Peoples tasks

• Other manifestations of cystic fibrosis - Ari
• What is cystic fibrosis? – Jacquie
• Incidence of cystic fibrosis? - Rushmi
• Pathophysiology - Dillys
• Prognosis/complications - Hasif
• Diagnosis – Sarah - me
• Pulmonary oedema/Pulmonary hypertension - Lionel
• Management
o Medicine – Georgia
o Surgical/preventative - Kylie
• Genetic basis of disease - Sam
o Genetic counselling (reproductive) - Ambu
• Degrees of severity of cystic fibrosis/screening - Steph
• Signs and symptoms of CF, reproductive - Nathan
• Support networks for cystic fibrosis - Jemima

Sorry this is so late guys, completely forgot... =(

Pathophysiology

Cystic fibrosis is an autosomal recessive trait caused by mutations at a single gene locus on the long arm of chromosome 7. Cystic fibrosis reflects the loss of function of the CFTR protein. The CFTR protein normally regulates the transport of electrolytes and chloride across epithelial cell membranes.

More than 1,000 mutations of the CFTR gene have been described to date.Phenotypic appearance depends on the type of mutation (ie, class), location of the gene, molecular mechanism, and interaction with other mutations, as well as genetic and environmental influences.

The most common mutation of the CFTR gene is caused by the deletion of phenylalanine at position 508 (DF508, or delta-F508) and occurs with varying frequency in different ethnic groups. Worldwide, this allele is responsible for approximately 66% of all CF chromosomes.

Screening
Of the 1,000 or more infants born yearly with CF, most are diagnosed at a mean age of 3 to 4 years. Of note, nearly 10% of CF cases are diagnosed in individuals older that 18 years. Newborn screening for cystic fibrosis has been instituted in eight states, although national screening plans have not been mandated. In all, 10% of affected infants in the United States are diagnosed at birth either by prenatal diagnosis (3%) or by newborn screening (7%). The currently available genetic screening tools for CF include the Guthrie test, in which measurements of the immunoreactive trypsinogen in dried blood are taken, and measurement of the most common CF mutations, including DF508.

• Screening should be offered to (1) adults with a family history of CF, (2) reproductive partners of individuals with cystic fibrosis, (3) couples in whom one or both individuals are Caucasian (including Ashkenazi Jewish persons) and are planning pregnancy, and
• Screening should be made available to non-Caucasian or Ashkenazi-Jewish individuals or couples.

Issues to keep in mind include the gestational age at which the couple presents for prenatal care, and the feasibility of pregnancy termination. These factors should be included in the CF screening discussion with parents.

Environmental Lung Diseases

Exposure to various dusts, gases, vapours and fumes can cause several types of lung diseases:

1) Acute bronchitis and pulmonary oedema
caused by irritants (eg. sulphur dioxide, chlorine, ammonia, nitrogen oxides)

2) Pulmonary fibrosis
caused by mineral dust

3) Asthma
caused by isocyanates (eg. polyurethane varnishes, industrial coatings, spray painting), colophony fumes (eg. soldering/welding, electronics), allergens (eg. animals, insects, antibiotics, flour, grain, latex), proteolytic enzymes in biological washing powders, complex salts of platinum in metal refineries and acid anhydrides and polyamine hardening agents in industrial coatings.

4) Extrinsic allergic alveolitis
caused by mouldy hay and vegetable material, handling of birds, turning of germinating barley, contaminated humidifying systems in air conditioners or humidifiers in factories, turning of mushroom compost, mouldy cheese and mouldy grapes.

5) Bronchial carcinoma
caused by industrial agents (eg. asbestos, polycyclic hydrocarbons, radon in mines)


Coal-worker's pneumoconiosis
Caused by dust particles being retained in small airways and alveoli of the lung. 2-stage disease:

Simple pneumoconiosis - reflects deposition of coal dust in the lung. Produces fine micronodular shadowing on CXR. May lead to development of progressive massive fibrosis.

