Pneumonia（2）在线视频

Hi!

This is Dr. Huang

from the First Affiliated Hospital

of Shantou University Medical College

Department of Pediatrics.

In “pneumonia” part one,

we talked about the classification

and epidemiology of pneumonia.

In part two,

we're going to introduce

pathophysiology

and clinical manifestations,

complications,

laboratory tests and imaging studies,

diagnosis and differential diagnosis,

and management of pneumonia.

Pneumonia patients' manifestations

are basically associated

with the pathophysiology

of the disease.

So in the following few minutes,

I will introduce

the clinical features of pneumonia

based on its specific pathophysiology.

Due to the inflammation of the

respiratory system,

most patients will develop a fever.

However,

please note that young infants

may be afebrile

and present with atypical symptoms

like poor feeding,

vomiting and no crying, etc.

In the respiratory system,

pathophysiologic changes of

increased secretions causing

obstruction of the airways and alveoli,

and consequent gas-exchange impairment,

may bring about the

development of cough,

sputum, wheezing, tachypnea,

nasal flaring, respiratory retractions,

crackles and cyanosis.

In the cardiovascular system,

the pathogens

and toxins produced by the pathogens

may cause myocarditis.

Hypoxia can cause contraction of

pulmonary arteries

leading to increased pressure

in the lungs.

The combination of myocarditis

and pulmonary hypertension

result in heart failure,

with which patients

will develop tachypnea,

tachycardia, cyanosis,

gallop rhythm, hepatomegaly,

or renal impairment.

As to the neurological system,

pathophysiologic changes of hypoxia,

hypercapnia

and toxins produced by pathogens

may result in cerebral edema,

some patients may therefore develop

intracranial hypertension

and exhibit irritability,

somnolence, unconsciousness,

seizure,

bulging anterior fontanel

and meningeal irritation signs.

In the gastrointestinal system,

hypoxia and sepsis

caused by pneumonia

can lead to ischemia,

hemorrhage and epithelial necrosis

of the GI tract,

so patients will develop

GI dysfunction

and present with anorexia,

emesis, diarrhea,

abdominal distention / paralytic ileus

and GI hemorrhage.

Patients may also develop water,

electrolytes and acid-base imbalance

due to the pathophysiologic changes

of hypoxia,

dehydration and malnutrition.

What kind of complications

may pneumonia patients develop?

Bacterial pneumonias

frequently cause inflammatory fluid

to collect in the adjacent

pleural space,

causing a pleural effusion

or if grossly purulent,

an empyema.

Small effusions may not

require any special management.

Large effusions

may restrict breathing

and require drainage.

Air dissection

within lung tissue

results in a pneumatocele,

or air pocket.

Scarring of the airways and lung tissue

may leave bronchi dilated,

resulting in bronchiectasis

and increased risk

for recurrent infections.

Severe adenovirus pneumonia

may result in bronchiolitis obliterans,

a subacute inflammatory process

in which the small airways

are replaced by scar tissues,

resulting in a reduction in lung volume

and lung compliance.

Laboratory studies.

The white blood cell count with

viral pneumonias

is often normal or mildly elevated,

with a lymphocytic predominance,

whereas with bacterial pneumonias

the WBC count

is elevated with neutrophilia.

Mild eosinophilia is characteristic

in infants

with Chlamydia trachomatis pneumonia.

Culture of sputum is of little value

in the diagnosis

of pneumonia in children

because good quality sputum

is rarely obtainable from children.

Blood cultures should be performed

to attempt to diagnose a bacterial

cause of pneumonia.

Blood cultures are positive

in 10 to 20% of bacterial pneumonia

and are considered to be confirmatory

if positive for a recognized

respiratory pathogen.

Mycoplasma pneumoniae

should be suspected

if cold agglutinins

with titers greater than 1:64 are

found in peripheral blood samples;

this may be confirmed

by Mycoplasma IgM

or more specifically

polymerase chain reaction.

The diagnosis of tuberculosis

is established by tuberculin skin test

and analysis of sputum

or gastric aspirates by culture,

antigen detection,

or PCR.

AP and lateral CXRs

are required

to localize the diseased segments

and to adequately visualize

infiltrates behind the heart.

There are characteristic X-ray

findings of pneumonia,

although there is much overlap

that precludes definitive diagnosis

by radiography alone.

Bacterial pneumonia

characteristically shows

lobar consolidation,

or a round pneumonia,

with pleural effusion

in 10% to 30% of cases.

Viral pneumonia

typically shows diffuse,

streaky infiltrates of

bronchopneumonia.

Atypical pneumonia,

such as

with Mycoplasma pneumoniae

and Chlamydia pneumoniae,

CXR shows increased

interstitial markings

or bronchopneumonia.

Ultrasound should be used

to assess size of pleural effusion

and whether they are freely mobile.

Computerized tomography

is used to evaluate severe disease,

lung abscesses, bronchiectasis,

and to delineate effusion.

To conclude,

if a patient has

manifestations of cough,

fever, tachypnea, or crackles,

we can make a

clinical diagnosis of pneumonia;

together with proper imaging studies,

the diagnosis of pneumonia

is confirmed.

In addition to diagnosing pneumonia,

we also need to identify

any complications.

Pneumonia must be differentiated

from other acute diseases,

including acute bronchitis,

bronchial foreign bodies,

asthma, etc.

Unlike pneumonia,

bronchitis has no

fixed crackles over the chest;

patients with bronchial foreign body

usually have a history of aspiration;

and those with asthma

often have normal chest radiographs.

How do we treat pneumonia?

Therapy for pneumonia includes

supportive and symptomatic treatment,

and depends on the degree of disease,

watch out for complications,

and you should have

knowledge of the agent

likely causing the pneumonia.

Although viruses cause most

community-acquired pneumonias

in young children,

in most situations,

experts recommend

empirical antibiotic treatment

for the most probable bacterial cause.

Now let's make a summary

of pneumonia,

including part one and part two.

Pneumonia is classified according

to a variety of characteristics.

Epidemiology is useful

in determining the etiology

of pneumonia.

Pathophysiology assists in

understanding the mechanisms

of manifestations.

Some cases of pneumonias

may develop complications

that need further evaluation

and treatment.

Laboratory and imaging studies

like chest X-rays

and CT

help us diagnose pneumonia

and detect any complications.

Pneumonia must be differentiated

from other similar acute diseases

like bronchial foreign bodies

and asthma.

Finally,

the therapy includes

supportive and symptomatic treatment,

and antibiotics if necessary.

That's all!

Thank you!