pediatric asthma and bronchiolitis

7/29/2019 Pediatric Asthma and Bronchiolitis

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2009/9/3


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Chronic disease of the tracheobronchial treecharacterized by airway obstruction,inflammation, and hyperresponsiveness

Generally reversible with appropriate,aggressive therapy


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4.8 million children younger than 18 years of age Prevalence of asthma has increased in all age groups

by 40 percent in the last decade Risk factors associated with the development of

asthma

low birth weight family history of asthma urban household low-income household race (children of African-American, Asian, and Hispanic

descent

Most children presenting with asthma do so beforeage 8 male predominance in the prepubertal age group ratio equalizes during adolescence


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Bronchial hyperreactivity genetic basis

usually initiated by environmental factors


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Asthma is a two-stage process bronchoconstriction due to histamine and

leukotriene release (early stage)

airway mucosal edema with mucous plugging (late

phase)


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Children are at higher risk of respiratoryfailure than an adult Increased compliance of the infant rib cage and

immature diaphragm contributes to increased work

of breathing and respiratory muscle fatigue Young lung tissue lacks elastic recoil and is more

prone to atelectasis

Airway walls are relatively thicker and result in

greater narrowing with bronchoconstriction


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Avoid delays in treatment Brief physical examination should be

performed before a detailed history isobtained

Examination of vital signs

Supplementary oxygen administration


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After initial stabilization, perform a completeexamination assess ventilation, accessory muscle use, and work of

breathing

nasal flaring, foreign bodies, and concurrent sinusitis "musical" polyphonic inspiratory and expiratory wheezes

may not always be present on lung examination and arenot prognostic of severity of disease

Extremities should be inspected to assess cyanosis and

clubbing Complete history (aspiration, choking, possible

ingestion should be included for all ages)


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Peak expiratory flow rate (PEFR) monitor response to acute treatment ongoing assessment and management of asthma values in liters per minute are based on the child's height decreased by 25 percent once wheezing is detected by

stethoscope PEFR of less than 50 percent indicates severe obstruction,

and less than 25 percent indicates possible hypercarbia In the ED, PEFR is an excellent tool to evaluate mild asthma

or for reevaluating patients after treatment Limited by patient cooperation in children younger than age

5 may not be feasible during an acute exacerbation

Forced expiratory volume in 1 s (FEV1) correlates with the degree of airway obstruction


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ABGA should be obtained in children with impending respiratory failure Hypoventilating if PEFR is less than 30 percent of predicted not responding as expected to treatment

Complete blood count and chemistries usually unnecessary unless there is a concurrent febrile

illness or coexisting disease

Chest x-ray not recommended routinely new-onset asthma, for severe episodes requiring

admission, or if pneumonia, pneumothorax, foreignbody, or pneumomediastinum are in the differentialdiagnosis


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Upper and lower respiratory causes Nonrespiratory causes


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cause bronchial smooth muscle relaxation continuous aerosolized therapy with albuterol

is safe, fast, and effective


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Unresponsive to the preceding therapy orrespiratory distress increases

Administered while intravenous lineplacement is attempted

0.01 mL/kg aqueous epinephrine 1:1000 to amaximum of 0.3 mL

may be repeated every 20 to 30 min for a

total of three doses


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Inhibit the secretion of inflammatory leukotrienes andprostaglandins Prevent and reverse the increase in vascular

permeability that leads to airway edema Early administration during the course of an acute

exacerbation is recommended for all patients unless the PEF is greater than 50 percent and there is animmediate response to the first treatment

when exercise-induced attacks occur in a previously wellchild

Dose : 2 mg/kg

There is no real advantage to the administration ofintravenous over oral glucocorticoids in the acutesetting


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Most children presenting in statusasthmaticus will be dehydrated because ofincreased insensible losses

Administer a bolus of fluid 20 mL/kg of NS


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Prevent bronchoconstriction induced by cyclicguanosine monophosphate

Additive benefit when used with albuterol

Ipratropium is a safe drug with few side effects and

may be given to patients of all ages The dosage of nebulized ipratroprium bromide is

as follows: Adolescents >14 years of age: 500 mcg in an initial

nebulization Children up to 14 years of age: 125 ~ 250 mcg in an initial

nebulization

Neonates: 25 mcg/kg in an initial nebulization


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Magnesium Sulfate exact mechanism of action is unknown tocolytic effects of magnesium sulfate on uterine smooth

muscle improvement in short-term pulmonary function given as 25 to 50 mg/kg IV over 20 min; this may be

repeated once Maximum dose for children is 2 g

Heliox generally available as 80:20 or 60:40 mixtures of

helium and oxygen

recommended for the asthmatic who does not improvewith conventional treatment but in whom intubation isnot imminent


