Pneumonia, by Brian Fissel and Dr. Patricia Stoeck.
Learning objectives.
By the end of this video, you will be able to--
list the risk factors for developing pneumonia,
identify the most common organisms
responsible for pneumonia by age group,
diagnose pneumonia, and determine its severity
by clinical presentation and physical examination--
identify when it is necessary to obtain
radiographs and other diagnostic testing,
which include viral testing.
Determine when hospitalization is necessary,
and formulate a plan for treatment,
and identify and formulate treatment plans
for common complications of pneumonia.
Introduction.
Pneumonia is an infection of the lung that
is common in pediatrics and that can have variable etiologies.
While most children recover uneventfully
it is a significant cause of morbidity and mortality
worldwide.
Pneumonia is the single greatest cause of death in children,
causing over 2 million deaths annually in children
younger than two years of age, and representing
20% of all deaths in this age group.
In the developed world, annual incidence is 3 to 4
per 1,000 children-- with an annual mortality
rate of less than 1 per 1,000.
There's increased incidence in colder months.
Pathophysiology.
Pneumonia is a lower respiratory tract infection
involving inflammation of the lung parenchyma particularly
the alveoli, interstitial space, and pleura.
The lungs contain many defense mechanisms
to prevent infection such as the cough reflex, mucociliary
drainage, and humoral and cell-mediated immunity.
Deficiencies in one or more of these mechanisms,
can lead to invasion by pathogens and cause pneumonia.
Other risk factors associated with higher rates of pneumonia
include poverty, multiple siblings,
exposure to tobacco smoke, prematurity,
and urban residents.
There are many pathogens that can cause pneumonia.
The most common offending organisms
in otherwise healthy children may
be broken down by the ages in which they are frequently seen.
Among neonates less than one-month-old,
infection is typically acquired from aspiration
of infected amniotic fluid.
So the most common causes of pneumonia in this age group
include group B Streptococci and E. coli.
Among infants 1 to 3 months of age,
viral pathogens such as respiratory syncytial virus
or RSV, human metapneumovirus, influenza, and parainfluenza
are the most common causes of pneumonia.
Afebrile pneumonia of infancy can also
be seen in this age group and is classically
due to chlamydia trachomatis acquired
during vaginal delivery.
Bordetella pertussis should also be considered
due to increasing incidence and significant morbidity
and mortality in this age group.
An infant with Bordetella pertussis infection
may, or may not have a fever.
Viruses remain the most common pathogens among children
aged four months to four years.
Most commonly RSV followed by parainfluenza, influenza,
adenovirus, and rhinovirus.
Up to 1/3 of children have a co-infection
with two or more viruses.
Bacterial pneumonia may be caused
by streptococcus pneumoniae, haemophilus influenza,
and moraxella catarrhalis.
Incidence of pneumonia due to the first two pathogens
has been less affected by vaccination
than meningitis or bacteremia.
Pneumonia due to atypical organisms such as mycoplasma
pneumoniae and chlamydophila species
is common among children aged five and older.
However, both the viral pathogens above
and typical bacterial organisms may also be causative.
Clinical presentation.
The most common presentation of pneumonia is fever and cough.
However, the challenge in clinically identifying
pneumonia lies in the fact that the presenting symptoms
are non-specific and can be subtle,
especially in young children.
Tachypnea is a particularly important finding
and is the most sensitive and specific sign
of pneumonia in infants.
Other symptoms include hypoxemia, abdominal pain
and increased work of breathing.
Increased work of breathing can manifest
as nasal flaring, accessory muscle use such as retractions
or grunting.
In neonates, pneumonia must be considered
when the following signs are present.
Respiratory distress soon after birth, lethargy, apnea,
tachycardia, poor feeding, irritability,
temperature instability, and abdominal distention.
The clinical presentation can help clue you
in on the cause of pneumonia.
Illness and bacterial pneumonia is often sudden in onset
and of greater severity.
Pneumonia secondary to atypical pathogens,
frequently has sudden onset fever
but is typically more progressive in its course
and can be associated with a broad array of symptoms,
including prolonged cough, malaise, myalgia, headache,
photophobia, and sore throat.
Afebrile pneumonia can also be seen
in infants less than four months of age,
and is classically due to chlamydia trachomatis.
It presents with rhinorrhea with or without conjunctivitis
and staccato cough as well as tachypnea
and diffuse inspiratory rales without fever on examination.
Viral pneumonia classically has gradual onset
and is often preceded by fever and upper respiratory
symptoms such as cough, rhinorrhea, or congestion.
Diagnosis.
The presenting symptoms of pneumonia
have a broad differential diagnosis.
In newborns, bacterial pneumonia in the first day of life
may be impossible to differentiate
from transient tachypnea of the newborn or respiratory distress
syndrome.
Thus, these patients are often treated empirically
for bacterial pneumonia.
Depending on the history bronchopulmonary dysplasia,
foreign body aspiration, and chronic pulmonary disorders,
including asthma, bronchiectasis,
and cystic fibrosis should be considered.
Aspiration pneumonia should be considered
in patients with oropharyngeal dysphagia,
gastroesophageal reflux, tracheoesophageal fistula,
cleft palate, and neuromuscular disorders.
Anatomical malformations such as bronchogenic cysts
and congenital lobar emphysema may also
be considered as part of the differential diagnosis.
