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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.
