to the left atrium and leftthe lungs and returned to the left atrium and left

ventricle.ventricle.

-- this increases workload on the left side of thethis increases workload on the left side of theheart, increased pulmonary vascular congestionheart, increased pulmonary vascular congestion

and potentially increased right ventricular pressureand potentially increased right ventricular pressure

and hypertrophyand hypertrophy


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IncidenceIncidence

-- the incidence of patent ductusthe incidence of patent ductus

arteriosus in a nonarteriosus in a non--premature infant ispremature infant is

approximately 5 to 10% of all congenitalapproximately 5 to 10% of all congenitalheart defectsheart defects

-- the incidence in the premature infant isthe incidence in the premature infant is

dramatically higher at 45% fin infants whodramatically higher at 45% fin infants who

weigh less than 1.750 grams and up to 80%weigh less than 1.750 grams and up to 80%

in infants weighing less than 1000 grams.in infants weighing less than 1000 grams.


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Clinical ManifestationsClinical Manifestations

-- the turbulent flow of blood from thethe turbulent flow of blood from the

aorta through the patent ductus arteriosus toaorta through the patent ductus arteriosus to

the pulmonary artery result in characteristicthe pulmonary artery result in characteristicmachinery like murmur, which is heardmachinery like murmur, which is heard

best at the middle to upper left sternalbest at the middle to upper left sternal

borderborder

-- widened pulse pressurewidened pulse pressure


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Assessment and DiagnosisAssessment and Diagnosis

*physical examination*physical examination-- on physical examination, the childon physical examination, the child

usually has a wide pulse pressure; the diastolicusually has a wide pulse pressure; the diastolic

pressure ( a measure of peripheral resistancepressure ( a measure of peripheral resistance

is low because of the shunt or runoff of bloodis low because of the shunt or runoff of bloodwhich reduces resistance).which reduces resistance).

-- a typical continuous (systolic anda typical continuous (systolic and

diastolic) machinery murmur will be heard atdiastolic) machinery murmur will be heard atthe upper left sternal border or under the leftthe upper left sternal border or under the left

clavicle in older childrenclavicle in older children


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*electrocardiography*electrocardiography

-- an ECG is generally normal,an ECG is generally normal,although it may demonstrate ventriclealthough it may demonstrate ventricle

enlargement if the shunt is largeenlargement if the shunt is large

*echocardiography*echocardiography

-- Echocardiography provides goodEchocardiography provides good

visualization of the open vesselvisualization of the open vessel

*radiography*radiography

-- Chest XChest X--ray is usually normal andray is usually normal and

diagnosis is generally made withdiagnosis is generally made with

echocardiographyechocardiography


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Therapeutic ManagementTherapeutic Management

* Pharmacologic and Medical Management* Pharmacologic and Medical Management

-- Medical management for the pretermMedical management for the preterm

infant may consist the administration of oral orinfant may consist the administration of oral or

IV Indomethacin, a prostaglandin inhibitorIV Indomethacin, a prostaglandin inhibitor

-- this lowers the PGE level and leadsthis lowers the PGE level and leads

to closure of the ductus arteriosusto closure of the ductus arteriosus

-- this drug can be repeated as manythis drug can be repeated as manyas three times 12 to 24 hours apartas three times 12 to 24 hours apart


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*Surgical Management*Surgical Management

-- if the medical management fails, the defect can beif the medical management fails, the defect can be

closed by insertion of Dacronclosed by insertion of Dacron--coated stainless steel coils bycoated stainless steel coils byinterventional cardiac catheterization when the child is 6 months tointerventional cardiac catheterization when the child is 6 months to

1 year1 year

cardiac catheterization:cardiac catheterization:

: a procedure in which a small radiopaque: a procedure in which a small radiopaque

catheter is passed through a major vein in the arm, leg pr neck intocatheter is passed through a major vein in the arm, leg pr neck into

the heartthe heart

: this procedure may be done as ambulatory or: this procedure may be done as ambulatory or

1 day surgery using conscious sedation1 day surgery using conscious sedation

: patients scheduled for cardiac catheterization: patients scheduled for cardiac catheterizationare kept NPO to 4 hours before the procedure to reduce theare kept NPO to 4 hours before the procedure to reduce the

danger of vomiting and aspiration during the proceduredanger of vomiting and aspiration during the procedure

: in neonates, an umbilical artery can be: in neonates, an umbilical artery can be

catheterizedcatheterized


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-- large defects can be closed surgicallylarge defects can be closed surgically

by ductal ligationby ductal ligation

:this involves major surgery:this involves major surgerybecause opening the chest (thoracotomy)because opening the chest (thoracotomy)

and manipulating the great vessels areand manipulating the great vessels are

necessary.necessary.


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Nursing ConsiderationsNursing Considerations

-- asses for possible side effects ofasses for possible side effects ofIndomethacin therapy, including reducedIndomethacin therapy, including reducedglomerular filtration, impaired platelet aggregationglomerular filtration, impaired platelet aggregationand diminished gastrointestinal and cerebral bloodand diminished gastrointestinal and cerebral bloodflowflow

-- ensure aseptic technique in the surgical andensure aseptic technique in the surgical andinvasive managementinvasive management

-- instruct patient scheduled for cardiacinstruct patient scheduled for cardiaccatheterization to be on NPO 2 to 4 hours beforecatheterization to be on NPO 2 to 4 hours before

the procedurethe procedure-- do not draw blood specimens form thedo not draw blood specimens form the

projected catheterization entry site before theprojected catheterization entry site before theprocedureprocedure


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Nurses have open hearts; hearts thatNurses have open hearts; hearts that

openly render services to patientsopenly render services to patients

alterations in oxygenation 3

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