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Theophylline competitive phosphodiesterase inhibitor

no longer used routinely

reserved for patients who clearly respond to it or

for those who remain refractory to other modes oftreatment


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Children responding well to conventionaltherapy may be discharged after 2 to 4 h oftreatment

Short ED observation period is recommended

for patients with an incomplete response butacceptable PEFR

Detailed discharge instructions should outlinemedication administration, inhaler use, and

follow-up All children should be referred to their

pediatrician for follow-up within 24 h


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Inflammation of the bronchioles Clinical syndrome of wheezing, chest

retractions, and tachypnea in childrenyounger than age 2 years


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Peak prevalence is from late October to May. Peak age of incidence in urban populations is

2 months and results in hospitalizationslasting 5 to 7 days

Disease in older children is usually milder


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Respiratory syncytial virus (RSV) causes 50 to70 percent of clinically significantbronchiolitis transmitted by direct contact with large droplets of

secretions and self-inoculation by contaminatedhands via the eyes and nose no significant transmission occurs by small-particle

aerosol

Non-RSV bronchiolitis is caused by

infiuenzavirus, parinfluenzavirus, echovirus,rhinovirus, Mycoplasma pneumoniae andChlamydia trachomatis


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Peripheral airway narrowing and variableobstruction Mucous plugging

necrosis of the respiratory epithelium and destruction

of ciliated epithelial cells Submucosal edema


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Symptoms range from minimal rhinorrhea tobronchiolitis or pneumonia and respiratoryfailure

Infection begins with nasal discharge,pharyngitis, and cough

Fever accompanies the first few days ofillness

Symptoms reach a peak at 3 to 5 days,generally resolving in 2 weeks


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Physical findings tachypnea greater than 50 to 60 breaths/min

tachycardia

mild conjunctivitis

chest retractions prolonged expiration with hyperresonant chest

wheezing

hypoxemia


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Suggested by clinical presentation, patient age,and history of RSV exposure or communityepidemic.

Immunofluorescence assays currently availableare extremely sensitive but not necessary for allpatients

Complete blood counts and chemistries may notbe helpful in diagnosis

Chest radiography to rule out pneumonia is

indicated for children with concurrentcardiopulmonary illness or those who are ill-appearing and hypoxemic


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Treatment is mainly supportive, the mostimportant therapy being supplementalhumidified oxygen

Increased insensible fluid loss occurs fromincreased work of breathing and can causesignificant dehydration that warrants a NS bolus

Fever should be controlled with acetaminophenor ibuprofen

Antibiotics should be reserved for identifiable

bacterial infections Workup for occult bacteremia is not required

unless they appear toxic


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Nebulized epinephrine effective treatment for wheezing of bronchiolitis found to reduce hospitalizations in children with

bronchiolitis compared with albuterol It can be used safely in hospitalized children up to every

2 h as a 0.1% solution (0.5 mL in 3.5 mL of NS) If used in the ED, recommend an observation period of 4

h before a disposition decision is made Generally, infants and children showing minimal

response or deterioration after a single treatment will

require hospitalization Albuterol and Ipratropium

limited role for bronchodilator therapy in the treatmentof bronchiolitis


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Glucocorticoids Controlled studies have failed to demonstrate any

proven benefit to the use of glucocorticoids

Ribavirin decrease viral protein synthesis improvement in oxygenation

those with immunodeficiency, cystic fibrosis,congenital heart disease, and severe illnesses of

infancy


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RSV Immune Globulin passive immunization monthly intravenous infusions recommended for infants with documented BPD and

for those with a gestational age of less than 35weeks

Palivizumab monoclonal antibody can be given by intramuscular injection

administered monthly desirable for children in whom vascular access is a

challenge


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Admission visible moderate to severe respiratory distress

hypoxia

apneic spells

dehydration sustained tachypnea (RR >60 breaths/min)

considered in all infants with a history of BPD,congenital heart disease, and immunocompromise


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Discharge mild disease

taking fluids well

whose parents are capable

Parents should be instructed on how toperform aggressive nasal suctioning andevaluate respiratory distress

Decongestants and antihistamines are ofquestionable benefit

pediatric asthma and bronchiolitis

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