Progressive massive fibrosis (PMF)- patients develop round fibrotic masses in upper lobes, sometimes having necrotic central cavities. Fibrosis likely due to immune responses. Apical destruction and disruption of lung results in emphysema and airway damage. Lung function tests show mixed restrictive and obstructive ventilatory defect with loss of lung volume, irreversible ariflow limitation and reduced gas transfer. Patient suffers considerable effort dyspnoea, usually with cough and sputum may be black. May progress to respiratory failure.

Silicosis
Caused by inhalation of silica (silicon dioxide). Dust is highly fibrogenic - silica is toxic to alveolar macrophages and readily initiates fibrogenesis. CXR and clinical features largely similar to PMF distinctive thin streaks of calcification may be seen around hilar lymph nodes ('eggshell' calcification).

Asbestosis
Defined as fibrosis of the lungs caused by asbestos dust, may or may not be associated with fibrosis of the parietal or visceral layers of pleura. Progressive disease characterised by breathlessness and accompanied by finger clubbing and bilateral basal end-inspiratory crackles. Mesothelioma often results, with patient presenting with pleural effusions, typically with persistent chest wall pain.

Byssinosis
Cotton mill workers present with symptoms starting on the first day at work with improvement as week progresses. Symptoms include chest tightness, cough and breathlessness. Cotton dust causes airflow limitations. Asthmatics are particularly affected. Endotoxins from the bacteria present in the raw cotton causes constriction of lung airways.

Berylliosis
When beryllium is inhaled, it can cause a systemic illness with clinical presentation similar to sarcoidosis. Due to progressive dyspnoea with pulmonary fibrosis.

Reference: Kumar and Clark (Clinical Medicine 6e)

CAM!

The alternative treatments for asthma and COPD are numerous. The recommended, or "supported by good scientific evidence" treatments include:

• Boswellia
• Buteyko breathing technique (BBT)
• Coleus
• Ephedra
• Psychotherapy
• Pycnogenol
• Yoga
  

Beyond this, however, are heaps of other 'factually unsupported treatments'.

Some alternative therapies for smoking cessation include:

• Certain herbal combinations, such as Kava Kava and Chamomile
• Acupuncture
• Hypnotherapy
• Relaxation Therapy.

pneumonia severity index (PSI)

Pneumonia Severity Index (PSI)

What is it?
A prediction rule to calculate the severity of a person with community acquired pneumonia (CAP). It is based on data that are commonly available upon presentation and divide patients into 5 different classes, according to the severity of the disease. Higher scores mean higher risk of death, admission to ICU and longer length of stay in the hospital. The patient may need to be treated as an inpatient.

How to use it?

The index is based on several criteria such as demographic factors, signs and symptoms as well as lab and radiographic findings. In the index, each different characteristic are assigned different points. Patient with the characteristic will add the points with the patient’s age (-10 for women). Eventually, all the points will be added up and the patient will be classified into 5 different classes, according to the points.

The index is as below, and the classes are included in the diagram.

What happen to the patient in the classes?

Patients in risk classes 1, 2 and 3 are regarded as at low risk of death and are mostly treated as outpatients unless there are other risk factors. The low risk patients in class 3 who look sick or needed further care can stay in the hospital for another 23 hours and monitored for deterioration. After the patient’s condition is better, patient will be allowed to leave the hospital.

As for patients grouped in class 4 (moderate risk) and 5 (high risk), they should be hospitalized due to their higher risks of death and complications.

There is an exception for patients with hypoxemia or PaO2 of >60mm Hg. These patients must be hospitalized regardless of their PSI score. This also applies to patients with metastatic disease (endocarditis, meningitis, osteomyelitis) or those infected with high risk pathogens such as Staph. aureus.

Hasif.

OTHER LUNG FUNCTION TESTS

LUNG FUNCTION TESTS

• Spirometry
• Gas diffusion tests,
• Body plethysmography,
• Inhalation challenge tests,
• Exercise stress tests

Spirometry

Pt breathes into a mouthpiece attached to a spirometer. The information collected by the spirometer may be printed out on a chart called a spirogram.

The more common lung function values measured with spirometry are:

· Forced vital capacity (FVC). This measures the amount of air you can exhale with force after you inhale as deeply as possible.

