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Respiratory Disease
By Dr. Lamarine
“I had a little bird
and its name was Enza,
I opened a window
And in-flu-enza.”
Children’s Song, 1918
RESPIRATORY RESPONSES
VITAL CAPACITY: the amount of air that can be expired (breathed out) after a maximum inspiration
RESIDUAL VOLUME: the air left in the lungs after a maximum expiration
TIDAL VOLUME: the depth of each breath
Breath can be controlled to a great extent but NOT to the point of death!
Functions:1. transports oxygen2. expels carbon dioxide waste
Nose is lined with mucous membranes that have folds (turbinates) providing extra area to warm and moisturize air
Anatomy:Alveolar sacs are clumps of alveoli with a common opening. Each alveolus
is only one cell thick. Pulmonary capillaries are right next to alveolar cells & they are only one cell thick.
Emphysema breaks down the walls between sacks & reduces the amount of gas that can be exchanged
RESPIRATORY SYSTEM
Pleura: thin membrane covers lungs & chest wall
Pleural cavity: potential space between lung & chest wall
Pneumothorax: condition when lung punctured & collapses
Pneumonia: inflammation of lungs
Legionnaires’ Disease: type of pneumonia caused by Legionella pneumophilia,1976
Pneumocystis jeroveci: fungus of low pathogenicity can cause fatal pneumonia in AIDS compromised
COMMON CAUSES OF PNEUMONIA
CAUSATIVE AGENT Percentage CasesBacteria
Streptococcus pneumoniae 50
Haemophilus influenza 10
Staphylococcus aureus 5
Mycobacteria 5
Viruses
Influenza virus 10
Fungi
Aspergillus fumigatus ---
Candida albicans
Pneumocystis jiroveci ---
Bacteria-like oranisms
Mycoplasma pneumonia 10
---
Pneumothorax: air in the chest
Air entering the pleural space between the lung & the chest wall causes loss of vacuum. Air comes from outside the chest or from inside (hole in lung). Lung collapses & air exchange does not occur.
Causes of pneumothorax: trauma; spontaneous; a ruptured bleb
CHRONIC OBSTRUCTIVE PULMONARY DISEASE: COPD
bronchitis; asthma; emphysema
EMPHYSEMA: (smoking/air pollution) alveoli rupture from chronic irritation; lose elasticity; blebs can’t exhale; more susceptible to infection/pneumonia
PULMONARY FIBROSIS: thickening makes lungs rigid restricting air flow (silicosis, asbestosis, byssinosis)
LUNG CARCINOMA: bronchogenic carcinoma1. squamous cell carcinoma2. adenocarcinoma3. large cell carcinoma (#1-3 all non-small cell carcinomas)4. small cell carcinoma (worst)
TUBERCULOSIS Mycobacterium tuberculosis (M. bovis in cattle) Initial infection from inhaled organisms Bacilli lodge in alveoli & multiply Macrophages eat but can’t destroy & may even carry to other
parts of lung or regional lymph nodes Eventually supermacrophages may destroy & necrotized
granulomas formed, scar & calcify Most cases no symptoms; may be visible on X-ray (usually not) + Mantoux skin test may be only evidence Usually ends here BUT healed granulomas may contain small #
viable organisms leading to progressive pulmonary TB if immunity weakened
Miliary TB when erodes into large BV (Anton Chekov/Byron) Small white nodules form (liver, spleen, kidney, stomach, etc.) Rx: many drug resistant strains; Iproniazid & surgical
resection
Some TB history
Old names: scrofula, phthisis, consumption, graveyard cough, White Death, Pott’s disease (spine), Addison’s disease (adrenals)
BCG (bacillus Calmette-Guerin) vaccination vs. TB, not used in U.S.
TUBERCULOSISMycobacterium tuberculosis
SYMPTOMS:
Primary TB: (initial infection walled off) no symptoms or minor cough, low fever, night sweats, lost weight, fatigue, weakness
Secondary TB: (reactivation when immunity weak) pus & blood in sputum, chest pain
Transmission: droplets from cough, talk, or spit; dried secretions; personal contact
1900: 2% of U.S. pop; 0.2% mortality1990s: reemergence; world wide 1.7 billion, 3 million annual deaths
1. AIDS compromised2. immigration pattern shift3. poverty, alcoholism, drug abuse4. antibiotic resistance (MDRT + XDR-TB-untreatable)
2 common but serious forms of TB:
1. tuberculous pneumonia2. miliary TB (like millet seeds)
diagnosis:1. Mantoux skin test (PPD)2. chest X-ray3. sputum test (acid-fast)4. blood test
Rx: combination antibiotics; DOT
Prevention:1. Rx for + cases2. improved living conditions3. animal (cows) control4. BCG vaccination (bacillus Calamette-Guerin) <70% success; some get
disease
ASTHMA
Bronchial asthma involves spasmodic contractions of smooth muscles in lungs; increased mucous secretions; shortness of breath & wheezing due to allergic reaction triggered by histamines released by mast cells (IgE)
ASTHMA THEORIES
1. Hygiene: too much cleanliness & lack of exposure to mycobacterium
2. Worm fighting: IgE underused
Whooping Cough (pertussis)
Recent increase in incidence/fear of vaccination & less effective vaccine
Bordetella pertussis (bacillus) Mortality related to secondary pneumonia Transmission via airborne droplets:
symptoms cold-like, cough with inspiratory whoop/mucous (see p.83)
Diphtheria
Corynebacterium diphtheriae Stays in upper respiratory system Deadly exotoxin producing pseudomembrane May occlude air passages leading to death
by suffocation Spread by direct contact, droplet, indirect via
fomites or milk Immunization!
STEP THROAT SYMPTOMS
Sudden onset of very sore throat Beefy red throat & tonsils, sometimes with white patches & pus Difficulty swallowing Fever over 101 degrees Tender, often swollen lymph nodes in neck Headache Shivers & shaking alternating with cold sweats In children, often nausea, vomiting & abdominal pain
Rx: rapid strep test for strep antigens (70-80% accurate) If negative, throat culture Prescribe antibiotics and cancel if culture negative or give prescription
but don’t fill until positive culture results are in.
H1N1 virus
(2 surface proteins: hemagglutinin & neurominidase)
Combination avian/swine/human viruses
Only 25% as infective as seasonal flu 36,000 Americans die on average from
seasonal flu
Historical Flu Outbreaks
1918, Spanish flu, H1N1 (killed 20 million;
2.5% mortality)
1957, Asian flu, H2N2
1968, Hong Kong flu, H3N2
1977, Spanish flu, H1N1
1997, Bird flu, H5N1 (2003 Viet Nam)
Bird flu kills 50% of victims (cytokine storm); a time bomb when it mutates ability to spread human-to-human; bird collapse?
Misinformation lead to mass slaughter of pigs: eating pork not a risk
Flu spread by sneezes and coughsH1N1 fragile outside the bodyBest prevention = vaccines2013: latest scare H7N9, birds
Swine Flu (2009)
FLU vs. COLD
influenza: (more likely if)
high fever
headache
severe aches + pains
fatigue + weakness
bedridden
cold: runny, stuffy nose
sneezing
sore throat
(fluids & rest for both; antibiotics won’t help)