Describe the general symptoms of respiratory disease. Discuss the key features of an influenza...

DISORDERS OF THE RESPIRATORY

SYSTEM

STUDY OBJECTIVES Describe the general symptoms of respiratory

disease.

Discuss the key features of an influenza infection.

Compare and contrast typical and atypical

pneumonia.

List specific organisms that are associated with

pneumonia.

Discuss the possible etiology of bronchial asthma.

What are some potential asthma triggers?

Compare and contrast the “early” and “late” phases of

asthma in terms of their effects on the respiratory

passages and clinical manifestations.

Describe how asthma attacks are classified based on

frequency and severity of attacks.

Describe the various means by which asthma might be

treated.

FUNCTION OF RESPIRATORY SYSTEM

1. Gas exchange (oxygen and carbon dioxide)

2. Regulation of blood pH (acid-base balance)

3. Olfaction (smelling)4. Defense mechanism

Respiratory structures such as the airways, alveoli and pleural membranes may all be affected by various disease processes.

These respiratory diseases include:

1. Infections such as pneumonia.

2. Obstructive disorders that obstruct airflow into and out of the lungs such as asthma, bronchitis and emphysema.

3. Restrictive disorders are conditions that limit normal expansion of the lungs such as pneumothorax, atelectasis, respiratory distress syndrome and cystic fibrosis.

4. Cancers or exposure to Inhaled particles alter the pulmonary function.

GENERAL SYMPTOMS OF RESPIRATORY DISEASE

Hypoxia : Decreased levels of oxygen in the tissues Hypoxemia : Decreased levels of oxygen in arterial

blood

Hypercapnia : Increased levels of CO2 in the blood

Hypocapnia : Decreased levels of CO2 in the blood

Dyspnea : Difficulty breathing Tachypnea : Rapid rate of breathing Cyanosis : Bluish discoloration of skin and mucous

membranes due to poor oxygenation of the blood Hemoptysis : Blood in the sputum

RESPIRATORY INFECTIONSInfections of the respiratory tract can occur in:1. The upper respiratory tract or 2. The lower respiratory tract, or3. Both.

Organisms capable of infecting respiratory structures include:

4. bacteria.5. viruses: the majority of upper respiratory tract infections

are caused by viruses as rhinovirus and parainfluenza virus.

6. fungi.

Depending on the organism and extent of infection, the manifestations can range from mild to severe and even life threatening.

UPPER RESPIRATORY TRACT INFECTIONS

The most common viral pathogens for the “common

cold” are rhinovirus, parainfluenza virus, respiratory syncytial virus, adenovirus and

coronavirus.

These viruses tend to have seasonal variations in their peak incidence.

They gain entry to the body through the nasal mucosa and the surfaces of the eye. They are readily spread from person to person via respiratory secretions.

The common cold

Manifestations of the common cold include:

Rhinitis: Inflammation of the nasal mucosa Sinusitis :Inflammation of the sinus mucosa Pharyngitis : Inflammation of the pharynx

and throat Headache Nasal discharge and congestion


Influenza is a viral infection that can affect the upper or

lower respiratory tract.

Three distinct forms of influenza virus have been identified: A,

B

and C, of these three variants, type A is the most common and

causes the most serious illness.

The influenza virus is a highly transmissible respiratory

pathogen.

Influenza

Because the organism has a high tendency for genetic mutation, new variant of the virus are constantly arising in different places around the world. Serious pandemics (spread of infection across a large region) of influenza are seen every 8 to 10 years as a result of this genetic mutation .


Symptoms of influenza infection: Headache Fever, chills Muscle aches Nasal discharge Unproductive cough Sore throat

Influenza

Influenza infection can cause marked inflammation of the respiratory epithelium leading to acute tissue damage and a loss of ciliated cells that protect the respiratory passages from other organisms.

As a result, influenza infection may lead to co-infection of the respiratory passages with bacteria.

It is also possible for the influenza virus to infect the tissues of the lung itself to cause a viral pneumonia.

Treatment of influenza: Bed rest, fluids, warmth Antiviral drugs

Influenza vaccine

InfluenzaUpper respiratory tract

Infections

Influenza vaccine Provides protection against certain A and B influenza strains that are expected to be prevalent in a certain year. The vaccine must be updated and administered yearly to be effective but will not be effective against influenza strains not included in the vaccine.

