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Asthma Management in Brief
Basic Lung Physiology
To understand treatment it helps to know the basics of lung
physiology.
 Our
bronchial tubes resemble a tree upside down with two main branches.
The tree-trunk represents the trachea, the big hollow tube in the
neck through which all the air we must breathe to survive passes in
and out again. One main bronchus goes to each lung, which then
branches and re-branches until the bronchi are like tiny hollow
twigs. These tiny ‘bronchioles’ each lead to an alveolus, a very
tiny air space lined with very thinly walled blood vessels. The
blood is separated from the air by a membrane so thin that oxygen
can be transferred into the blood, and the CO2 got rid of in the
exhaled breath
Every bronchus also has its own veins and arteries which branch and
re-branch in the same way as the air containing tubes, so that the
lung resembles a fine sponge
The actual area exposed to the air in the alveoli, if spread out
flat, is enormous, and has been estimated to be about the size of a
tennis court, making an organ ideal for exchanging gases
The larger bronchial tubes also
have muscles which go round and round the tubes, and they are lined
with cells which manufacture mucus and sputum. The mucus normally
causes no problems because the cells that cover the inside of the
bronchi have tiny cilia on the inside surface which are constantly
wafting the mucus upwards to the trachea to be swallowed harmlessly.
If there is too much sputum for the cilia to clear, it has to be
coughed up to clear the tubes.
When an asthmatic patient inhales an allergen to which the bronchi
are sensitive the result is contraction of the bronchial muscles,
swelling of the wall of the bronchus and the secretion of thick
sputum which partially obstructs the airways as it is so thick and
sticky that the cilia cannot move it.. The sputum contains cells
which are ordinary white cells in an infection, eosinophils in
allergic asthma, or a mixture of both .
The bronchi become clogged with
sputum, causing loud wheezing on breathing out. Because It is easier
to breathe in than out in asthma air becomes trapped in the lungs,
and enough fresh air does not reach the alveoli to deliver oxygen to
the blood and get rid of the C02.
Treatment of
Asthma
 The
muscles round the bronchi can be relaxed by inhaling bronchodilator
drugs like Ventolin (salbutamol) which act immediately, but only
last for a few hours. Long acting bronchodilators or oral steroids
may also be needed such as Serevent (salmeterol). Many similar drugs
are in common use.
The secretion of excess sputum caused by the allergic reaction can
be stopped by giving oral steroids, which are absorbed into the
blood circulation and distributed, by the blood vessels which
accompany the bronchi, to the lining of the bronchus. The effect is
to suppress the allergic reaction, stop the production of thick
sputum, clear the airways, and relieve the asthma.
Steroids by mouth in high dosage for a week or two are extremely
effective to control asthma, and side-effects are very rare indeed.
Given continuously oral steroids eventually cause troublesome
side-effects, so that both doctor and patient may have to choose
between the benefits and the side-effects. This is a situation where
finding the cause is very important, especially if the cause is
avoidable.,
Inhaled
Steroids - a New Era in Asthma treatment
Inhaling the steroid from an aerosol, so that the drug is deposited
on the inside of the bronchi without flooding the circulation with
steroids and affecting the whole body, had been tried without
success in Edinburgh from 1968.
This was the situation in 1971, when I was given the opportunity to
conduct a final trial before the makers threw the aerosol away as
useless. For this trial I selected allergic asthmatics with
eosinophil cells in their sputum, and they were all using their own
peak flow meters to produce objective data.
The effectiveness of the steroid aerosol was soon obvious, the
makers decided not to bin it, and the results were published in the
BMJ. Soon it was authorised for prescription as “Becotide” in UK,
and trials all over the world confirmed our results. Most
importantly, many patients dependent on oral steroids for years
could now be controlled by inhaled steroids instead, without the
side effects. To a large extent it no longer mattered what was
causing the asthma because most cases could be controlled with
Becotide or similar inhaled steroid, plus bronchodilators to control
spasm of the muscles round the bronchi.
Since then many other inhaled steroids and bronchodilators have been
developed, but the general principles of treatment are the same as
described above.
 Emergency Treatment of
Asthma
If many bronchi become semi-blocked or blocked it is obvious that no
particles of
inhaled steroid aerosol can possibly reach the bronchi to suppress
the reaction, and broncho-dilators to relax the bronchial muscles
also become ineffective. The narrower the bronchi the fewer inhaled
steroid particles
 and broncho-dilators can reach the bronchial
lining, so the asthma becomes out of control, thus developing a
vicious circle. Hence there is clearly a point where inhaled
treatments become more and more useless. It is very important that
the patient realises this by checking with the peak flow meter, does
not persevere with inhaled treatment only, does seek urgent medical
advice, or has a supply of oral steroid to take in an emergency.