· Forced expiratory volume (FEV). This measures the amount of air you can exhale with force in one breath. The amount of air you exhale may be measured at 1 second (FEV1), 2 seconds (FEV2), or 3 seconds (FEV3). FEV1 divided by FVC can also be determined.

· Peak expiratory flow (PEF). This measures how quickly you can exhale. It is usually measured at the same time as your forced vital capacity (FVC).

· Maximum voluntary ventilation (MVV). This measures the greatest amount of air you can breathe in and out during one minute.

· Vital capacity (VC). This is the amount of air (in liters) moved out of the lung during normal breathing.

· Total lung capacity (TLC). This measures the amount of air in your lungs after you inhale as deeply as possible.

· Functional residual capacity (FRC). This measures the amount of air in your lungs at the end of a normal exhaled breath.

· Expiratory reserve volume (ERV). This measures the difference between the amount of air in your lungs after a normal exhale (FRC) and the amount after you exhale with force (RV).

Gas diffusion tests

Gas diffusion tests measure the amount of oxygen and other gases that cross the lungs' alveoli per minute. These tests evaluate how well gases are being absorbed into your blood from your lungs. Gas diffusion tests include:

· Arterial blood gases, which determine the amount of oxygen and carbon dioxide in your bloodstream.

· Carbon monoxide diffusing capacity (also called transfer factor, or TF), which measures how well your lungs transfer a small amount of carbon monoxide (CO) into the blood. Two different methods are used for this test. If the single-breath or breath-holding method is used, you will take a breath of air containing a very small amount of carbon monoxide from a container while measurements are taken. In the steady-state method, you will breathe air containing a very small amount of carbon monoxide from a container. The amount of carbon monoxide in the breath you exhale is then measured. Diffusing capacity provides an estimate of how well a gas is able to move from your lungs into your blood.

Body plethysmography

Body plethysmography may be used to measure:

· Total lung capacity (TLC), which is the total amount of air your lungs can hold. For this test, you sit inside an airtight booth called a plethysmograph and breathe through a mouthpiece while pressure and air flow measurements are collected.

· Residual volume (RV), which is the amount of air that remains in your lungs after you exhale as completely as possible. For this test, you sit inside the plethysmograph booth and breathe a known amount of a gas (either 100% oxygen or a certain amount of helium in air). The test measures how the concentration of the gases in the booth changes.

Inhalation challenge tests

Inhalation challenge tests are done to measure the response of your airways to substances (allergens) that may be causing asthma or wheezing. The tests also may determine the effect of chemicals such as histamine or methacholine on your airways. These tests are also called provocation studies.

During inhalation testing, increasing amounts of an allergen or substance (eg histamine) are inhaled through a nebulizer, a device that uses a face mask or mouthpiece to deliver the allergen in an aerosol form. Before and after inhaling the substance, spirometry readings are taken to evaluate lung function.

In rare cases, a bronchospasm can occur with inhalation challenge testing. Pts require close monitoring

Exercise stress tests

Exercise stress tests evaluate the effect of exercise on lung function tests. Spirometry readings are done after exercise and then again at rest.

Diagnosis and Investigations - Sarah

Diagnosis and investigations of COPD
Diagnosis
Patients with COPD usually are current or past smokers over the age of 40 with a history of shortness of breath upon physical exertion and chronic productive cough. The physical examination may show a barrel chest, decreased breath sounds, and wheezing. Signs of right-sided heart failure, such as oedema, tender liver, and distended abdomen (caused by fluid accumulation in the abdomen; called ascites) may be noted as well. COPD is a diagnosis of history (in the case of chronic bronchitis), or a diagnosis of anatomy (in the case of emphysema). Clubbing of the fingers rarely occurs in COPD and warrants investigation for other causes.

Investigations
• Spirometry -
• Pre- and post-bronchodilator – to rule out asthma
• Resting oxygen saturation measurement suggested in moderate or severe disease
• Arterial blood gas (ABG) measurement recommended in moderate or severe disease or if oxygen saturation is less than 92%.

