Bronchiolitis.pdf

7/23/2019 Bronchiolitis.pdf

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Bronchiolitis (See Also: Respiratory Syncytial Virus)

Acute lower respiratory tract infection causing obstruction of the small to medium conducting airways of the lung

GENERAL PREVENTIN

The ma!or means of pre"enting bronchiolitis is strict obser"ance of infection control# with fre$uent handwashing#

a"oidance of %nown ill contacts and crowded places# and limiting e&posure to daycare and secondhand smo%e'

EPI(E)ILG*

• +een in all geographic areas

• In the ,+# occurs from late fall through the winter and early spring' The Respiratory +yncytial Virus

-R+V. epidemic season begins earlier in the southeastern ,+# and in some areas -e'g' /lorida#

0awaii. can occur throughout the year' Parainfluen1a 2 occurs throughout the year# as does

adeno"irus' Influen1a "irus epidemics usually begin in late fall# pea% in 3anuary4/ebruary# and wane

by April' 0uman metapneumo"irus pea%s slightly later in the year -)arch. than does R+V -3anuary.'

• R+V infects most children within the 5st 6 years of life7 89: of those hospitali1ed are younger than ;

months' The infection rate is ;<'<45== in infants >5 year of age7 by 6 years of age# ?9: of children

ha"e e&perienced an R+V infection'

• R+V reinfection occurs in 8=@98: of children followed# and reinfection within the same R+V season is

possible'

• Appro&imately 546 of all children e&perience an infection with parainfluen1a 2 before 5 year of age'

• R+V infection is the leading cause of hospitali1ation in infants >5 year old and causes 56=#===

hospitali1ations per year in children >8 years of age in the ,+' 0ospitali1ation occurs in 6'< of e"ery

5#=== children with a parainfluen1a lower respiratory tract infection'

• )ortality associated with primary R+V infection in otherwise healthy children has been estimated to

be 2'5 deaths per 5==#=== personByears in infants >5 year of age# and is C5@2: among children with

underlying conditions' It is the most common "iral cause of death in infants >5 year old'

• Ris% factors for ac$uisition of R+V infectionD

5' irth during the months of April through +eptember

6' (ay care attendance or older siblings in day care

2' Frowded li"ing condition

' Lower socioeconomic status

8' E&posure to en"ironmental tobacco smo%e or other air pollutants

;' Lower cord serum R+V antibodies

9' Absence of breastfeeding

<' )ultiple births

• ,p to 8=: of infants with bronchiolitis de"elop subse$uent whee1ing'

• Patient groups at high ris% of se"ere R+V diseaseD

5' Premature infants ->2; wee%sH gestation.



6' Infants 5= wee%s of age at time of R+V infection

2' Fongenital heart disease

' Fhronic lung disease -including bronchopulmonary dysplasia JP(K.

8' Low birth weight

;' Fystic fibrosis

9' Fompromised immune function -from chemotherapy# transplant# congenital or ac$uired

immunodeficiencies.

RI+ /AFTR+

Genetics

Genetic bac%ground is unclear# but se"erity of R+V infection may be determined byD

• +ingle nucleotide polymorphisms close to the ILB< gene

• +ingle nucleotide polymorphisms close to the ILB5= gene

• "erproduction of ILB

• Polymorphisms of the surfactant proteinB( gene

• Genetic "ariants in a receptor for chemo%ines# the FF chemo%ine receptor 8

PAT0P0*+ILG*

• R+V is the most common cause of this illness -8=@?=: of those infants hospitali1ed.'

• ther agents associatedD

5' Rhino"irus

6' 0uman parainfluen1a "iruses

2' Influen1a "irus

' Adeno"irus

8' 0uman metapneumo"irus

;' Mycoplasma pneumoniae -in older children.

