Chapter 21 Respiratory Tract Infections, Neoplasia, and Childhood Disorders

Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 21

Respiratory Tract Infections, Neoplasia, and

Childhood Disorders


Upper Respiratory

Viruses in Adults

Upper Respiratory

Viruses in Adults

• Common cold

• Rhinosinusitis

• Influenza


The Common ColdThe Common Cold• Rhinoviruses

– Occur in early fall and late spring in persons between ages 5 and 40

• Parainfluenza viruses

– Occur in children younger than 3

• Respiratory syncytial virus

– Occurs in winter and spring in children younger than 3

• Coronaviruses and adenoviruses

– Occur in winter and spring


Rhinosinusitis (Sinusitis)Rhinosinusitis (Sinusitis)

• Infection or allergy obstructs sinus drainage

• Acute: facial pain, headache, purulent nasal discharge, decreased sense of smell, fever

• Chronic: nasal obstruction, fullness in the ears, postnasal drip, hoarseness, chronic cough, loss of taste and smell, unpleasant breath, headache


InfluenzaInfluenza

• In the United States, approximately 36,000 persons die each year of influenza-related illness

• Transmission is by aerosol (three or more particles) or direct contact

• Upper respiratory infection (rhinotracheitis)

– Like a common cold with profound malaise

• Viral pneumonia

– Fever, tachypnea, tachycardia, cyanosis, hypotension

• Respiratory viral infection followed by a bacterial infection


Question Question

For which viruses is a 2-year-old most at risk?

a. Rhinoviruses

b. Parainfluenza viruses

c. Respiratory syncytial virus (RSV)

d. All of the above

e. b and c


Answer Answer

d. b and c

Rationale: Slightly older children (> 5 y) are at risk for rhinoviral infections. Children under the age of 3 are at risk of infection from both parainfluenza viruses and RSV.


Mechanism of Viral Infection and TreatmentMechanism of Viral Infection and Treatment

amantadine, rimantadine

zanamivir, oseltamivir


Pneumonia—Inflammation of Alveoli and BronchiolesPneumonia—Inflammation of Alveoli and Bronchioles

• Typical: bacteria in the alveoli

– Lobar: affect an entire lobe of the lung

– Bronchopneumonia: patchy distribution over more than one lobe

• Atypical

– Viral and mycoplasma infections of alveolar septum or interstitium


Onset of PneumoniaOnset of Pneumonia• Signs of systemic

inflammation

– Malaise

– Chills and fever

Infection

Inflammation

Serous exudateCongestion,

productive cough


• Blood-tinged sputum

• Pleuritic pain

serous exudate

fibrous exudate: RED

HEPATINIZATIONconsolidation

WBCs denature hemoglobin:

GRAY HEPATINIZATION


If WBCs Overcome the InfectionIf WBCs Overcome the Infection

WBCs denature hemoglobin:

GRAY HEPATINIZATION

WBCs destroy fibrous proteins and liquefy

exudate: it is reabsorbed into the circulation

resolution


Question Question

Tell whether the following statement is true or false.

In the progression of pneumonia, serous exudate develops before fibrous exudate.


Answer Answer

True

Rationale: Serous exudate develops (just after inflammation) before fibrous exudate, and is characterized by a congested, productive cough. If the pneumonia does not resolve at this stage, fibrous exudate develops, and the patient will experience pleuritic pain (worse when taking a deep breath or coughing) and may expectorate blood-tinged sputum.


TuberculosisTuberculosis

• World’s foremost cause of death from a single infectious agent

• Causes 26% of avoidable deaths in developing countries

• Drug-resistant forms

• Mycobacterium tuberculosis hominis

– Aerobic

– Protective waxy capsule

– Can stay alive in “suspended animation” for years


Initial TB InfectionInitial TB Infection• Macrophages begin a

cell-mediated immune response

• Takes 3–6 weeks to develop positive TB test

• Results in a granulomatous lesion

or Ghon focus containing

– Macrophages

– T cells

– Inactive TB bacteria

TB bacteria inhaled

ingested by macrophages

in lungs

macrophages present them

to T cells

activated T cells

kill bacteria

activated T cells stimulate

macrophages to kill bacteria more

efficiently


Ghon complexGhon complex

• Nodules in lung tissue and lymph nodes

• Caseous necrosis inside nodules

• Calcium may deposit in the fatty area of necrosis

• Visible on x-rays


DiscussionDiscussion

Someone in your class has a positive TB test.