References
http://www.pulmonologychannel.com/copd/diagnosis.shtml
www.nhlbi.nih.gov/health/dci/Diseases/Copd/Copd_Diagnosis.html
Netters Clinical Anatomy

Pathophysiology of COPD

Pathophysiology of COPD

The most consistent pathological finding is hypertrophy and increase in number of mucus secreting goblet cells of the bronchial tree, evenly distributed through the lung but mainly seen in the large bronchi- in addition, in the more severe cases, the bronchi themselves are obviously inflamed and pus is seen in the lumen.

Microscopically there is infiltration of the walls of the bronchi and bronchioles with acute and chronic inflammatory cells and lymphoid follicles in severe disease (the lymphocyte infiltrate is predominantly CD8+). - initially when the small airways are affected, this can be reversed like in the improvement of airway function when smoking is stopped early!

As the disease increases in severity, squamous cell metaplasia arises, as well as fibrosis of the bronchial walls. These changes in turn cause developments in airflow limitation.

[metaplasia= the change in the type of adult cells in a tissue to a form abnormal for that tissue]

Reference- Kumar and Clark-Clinical medicine (pg900)

Jacqui.

what was my task?

Hi guys! I went to do my pcl task today with the idea that i was doing bronchiectasis, but evidently that is NOT my task, as dilys has done a beautiful job with it already! Does anyone know what my task is/what it could be? i was SO sure it was bronchiectasis :P
Any help would be much appreciated! Hopefully you're all enjoying the "break"!
xox Steph

Treatment of COPD

Treatment of COPD

Management

Smoking cessation – can slow deterioration, prolong time before disability and death
Drugs

Bronchodilators
- beta-adrenergic agonist - Salbutamol – bronchodilation - less breathless
- antimuscarinic agents – titropium, ipratropium, oxitropium – more prolonged and greater bronchodiation
- patients may find inhalers and spacers difficult to use

Corticosteroids
- prevents inflammation
- prednisolone – 2 weeks initlally
- if there is improvement in airflow – stop prednisolone, add inhaled corticosteroid

Antibiotics
- should be given in acute exacerbations of COPD, as it can prevent hospitalisation and further lung damage
- patients should have antibiotics at home – as soon as their sputum turns yellow/green, they should take them
- amoxicillin-resistant H. Influenza – use co-amoxiclav
- eradication of infection and keeping lower respiratory tract free of bacteria can help to prevent deterioration of lung function

Diuretic treatment
- required for oedematous patients
- Loop diuretics (frusemide), thiazide diuretics (idapamide), potassium sparing diuretics (spironolactone, eperenone)
- Daily weights should be recorded during acute episodes in hospital

Alpha-1 antitrypsin replacement
- Recommended for patients with a serum level of this below 310 mg/L and abnormal lung function
- Low alpha-1 antitrypsin – primary manifestation is emphysema
- It is still uncertain whether this modifies the long term progression of COPD

Vaccines
- Yearly influenza vaccine
- Polyvalent pneumococcal vaccine – lifetime

Treatment of respiratory failure
· Primary aim – increase arterial oxygen pressure with oxygen therapy
o Type I respiratory failure (low arterial oxygen pressure, normal carbon dioxide arterial pressure) - safe to administer as much oxygen as needed to return arterial oxygen pressure to normal
o Type II respiratory failure à arterial carbon dioxide pressure is elevated - additional oxygen will lead to a rise in arterial carbon dioxide pressure (small increases can be tolerated, but not if the pH falls, especially if it falls below 7.25 - use respiratory stimulant or artificial ventilation
o Initially, 24% oxygen is given à can be increased if arterial carbon dioxide pressure does not rise to unacceptable levels

· Removal of retained secretions
o Encourage patient to cough to remove secretions
o Physiotherapy, bronchoscopy, aspiration via an endothelial tube

· Respiratory support
o Tight-fitting facial masks – deliver positive airway pressure ventilator support

· Respiratory stimulants
o Doxapram – iv – stimulates coughing, can help clear secretions

· Corticosteroids, antibiotics and bronchodilators in acute periods

- Rushmi

Bronchiectasis

The term ‘bronchiectasis’ (bron-kee-ek’-tas-is) describes the condition where airways are abnormally and permanently dilated. Causes can be of congenital or acquired origin.

