Respiratory System Disorders - 2 Flashcards
Lobar Pneumonia
Usually caused my streptococcus pneumoniae (pneumococcus) and the infection is localized in one or more lobes.
First stage is congestion - microbe sometimes colonizes the nasopharynx without producing symptoms. Inflammation and vascular congestion develop in the alveolar wall, exudate forms in the alveoli, interferes with oxygen diffusion. Neutrophils, RBCs and fibrin accumulate in the alveolar exudate, forming a solid mass in the lobe, called consolidation. Presence of RBCs products typical rusty sputum. Produces pleuritic pain (pleurisy or pleuritis).
Infection can spread into the pleural cavity causing empyema - can cause adhesions between the pleural membranes.
Filling of alveoli with exudate reduces diffusion of gases, decreases blood flow, hypoxia results.
Oxygen deficit leads to metabolic acidosis.
Typical manifestations of pneumococcal pneumonia
Sudden onset
High fever with chills, fatigue and leukocytosis
Dyspnea, tachypnea, tachycardia
Pleuritic pain with splinting
Rales - initially over affected lobe, then disappearing
Productive cough with rusty sputum
Confusion and disorientation if infection is severe.
Treated with antibacterial medications and supportive measures, fluids, drugs to reduce fever and oxygen.
Bronchopneumonia
Diffuse pattern of infection in both lungs, more often lower lobes
Caused by multiple bacteria, begin in the bronchial mucosa and spread into the local alveoli. Pooled secretions in the lungs become infected by organisms draining from upper passages, inflammation forms in the alveoli and interferes with oxygen diffusion.
Onset insidious with moderate fever, cough and rales
Dyspnea
Productive cough with yellow / green sputum.
Legionnaires’ Disease
Pneumonia caused by gram-negative bacteria - Legionella pneumophilia.
Thrives in moist environments like spas.
Nosocomial
Organism is found inside pulmonary macrophages
Causes severe congestion and consolidation with necrosis in lung, possibly fatal.
Primary Atypical Pneumonia
Often viral or mycoplasma (small bacterium, lacks cell wall)
Involves interstitial inflammation
Transmitted by aerosol, not highly contagious
Frequent cough
Viral caused by influenza A or B, as well as adenoviruses and RSV.
Starts with inflammation in the mucosa of the upper respiratory tract, then descends to involve lungs
Inflammation is diffuse and interstitial, little exudate, unproductive cough, rales not pronounced
Severe cases can be complicated by secondary bacterial infection.
Self-limiting
Pneumocystis carinii Pneumonia
PCP
Atypical
Occurs as opportunistic, often fatal infection in patients with AIDS.
Fungal, inhaled, attaches to alveolar cells causing necrosis and diffuse interstitial inflammation. Alveoli fill with exudate and fungi.
Difficulty breathing, nonproductive cough
Severe Actue Respiratory Syndrome (SARS)
Atypical pneumonia
Coronavirus - RNA virus, transmitted by respiratory droplets during close contact
Incubation period 2-7 days
Flulike syndrome - fever, headache, myalgia, chills, anorexia, diarrhea
Dry cough, dyspnea
Patchy areas of interstitial congestion and hypoxia increases rapidly, mechanical ventilation often required.
Lymphopenia and thrombocytopenia often present
Elevated liver enzymes - liver damage
Third stage - severe, sometimes fatal respiratory distress.
Identification difficult because antibodies are not present until 3 weeks after onset and nonspecific early manifestations.
Tuberculosis
Increasing particularly among AIDS patients in Africa.
1-2% drugs resistant
Disease of poverty and crowding
Large number of latent cases, 10% will progress to active pulmonary TB
Mycobacterium tuberculosis - primarily affects lungs, may invade other organs.
Aerobic, slow-growing, can survive in dried sputum for weeks, normal response by neutrophils does not occur.
Two stages: TB infection and TB disease.
Primary infection: microorganisms first enter lungs, are engulfed by macrophages and cause local inflammatory reaction, usually on periphery of upper lobe.