Because chronic asthmatics become accustomed to their condition they
can easily underestimate the severity of their asthma. Asthma can be
much worse than it seems to be so it is essential to check with a
peak flow meter, which should be possessed by every serious
asthmatic
In my opinion, and that of most consultant physicians nowadays, all
patients with unstable asthma liable to severe attacks should have a
supply of steroid tablets in their possession at all times so that
they can take up to 40 mgms of Prednisolone or equivalent
corticosteroid drug at once when necessary, especially if there is
any difficulty in obtaining medical help or advice.
Delay can be dangerous, as many deaths from asthma have been found
to be due to not having steroids soon enough. The commonest cause of
death was not getting oral steroids at all because the severity of
the asthma had been underestimated by patient and/or doctor. In my
experience this aggressive steroid policy has never caused problems,
but delayed giving of oral steroids has produced many serious
situations and deaths.
In my long experience short-term high dose steroids, even 40mgms
Prednisolone a day or more for as long as three weeks, has never
caused significant side-effects. The steroid tablets are absorbed
into the bloodstream to reach the lining of the blocked and
semi-blocked bronchi to dissolve the cells and sticky mucus from
beneath the bronchial lining.
 After some days on a high dose the
steroids should open up the airway so that the oral steroids can be
phased out and the inhaled steroid can once more reach the bronchi
and keep the asthma under control again.. It is the indefinite
duration oral steroids that cause side-effects. Even then low doses
of oral steroids for many years do not always cause troublesome
side-effects
The steroid usually prescribed is Prednisolone which has been
enteric coated to prevent the drug dissolving in the stomach and
causing ulcers, but I have seen only one bleeding ulcer from
steroids since 1956. The red enteric coating on the Prednisolone
tablets is intended to delay the absorption of the tablet until it
reaches the intestine, avoiding liberating the drug in the stomach.
In occasional cases I have found that this coating prevents
absorption altogether just when it is most needed and the tablets
literally go down the drain. In some patients 40mgms of enteric
coated Prednisolone per day for weeks had been totally ineffective,
and in two instances admission for intensive care was required.
My preferred steroid for many years has been Betnesol (betamethasone phosphate) because it dissolves in water, can be well
diluted in any fluid to prevent any gastric irritation, is absorbed
almost as fast as an intravenous injection, and is much more
acceptable than tablets for children. In the few cases who had not
responded to large doses of enteric Prednisolone the administration
of this soluble steroid caused dramatic improvement in only a few
hours, but surprisingly this soluble steroid it is largely unheard
of and is very seldom prescribed. Unfortunately this steroid
contains erythrosine dye which is quite unnecessary and can cause
problems in some patients, but because of regulations it would
entail much red tape and expense to alter the formulation, and
allergy to this dye is very uncommon.
Qvar - A Significant Breakthrough in Steroid Aerosols
From 1970 onwards the propellant gas in Becotide inhalers
was ChloroFlouroCarbon or CFC. The liquid gas contained a suspension
of tiny particles of the steroid drug which was inhaled and settled
on the walls of the bronchi to suppress the allergic reaction.
 Using
radioactive aerosols of Becotide (Beclomethasone Dipropionate) in a
CFC inhaler it was demonstrated that the particles of suspended
steroid drug reached only the larger bronchi, and hardly any reached
the smallest bronchi, as shown. When it was discovered that escaped
CFC gases, used world-wide for refrigeration and air-conditioning,
were destroying the ozone layer which protects the world from too
much ultra-violet radiation, these gases were banned world-wide,
including medical aerosols. Fortunately a substitute gas ( Hydro-flouro-alkane
or HFA) was discovered which is even better than CFC because instead
of the drug being suspended it is dissolved in the liquid gas. The
result is that for the first time really tiny particles of the
steroid drug as small as one micron, penetrate down to the very
smallest bronchus, as shown.
This is of great potential importance for chronic asthmatic children
who may have to take a steroid aerosol for life because for the very
first time the whole developing bronchial tree can be be treated by
with steroid aerosols .
These developments were about ten years ago but these aerosols have
not been used widely until recently when all aerosols for asthma
have had to change to HFA because of the global ban on CFCs . As
long ago as 2003 I wrote to the editor of the Lancet pointing out
the importance of these developments but with no effect. The first
aerosol to generate the finest particles was called Qvar and used
Beclomethasone, the very first steroid aerosol from 1968, but was
very seldom prescribed, and some pharmacy advisers would not let GPs
prescribe it . In fact GPs had become so fixed in their prescribing
that it has taken about ten years to change it.
Some inhaled steroids are administered as inhaled powders composed
mainly of lactose, a sugar derived from milk which may contain
traces of milk protein. Milk sensitive patients can have their
asthma made much worse if this fact is not known. The particles are
obviously larger and will not penetrate the bronchial tree deeply
enough.