• R+V is transmitted byD

5' Flose contact with infected secretions# large particle aerosols# and fomites

6' +elfBinoculation of con!uncti"ae or nose with infected hands

2' +ecretions that remain infectious on countertops and stethoscopes for up to ; hours# rubber

glo"es for 5'8 hours# and on hands or tissue for C2= minutes

• Influen1a "irus and adeno"irus are spread by small droplets that remain airborne and which are then

inhaled'

• Viral sheddingD ,p to 65 days after infection# but can e&tend to se"eral wee%s or months in

immunocompromised patients



• Virus proliferates in the nasal epithelium# resulting in cory1a with profuse rhinorrhea'

• Infected secretions are aspirated into the lower respiratory tract' /rom there# "irus infects bronchiolar

epithelial cells of airways 98@2== microns in diameter'

• Infection causes necrosis and sloughing of cells into the airway lumen' There is goblet cell

proliferation and mucus hypersecretion' The airway lumen becomes filled with debris consisting of

dead cells and mucus resulting in plugging# which causes partial or complete airway obstruction#

increased airways resistance# hypo&emia# and decreased lung compliance'

• Polymorphonuclear leu%ocytes are the predominant inflammatory cell type reco"ered from

bronchoal"eolar la"age -AL. fluid of infants with documented R+V bronchiolitis7 a subset may also

ha"e an ele"ated number of eosinophils in AL fluid'

• )ononuclear cells -lymphocytes and macrophages. infiltrate the peribronchial tissue# leading to

airway wall and interstitial edema'

• R+VBinduced changes in the bronchiolar epithelium can last beyond the acute infection' Regeneration

of bronchiolar epithelium ta%es wee%s to months and lags behind clinical signs of reco"ery'

Diagnosis

0istory

• Rhinorrhea with clear to white copious nasal secretionsM

• FoughingM Initially hoarse cough for 2@8 days7 progresses to deep wet cough of increased fre$uency

• Poor feedingM Early sign of respiratory fatigue7 may lead to dehydration

• LowBgrade fe"erM Fharacteristic of disease7 not a reliable mar%er of se"erity of disease# but

contributes to increased insensible fluid loss

• Restlessness or lethargyM )ay indicate impending respiratory failure -hypo&emia and4or

F6 retention.

• ApneaM Fan be sole presenting sign in younger infants7 if respiratory distress is present# suggests

impending respiratory failure

• Fyanosis4color change or increased wor% of breathingM Impending respiratory failure

Physical E&am

• General appearanceD

5' Interacti"e "ersus illBappearing

6' Paro&ysmal cough -most common sign.# not associated with a whoopO

2' Poor oral inta%e

• 0EENT e&am

5' Nasal flaring

6' Nasal congestion with copious secretions

• Pulmonary e&amination

5' Pattern of breathingD Apnea or periodic breathing



6' TachypneaD 9=4min is associated with se"ere illness

2' Nasal flaring and accessory muscle use

' Intercostal retractions -increased resistance# decreased compliance.7 subcostal retractions

-hyperinflation.

8' Thoracoabdominal asynchrony

;' 0yperresonance to percussion

9' (iffuse# highBpitched heterophonous whee1ing

<' Prolonged e&piratory phase

?' /ine inspiratory crac%les -may be heard in both bronchiolitis and pneumonia.

5='(iffuse rhonchi

• ther findingsD

5' +igns of dehydration

6' LowBgrade fe"er

2' Tachycardia

' radycardia associated with apnea

8' Possible cyanosis of nail beds and oral mucosa

;' Li"er and spleen typically caudally displaced by hyperinflated lungs

TE+T+

LARATR*

• Pulse o&imetryD To assess o&ygenation

• Arterial blood gasD

5' (egree of hypo&emia -determine ABa gradient.

6' E"idence of respiratory failure and respiratory acidosis with F6retention -late finding.

• +erum electrolytesD +ic%est patients may ha"e +yndrome of Inappropriate AntiBdiuretic 0ormone

release and hyponatremia7 may also see abnormalities in those infants with significant dehydration7

not useful in the ma!ority of infants with milder disease

• R+V serology -acute and con"alescent serum samples.D No practical application for clinical use

• Rapid "iral identificationD

5' est samples for testingD

• Nasopharyngeal aspirate

• Nasopharyngeal wash

6' Ade$uate samples for testingD

• Nasal swab



• Tracheal aspirate

• AL fluid

• Rapid testsD

5' Immunofluorescence assay -direct or indirect.D

• <8: sensiti"ity and specificity

• Results in 8 minutes

• Negati"e predicti"e "alue <9:

6' En1yme immunoassay -EIA.D

• ;=@?=: sensiti"ity

• 9=@?8: specificity

• Negati"e predicti"e "alue 98@?<:

