Chapter 15

1. Chapter 15 The Respiratory System

2. Respiratory/Circulatory A Cooperative Effort • Oxygen delivery to the tissues and waste product removal requires a cooperative effort of the respiratory and circulatory systems • The respiratory system oxygenates the blood and removes carbon dioxide • The circulatory system transports these gases in the bloodstream

3. Lung Components • System of tubes to conduct air into and out of the lungs • Bronchi: largest conducting tube • Bronchioles (little bronchi): next in size • Terminal Bronchioles: smallest • Respiratory Bronchioles: tubes distal to terminal bronchioles; they have alveoli projecting from their walls. Transport air but also participate in gas exchange • Alveoli where oxygen and carbon dioxide exchange between air and pulmonary capillaries • Lung divided into large segments called lobes, each one consisting of smaller units, lobules

4. Structure Terminal Air Passages

5. Respiration: Function • Acinus or respiratory unit: functional unit of the lung • Respiration has two functions • Ventilation • Air movement caused by movement of ribs and diaphragm • Gas exchange • Gases diffuse between blood, tissues, and pulmonary alveoli due to differences in their partial pressures

6. Pulmonary Function Tests • Vital capacity • One-second forced expiratory volume (FEV1) • Arterial PO2 and PCO2

7. The Pleural Cavity • Lungs are covered by a thin membrane called pleura, which also extends over the internal surface of the chest wall • The potential space between the lungs and the chest wall is called pleural cavity • Intrapleural pressure is less than the intrapulmonary pressure • The negative intrapleural pressure is caused by the tendency of the stretched lung to pull away from the chest wall • A release of the vacuum in the pleural cavity leads to a collapse of the lung - Atelectasis

8. How Does the Vacuum get released? • A hole is created in the pleura – known as a pneumothorax • The hole can be one from the outside of the body “traumatic pneumothorax” – example – knife wound – this allows higher pressure outside air to enter the pleural space • The hole can be one from the inside where an surface alveoli bursts “spontaneous pneumothorax”– this allows higher pressure lung air to enter the pleural space • The air in the pleural space can cause a collapse of the lung “atelectasis”

9. Pneumothorax Pathogenesis/Manifestations Pathogenesis • Lung injury or pulmonary disease that allows air to escape into the pleural space • Stab wound or penetrating injury to the chest wall • Spontaneous – generally in young healthy persons Manifestations • Chest pain • Shortness of breath • Air in pleural cavity • Tension pneumothorax

10. Tension Pneumothorax • Development of a higher than atmospheric pressure in the pleural cavity – creating a tension • Can accompany any type of pneumothorax • Upon inhalation air enters pleural space – due to drop in intrapleural pressure • On exhalation – air gets trapped due to the edges of the tear compressing as a result of the increased intrapleural pressure – thus the pressure in the intrapleural space is getting greater and greater • Heart and Mediastinal structures shifted away from pneumothorax

11. Pneumothorax Treatment • A chest tube is inserted into the pleural cavity and left in place until tear in lung heals • Prevents accumulation of air in pleural cavity • Aids reexpansion of lung

12. Atelectasis An incomplete expansion of the lung, a collapse of a part of the lung There are two types 1. Obstructive atelectasis: complete bronchial obstruction by • Mucous secretions, tumor, foreign object • Resulting in collapse of the part of the lung supplied by the blocked bronchus • Can also develop as a postoperative complication, where because of the pain, the patient does not cough or breathe deeply, accumulating mucous secretions

13. Atelectasis 2. Compression atelectasis • External compression on the lung • Fluid, air, or blood in the pleural cavity, reducing its volume and preventing lung expansion

14. Pneumonia An inflammation of the lung • The exudate spreads unimpeded through the lung • Filling the alveoli • The affected portions of the lung become relatively solid (consolidation) • At times, the exudate reaches the pleural surface

15. Pneumonia Classification Classification • Etiology: most important because it serves as a guide for treatment • Bacteria, chlamydia, mycoplasmas, rickettsiae, viruses, fungi • Anatomic distribution of the inflammatory process- describes what part of the lung is involved • Lobar: entire lung (bacteria, neutrophil infiltration) • Bronchopneumonia (bacteria, neutrophil infiltration): parts of one or more lobes adjacent to the bronchi – bronchopulmonary segments

16. Pneumonia Classification • Interstitial pneumonia or primary atypical pneumonia (virus or mycoplasma; lymphocyte, monocyte, and plasma cell infiltration): alveolar septa affected • Predisposing factors that lead to its development • Any condition associated with poor lung ventilation and retention of bronchial secretions • Postoperative – atelectasis and secondary bacterial infection • Aspiration • Obstruction

