Asthma, by Julia Pian and Dr. Laura Chiel.
Learning objectives-- by the end of this video, the learner
will understand the pathophysiology,
clinical presentation, diagnosis,
and management of childhood asthma
in the inpatient and outpatient setting.
Introduction-- asthma is one of the most common
pediatric diseases with 1 in 10 pediatric patients
in the United States carrying the diagnosis.
The disease commonly manifests as wheezing--
[WHEEZING SOUNDS]
--breathlessness, chest tightness, and coughing,
and can cause significant morbidity and mortality.
Pathophysiology-- the underlying pathophysiology of asthma
is reversible airflow obstruction.
There are three main mechanisms that cause this obstruction--
bronchoconstriction, inflammation, and secretions.
Bronchoconstriction occurs through constriction
of smooth muscles around airways and is
mediated through parasympathetic muscarinic M3 receptors.
Inflammation refers to airway wall edema and inflammatory
cell infiltration in the submucosa,
including eosinophils, activated helper T-cells, mast cells,
and sometimes neutrophils.
Finally, increased airway secretions
can narrow the airway lumen.
These secretions are made up of mucus, desquamated lining
cells, and intraluminal eosinophils.
Clinical presentation-- asthma generally
presents at a young age with approximately 80%
of children with asthma developing symptoms
before age 5.
Some common triggers of asthma exacerbations in children
include viral upper respiratory infections, smoke,
seasonal change, cold weather, cockroaches, mold,
and other environmental factors.
The most common symptoms of asthma
are cough and wheezing with breathlessness,
chest tightness, chest pressure, and chest pain also described.
There are a number of different features of cough
that should raise concern for asthma.
These include nocturnal cough, a cough that
varies with the seasons, a cough that
lasts more than three weeks, or a cough in response
to specific exposures, such as cold air or exercise.
The cough of asthma is usually dry and hacking,
but may produce clear or white sputum.
The wheeze of asthma is produced due to the narrowed airways
and tends to be heard on expiration.
This wheeze can sometimes be appreciated
without a stethoscope.
If the patient has a silent chest an physical exam
during an asthma exacerbation, this
may represent a dangerous limitation of airflow
and escalation of care should be considered.
Other important elements of the history to include
are symptom control, use of a controller medication,
known asthma triggers, impact on participation
in school and activities, previous exacerbations
including hospitalizations, ICU admissions, or intubations,
and a personal medical history or a family history of atopy.
Atopy is a hypersensitivity to allergens
and a common triad of atopic diseases are asthma, eczema--
also known as atopic dermatitis--
and allergic rhinitis.
Diagnosis-- when a child presents with cough, wheezing,
and breathlessness, the differential diagnosis
should include asthma, bronchiolitis, foreign body
in the airway, anaphylaxis, and other causes
of airway obstruction.
Asthma is suspected to be the most likely diagnosis based
on history and physical exam.
Spirometry can be performed in the outpatient setting.
Reversible airflow obstruction with FEV1, less than 80%
of expected, and reduced FEV1 over FVC ratio
can help confirm the diagnosis of asthma.
However, normal pre-bronchodilator spirometry
does not rule out asthma.
Children under five years of age are typically
too young to perform spirometry.
You may hear providers use the term reactive airway
disease for very young children who have symptoms of asthma,
but this label is nonspecific and may lead
to underdiagnosis of asthma.
In children who are too young to perform spirometry,
improvement in symptoms with the trial of bronchodilator
may help establish the diagnosis.
A chest X-ray is not required or recommended
to make a diagnosis of asthma, but it
may be done to rule out other conditions on the differential
diagnosis.
The chest X-ray in asthma is often normal,
but may show hyperinflation, bronchial thickening,
or atelectasis.
Venous blood gas samples may be obtained
for patients with severe asthma exacerbations.
Because patients with asthma exacerbations are tachypneic,
CO2 values are expected to be low.
A normal CO2 may suggest that the patient is not effectively
ventilating and that the patient is
at risk for impending respiratory failure.
Management-- the management of asthma focuses on two main
areas--
pharmacologic therapy and asthma education.
As described previously, asthma is
a result of bronchoconstriction, inflammation,
and increased secretions.
Each of the medications used to treat asthma
targets one of these mechanisms.
Bronchoconstriction is treated most commonly
with albuterol, a beta 2 agonist which
leads to smooth muscle relaxation around the airways.
In more severe cases, intravenous magnesium sulfate
is also used to address bronchoconstriction.
Inflammation is addressed with various forms of steroids
depending on the situation.
Some children use inhaled corticosteroids daily.