The
Importance of Investigation of Childhood Asthma
The prevalence of Asthma continues to increase year on year,
allergies are more important as a cause of asthma and eczema in
children than in adults, and many severely asthmatic children will
grow up into asthmatic adults. When asthma is allowed to become
chronic permanent changes will eventually become established by
‘remodelling’ of the bronchial tubes whereby the walls become
thicker and stiffer. Even if the cause is identified and avoided
completely it will be a long time before the irritability of the
bronchi will cease, hence ‘remodelling’ may be irreversible. More or
less effective suppression of the allergic inflammation in the
bronchi with drugs is usually the only treatment in the UK today.
This inadequate therapeutic approach will inevitably lead to an
increase in numbers of chronic asthmatic adults.
 It is surprising how few Paediatricians (medical professionals who
specialise in children) do not seem to be interested in finding out
why their hospital wards are crowded with wheezing children.
Asthmatic children often do not get better spontaneously at age
seven or fourteen years, yet parents may still be assured that they
will do so. Even those children who lose their asthma in
adolescence quite often relapse in later life. Even when asthma is
effectively suppressed with drugs these children are still becoming
permanently programmed to respond to common allergens such as dust
mite.
This is because the allergic reactions in the bronchi are only
suppressed, not stopped altogether.. This also means that even if
these allergy victims are properly investigated and their allergies
sorted out after they have grown up into adults, the prospect of
really significant improvement is less than it would have been if
they had had proper investigation and treatment when they were young
and completely reversible. This suggests that in future the numbers
of established chronic asthmatics will increase, unless the allergic
factor is properly dealt with in childhood, not in adulthood when it
may be too late.
General Management of Asthma
Full instructions on avoidance of the common causes of asthma and
guidelines for treatment are freely available today from many
sources, and should be in full operation in any medical practice
where there is a special asthma clinic, so there would be little
point in repeating them here. This has gradually come to pass over
the years, and has led to a great improvement in management.
The stressed GP has neither time nor the knowledge to investigate
asthma, but the nurse specialist has the time, has a special
interest, and should be able to carry out skin testing, although
this is still uncommon. Advice on the importance of pets in causing
allergies is seldom pursued as vigorously as it should be and advice
on avoidance not taken seriously, or ignored The main role of the
nurse specialist is to make sure the patients use inhalers and peak
flow meters properly, and have a management plan.
 Measures to reduce the dust mite, the most common cause of asthma,
chronic rhinitis, and eczema, are difficult and expensive. Powerful
and expensive vacuum cleaners are advocated for the removal of the
mites, but cannot drag the mites out from the depths of the carpets.
In recent times the availability of affordable laminated flooring to
replace the fitted carpets which have been an ideal home for mites
for many years has been very helpful. Special mite-proof covers for
mattress and pillows are helpful, but expensive.
Pillows with synthetic fibre stuffing have been sold as
‘anti-allergenic’ for many years, but have recently been clearly
proved to accumulate a huge mite population in a few months, much
worse than the down pillows doctors have been advising patients to
throw away!. This is because down pillows have finer woven covers
which are less permeable for mite faeces, and of course they are
much more comfortable.
There is no doubt that a very large and lucrative market has grown
up in selling all these measures to fight the mite, and that most
people know that the mite is a major problem for allergy, but the
results are often disappointing. My personal experience with
Acarosan to kill off the mites is another story which will be told in a special section
of this website.
 Steroid Phobia and unreasonable fear of side-effects is very common,
but except for unavoidable long-term use of oral steroids, when the
side-effects can be regarded as the price that has to be paid for
the beneficial effects of the drug, these fears are grossly
exaggerated. Inhaled steroids for asthma, such as Becotide,
Pulmicort, Budesonide, Flixotide, Qvar, and others, and also steroid
nasal sprays, rarely cause any problems except for occasional
thrush. Many children who attended my clinic started using Becotide
from 1970, when they took part in the very first trials, and are
still using it daily without problems over forty years later.
When chronic asthmatics become pregnant there is often fear of
side-effects on the foetus which are quite unfounded. I will never
forget a patient who died of asthma because the obstetrician who was
looking after her did not ask my advice and withheld steroids until
it was too late. It seems glaringly obvious that lack of oxygen due
to the asthma is much more likely to harm the foetus than steroids,
yet there are still misgivings by both doctors and patients about
steroids in pregnancy.
Steroid phobia also applies to inhaled steroids, steroid creams, and
other steroids which are applied locally to the part of the body
which requires treatment. It takes years to produce thinning of the
skin and bruising from using creams, and local applications hardly
ever cause generalised effects unless used very excessively..
Unfortunately patients may not use their inhalers or creams for fear
of side-effects and even withhold these treatments from their
children with asthma or eczema. It seems that these concerns are
seldom explained to patients, who may not ask for advice during a
hurried consultation. |