An infection or any condition that injuries the airways may slowly impaired airways’ ability to clear out mucus i.e. bronchiectasis itself is not an infection, but a condition developed secondary to an infection or injury to the airways. As mucus builds up, the environment favours ongoing infections, e.g. pneumonia, tuberculosis, fungal infections etc. Each infection or injury causes more damage to the airways.

The recurrent inflammation of the bronchial walls causes the airways to become stretched out, flabby and scarred. The thickening and damage to the bronchial walls are irreversible and incurable.

Congenital causes of bronchiectasis:
- Pulmonary sequestration
- Deficiency of bronchial elements

Acquired causes of bronchiectasis:
- Pneumonia
- Tuberculosis
- Lungs tumors
- Foreign bodies

Person with bronchiectasis develops symptoms gradually. This includes:
- Coughing up yellow sputum
- Dypsnoea due to airflow limitation

In severe cases, patient may suffer from:
- Cough up blood (haemoptysis)
- Bad breath (halitosis)
- Episodes of pneumonia
- Weight loss
- Fatigue

On examination, patients presents with signs including:
- Wheeze
- Crackles
- Clubbing

Possible investigations are:
- Chest x-ray and CT to locate bronchial dilation or wall thickening
- Sputum culture to determine presence of bacteria
- Lung function test to find out severity of damage to lungs

Treatment
- Antibiotics to treat recurrent respiratory infections
- Corticosteroids help reduce inflammation of lungs

Micro organisms in Pnuemonia

Viruses
Viral pneumonia is commonly caused by viruses such as influenza virus, respiratory syncytial virus (RSV), adenovirus, and metapneumovirus. Herpes simplex virus is a rare cause of pneumonia except in newborns. People with weakened immune systems are also at risk of pneumonia caused by cytomegalovirus (CMV).
Bacteria
The most common causes of bacterial pneumonia are Streptococcus pneumoniae, Gram-positive bacteria and "atypical" bacteria. The term "atypical" is used because atypical bacteria commonly affect healthier people, cause generally less severe pneumonia, and respond to different antibiotics than other bacteria.
Streptococcus pneumoniae, often called "pneumococcus", is the most common bacterial cause of pneumonia in all age groups except newborn infants.
"Atypical" bacteria which cause pneumonia include Chlamydophila pneumoniae, Mycoplasma pneumoniae, and Legionella pneumophila. Another important Gram-positive cause of pneumonia is Staphylococcus aureus, with Streptococcus agalactiae being an important cause of pneumonia in newborn babies. Gram-negative bacteria cause pneumonia less frequently than gram-positive bacteria. Some of the gram-negative bacteria that cause pneumonia include Haemophilus influenzae, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa and Moraxella catarrhalis. These bacteria often live in the stomach or intestines and may enter the lungs if vomit is inhaled.

Definition and Risk Factors of COPD

Definition of COPD
disease state that has airflow limitation that is not fully reversible. It is usually both progressive and associated with abnormal inflammatory response of the lungs to noxious particles or gases.

Risk Factors
Cigarette Smoking
- 90% of cases. Long-term exposure to toxic particles & gases.
- However, only 10-20% of smokers get COPD, indicating individual susceptibility.
- Development of COPD related to no. of cigarettes/day: risk of death from COPD with pt smoking 30 cigarettes/day is 20x a non-smoker.

How?
- infiltrated by neutrophil granulocytes in lumen of bronchial tree & small airways
- granulocytes can release elastases & proteases - may produce emphysema
- alpha-1 antitrypsin is a major serum antiprotease which can be inactivated by cigarette smoke
- hypertrophy of mucous glands in larger airways from persistent irritation
- smoke has adverse effect on surfactant = overdistention of lungs

Occupational Exposure. Air Pollution
Great increase found during periods of heavy atmospheric pollution. eg coal mining

Genetics- alpha-1 antitrypsin deficiency
- alpha-1 antitrypsin inhibitor is an antiproteinase inhibitor produced in the liver secreted into the blood - diffuses into lungs.
- functions as an antiprotease that inhibits neutrophil elastase, a proteolytic enz that destroys alveolar wall connective tissue
- more than 75 alleles of the gene has been described, 3 main phenotypes are MM(normal),MZ(heterozygous deficiency) & ZZ(homozygous)
- accounts for about 2% of emphysema cases