The influenza vaccine is particularly indicated in elderly people, in individuals weakened by other disease and in health-care workers

Drugs for Treating Influenza: Amantidine

Neuraminidase inhibitors (Zanamavir, Oseltamivir)

Upper respiratory tract InfectionsInfluenza

LOWER RESPIRATORY TRACT INFECTIONS

The respiratory tract is protected by a number of

very effective defense mechanisms designed to

keep infectious organisms and particulates from

reaching the lungs .

For an organism to reach the lower respiratory tract,

the organism must be particularly virulent and present

in very large number or the host defense barriers must

be weakened.

Factor that might weaken the respiratory defense barriers: Cigarette smoking, which can paralyze

the cilia lining the cells of the respiratory passages and impair removal of secretions, particles and microorganisms.

The presence of a respiratory pathogen such as the cold or influenza virus .


Defenses of the Respiratory System1. Moist, mucus-covered surfaces : Trap particles and

organisms2. Cell surface IgA, lysosomes3. Ciliated epithelium : Clears trapped particles and

organisms from airway passages4. Cough reflex and epiglottis : Prevents aspiration of

particles and irritants into lower airways5. Pulmonary macrophages : Phagocytize foreign

particles and organisms in the alveolar spaces


Pneumonia is a condition that involves inflammation of lower

lung structures such as the alveoli or interstitial spaces.

It may be caused by bacteria , viruses or parasites such as

pneumocystis carinii.

The prevalence and severity of pneumonia have been

heightened in recent years due to the emergence of HIV as well

as antibiotic resistance.

Pneumonia may be classified according to the pathogen that

is responsible for the infection.

Pneumonia


There tend to be distinct organisms that cause pneumonia in the hospital setting vs. the community

setting.

Individuals Most at Risk for Pneumonia Elderly Those with viral infection Chronically ill AIDS or immunosuppressed patients Smokers Patients with chronic respiratory disease e.g. bronchial asthma.

Pneumonia


A second classification scheme for pneumonia is based on the specific structures of the lung that the organisms infect and includes typical and atypical pneumonia.

Typical pneumonia• Usually bacterial in origin.• Organisms replicate in the spaces of the alveoli.

Manifestations:• Inflammation and fluid accumulation are seen in the

alveoli.• White cell infiltration and exudation can been seen on

chest radiographs.• High fever, chest pain, chills, and malaise are present.• Purulent sputum is present.• Some degree of hypoxemia is present.

Pneumonia

Atypical pneumonia• Usually viral in origin.• Organisms replicate in the spaces around the alveoli.

Manifestations:• Milder symptoms than typical pneumonia.

• Lack of white cell infiltration in alveoli.• Lack of fluid accumulation in the alveoli.• Not usually evident on radiographs.

• May make the patient susceptible to bacterial pneumonia.

Lower respiratory tract Infections

Pneumonia

Opportunistic organisms A number of organisms not commonly associated with

respiratory illness in otherwise healthy individuals can

cause severe respiratory infections and pneumonia in

patients with HIV or those who are immunocompromised

as a result of immune suppressive therapy.

These organisms include mycobacteria, fungus (Histoplasma)

and protozoa (Pneumocystis carinii).

Treatment of these organisms requires specific drug

therapy, and, in the case of protozoa and fungi, the organisms

are very difficult to kill.


Pneumonia

Treatment of pneumonia:

• Antibiotics if bacterial in origin.

• Oxygen therapy for hypoxemia.

• A vaccine for pneumococcal pneumonia is currently available and highly effective. This vaccine should be considered in high-risk individuals.


Pneumonia

OBSTRUCTIVE RESPIRATORY DISORDERS

Asthma is a condition characterized by reversible bronchospasm

and chronic inflammation of airway passages.

The incidence of asthma has been steadily increasing in recent

years.

Although the exact etiology is still uncertain, there appears

to be a definite genetic predisposition to the development of asthma.

A key component of asthma appears to be airway “hyper reactivity”

in affected individuals. Exposure to certain “triggers” can induce

marked bronchospasm and airway inflammation in susceptible patients

Bronchial asthma

Individuals with asthma appear to produce large amounts

of the antibody IgE that attach to the mast cells present in

many tissues.

Exposure to a trigger such as pollen will result in the

allergen-binding mast cell-bound IgE, which in turn causes the

release of inflammatory mediators such as Histamine ,

Leukotrienes and Eosinophilic Chemotactic factor.