A thorough history and physical examination
is often sufficient to diagnose uncomplicated pneumonia.
When asking about history the onset of symptoms and nature
of the cough such as whether it is wheezy or paroxysmal,
can help narrow the diagnosis and roll out
anatomical malformations and exacerbations
of underlying chronic pulmonary disorders.
Non-respiratory symptoms such as lethargy, irritability,
and poor appetite can help determine illness severity.
Verification of immunization status
is important to rule out serious pathogens
such as Bordetella pertussis or haemophilus influenza
and influences management decisions.
Physical examination should include an assessment
of vital signs particularly the presence
of fever and tachypnea.
Pulse oximetry should be performed
in all children with suspected pneumonia
to assess for hypoxemia.
A thorough pulmonary examination is
necessary for evaluating pneumonia
and can provide clues to the etiology.
Bacterial pneumonia often presents with lobar pneumonia.
Examination of the affected lobe will
reveal rales or diminished breath sounds
on auscultation and dullness to percussion.
Viral pneumonia however, is often
a diffuse process with low pitch wheezing
heard throughout the chest.
Rapid nasopharyngeal testing for viral infections
should be performed in the evaluation of pneumonia.
As it can decrease the need for additional diagnostic testing
and unnecessary antibiotic use.
Other studies including chest radiographs, blood cultures,
and complete blood count are not necessary for mild, lower
respiratory symptoms consistent with pneumonia in children
well enough to be treated in the outpatient setting.
Indications for obtaining chest radiographs
include hypoxemia, significant respiratory distress,
failure of initial antibiotic treatment, and hospitalization.
Severe pneumonia is an indication
for other testing such as blood, and/or sputum cultures,
viral testing, complete blood count, and acute phase
reactants to help identify pathogens and monitor treatment
efficacy.
Management.
Appropriate treatment of pneumonia
depends on the severity of illness
and whether the patient requires hospitalization.
Indications for hospitalization include
moderate to severe pneumonia as defined
by respiratory distress, sustained oxygen
saturation of less than 90%, or toxic appearance.
Infants less than 3 to 6 months of age
should be hospitalized due to the risk of hypoxemia,
bacteremia, and rapid deterioration.
Outpatient management of pneumonia
depends on the age and offending pathogen. Preschool aged
children who frequently have viral pneumonia are not
routinely treated with antimicrobials.
For fully immunized children of all ages with suspected
bacterial pneumonia, high dose oral amoxicillin
is the first line treatment for adequate coverage
of streptococcus pneumoniae.
Macrolides such as azithromycin, are first line treatment
for children with signs and symptoms
consistent with atypical pneumonia.
Though incidents of resistance is rising.
The macrolide erythromycin is first-line treatment
for afebrile pneumonia of infancy
due to chlamydia trachomatis.
To achieve maximal benefit antiviral therapy
with oseltamivir should be initiated
within 48 hours of symptom onset for children
with signs and symptoms consistent with influenza.
Especially in children with underlying conditions of higher
risk of complications.
It is not necessary to delay initiation of therapy
until confirmatory test results are known.
Inpatient management of pneumonia
depends primarily on immunization status
and suspected pathogens.
Fully immunized children with suspected bacterial pneumonia,
should receive ampicillin intravenously
for coverage of Streptococcus pneumoniae.
For children who are not fully immunized,
live in areas with high levels of penicillin resistant
streptococcus pneumonia, have complications, or have
a life threatening infection, first line treatment
is a third generation parenteral cephalosporin
such as ceftriaxone.
Hospitalized children with pneumonia
due to atypical organisms should be
treated with dual therapy involving
a beta lactam plus a macrolide or tetracycline
or a fluoroquinolone monotherapy.
Treatment of children with pneumonia
due to suspected staphylococcus aureus,
should include dual therapy with a beta-lactam antibiotic
and either vancomycin or clindamycin
for coverage of methicillin resistant Staphylococcus
aureus.
Complications.
A number of complications can occur
in pneumonia including pleural effusion, empyema,
and abscesses.
Pleural effusions are typically seen with pneumococcal
and mycoplasma pneumonias.
Whereas necrotic pneumonias and empyemas are more
associated with a group A streptococci and staphylococcal
pneumonia.
Small, stable effusions can be observed.
Whereas, patients who are ill appearing or have
large or loculated effusions may require thoracentesis
and chest tube placement.
Pulmonary abscesses do not usually require drainage.
Methicillin-sensitive and methicillin-resistant
Staphylococcus aureus cause the majority
of abscesses in children who are otherwise healthy
and should be treated with a third generation cephalosporin,
and either vancomycin, or clindamycin as determined
by susceptibility testing.
Summary.
In summary pneumonia is a lower respiratory tract infection,
most frequently caused by viruses in young children
and bacteria including atypical organisms in older children.
It often resolves uneventfully but can
have significant morbidity and mortality,
especially, when there is underlying chronic disease
or a complicated pneumonia.
Typical findings on clinical exam
include fever, cough, and tachypnea.
Most children with pneumonia can be
managed with supportive measures,
and if indicated antibiotics on an outpatient basis.
However.
Patients with more severe disease
may require hospitalization and parenteral antibiotics.
While most of these children improve
after 2 to 3 days of treatment, a proportion of patients
may require further evaluation for complications
such as pleural effusion and pulmonary abscesses.
Thank you for watching this video on pneumonia.