2 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.
3 Discuss the possible etiology of bronchial asthma 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.
6 Function of respiratory system Gas exchange (oxygen and carbon dioxide)Regulation of blood pH (acid-base balance)Olfaction (smelling)Defense mechanism
7 Respiratory structures such as the airways, alveoli and pleural membranes may all be affected by various disease processes.These respiratory diseases include:Infections such as pneumonia.Obstructive disorders that obstruct airflow into and out of the lungs such as asthma, bronchitis and emphysema.Restrictive disorders are conditions that limit normal expansion of the lungs such as pneumothorax, atelectasis, respiratory distress syndrome and cystic fibrosis.Cancers or exposure to Inhaled particles alter the pulmonary function.
8 General symptoms of respiratory disease Hypoxia : Decreased levels of oxygen in the tissuesHypoxemia : Decreased levels of oxygen in arterial bloodHypercapnia : Increased levels of CO2 in the bloodHypocapnia : Decreased levels of CO2 in the bloodDyspnea : Difficulty breathingTachypnea : Rapid rate of breathingCyanosis : Bluish discoloration of skin and mucous membranes due to poor oxygenation of the bloodHemoptysis : Blood in the sputum
9 Respiratory infections Infections of the respiratory tract can occur in:The upper respiratory tract orThe lower respiratory tract, orBoth.Organisms capable of infecting respiratory structures include:bacteria.viruses: the majority of upper respiratory tract infections are caused by viruses as rhinovirus and parainfluenza virus.fungi.Depending on the organism and extent of infection, the manifestations can range from mild to severe and even life threatening.
10 Upper respiratory tract Infections The common coldThe most common viral pathogens for the “commoncold” are rhinovirus, parainfluenza virus,respiratory syncytial virus, adenovirus and coronavirus.These viruses tend to have seasonal variations intheir 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.
11 Manifestations of the common cold include: Rhinitis: Inflammation of the nasal mucosaSinusitis :Inflammation of the sinus mucosaPharyngitis : Inflammation of the pharynx and throatHeadacheNasal discharge and congestion
12 Upper respiratory tract Infections InfluenzaInfluenza is a viral infection that can affect the upper orlower respiratory tract.Three distinct forms of influenza virus have been identified: A, Band C, of these three variants, type A is the most common andcauses the most serious illness.The influenza virus is a highly transmissible respiratory pathogen.
13 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 .
15 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.
17 Provides protection against certain A and Influenza vaccineProvides protection against certain A andB influenza strains that are expected to beprevalent in a certain year.The vaccine must be updated and administered yearlyto be effective but will not be effectiveagainst influenza strains not included in the vaccine.The influenza vaccine is particularly indicated inelderly people, in individuals weakened by otherdisease and in health-care workers
19 Lower respiratory tract Infections The respiratory tract is protected by a number ofvery effective defense mechanisms designed tokeep infectious organisms and particulates fromreaching the lungs .For an organism to reach the lower respiratory tract,the organism must be particularly virulent and presentin very large number or the host defense barriers mustbe weakened.
20 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 .
21 Lower respiratory tract Infections Defenses of the Respiratory SystemMoist, mucus-covered surfaces : Trap particles and organismsCell surface IgA, lysosomesCiliated epithelium : Clears trapped particles and organisms from airway passagesCough reflex and epiglottis : Prevents aspiration of particles and irritants into lower airwaysPulmonary macrophages : Phagocytize foreign particles and organisms in the alveolar spaces
22 Lower respiratory tract Infections PneumoniaPneumonia 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.
23 Lower respiratory tract Infections PneumoniaThere tend to be distinct organisms that causepneumonia in the hospital setting vs. the community setting.Individuals Most at Risk for PneumoniaElderlyThose with viral infectionChronically illAIDS or immunosuppressed patientsSmokersPatients with chronic respiratory disease e.g. bronchial asthma.