17. Clinical features of pneumonia • Manifestations of systemic infection • Feeling ill • Elevated temperature • Increased white blood cell count • Manifestations of lung inflammation • Cough • Purulent sputum • Pain on respiration if involves pleura • Shortness of breath

18. Legionnaires’ Disease • First known occurrence 1976 at American Legion Convention in Philadelphia • Gram-negative rod shaped bacteria called Legionella pneumophila • Found in moist environments • Airborne infection – not spread from human to human • Treated by appropriate antibiotics

19. SARSSevere Acute Respiratory Syndrome • A highly communicable serious pulmonary infection, caused by an unusual coronavirus that has spread rapidly through several countries since it was first identified in late 2002 • In 2003 a Chinese Physician became ill while staying in a hotel in Hong Kong along with 12 other hotel occupants – they flew out to other countries and it spread • Many become seriously ill and some die (5% of patients –higher rate in patients with other diseases like diabetes) from Respiratory Distress Syndrome

20. The SARS-associated virus is a unique RNA virus not closely related to other coronaviruses and the first one to cause severe disease in people. The virus has crown like (corona) spikes projecting from its surface • The virus probably was an animal virus that mutated and was able to infect humans • Virus present in the blood during early stages then in feces later • Can survive in the environment for up to 3 hours. • Incubation period 2 to 7 days but may be up to 10 days. • Illness begins with chills, fever and sometimes mild respiratory symptoms and occasionally diarrhea. After 3 -7 days it manifests as a lower respiratory tract infection with varying severity. • The most infected need mechanical ventilation • Can be transmitted from person to person through coughing, sneezing, by hands, towels, and other items contaminated with the virus • There are no effective antiviral drugs that can influence the course of the disease

21. Swine Flu • Swine influenza (also swine flu) refers to influenza caused by any virus of the family Orthomyxoviridae, that is endemic to pig (swine) populations. Strains endemic in swine are called swine influenza virus (SIV), and all known strains of SIV are classified as Influenza virus A (common) or Influenza virus C (rare).Influenzavirus B has not been reported in swine. All three classes, Influenzavirus A, B, and C, are endemic in humans

22. People who work with poultry and swine, especially people with intense exposures, are at risk of infection from these animals if the animals carry a strain that is also able to infect humans. SIV can mutate into a form that allows it to pass from human to human. The strain responsible for the 2009 swine flu outbreak is believed to have undergone this mutation. • In humans, the symptoms of swine flu are similar to those of influenza and of influenza-like illness in general

23. Signs and Symptoms • Main symptoms of swine flu in humans. • According to the Centers for Disease Control and Prevention (CDC), in humans the symptoms of swine flu are similar to those of influenza and of influenza-like illness in general. Symptoms include fever, cough, sore throat, body aches, headache, chills and fatigue. A few more patients than usual have also reported diarrhea and vomiting.

24. Because these symptoms are not specific to swine flu, a differential diagnosis of probable swine flu requires not only symptoms but also a high likelihood of swine flu due to the person's recent history. For example, during this 2009 swine flu outbreak in the United States, CDC advised physicians to "consider swine influenza infection in the differential diagnosis of patients with acute febrile respiratory illness who have either been in contact with persons with confirmed swine flu, or who were in one of the five U.S. states that have reported swine flu cases or in Mexico during the 7 days preceding their illness onset.“[A diagnosis of confirmed swine flu requires laboratory testing of a respiratory sample (a simple nose and throat swab).

25. Pathophysiology • Influenza viruses bind through hemagglutinin onto sialic acid sugars on the surfaces of epithelial cells; typically in the nose, throat and lungs of mammals and intestines of birds (Stage 1 in infection figure). Swine flu in humans • People who work with poultry and swine, especially people with intense exposures, are at increased risk of zoonotic infection with influenza virus endemic in these animals, and constitute a population of human hosts in which zoonosis and re-assortment can co-occur.

26. Transmission of influenza from swine to humans who work with swine was documented in a small surveillance study performed in 2004 at the University of Iowa. This study among others forms the basis of a recommendation that people whose jobs involve handling poultry and swine be the focus of increased public health surveillance. • The 2009 swine flu outbreak is an apparent re-assortment of several strains of influenza A virus subtype H1N1, including a strain endemic in humans and two strains endemic in pigs, as well as an avian influenza.

27. The CDC reports that the symptoms and transmission of the swine flu from human to human is much like that of seasonal flu. • Common symptoms include fever, lethargy, lack of appetite and coughing, while runny nose, sore throat, nausea, vomiting and diarrhea have also been reported. • It is believed to be spread between humans through coughing or sneezing of infected people and touching something with the virus on it and then touching their own nose or mouth. Swine flu cannot be spread by pork products, since the virus is not transmitted through food. • The swine flu in humans is most contagious during the first five days of the illness although some people, most commonly children, can remain contagious for up to ten days.

