Pathophysiology Exam 4.23

Disorders of the Respiratory System (23)

Common cold. Viral or bacterial? Most common causative agent?

Viral

Rhinoviruses are most common cause

Common cold. How is it transmitted? How is it treated?

Direct contact

Antibiotics are not recommended. Self-limited illness, symptomatic treatment, rest, anti-pyretic drugs.

Rhinosinusitis. Timeline and causes of acute vs chronic

Acute- 5 days to 4 weeks

Acute- Virus, bacterial, mixed.

Chronic- More than 12 weeks

Chronic- Bacterial or fungal. Can cause nasal polyps.

Caused by obstruction of sinus drainage.

Rhinosinusitis. Differential symptoms between sinus infection and common cold.

Acute Rhinosinusitis- Facial Pain. Purulent drainage. Decreased sense of smell. Pain with bending. Pain in teeth.

Chronic- Sinus Pressure.

Differential symptom- Sinus headache (worse with bending over, coughing, sneezing).

Rhinosinusitis Treatment.

Viral- Self-limiting.

Bacterial- Antibiotics

Nasal Polyps- may require surgery

Symptom Management- Intranasal corticosteroids, decongestants. Mucolytics.

Influenza. Compare and contrast type A and type B.

Type A- Infects humans, birds, mammals

—Flu A can develop new HA & NA subtypes that population isn’t protected against

Epidemic and pandemic potential

Type B:

Humans only; far less antigenic shift

Influenza. Difference between antigenic shift and antigenic drift

Antigenic shift = major genetic rearrangement of HA or NA (essentially results in a “new” virus)

Antigenic drift = minor changes to HA & NA through mutation

How is the flu transmitted?

Inhalation of infectious respiratory droplets

—Highly contagious

Potential complications of the flu

Viral Pneumonia

—Rapid progression of fever, tachypnea, cyanosis, and hypotension. Can cause hypoxemia and death within a few days.

Secondary Bacterial Infections

—Sinusitis, otitis media, bronchitis, and bacterial pneumonia

Influenza treatment and prevention

Treatment—

—Limit infection to upper respiratory tract

—Rapid tests for early detection

—Antiviral drugs (E.g., Tamiflu)

Prevention

Yearly vaccination recommended for everyone >6 months

Pneumonia. Conditions.

inflammation of the parenchymal structures of the lung (bronchioles and alveoli)Pnu

Pneumonia. At risk patients for mortality?

immunocompromised and elderly people and people with debilitating diseases.

Nosocomial.

Pneumonia. Atypical and typical Pneumonia.

Type of agent:

-Typical – Bacterial; infection & fluid accumulation in air-filled spaces of alveoli

-Atypical – Viral or mycoplasma infection of alveolar septum and interstitial space

Tuberculosis. Groups of people at high risk for infection? High severity and death?

#1 cause of death in people with HIV

Major cause of deaths related to antimicrobial resistance

Tuberculosis. Causative agent, resistance to destruction, transmission.

Causative agent- Mycobacterium tuberculosis

Resistance to destruction- Unique waxy capsule. Macrophages can capture but not kill.

Transmission-Inhalation of infected respiratory droplets

Tuberculosis. Granuloma and Ghon complex formation and appearance.

Ghon complex = the combination of the primary lung lesion and lymph node granulomas

—Undergoes caseous necrosis (white, cheese-like)

—Eventual healing and calcification (visible on x-ray)

TB. Latency and contagion of latent TB.

Healed dormant lesion is not contagious may reactivate and cause secondary TB. Contagious when active again.

Pathogenesis of secondary TB.

Cause:

Reinfection or reactivation of latent infection

Immediate cell-mediated response walls off infection

Cell-mediated hypersensitivity enhances tissue damage and leads to cavitation (destruction of lung tissue) and increased dissemination

Fungal infection of lungs. At risk groups for severe infection.

Most are asymptomatic, but can be severe or fatal in heavy exposure or immunocompromised individuals

Lung Cancer. Risk factors and general prognosis.

Risk Factors:

Cigarette Smoking: causes >80% of cases

Industrial hazards (E.g., asbestos)

Familial predisposition (genetic)

Cancer survivors who have had radiation therapy to the chest.

GP- Depends on type, stage, and grade

Lung cancers are often aggressive, locally invasive, and widely metastatic

Lung cancers are often diagnosed late, thus prognosis is generally poor with a low 5-year survival rate

Small Cell Lung Cancer. Histopathology.

Small round to oval cells that grow in clusters

Presence of neurosecretory granules

SCLC. Characteristics. Common site of metastatis. Prognosis. Treatment.

