CPT2: Asthma Flashcards
What is Asthma?
A chronic obstructive lung disease characterised by periods of reversible airway obstruction and hyper responsiveness of the lungs
Common symptoms
Severe symptoms
Common:
- Chest Tightness
- Shortness of breath/ dyspenia
- Coughing
- Variable exipatory airflow
- Wheeze
Severe:
- Night time wakening
- Use of acessory muscles in bretahing
- Continued shortness of breath
What can be causes of asthmatic attacks?
Inflammatory based:
- Allergen - hair, dust
- Bacterial/ varial pathogen
- Chemical - aeorol
Direct irritant:
- Rapid temp change
- Humidity change
- Exerice
- Emotion - laughing
Other:
- Smoking
- Medication e.g. NSAIDs
- Airpollution
- Genetics
What are the 2 main elements involved in the pathophysiology of asthma?
2 Main elements in the pathophysiology: Hyperresponsiveness of the lungs and inflammation of the airway.
What is the pathophysiology?
In acute asthmatic exacerbations there is contraction of smooth muscle in the airway and inflammation of airway walls which both narrow the airway and reduces movement of air in the lungs.
A trigger e.g. allergen activates the inflammatory resonse and type 2 Helper T cells. These T cells release interluekens which activate other immune cells - eosinophils, B Cells, Neutrophils. It also leads to production of IgE which acts on mast cells to release histamine. The histamine causes the smooth muscle in the airway walls to contract.
The WBCs release further mediators e.g. NO, TNF-a, PGs, cytokines which cause mucus production, blood vessel leakage, oedema, smooth muscle and fibroblast proliferation and bronchial smooth muscle contraction.
This and hyperresposiveness leads to the symptoms experienced in asthma.
What does diagnosis involved and which tests should be carried out?
1. Clinical history:
- Wheeze, cough, breathlessness
- Episodes, seasonal, dinural variation
- Triggers
- Family/ personal history of atopic diseases
2. Physical Examination:
- Expiratory Polyphonic wheeze
3. Pulmonary tests:
- Spiromtry
- PEFR
- FENO
- Bronchial Challenge
- Allergy
What does spiromtry test measure?
What parameters does it measure?
The volume and rate of air forced out of the lungs after maximum expiration
FVC (Forced vital capacity), FEV1 (Foreced expiratory volume after 1 second - most air should be out by 1s), FEV1/FVC ratio
What is spirometry used to differentiate between?
Hint think classes of disease
Obstructive and Reversible lung diseases:
Obstructive - Airways narrowed therefore Rate decrease but volume constant
Restricive - Lungs cant fully expand so Rate constant and Volume decreases
Spiromitry measures degree of lung function and reversibility. What results would demonstrate asthma?
As Asthma is a reversible airway disease then after administration of a SABA (salbutamol) there should be an increase in lung function of 200-400ml
What does PEFR meausre
Measures maximum flow rate generates during a forceful expiration from full lungs
What is the diagnosis of asthma in terms of PEFR?
Asthma is diagnosed if PEFR varies by at least 20% 3 days of the week over several weeks or is increased by at least 20% by a bronchodilator.
Reversibility
Why is PEFR handy?
How do you know if obstruction is present?
Obstruction identified if PEFR less than PB or predicted according to heigh, sex and age
Patients can measure at home. It can act as an early warning sign of deteoriation. It also provides the patient with confidence as can see med working
What is the FeNO test and why is it relevent?
No produced during inflammatory response therefore raised levels can be diagnostic of asthma.
Tube with mouth piece attached to monitor that detects NO in breath. Deep breath through mouth then slow exhalation. Can be repeated 3 times.
Who should the FeNO test be offered too?
What results suggest asthma?
- All adults (>40ppb)
- Children 5-16 whose spirometry was normal or obstructive without reversibility (>35ppb)
What is the bronchial challenge?
Histamine or methacholine given as an aerosol mist or dry powder formulation is slowly breathed un at increasing doses. Spirometry done between rise in dose to determine response of lungs
Hypersensitive lungs irritated more quickly
Why is allergy testing done?
To determine allergens
Skin prick
Look at diagnosis chart
What is the severity classification of asthma?
How is asthma control assessed?
Asthma control test: 5 questions with scoring to determine control
Over 20 = Well controled
Results of 15 and under = Very poorly controlled
How is risk in asthma checked?
Asthma risk checker
What are the goals of therpy in asthma?
- Accurate asthma diagnosis and severity
- Prevent and control symptoms
- Reduce frequency of exacerbations
- Provide self management and recoginisation of deteoriation symptoms
What would complete control be classed as?
FEV1 and PEFR of >80% of predicted or best
What is the approach to managing asthma?
Approach to management
- Start treatment at the level most appropriate to initial severity.
- Achieve early control.
- Maintain control by:
- increasing treatment as necessary
- decreasing treatment when control is good.
Before initiating a new drug therapy always check adherence with existing therapies, check inhaler technique and eliminate trigger factors.
What are the steps in Asthma treatment?
All levels should have SABA unless using MART:
- SABA (consider low dose ICS)
- ICS for preventor (Beclametasone inhaler) and SABA as reliver
- Add LABA to inhaled ICS. Either MART or fixed dose preventor and Reliver SABA
- Add on therapy, either:
- Increase dose ICS to medium
- Add LTRA
- (If no response to LABA consider stopping LABA)
- Specialist therpy required:
- High dose ICS, LAMA, MR Theophyilline, oral steriods