Lymphocytes and macrophages cluster to form a granuloma at site of inflammation. Forms a tubercle, in the center caseation necrosis develops - dead macrophages and necrotic material
Healthy person - lesions remain small, become walled off by fibrous tissue, calcifying - called Ghon complexes. Bacilli may remain viable in the dormant state
Hypersensitivity reaction - basis for tuberculin test - several weeks aftern exposure the person has become hypersensitive and will produce a positive skin reaction in response to tuberculoprotein.
Low resistance - primary infection may progress.
Miliary or extrapulmonary tuberculosis - rapidly progressive form, multiple granulomas affect large areas of lungs and rapidly disseminate into the circulation and to other tissues like bone or kidney, often arises years after primary infection, bacilli are reactivated.
Secondary or reinfection - stage of active infection
Cavitation occurs - formation of a large open area in the lung and erosion into bronchi and blood vessels.Bacilli are present in sputum, where they can be passed.
How do you become infected with tuberculosis?
Mycobacterium tuberculosis - transmitted by oral droplets released from a person with active infection that are inhaled into the lungs Crowded conditions Lowered immunity Malnutrition Alcoholism
Signs and symptoms of TB
Primary is asymptomatic, onset of secondary and active is insidious, systemic signs often appear first like anorexia, malaise, fatigue and weight loss. Low-grade fever and night sweats, prolonged cough becomes increasingly severe. As cavitation develops sputum becomes purulent and often contains blood.
Histoplasmosis
Fungal infection
Histoplasma capsulatum and its spores can be inhaled on dust particles
Opportunistic
Common in AIDS
Found as a parasite inside macrophages.
Effects are similar to TB
First stage asymptomatic, followed by 2nd stage of active infection
Second stage involves granuloma formation and necrosis and consolidation in lungs as well as possible spread to other organs
Cough, fatigue, fever, night sweats
Anthrax
Bacterial infection of skin, respiratory tract and GI tract of humans and cattle
Causative organism is gram-positive bacillus that forms grayish-white spores that remain visible for long periods of time
Flulike symptoms, incubation period of 1 to 7 days
Acute respiratory distress occurs with mediastinal widening and fever
Shock due to release of toxins
Cystic fibrosis
Inherited disorder, common in children
1 in 3600 live births in Canada, mean survival is 37 years.
Relate to a protein involved in chloride ion transport in the cell membrane. This defect in the exocrine lands causes abnormally thick secretions such as tenacious mucus
First seen in the lungs and pancreas where sticky mucus obstructs passages
In lungs - mucus obstructs airflow causing air trapping or atelectasis with permanent damage to the bronchial walls
Stagnant mucus promotes bacterial growth and causes infections and add to destruction of lung tissue.
Pancreas - ducts of exocrine glands become blocked - leads to deficit of pancreatic digestive enzymes and malabsorption and malnutrition, can result in diabetes mellitus.
Liver - bile ducts may be blocked by viscid mucus preventing bile from reaching the duodenum and interfering with digestions and absorption of fats and fat soluble vitamins. Can cause biliary cirrhosis.
Thick mucus obstructs vas deferens and cervix.
Autosomal recessive disorder
Signs of cystic fibrosis
Meconium ileus at birth
Salty skin
Malabsorption - steatorrhea, abdominal distention, failure to gain weight
Chronic cough, frequent respiratory infections
Hypoxia, fatigue, exercise intolerance.
Treatment for cystic fibrosis
Replacement therapy for pancreatic enzymes bile salt replacement
Dietary changes
Avoiding dehydration
Intensive chest physiotherapy
Bronchodilators and humidifiers
Cause of death is usually respiratory failure
Lung cancer
Benign tumors are rare
90% of lung cancers are related to smoking
Secondary metastatic cancer develops because venous return and lymphatics bring tumor cells from distant sites in the body - provides first hospitable environment where tumor cells can lodge
First change - metaplasia - associated with smoking and chronic irritation, leaves lung tissue more vulnerable to irritants and inflammation from smoking.
Stage 1 are localized, Stage 3 are disseminated
Common sites of metastases are brain, bone and liver.
