Asthma
It's a biggie but a goodie! Asthma is a disease which is common in both children and adults. You need to know about it, how to manage it, how to diagnose it and how to explain Einstein's Special Theory Of Relativity. OK, you don't need to the last of these but it might help...I'll get on with it shall I.
Definition
Chronic, episodic inflammation of the airways caused by hypersensitive reaction to an allergen.
Epidemiology
According to Asthma UK, 5.2 million people, including 1.1 million children in the UK suffer from Asthma. Hence, it is a very important disease.
Pathophysiology
Books have been devoted to describing the pathophysiology of asthma. Put very simply, it's an immune response causing your airways to constrict and inflame. Foreign bodies (stimuli/allergens/crap are all valid terms) such as dust, pollen, smoke... enter the airways. In most people, this causes no problems. Asthmatics however, are hypersensitive and so their bodies mount an immune response. This causes the release of IgE antibodies.
This is important in understanding the bronchoconstriction (the "constrict" bit from above). Smooth muscle (which surrounds airways) have Beta-2 receptors which, when blocked, result in the smooth muscle to constrict. "So they get blocked but what does the blocking, Mr Chowdhury?", I hear you say. Well, this is where IgE comes into it. It blocks it.
The bronchial inflammation (the "inflame" bit from above) is also an immune response. Inflammation is a non-specific defence mechanism of the body and it's no different in the lungs. Except for the whole, blocking the airway and potentially killing you thing. But the biochemistry is pretty much the same (not that I remember it).
Risk Factors
Basically, it comes down to: atopy which are conditions like eczema or hayfever based on that old chestnut, hypersensitivity; family history of asthma or any atopic conditions; being a boy; external factors like smoking, pets, house dust mites etc.
Clinical Features
There are basically four:
- Shortness of breath
- Wheeze
- Chest tightness
- Cough, usually worse at night.
Pretty easy, huh. The shortness of breath comes in episodes accompanied by the chest tightness. However, the history also needs to cover what effect the asthma is having on the kid's life. You need to ask about frequency of the symptoms; the effect on the kid's life (what is he not able to do); time away from school in the last 6 months; playing sport; sleep; and the longest symptom-free period.
Acute asthma can be found below.
Classification
Infrequent episodic asthma is what 75% of children have and it consists of fewer than four episodes a year. They are symptom free between attacks.
Frequent episodic asthma sufferers make up a further 20% of asthmatics. These children have symptoms every 2-4 weeks.
Persistent asthma makes up <5% of children with asthma. As the name suggests, these are children with persistent symptoms.
Exercise-induced asthma is asthma which only comes on after exercise.
Investigations
Generally, investigations in asthma are unnecessary. Skin tests can used for specific allergens but not for diagnosis of the condition. Chest X-ray can show hyperinflation and can be used in infants to rule out a congenital abnormality. The only investigation that is really necessary is peak flow.
This is only done in over 5s because it is very hard to do peak flow on a two-week old. You should check the value against that of PEFR chart (peak expiratory flow rate).
Management
Managing asthma is based on symptom relief and requires a stepwise approach, adding in treatments depending on how good symptom control is.
Step 1: Beta-2 bronchodilator
Step 2: Add inhaled steroids
Step 3: Add high-dose inhaled steroid
OR low-dose inhaled steroid and long-acting bronchodilator and/or leukotriene
Step 4: Add high-dose inhaled steroid (if you haven't already) and/or long-acting bronchodilator and/or theophylline
OR Ipratropium and/or leukotriene and/or alternate-day prednisolone
Management Of Acute Asthma
The first thing you need to do is recognise it and recognise if it's severe or even life-threatening.
Severe asthma means:
- Too breathless to talk or feed
- Respiratory rate of >50 breaths/min
- Pulse >140bpm
- Peak flow <50% predicted or best.
Life-threatening means:
- Peak flow <33% predicted or best
- Fatigue, agitation, drowsiness
- Cyanosis
- Silent chest
- Poor respiratory effort
Once you've recognised severe or, indeed, life-threatening asthma you probably ought to do something about it. Relatives are often annoyed by doctors who ignore severe or life-threatening acute asthma because the patients often die. This is undesirable.