28. Diagnosis • made by sending a specimen, collected during the first five days, to the CDC for analysis. Treatment • The swine flu is susceptible to four drugs licensed in the United States, amantadine, rimantadine, oseltamivir and zanamivir, however, for the 2009 outbreak it is recommended it be treated under medical advice only with oseltamivir and zanamivir to avoid drug resistance. • The vaccine for the human seasonal H1N1 flu does not protect against the swine H1N1 flu, even if the virus strains are the same specific variety, as they are antigenically very different.

29. Prevention • Recommendations to prevent infection by the virus consist of the standard personal precautions against influenza. This includes frequent washing of hands with soap and water or with alcohol-based hand sanitizers, especially after being out in public. People should avoid touching their mouth, nose or eyes with their hands unless they've washed their hands. If people do cough, they should either cough into a tissue and throw it in the garbage immediately, cough into their elbow, or, if they cough in their hand, they should wash their hands immediately. • Vaccines that are effective against the current strain are being developed.

30. Pneumocystis Pneumonia • Humans and many animals harbor this microorganism – Pneumocystis carinii • Caused by protozoan parasite of low pathogenicity • Does not affect normal persons • Affects immunocompromised persons • Persons with AIDS • Persons receiving immunosuppressive drugs • Premature infants whose immune defenses are poorly developed • Organisms injure alveoli, leading to exudation of protein-rich material into alveoli • Dyspnea • Cough • Pulmonary consolidation

31. Cysts demonstrated by special stains • Within the cysts are sporozoites- when released from the cysts these organisms mature and enlarge into trophozoites. Some trophozoites give rise to more cysts, repeating the cycle but some attack the lining of the alveoli (destruction). • Evidence of pulmonary consolidation visualized on chest radiograph • Diagnosis established by biopsy of lung tissue obtained by bronchoscopy • Treatment • Drugs that inhibit growth of organism • Infection has high mortality

32. Tuberculosis • It is a special type of pneumonia caused by Mycobacterium tuberculosis – an acid – fast bacteria • Because the tubercle bacillus has a capsule composed of waxes and fatty substances, it is more resistant to destruction than others – thick cell wall • As a result of this organism’s resistance – monocytes accumulate around the bacteria – many fuse with the bacteria attempting phagocytosis – but the fusion produces a large multinucleated “giant cell”. Lymphocytes and plasma cells surround the area – followed by fibrous tissue proliferation. The central portion becomes necrotic – thus a granuloma is formed. TB is termed a granulomatous disease.

33. Manifestations • Course of infection • Acquired from organisms inhaled in airborne droplets • Organisms lodge within pulmonary alveoli where they proceed to multiply • Initially the organisms do not elicit a marked inflammatory reaction because they do not produce any toxins or destructive enzymes • Macrophage phagocytose the bacteria but are unable to destroy them – they may even carry the organisms to other parts of the lung and into regional lymph nodes. • After several weeks cell-mediated immunity develops • Sensitized T- cytotoxic lymphocytes attract and activate macrophages – the activated macrophages attack and destroy many of the organisms forming the characteristic granulomas formed • In the majority of cases the person is unaware they have been infected – no symptoms • Infection arrested in majority of cases • Outcome depends • Number of organisms inhaled • State of body’s defenses • May heal by scarring or progress to cavitation

34. Sometimes the granuloma is large enough to be seen on X-ray but most of the times it is too small • The positive skin test reveals the infection • Cell-mediated immunity generally controls the infection • The healed granuloma may contain small numbers of viable organisms and the infection may become reactivated when the immune system drops • In some individuals the primary infection does not respond favorably to the immune system fight • The granuloma may extend into a nearby bronchus and necrotic inflammatory tissue is discharged into it • A cavity may form • If the person gets reactivation of the bacteria (becomes active) and they have cavitation (into bronchus) their sputum can be infectious to others

35. Most cases of active TB do not result from the initial infection – but rather by a reactivation – however some are due to a reinfection (new case) • How does reactivation occur- it is due to a drop in the immune system action as a result of AIDS, other debilitating diseases, treatment with corticosteroids, treatment with immunosuppressive therapy

36. Miliary and tuberculous pneumonia are two uncommon but extremely serious forms of TB • Miliary Tuberculosis • Mass of tuberculous inflammatory tissue erodes into a large blood vessel thus dissemination of organisms by bloodstream • Miliary is derived from the resemblance of multiple foci of disseminated TB (seen in liver, spleen, kidney and other tissues) to millet seeds. These are foci of small white nodules from about 1 – 2 mm in diameter (like millet seeds) • TB pneumonia is an overwhelming infection characterized by extensive TB consolidation on one or more lobes of the lung. Persons with AIDs and other immunocompromised persons are prone to this type of rapidly progressive infection