The response of a patient with asthma to these triggers

can be divided into an “early phase” and a “late phase.”

Obstructive Respiratory Disorders

Bronchial asthma

**Some Potential Asthma Triggers** Allergens — Pollen, pet dander, fungi, dust and

mites Cold air Pollutants Cigarette smoke Strong emotions Exercise Respiratory tract infections


Bronchial asthma

Clinical Classification of Asthma

Mild intermittent : Attacks occur 2 times per week or less

Mild persistent : Attacks occur more than 2 times per week

Moderate persistent : Attacks occur daily or almost daily

and are severe enough to affect activity

Severe persistent : Attacks are very frequent and persist

for a long period of time; attacks severely limit activity


Bronchial asthma

Early phase of asthma:

The early phase of asthma is characterized by:

a. marked constriction of bronchial airways (bronchospasm)

b. edema of the airways

c. production of excess mucus.

The bronchospasm that occurs may be the result of the increased release of certain inflammatory mediators such as histamine, prostaglandins and bradykinin that, in the early stages of asthmatic response, promote bronchoconstriction rather than inflammation.


Bronchial asthma

Late phase of asthma:

The late phase of asthma can occur several hours after

the initial onset of symptoms and manifests mainly

as an inflammatory response.

The primary mediators of inflammation during the

asthmatic response are the white blood cells Eosinophils

that stimulate mast cell degranulation and release

substances that attract other white cells to the area.

Subsequent infiltration of the airway tissues with white

blood cells such as Neutrophils and lymphocytes also contributes

to the overall inflammatory response of the late phase of asthma.


Bronchial asthma

Manifestations of asthma : Coughing, wheezing Difficulty breathing Rapid, shallow breathing Increased respiratory rate Excess mucus production Significant anxiety


Bronchial asthma

Staging of the Severity of an Acute Asthma Attack- Stage I (mild)

Mild Dyspnea Diffuse wheezing Adequate air exchange

- Stage II (moderate) Respiratory distress at rest Marked wheezing


Bronchial asthma

- Stage III (severe) Marked respiratory distress Cyanosis Marked wheezing or absence of breath sounds

- Stage IV (respiratory failure) Severe respiratory distress, lethargy, confusion,

prominent pulsus paradoxus

Possible complications of asthma can include :

Severe acute Asthma (status asthmatics), which is a life-threatening condition of prolonged bronchospasm that is often not responsive to drug therapy.

Pneumothorax : is also a possible consequence as a result of lung pressure increases that can result from the extreme difficulty involved in expiration during a prolonged asthma attack.

Respiratory failure: marked hypoxemia and acidosis might occur.


Bronchial asthma

Treatment of asthma:

The appropriate drug treatment regimen for asthma is based on the

frequency and severity of the asthma attacks and may include the

following:

1. Avoidance of triggers, and allergens. Improved ventilation

of the living spaces, use of air conditioning.

2. Bronchodilators (examples: albuterol, terbutaline): Short

acting β-Adrenergic receptor activators May be administered as

needed in the form of a nebulizer solution using a metered

dispenser or may be given subcutaneously. These drugs block

bronchoconstriction but do not prevent the inflammatory

response.


Bronchial asthma

3.Xanthine drugs (example: theophylline) :

Cause bronchodilation and also inhibit the late phase of asthma. These drugs are often used orally as second-line agents in

combination with other asthma therapies such as steroids. Drug like theophylline can have significant central nervous system,

cardiovascular and gastrointestinal side effects that limit their overall usefulness.

4.Cromolyn sodium :Anti-inflammatory agent that blocks both the early and late phase of asthma. The mechanism of action is unclear but may involve mast cell function or responsiveness to allergens.


Bronchial asthma


Bronchial asthma

5. Anti-inflammatory drugs (corticosteroids) :

- Used orally or by inhalation to blunt the inflammatory response

of asthma.

- The most significant unwanted effects occur with long-term oral

use of corticosteroids and may include immunosuppression ,

increased susceptibility to infection, DM , HTN and osteoporosis .

6. Leukotrienes modifiers (example: Zafirlukast) :

- New class of agents that blocks the synthesis of the key

inflammatory mediators, leukotrienes.

Thank you

Describe the general symptoms of respiratory disease. Discuss the key features of an influenza...

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