• Results in 58@2= minutes

• (oes not re$uire the presence of "iable "irus

2' Re"erse transcriptase polymerase chain reaction -RTBPFR.D

• ?2'8@5==: sensiti"ity

• ;2'?@5==: specificity

• Results in >5 hour

• Viral cultureD

5' Fulture of nasopharyn&

6' Fonsidered gold standard'O )ay ta%e up to 5 days for results

2' +ensiti"ity and specificity highly dependent on $uality of sample# handling of specimen# and

time to deli"ery to "irology laboratory

I)AGING

Fhest radiography findings includeD

• 0yperinflation# flattened diaphragms

• Peribronchial thic%ening

• Patchy or more e&tensi"e atelectasis

• Possible collapse of a segment or a lobe

• (iffusely increased interstitial mar%ings commonly seen

(I//ERENTIAL (IAGN+I+

• Pneumonia -"iral or bacterial.

• Asthma

• Gastroesophageal reflu& -GER.



• /oreign body aspiration

• E&posure to no&ious agents -chemicals# fumes# to&ins.

• F0/

• Fystic fibrosis

Treatment

GENERAL )EA+,RE+

• )ost cases are mild and may be treated at home'

• Ade$uate fluid inta%e

• )aintenance of nasal airway patencyD

5' +hortBterm nasal decongestant

6' +uction secretions with suction bulb

T0ER

• Fareful fluid hydration7 deficit plus C642 maintenance fluids

• +upplemental o&ygenD

5' Gi"en to any patient with hypo&emia

6' Preferably warmed and humidified by nasal cannula# head bo&# or tent

• )anagement to o"ercome airway obstructionD

5' ronchodilatorsD

• +ome -but not all. infants with bronchiolitis will impro"e clinically with

bronchodilator administration' A trial of an aerosoli1ed Badrenergic agent with

critical assessment to see if there is any relief of symptoms is reasonable'

• Infants with a prior history of whee1ing or familial history of asthma or atopy are

more li%ely to respond to bronchodilators'

• Theophylline is not usually useful as a bronchodilator in bronchiolitis# and may

potentially worsen GER# if present' It may be useful in the infant with impending

respiratory failure or apnea due to its ability to increase diaphragmatic

contractility# respiratory dri"e# and F6 responsi"eness'

6' Nebuli1ed epinephrineD

• Potentially beneficial in infants with moderate to se"ere bronchiolitis' It is both an

QB and Breceptor agonist'

• oth racemic epinephrine -='5 mL4%g of 6'68: solution. and LBepinephrine ha"e

been studied separately and showed beneficial results compared with B

agonists'

2' Anticholinergic agentsD Ipratropium bromide has not been shown to be effecti"e in the

treatment of bronchiolitis'



' ForticosteroidsD

• In pre"iously healthy infants# corticosteroids are not routinely recommended' ,se

of systemic -oral or parenteral. steroids may confer a small benefit in shortening

duration of hospital stay or symptoms ->546 day.'

• Effects of steroids may be greater in infants with more se"ere disease or

impending respiratory failure'

• ,se of inhaled corticosteroids does not decrease duration of symptoms or

recurrence of cough and whee1ing after acute bronchiolitis resol"es'

8' Leu%otriene modifiersD

• Infants who de"elop whee1ing with R+V infection ha"e high concentrations of

cysteinyl leu%otrienes and histamine in respiratory secretions'

• ne series demonstrated an increase in symptomfree days among infants who

too% montelu%ast in the month after hospitali1ation for an acute R+V infection'

• No studies ha"e e"aluated the use of leu%otriene modifiers during the acute

phase of bronchiolitis'

;' )ucolyticsD

• Recombinant human (Nase and N Bacetyl cysteine are not effecti"e in shortening

the duration of symptoms in infants with bronchiolitis'

• 0ypertonic saline -2:. aerosoli1ed in combination with epinephrine may shorten

length of hospitali1ation compared to use of epinephrine alone'

9' +urfactantD

• +hown to pre"ent progression of deterioration in lung mechanics in a small

number of infants with respiratory failure re$uiring mechanical "entilation

secondary to R+V bronchiolitis

<' 0elio&D

• 0elium@o&ygen mi&tures used in place of nitrogen@o&ygen -air. ha"e been

shown to impro"e clinical score and shorten IF, stays in small series of infants

with se"ere bronchiolitis'

• The gas does not alter the course of the underlying illness# but because helium is

less dense than nitrogen# resistance in areas of turbulent flow is decreased'