Infections
COPD patients cope badly with respiratory infections - often precipitating cause of acute exacerbations. however, role of infection in the development of progressive airway limitation is far less clear

Treatment of Acute Asthma

Treatment of Acute Asthma i.e. asthma attacks
Also called rescue medications, you use quick-relief medications as needed for rapid, short-term relief of symptoms during an asthma attack, or before exercise, if recommended by a physician. Only use these medications as often as your doctor tells you to. If you need to use these medications too often, you probably need to adjust your long-term control medication. Keep a record of how many puffs you use each day. Types of quick-relief medications include:

• Short-acting beta-2 agonists, such as albuterol. These medications, called bronchodilators, may be administered via inhalation, pill form, liquid or injection methods. They act to ease breathing by temporarily relaxing the smooth muscle in the airways which contain many B2-receptors. They act within minutes, and effects last four to six hours. These are the first line of treatment for miled to moderate acute asthma. COmmonly used is a salbutamol-based B2-agonist, administrated by inhalation and known as "ventolin" **when beta-2 agonists are required on a regular basis i.e. more than once a day, then regular administration of an inhaled steroid may be included in the treatment plan**
  
• Ipratropium (Atrovent). Your doctor might prescribe this inhaled anticholinergic for the immediate relief of your symptoms. Like other bronchodilators, ipratropium relaxes the airways, making it easier to breathe. Ipratropium is mostly used for emphysema and chronic bronchitis.
  
• Oral and intravenous corticosteroids to treat acute asthma attacks or very severe asthma. Examples include prednisone and methylprednisolone. These medications relieve airway inflammation. They may cause serious side effects when used long term, so they're only used to treat severe asthma symptoms.
  
• Also, incases of acute severe asthma, oxygen may be administered with the nebulized or intravenous B2-agonists.
  

PCL 5 – ANNA’s OUT OF BREATH

- Link between Asthma, Hayfever and Eczema

o ‘Atopic’ individuals – if you have one your likelihood of having another increases substantially. Similarly, if a family member has an atopic condition, the individual has an increased likelihood of having the condition.
o Atopic disorders are traditionally characterised by a wealing skin reaction
o We know that asthma is an inflammatory condition, the same is true for Hayfever and Eczema. There are several key cells involved in this inflammatory process –
§ Mast cells – increased in the epithelium and release histamine, prostaglandin and leukotrienes à it is this which causes the immediate inflammatory reaction
§ Eosonophils
§ Macrophages and lymphocytes
o Process is not completely known but is associated with –
§ Increased Th2 CD4 lymphocytes in the skin (drive inflammatory process)
§ Increased IgE levels
o Increased IgE levels
§ can be the result of either genetic or environmental factors
§ link between IgE levels and the prevalence of asthma and responsiveness of airways
o Many genes play a key role in asthma development
§ IL-3, IL-4, IL-5, IL-9, IL-13 and GM-CSF affect Mast Cell and Eosinophil levels
o Current suggestion
§ Growing up in a ‘clean’ environment may predispose towards an IgE response to allergens and vice versa
o Intrinsic asthma is IgE related – triggers include allergens from animals, flour and grain, latex
o Atopic individuals develop occupational asthma more rapidly when exposed to agents causing the development of specific IgE antibody
o In asthma the epithelium of the conducting airways is damaged and stressed with loss of ciliated columnar cells onto the lumen. As the epithelium is a major source of mediators, cytokines and growth factors that serve to enhance inflammation à damage to the epithelium makes it more vulnerable to allergens (such as those which cause hayfever)

risk factors for asthma

Risk factors for asthma:

1. Constitutional factors: predisposes the person to development of asthma or particular outcomes of asthma.

a. Family history: Although asthma is not a hereditary disease, but having parents with asthma history predisposes the offspring with high probability to get the disease due to genetic inheritance.