24 Lower respiratory tract Infections PneumoniaA 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.
25 Lower respiratory tract Infections PneumoniaAtypical 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.
26 Lower respiratory tract Infections PneumoniaOpportunistic organismsA number of organisms not commonly associated withrespiratory illness in otherwise healthy individuals cancause severe respiratory infections and pneumonia inpatients with HIV or those who are immunocompromisedas a result of immune suppressive therapy.These organisms include mycobacteria, fungus (Histoplasma)and protozoa (Pneumocystis carinii).Treatment of these organisms requires specific drugtherapy, and, in the case of protozoa and fungi, the organismsare very difficult to kill.
27 Lower respiratory tract Infections PneumoniaTreatment 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.
28 Obstructive Respiratory Disorders Bronchial asthmaAsthma is a condition characterized by reversible bronchospasmand chronic inflammation of airway passages.The incidence of asthma has been steadily increasing in recentyears.Although the exact etiology is still uncertain, there appearsto 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 inducemarked bronchospasm and airway inflammation in susceptible patients
29 Obstructive Respiratory Disorders Bronchial asthmaIndividuals with asthma appear to produce large amountsof the antibody IgE that attach to the mast cells present inmany tissues.Exposure to a trigger such as pollen will result in theallergen-binding mast cell-bound IgE, which in turn causes therelease of inflammatory mediators such as Histamine ,Leukotrienes and Eosinophilic Chemotactic factor.The response of a patient with asthma to these triggerscan be divided into an “early phase” and a “late phase.”
32 Obstructive Respiratory Disorders Bronchial asthmaClinical Classification of AsthmaMild intermittent : Attacks occur 2 times per week or lessMild persistent : Attacks occur more than 2 times per weekModerate persistent : Attacks occur daily or almost dailyand are severe enough to affect activitySevere persistent : Attacks are very frequent and persistfor a long period of time; attacks severely limit activity
33 Obstructive Respiratory Disorders Bronchial asthmaEarly phase of asthma:The early phase of asthma is characterized by:marked constriction of bronchial airways (bronchospasm)edema of the airwaysproduction 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.
34 Obstructive Respiratory Disorders Bronchial asthmaLate phase of asthma:The late phase of asthma can occur several hours afterthe initial onset of symptoms and manifests mainlyas an inflammatory response.The primary mediators of inflammation during theasthmatic response are the white blood cells Eosinophilsthat stimulate mast cell degranulation and releasesubstances that attract other white cells to the area.Subsequent infiltration of the airway tissues with whiteblood cells such as Neutrophils and lymphocytes also contributesto the overall inflammatory response of the late phase of asthma.
36 Obstructive Respiratory Disorders Bronchial asthmaStaging of the Severity of an Acute Asthma Attack- Stage I (mild)Mild DyspneaDiffuse wheezingAdequate air exchange- Stage II (moderate)Respiratory distress at restMarked wheezing
37 - Stage IV (respiratory failure) - Stage III (severe)Marked respiratory distressCyanosisMarked wheezing or absence of breath sounds- Stage IV (respiratory failure)Severe respiratory distress, lethargy, confusion, prominent pulsus paradoxusLethargy كسلa pulsus paradoxus (PP), also paradoxic pulse or paradoxical pulse, is defined as an abnormally large decrease in systolic blood pressure and pulse wave amplitude during inspiration.
38 Obstructive Respiratory Disorders Bronchial asthmaPossible 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.Pneumothorax is defined as the presence of air or gas in the pleural cavity
39 Obstructive Respiratory Disorders Bronchial asthmaTreatment 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.
40 Obstructive Respiratory Disorders Bronchial asthma3.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 phaseof asthma. The mechanism of action is unclear but may involvemast cell function or responsiveness to allergens.
41 Obstructive Respiratory Disorders Bronchial asthma5. Anti-inflammatory drugs (corticosteroids) :- Used orally or by inhalation to blunt the inflammatory responseof asthma.- The most significant unwanted effects occur with long-term oraluse 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 keyinflammatory mediators, leukotrienes.