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)