b. Genetic mutations: Studies showed that a specific gene may have been associated with asthma development. The gene, ADAM33 is located on chromosome 20 and is expressed in lung and muscle cells. Mutations on this gene may predispose the person to having asthma. The gene causes airways to over-respond and constrict airway passages.

c. Gender: Males are more susceptible to get asthma after birth compared to females. The reason may be due to the fact that a man’s airway size is smaller compared to a woman. However, the percentages drops as males grow up, and at around the age of 20, the rates are similar for both genders. After the age of 40, females tend to have higher chances to get the disease compared to males.

d. Allergic (atopy) predisposition: Atopy is allergic hypersensitivity to different parts of the body that do not come in contact with allergens, but triggers allergic reactions (anaphylaxis). Studies showed that many children with eczema during when they are young have higher chances to develop asthma.

2. Environmental exposures or other factors: associated with increased risk of acquiring asthma or having certain outcomes of the disease.

a. Exercise: exercise can induce asthma for people who are more sensitive to changes in temperature and humidity of the air. When resting, the person breathes through nose that serves to warm and humidify the air inhaled. However, when exercising, the person tends to breathe through mouth and the air being inhaled is colder and drier. The difference between the humidity of air in lungs and the inhaled ones triggers the allergic reaction. Airway begins to swell and secrete large amount of mucous. This obstructs the airway, making it difficult to breathe and thus, leads to asthma (COPD).

b. Viral infections: viral infections activate eosinophils that readily gathered along the nerves in the lungs. This will then cause eosinophils to release a protein called major basic protein (MBP) which has been discovered to block the action of M2 receptors and keeps the receptors from turning off Ach release. High Ach leads to increased constriction of the airways.

c. Irritants (smoking, pollutants): smoking damages cilia in the airways, preventing the cilia from performing their normal function, clear mucous and dust out of the respiratory system. Smoking also cause lungs to secrete more mucous than normal, resulting in marked increase in mucous accumulation in the airways, obstructing the air pathway.

d. Allergies: hypersensitivity due to exposure to a particular allergen resulting in marked increase in reactivity to that antigen on subsequent exposure. Among the common allergens are: dust mites, fungi, animal proteins, fur.

e. Pregnancy: Mothers who smoke during pregnancy can lead to having infants with lower pulmonary function compared to those who are not.

Effects of Smoking

Refer to http://medpcl01.blogspot.com/2009/03/effects-of-smoking.html

Asthma correlation: Cigarette smoke is an irritant that causes airway hyper-responsiveness (i.e. intrinsic asthma). Early childhood exposure to maternal smoking also increases IgE response to allergens (i.e. extrinsic asthma).

Reference: Kumar and Clark (Clinical Medicine)

Astma PLan

ACTION ASTHMA PLAN

Why make an asthma plan?
reduces absences from work or school
reduces hospital admissions
reduces emergency visits to general practice
reduces reliever medication use
improves lung function.

AIMS?
The aim of an asthma action plan is to help the person with asthma and/or their carer take early action to prevent or reduce the severity of an asthma attack.
The asthma action plan may be based on symptoms and/or peak expiratory flow (PEF) measurements and is individualised according to the pattern of the person’s asthma.
In children, symptom-based plans are preferred.
Once completed, the asthma action plan is given to the person with asthma and/or their carer to keep.

FEATURES OF A PLAN
be in a written format
be individually prescribed, rather than a general example
contain information that allows the patient and/or their carer to recognise exacerbations (flare-ups)
contain information on what action to take in response to those exacerbations.
Maintenance/preventer therapy: doses and frequencies of regular medications
Treating exacerbations: how to adjust treatment in response to particular signs and symptoms
Managing increased severity: when to start oral corticosteroids and seek medical advice
Danger signs: when and how to seek urgent medical help

PEF
This is a measure of maximum expiratory flow occurring just after the start of a forced expiration from the point of maximum inspiration (total lung capacity).
Within the plan should also include changes over time regarding Peak expiratory flow measurements, particularly for those with more severe asthma. PEF is a good measurement of whether the asthma may be getting worse or better, thus measures can be put into place to handle such changes early rather than later.

