2. Asthma Flashcards
Name the components that make up the conducting portion of the lungs?
Nostril Nasal Cavities Oral Cavity Pharynx (nasopharynx, oropharynx and laryngopharynx) Larynx Trachea Primary bronchi Secondary bronchi Tertiary bronchi Bronchioles Terminal bronchioles
Name the components that make up the respiratory portion of the lungs?
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Alveoli
Describe the structure of the trachea.
- Wide flexible tube
- Contains 20 tracheal cartilages which are C-shaped rings of hyaline cartilage
- Gap between rings is made up by the trachealis muscle
In the bronchioles, what are the goblet cells replaced by? What function does it perform
Clara cells which secrete surfactant that prevent alveoli collapse
Parasympathetic innervation to the smooth muscle in the walls of the airways causes the muscles to do what?
Causes them to contract, thus the airways narrow
What are type 1 pneumocytes and where are they found?
They are found in the alveoli of the lungs
They are large flattened cells making up 95% of total alveolar area, are they present a very thin diffusion barrier for gases.
What are type 2 pneumocytes and where are they found?
They are found in the alveoli of the lungs.
Despite making up 5% of the total alveolar area, they make up 60% of total number of cells.
They secrete ‘surfactant’ which decreases the surface tension between the thin alveolar walls, and stops alveoli collapsing when you breathe out.
Describe asthma.
Asthma is a chronic inflammatory condition of the airways that causes episodic exacerbations of bronchoconstriction.
In asthma there is reversible airway obstruction that typically responds to bronchodilators such as salbutamol. This bronchoconstriction is caused by hypersensitivity of the airways and can be triggered by environmental factors.
How can asthma be categorised?
- Atopic or Non- Atopic
- Intermittent or Persistant.
Atopic means triggered by the environment, which is most common form. It is mediated by systemic IgE production
Non-atopic is intrinsic, meaning its not caused by exposure to an allergen and is far less common. The inflammation is mediated by local IgE production
What T-helper cell is normally found in the lung? Which one is found in those with asthma? Whats the difference between them?
Normally its T-helper 1, which promotes inflammation by increasing cell mediated immunity.
However in asthma its T-helper 2, which promotes inflammation by increasing humoral immunity (antibody production)
What is the triad of asthma characteristics?
- Smooth muscle contraction
- Smooth muscle hypertrophy
- Mucus hyper-secretion
What are the risk factors of asthma?
- Family history of asthma
- A history of having atopic conditions
- Allergies
- Nasal polyps
- GORD
- Obesity
What are typical triggers for an asthma attack?
- Infection
- Night time or early morning
- Exercise
- Animals
- Cold/damp weather
- Dust / pollen
- Strong emotions
What are the symptoms of asthma?
- Shortness of breath
- Wheeze
- Chest Tightness
- Dry Irritating cough
How is the wheeze in asthma described?
Bilateral widespread “polyphonic” wheeze
According to NICE, how should asthma be diagnosed?
Asthma should never be diagnosed without definitive testing.
First line tests include
- Fractional exhaled nitric oxide (FeNO) - Levels of nitric oxide in breath increases with inflammation. A level over 40 parts per billion (ppb) is a positive test for an adult, and 35 ppb for a child.
- Spirometry with bronchodilator reversibility - A FEV1/FVC ratio of less than 70% is considered as a positive test for obstructive airway disease. These individuals are then offered a bronchodilator. If they have an improvement in FEV1 of 12% or more, plus an increase in volume of 200ml or more, then it’s a positive test.
According to NICE, how should asthma be managed?
- Add short-acting beta 2 agonist inhaler (e.g. salbutamol) as required for infrequent wheezy episodes.
- Add a regular low dose inhaled corticosteroid.
- Add an oral leukotriene receptor antagonist (i.e. montelukast).
- Add LABA inhaler (e.g. salmeterol). Continue the LABA only if the patient has a good response.
- Consider changing to a maintenance and reliever therapy (MART) regime.
- Increase the inhaled corticosteroid to a “moderate dose”.
- Consider increasing the inhaled corticosteroid dose to “high dose” or oral theophylline or an inhaled LAMA (e.g. tiotropium).
- Refer to a specialist.
What long term management do asthma patients require?
- Individual asthma self-management programme
- Yearly flu jab and pneumococcal vaccination
- Yearly asthma review
- Advise exercise and avoid smoking
What 3 questions are important during an annual asthma review?
- In the last month have you had difficulty sleeping due to your asthma (including cough symptoms, shortness of breath)?
- Have you had your usual asthma symptoms (eg, cough, wheeze, chest tightness, shortness of breath) during the day?
- Has your asthma interfered with your usual daily activities (eg, school, work, housework)?
How is an acute asthma attack graded?
Moderate : 50-75% predicted PEFR. This is the only criteria for a moderate asthma attack
Severe : 33-50% predicted PEFR
Life-threatening : <33% predicted PEFR
What are the criteria for a severe asthma attack vs a life threatening asthma attack
Severe
- PEFR 33-50% predicted
- Resp rate >25
- Heart rate >110
- Unable to complete sentences
Life-Threatening
- PEFR <33%
- Sats <92%
- Becoming tired
- No wheeze. This occurs when the airways are so tight that there is no air entry at all. This is ominously described as a “silent chest”.
- Haemodynamic instability (i.e. shock)
What is the treatment for a moderate asthma attack?
- Nebulised beta-2 agonists (i.e. salbutamol 5mg repeated as often as required)
Nebulised ipratropium bromide
Steroids. Oral prednisolone or IV hydrocortisone. These are continued for 5 days
Antibiotics if there is convincing evidence of bacterial infection
What is the treatment for a severe asthma attack?
Oxygen if required to maintain sats 94-98%
Aminophylline infusion - done under senior guidance
Consider IV salbutamol - done under senior guidance
What is the treatment for a life-threatening asthma attack?
IV magnesium sulphate infusion - done under senior guidance
Admission to HDU / ICU
Intubation in worst cases – however this decision should be made early because it is very difficult to intubate with severe bronchoconstriction