• This in turn can decrease breathing effort# respiratory rate# and heart rate'

?' AntibioticsD

• Not usually indicated

• ther than otitis media# the incidence of concurrent serious bacterial infection

-pneumonia# meningitis# sepsis. is >6: in healthy infants with no underlying

disease who ha"e R+V bronchiolitis'

5='Anti"iral agents -riba"irin.D +ee Respiratory +yncytial Virus

55'Immunoprophyla&isD +ee Respiratory +yncytial Virus



T0ER

• 0istorical ris% factors for se"ere diseaseD

5' >6 months of age

6' Gestational age >2; wee%s

2' ,nderlying cardiopulmonary disease -e'g'# hemodynamically significant heart disease#

P(.

• Immunodeficiency or other highBris% group for de"eloping se"ere disease

• Flinical ris% factors for se"ere disease

• Presence of apnea# tachypnea -respiratory rate 9=4min.# retractions# poor feeding# pallor# lethargy# or

agitation -signs of impending respiratory failure.

• Pulse o&imetry >?8: in room air

• Atelectasis on chest radiograph

Follow-up Recommendations

EPEFTE( F,R+E4PRGN+I+

• /or most pre"iously healthy infants# the prognosis is good'

• Premature infants of 26@28 wee%sH gestation hospitali1ed for bronchiolitis ha"e been shown to ha"e

an increased number of subse$uent hospitali1ations for respiratory problems# a greater number of

outpatient "isits# and an increased ris% of sudden death compared with those who were not

hospitali1ed for bronchiolitis'

• )ortality associated with primary R+V infection in otherwise healthy infants is ='==8@='=6:'

• )orbidity and mortality are considerable in patients with an underlying chronic disease'

• ,p to 8=: of infants with bronchiolitis de"elop subse$uent episodes of recurrent whee1ing until 55

years of age'

• ronchiolitis obliterans may be a se$uela in patients infected with adeno"irus or Mycoplasma

pneumoniae'

P++ILE F)PLIFATIN+

• Fommon complicationsD

5' titis media

6' Pneumonia

2' Aspiration syndrome

' Respiratory failure re$uiring mechanical "entilation

• Apnea# either as a presenting symptom or in association with increasing respiratory distress

• +yndrome of inappropriate A(0 release -ris% for o"erhydration.

• +epsisli%e syndrome



PATIENT )NITRING

• )ost infants with no underlying disease impro"e within 2@8 days' In some# nasal congestion and

cough may continue for 5@2 wee%s' Premature infants and those with underlying cardiopulmonary

disease typically e&perience a protracted illness'

• Those who need mechanical "entilation may ha"e difficulties with e&tubation due to e&cessi"e

secretions and atelectasis'

• As many as 8=: of infants will ha"e recurrent whee1ing through the 5st decade of life'

T0ER

• Impending respiratory failure -increased breathing effort# retractions# hypo&emia# F6 retention#

lethargy.

• +udden deterioration suggesting atelectasis due to mucous plugging

• /atigue may occur in infants who ha"e prolonged and e&tensi"e disease'

• /atigue will manifest with increased pF6and worsening hypo&emia'

FLINIFALD

• 0ypo&emia is common# so always monitor o&ygen saturation'

• e aware of apnea'

• In cases of clinical bronchiolitis# causes of falseBnegati"e ELI+A testsD

5' Poor $uality of sample

6' +ample contamination

2' Insufficient sample

' NonBR+V bronchiolitis

Freuently As!ed "uestions

• SD 0ow did my child get bronchiolitisM

• AD R+V bronchiolitis is a common# seasonal# lower respiratory tract infection that is easily

transmissible'

• SD Fan my child become reinfectedM

• AD Fhildren can become reinfected with R+V bronchiolitis# and infection can occur more than once

during the same respiratory season'

• SD (o patients with bronchiolitis need to be isolatedM

• AD R+VBpositi"e patients need to be isolated with other R+VBpositi"e patients and from uninfected

patients' Patients recei"ing riba"irin should be %ept in isolation'

• SD ill my child de"elop asthmaM

• AD Recurrent whee1ing has been described in up to 8=: of infants with R+V bronchiolitis' 0owe"er#

most data are retrospecti"e and obser"ational' hether R+V per se can contribute to the

de"elopment of asthma and allergic sensiti1ation remains unclear'

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