37. Extrapulmonary tuberculosis • Result of hematogenous spread of tubercle bacilli – thus a secondary infection • Sites • Kidneys • Bone • Uterus • Fallopian tubes Sometimes the secondary infection may progress even though the pulmonary infection has healed leading to an active extrapulmonary TB without clinically apparent pulmonary TB

38. Tuberculosis Diagnosis • Skin test (Mantoux): a positive test reveals recent infection • chest x-ray: when the granuloma is large enough to be detected – or see pulmonary infiltrates • sputum culture – acid fast bacteria

39. The tuberculosis skin test (also known as the tuberculin test or PPD test) is a test used to determine if someone has developed an immune response to the bacterium that causes tuberculosis (TB). This response can occur if someone currently has TB, if they were exposed to it in the past, or if they received the BCG vaccine against TB (which is not performed in the U.S.). • The tuberculin skin test is based on the fact that infection with M. tuberculosis produces a delayed-type hypersensitivity skin reaction to certain components of the bacterium.

40. The components of the organism are contained in extracts of culture filtrates and are the core elements of the classic tuberculin PPD (also known as purified protein derivative). This PPD material is used for skin testing for tuberculosis. Reaction in the skin to tuberculin PPD begins when specialized immune cells, called T cells, which have been sensitized by prior infection, are recruited by the immune system to the skin site where they release chemical messengers called lymphokines. These lymphokines induce induration (a hard, raised area with clearly defined margins at and around the injection site) through local vasodilation (expansion of the diameter of blood vessels) leading to fluid deposition known as edema, fibrin deposition, and recruitment of other types of inflammatory cells to the area.

41. An incubation period of two to 12 weeks is usually necessary after exposure to the TB bacteria in order for the PPD test to be positive.

42. Tuberculosis Treatment • Cell-mediated immunity generally controls the infection • The healedgranulomas, however, may contain small numbers of viable organisms, and the infection may become reactivated • Not all primary infections respond as favorably • If a large number of organisms are inhaled or if the host is compromised (body’s defenses are inadequate), the inflammation will progress, causing more destruction of lung tissue

43. Tuberculosis • People who have active progressive tuberculosis with a tuberculous cavity can infect others because they can discharge large numbers of tubercle bacilli in the sputum • Treatment • Antibiotics and Chemotherapeutic agents • Drug-resistant tuberculosis treatment • More prolonged • Results less satisfactory • Drugs recommended • Following conversion of a negative into positive skin test reaction • Patients with inactive tuberculosis who have increased risk

44. Bronchitis An inflammation of the tracheobronchial mucosa • Acute bronchitis • Common and self-limiting • Chronic bronchitis – often associated with emphysema in COPD • Secondary to chronic irritation by smoking or atmospheric pollution

45. Bronchiectasis • Walls weakened by inflammation and dilate • Distended bronchi retain secretions • Chronic cough • Production of large amounts of purulent sputum • Diagnosed with bronchogram • A specialized X-ray which consists of taking films after instilling a radiopaque oil into the trachea and bronchi. The oil covers the mucosa of the bronchi, and the abnormal bronchi can be recognized as dilated • Only effective treatment is surgical resection of affected segments of lung

46. Upper Respiratory System – From nose and mouth down to Lungs – (includes nose, mouth, pharynx, larynx, and trachea • Lower Respiratory System – Mainstem bronchus to Alveoli • Upper Airway – From nose and mouth to and inclusive of larynx (voice box) • Lower Airway – Trachea down to alveoli

47. Chronic Obstructive Pulmonary Disease COPD

48. Chronic Obstructive Pulmonary Disease • Emphysema and chronic bronchitis occur together so frequently that they are usually considered a single entity, designated COPD • Emphysema is characterized by loss of elasticity (increased pulmonary compliance) of the lung tissue caused by destruction of structures feeding the alveoli • Chronic bronchitis – Secondary to chronic irritation by smoking or atmospheric pollution Clinical manifestations • Dyspnea • Cyanosis

49. Chronic Obstructive Pulmonary Disease The chief clinical manifestations of any type of chronic pulmonary disease are • Dyspnea: sensation of shortness of breath • Cyanosis: blue tinge of skin and mucous membrane from an excessive amount of reduced hemoglobin in the blood

50. The three main anatomic derangements in COPD are • Inflammation and narrowing of the terminal bronchioles • Dilatation and coalescence of pulmonary air spaces • Loss of lung elasticity