Question:

• What does this mean?

• Are you at risk of infection?


Primary TBPrimary TB primary TB

usually isolated in

Ghon foci

bacteria are

inactive

not contagious

if immune response is inadequate, bacteria multiply in the lungs

progressive primary TB


Miliary TBMiliary TB

• Miliary TB lesions look like grains of millet in the tissues

• Meat inspection was introduced to keep them out of the food supply

• Pasteurization of milk was introduced to keep TB out of the milk supply

progressive primary TB

signs of pneumonia

bacteria in sputum and

exhaled droplets

bacteria may erode blood vessels and

spread through the body

MILIARY TB


Secondary TBSecondary TB

• Reinfection from inhaled droplet nuclei

• Reactivation of a previously healed primary lesion

• Immediate cell-mediated response walls off infection in airways

• Bacteria damage tissues in the airways, creating cavities

• Signs of chronic pneumonia: gradual destruction of lung tissue

• “Consumption”: eventually fatal if untreated


Question Question

Which type of TB may be reactivated if the patient becomes immunocompromised?

a. Primary

b. Latent

c. Miliary

d. Secondary


Answer Answer

d. Secondary

Rationale: Secondary TB, often referred to as reactivation or reinfection TB, may occur if patients are reexposed to TB bacilli (after a primary infection) or if they become immunocompromised (they are unable to contain the infection).


Cavitary TuberculosisCavitary Tuberculosis


Lung CancerLung Cancer

• Bronchogenic carcinoma

– Arises from epithelial cells lining the lungs

– Small-cell lung cancer

– Non–small-cell lung cancer

º Large-cell carcinoma

º Squamous cell

º Adenocarcinoma


Manifestations of Lung CancerManifestations of Lung Cancer

• Changes in organ function (organ damage, inflammation, and failure)

• Local effects of tumors (e.g., compression of nerves or veins, gastrointestinal obstruction)

• Ectopic hormones secreted by tumor cells (paraneoplastic disorders)

• Nonspecific signs of tissue breakdown (e.g., protein wasting, bone breakdown)


Respiratory Distress SyndromeRespiratory Distress Syndrome

• Lack of surfactant; infants are not strong enough to inflate their alveoli

• Protein-rich fluid leaks into the alveoli and further blocks oxygen uptake

• Treatment with mechanical ventilation may cause bronchopulmonary dysplasia and chronic respiratory insufficiency


Question Question


Premature infants are at greater risk of developing respiratory distress syndrome (RDS) than term infants.


Answer Answer

True

Rationale: RDS occurs due to a lack of surfactant in the alveoli (the surfactant is produced by alveolar cells, and keeps them inflated). Surfactant is typically produced from week 28 (gestational age) through term (40–42 weeks). The more premature the infant/neonate, the greater the likelihood that there will be insufficient surfactant to sustain ventilation.


Respiratory Obstruction in ChildrenRespiratory Obstruction in Children

• Increased airway resistance

– Extrathoracic airways (upper airways)

º Prolonged inspiration; inspirational stridor

º Inspiratory retractions as ribs are moved outward and body wall does not expand with rib cage

– Intrathoracic airways (lower airways)

º Prolonged expiration with wheezing

º Rib cage retractions as ribs are pulled inward, but air does not leave lungs


Obstructive DisordersObstructive Disorders

• Upper airway

– Croup

– Epiglottitis

• Lower airway

– Acute bronchiolitis


Question Question


Epiglottitis causes stridor.


Answer Answer

True

Rationale: Epiglottitis affects the upper airway (inflammation causes the lumen of the upper airway to become more narrow). When the child inspires, it is difficult to pass air through the narrowed airway. This causes noisy inspiration/stridor.

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Chapter 21 Respiratory Tract Infections, Neoplasia, and Childhood Disorders