During an acute exacerbation, a short course
of IV or oral steroids is given to achieve control.
Finally, ipratropium can help reduce secretions as well as
bronchodilate.
Of note, many medications can be delivered
via inhaler or via nebulizer.
The mode of delivery is determined based on patient age
and availability.
Outpatient management-- let's discuss the outpatient
treatment of asthma.
Some patients with asthma can be managed
with an albuterol inhaler as needed.
Medication that is used only when a patient is symptomatic
is called a rescue medication.
However, many asthma patients require
daily therapy to control their symptoms,
or a controller medication.
A stepwise treatment letter issued by the National Asthma
Education and Prevention Program is
used to gradually step up treatment
based on symptom severity.
Each category of severity is determined
by the number of days per week that a patient experiences
symptoms, the number of nighttime awakenings
that occur per week, how often they need
to use their short-acting beta agonist,
and how severely their symptoms interfere
with daytime activities.
With each step in severity, the patient
will either increase the dose of a current medication
or add another medication to the regimen.
For example, if a patient with mild intermittent asthma
is found to be using the rescue inhaler more than two days
per week, categorizing them as having mild persistent asthma,
a daily low dose inhaled corticosteroid
would be prescribed in addition to their short-acting beta
agonist.
If this same patient worsens and is later
categorized as having moderate, persistent asthma,
a daily long-acting beta agonist such as salmeterol
may be added to their regimen along
with their daily inhaled corticosteroid
and short-acting beta agonist.
When children present to the emergency department
with an asthma exacerbation, a scoring tool
may be used to determine severity and management
follows accordingly.
In moderate to severe cases, patients
are often given albuterol and ipratropium
to combat bronchoconstriction and help reduce secretions.
Sometimes they are given three doses of nebulized albuterol
and ipratropium back-to-back.
You may hear providers refer to three doses of albuterol
and ipratropium given back-to-back as a unineb,
or a unified nebulizer.
We recommend against using this language as its meaning is not
clear to all providers.
The patient is also given IV or oral steroids
to help reduce inflammation.
The albuterol treatments are then spaced out over time
based on clinical symptoms.
In particular, a patient's work of breathing,
oxygen saturation, respiratory rate, respiratory exam,
and dyspnea are used to help determine whether treatments
can be spaced out further.
If a child remains symptomatic despite frequent albuterol
treatment, magnesium is considered to further aid
against bronchoconstriction.
Hospitals use institution-specific criteria
based on the time interval between albuterol treatments
to determine whether children can be discharged,
should be admitted to the general floor,
or should be admitted to an ICU.
Inpatient management-- on the general pediatrics floor,
patients will continue treatment with albuterol
until they can reliably space treatments far enough
apart to allow safe administration of treatment
at home.
They will also continue on their home asthma
controller medications and the systemic steroid course started
in the emergency department.
Asthma education will be conducted with the family
and an asthma action plan put in place
before the patient is discharged.
Treatment for a patient admitted to an ICU
may include non-invasive ventilation, terbutaline,
and heliox.
Intubation is avoided unless absolutely
necessary as intubation and positive pressure
ventilation is associated with high mortality
rate in children.
The management of asthma in the ICU
is beyond the scope of this video.
Asthma education-- families should
be counseled on the importance of avoiding the patient's
asthma triggers such as allergens, animal
dander, fragrances, or smoke.
They should be encouraged to practice good hand hygiene
and to obtain the flu vaccine annually to prevent
respiratory infections.
The proper administration of medication
should be reviewed, including how to use a metered dose
inhaler and the importance of using a spacer
to effectively deliver the inhaled medication
to the airways and prevent the development of oral thrush.
The concepts of rescue and controller medications
should be reviewed.
Every family should have an asthma action plan, a document
which details how to care for the child's
asthma on typical days and on days when the child is at risk
for worsening asthma symptoms, such as in the setting
of a respiratory illness or exposure to other triggers.
In summary, asthma is the most common pediatric disease
in developed countries caused by reversible airflow obstruction
due to bronchoconstriction, inflammation, and secretions.
It is most commonly clinically diagnosed
in children before the age of 5 and presents as recurrent cough
and wheezing.
The mainstays of treatment are short-acting beta agonists,
such as albuterol, steroids, and antimuscarinic agents
such as ipratropium.
As an inpatient, patients are managed
based on the frequency of albuterol nebulizer
treatments needed.
As an outpatient, patients are managed
based on the severity of the symptoms
in a stepwise treatment ladder.
Asthma education is essential to help children
achieve asthma control.
Thank you for watching this video on asthma.