Characteristics:

Highly malignant, wide infiltration, early dissemination, rarely resectable

Brain metastases common

Prognosis:

Poor

The general 5-year survival rate for people with SCLC is 7%

Treatment:

Chemotherapy with or without radiation

Surgery is generally not recommended

NSCLC. Squamous cell carcinoma. Common patient group? possibility for earlier detection?

Most commonly found in men with smoking history

Often originates in the central bronchi as intraluminal growth (gets coughed up - early detection possible by examining sputum)

NSCLC. Adenocarcinoma. Common patient group?

—Most common type of lung cancer in North America; most common type for women and nonsmokers

—Originate in the bronchiolar or alveolar tissues, most located peripherally

—Poorer prognosis than squamous cell

NSCLC. Large cell carcinoma. Histopathology and anaplasia.

Large, polygonal cells; occur in the periphery of the lung

Highly anaplastic, early dissemination, poor prognosis.

NSCLC treatment

Treatment: Surgery, radiation therapy, and chemotherapy

Paraneoplastic syndrome.

Cause:

Due to hormones secreted by the cancer cells

Clinical Manifestations:

May precede the onset of other signs of lung cancer

Examples:

Squamous Cell Carcinoma

Hypercalcemia (parathyroid-like peptide secretion)

Small Cell Lung Cancer:

Cushing syndrome - adrenocorticotropic hormone (ACTH) secretion → increased cortisol

SIADH - syndrome of inappropriate antidiuretic hormone secretion

Lung cancer symptoms and changes in lung function.

Constitutional symptoms of cancer

—Fatigue, decreased appetite, and weight loss

Changes in lung function

—Chronic cough, shortness of breath, and wheezing

Superior vena cava syndrome due to compression

Pleural effusion

Metastases (brain, bone, and liver)

Respiratory disorders in children. Familiar terms?

Chest wall retraction - abnormal inward movements of the chest wall during inspiration

Nasal flaring - enlargement of the nares which helps reduce the nasal resistance and maintain airway patency; increased work of breathing

Stridor - an audible crowing sound during inspiration caused by the increased turbulence of air moving through the obstructed extrathoracic (upper) airways

Grunting - an audible noise emitted during expiration as the child tries to raise the end-expiratory pressure by closing the glottis

Wheezing – a whistling sound during expiration due to obstruction and collapse of the intrathoracic (lower) airway

Respiratory distress syndrome. Patient population of occurrence.

One of the most common causes of respiratory disease in premature infants

Respiratory Distress syndrome. Cause?

Immature lung structures

Lack of surfactant – alveolar collapse

Protein-rich fluid leaks into the alveoli – barrier to gas exchange

Respiratory distress syndrome. Manifestations and treatment.

Clinical Manifestations:

Central cyanosis, difficulty breathing, grunting

Treatment:

Oxygen supplementation, continuous positive airway pressure, mechanical ventilation (may cause bronchopulmonary dysplasia and chronic respiratory insufficiency)

Surfactant

Bronchopulmonary Dysplasia. Patient population?

Chronic lung disease that develops in premature infants after prolonged treatment for RDS

Bronchopulmonary Dysplasia. Clinical manifestations.

Chronic respiratory distress: persistent hypoxemia, reduced lung compliance, increased airway resistance, severe expiratory flow limitation

Pulmonary hypertension (due to increased pulmonary vascular resistance) and cor pulmonale (enlargement and weakening of right side of heart)

Severe: clubbing of the fingers

Cause:

Mechanical/positive-pressure ventilation or prolonged oxygen supplementation causes injury to premature lung

Infectious respiratory obstruction. Croup, epiglottis, acute bronchitis.

Upper airway

Croup: more common, usually benign, self-limiting

Epiglottitis: rapidly-progressing, life-threatening

Lower airway

Acute bronchiolitis: can be severe

IRO. Causative pathogens?

Epiglottis-

Bacterial: H. influenzae type B

Streptococcus pyogenes, S. pneumoniae, S. aureus

Croup-

Viral: Parainfluenza virus

Bronchiolitis-

Viral: Respiratory syncytial virus

IRO. Features/symptoms of each type.

Epiglottis-

appears very sick and toxic; sits with mouth open and chin thrust forward; Low-pitched stridor, difficulty swallowing, fever, drooling, anxiety; danger of airway obstruction and asphyxia

Croup-

Inspiratory stridor, hoarseness and a barking cough; usually occurs at night; relieved by exposure to cold or moist air

Bronchiolitis-

Breathlessness; rapid, shallow breathing; wheezing; cough; and retractions of lower ribs and sternum during inspiration

IRO. X-ray signs.

Epiglottis-

a "thumbprint" or enlarged epiglottis appears on a lateral neck X-ray

Croup-

"steeple sign" indicative of subglottic narrowing

Bronchiolitis-

hyperinflation and patchy atelectasis

often doesn’t require imaging.