Ambu

PCL 5 – ANNA’s OUT OF BREATH

- Link between Asthma, Hayfever and Eczema

o ‘Atopic’ individuals – if you have one your likelihood of having another increases substantially. Similarly, if a family member has an atopic condition, the individual has an increased likelihood of having the condition.
o Atopic disorders are traditionally characterised by a wealing skin reaction
o We know that asthma is an inflammatory condition, the same is true for Hayfever and Eczema. There are several key cells involved in this inflammatory process –
§ Mast cells – increased in the epithelium and release histamine, prostaglandin and leukotrienes à it is this which causes the immediate inflammatory reaction
§ Eosonophils
§ Macrophages and lymphocytes
o Process is not completely known but is associated with –
§ Increased Th2 CD4 lymphocytes in the skin (drive inflammatory process)
§ Increased IgE levels
o Increased IgE levels
§ can be the result of either genetic or environmental factors
§ link between IgE levels and the prevalence of asthma and responsiveness of airways
o Many genes play a key role in asthma development
§ IL-3, IL-4, IL-5, IL-9, IL-13 and GM-CSF affect Mast Cell and Eosinophil levels
o Current suggestion
§ Growing up in a ‘clean’ environment may predispose towards an IgE response to allergens and vice versa
o Intrinsic asthma is IgE related – triggers include allergens from animals, flour and grain, latex
o Atopic individuals develop occupational asthma more rapidly when exposed to agents causing the development of specific IgE antibody
o In asthma the epithelium of the conducting airways is damaged and stressed with loss of ciliated columnar cells onto the lumen. As the epithelium is a major source of mediators, cytokines and growth factors that serve to enhance inflammation à damage to the epithelium makes it more vulnerable to allergens (such as those which cause hayfever)

Diagnosis of Asthma

Asthma symptoms include:

intermittent dyspnoea
Chest tightness or pain
Trouble sleeping by SOB, coughing or wheezing
Audible whistling or wheezing sound when exhaling
Bouts of coughing or wheezin worsened by a respiratory virus eg. cold/flu
acid reflux: known association with asthma

Getting worse..
An increase in the severity and frequency of above
A fall in peak flow rates as measured by a peak flow meter
An increased need to use bronchodilators — medications that open up airways by relaxing the surrounding muscles

Signs:
tachypnoea
audible wheeze
hyperinflated chest
hyperresonant percussion
diminished air entry
widespread polyphonic wheeze

Severe attack:
inability to complete statements, pulse >110bpm, respiraory rate >25.min, PEF 33-50% of predicted

Life-threatening attack:
silent chest, cyanosis, bradycardia, exhaustion, PEF <33% of predicted, confusion, feeble respiratory effort

Diagnosis

Acute:

PEF (peak expiratory flow)
sputum culture
FBC (full blood count)
U&E (Urea & electrolyte)
CRP (C-reactive protein)
blood cultures
ABG (arterial blood gas) analysis shows normal or slightly reduced PaO2 and low PaCO2 (hyperventilation)
[if PaCO2 is raised, transfer to high dependency unit for ventilation, as this shows failing respiratory effort]
CXR (to exclude infection or pneumothorax)

Chronic:

PEF monitoring
diurnal variation of >20% on >3 days a week for 2 weeks
spirometry
obstrucive defect (decrease FEV1/FVC, increase RV)
CXR:hyperinflation

skin-prick test: allergens identification

PEF
- >20% difference on >3days in a week for 2 weeks (marked morning dipping common)
- >20% improvement following treatment
- >20% decrease following exposure to trigger

Based on clinical history & exam: eczema, allergic conditions, family history

IN CHILDREN:
Unable to use airway f(x) test. Medical history and improvement shown with an inhaled bronchodilator medication.

NEW: Chemical marker of Exhaled NO. Higher levels of NO = higher severity of asthma (expensive though..)

DDx

pulmonary oedema ('cardiac asthma')
COPD (often coexist)
large airway obstruction (foreign body/tumour)
SVC obstruction (wheeze/dyspnoea not episodic)
pneumothorax
PE
bronchiectasis
obliterative bronchiolitis (in elderly)

Source: mayoclinic, oxford handbook of clinical medicine