a generally chronic condition that is characterized by
recurring attacks of wheezing, coughing, and labored breathing; it
may be caused by allergies, physical exertion, chemical irritation,
or emotional stress. (From a Greek word meaning "panting.")
Typical findings in an asthmatic chest radiograph include
hyperexpanded lungs evident best with flattened diaphragms and
narrowed cardiac shadow and mediastinum. On a lateral projection the
chest may appear "barrel" shaped.
The radiograph may be normal or show hyperinflation.
Areas of segmental and subsegmental atelectasis may occur due to
mucus plugging or smooth muscle hypertrophy. Central bronchial wall
thickening is common. Radiographs are helpful to exclude an acute
abnormality such as pneumonia or pneumothorax.
Preferred Examination: CXR remains the initial imaging
evaluation in most individuals with symptoms of asthma. The value of
CXR is in revealing complications or alternative causes of wheezing
and the minor importance of wheezing in the diagnosis of asthma and
its exacerbations. CXR usually is more useful in the initial
diagnosis of bronchial asthma than in the detection of
exacerbations, although it is valuable in excluding complications
such as pneumonia and asthma mimics, even during exacerbations.
High-resolution CT (HRCT) is a second-line examination. It is useful
in patients with chronic or recurring symptoms and in those with
possible complications such as allergic bronchopulmonary
aspergillosis and bronchiectasis.
Limitations of Techniques: CXR is limited by frequent and sometimes
subjective findings that are not specific for asthma; these
nonspecific findings include airway thickening and hyperinflation.
Nevertheless, in the appropriate clinical setting, CXR findings can
support the diagnosis of asthma.
HRCT is more costly than CXR and exposes the patient to more
radiation. Nevertheless, CT scans can demonstrate a number of
findings that support the diagnosis of asthma; examples of such
findings include bronchial wall thickening, bronchiectasis, mucoid
impaction, and airtrapping, among others.
Asthma is a chronic lung condition. It is characterized by
difficulty in breathing.
People with asthma have extra sensitive or hyperresponsive airways.
The airways react by narrowing or obstructing when they become
irritated. This makes it difficult for the air to move in and out.
This narrowing or obstruction can cause one or a combination of the
wheezing, coughing, shortness of breath, chest tightness
This narrowing or obstruction is caused by:
Airway inflammation (meaning that the airways in the lungs become
red, swollen and narrow)
Bronchoconstriction (meaning that the muscles that encircle the
airways tighten or go into spasm)
Signs of asthma
Primarily, asthma is manifested by a sudden or prolonged onset of
airway narrowing, which accounts for the varying degrees of airway
obstruction and accompanying sensation of an inability to breathe in
and, more importantly, to breathe out; these symptoms herald
hyperinflation. The total lung capacity (TLC), functional residual
capacity (FRC), and residual volume (RV) increase.
The hallmark of airway obstruction is a reduction in ratio of the
forced expiratory volume in 1 second (FEV1) and the FEV1 to the
forced vital capacity (FVC). However, the earliest effects of airway
disease are believed to occur in the small airways (<2 mm in
diameter), and they are more difficult to measure reliably with
standard pulmonary function tests (PFTs), such as tests of the
following: forced expiratory flow after 50% of vital capacity has
been expelled (FEF50), forced expiratory flow after 25-75% of vital
capacity has been expelled (FEF25-FEF75) and maximum midexpiratory
flow rate (MMEFR). Less common evaluations include tests of airway
resistance (RAW) and single-breath carbon monoxide diffusion
capacity (DLCO/VA). With the former, resistance is markedly
increased, although the findings are highly variable; with the
latter, results are normal or slightly elevated in uncomplicated
asthma (Collard, 1994; Boulet, 1995).
Whether the more severe and permanent features of distal airway
obstruction and coexisting emphysema supervene in the later and more
complicated stages of asthma is controversial. However, in one
study, patients with partially reversible airway obstruction that
persisted after optimal corticosteroid treatment had a normal
diffusion capacity that was comparable to that of patients with
completely reversible asthma (Hudon, 1997). The functional
abnormalities reflect airway narrowing that results from multiple
causes, including bronchial smooth muscle contraction; mucous
plugging from mucous gland hypersecretion; submucosal, peribronchial,
and interstitial edema from loss of capillary and arteriolar
cellular interconnections; and cellular infiltrative changes
involving plasma cells, lymphocytes, macrophages, and leukocytes.
Chronic or incompletely reversible asthma is characterized by
variable obstruction; a more fixed degree of airway narrowing may
also be present in some patients. With repeated episodes of
clinically important airway narrowing, generalized thickening of the
airways occurs as a result of smooth muscle hyperplasia,
postinflammatory thickening of the bronchial basement membranes, and
mucous gland hypertrophy.
Complications of asthma often are more apparent than the direct
airway imaging findings that are the sequelae of asthma.
Spontaneous pneumothorax is an uncommon but well-recognized
The chest radiograph (CXR) is an important tool in the examination
of patients with an exacerbation of asthma, but patients should not
be left waiting in the treatment room for CXR before treatment
Pneumothorax may be evident radiographically before it is identified
clinically (Gay, 1978).
Pneumothorax often occurs during recurrent episodes of bronchospasm,
as well as in other conditions. The presence of an air-fluid level
in a hydropneumothorax can be confused with pneumatocele, infected
cysts, and cavitary lung disease.
An unusual condition of diffuse pulmonary ossification associated
with pneumothorax is described in a patient with bronchial asthma
Pneumomediastinum can occur, particularly in young adults (see
Images 1-2). The pathophysiologic nature of the process, as
previously determined from animal studies, is reported (Jamadar,
1996). Using perfluorocarbon liquid ventilation in a hypoxic patient
with status asthmaticus and tension pneumothorax, the authors traced
the heavily radiopaque substance through ruptured alveoli, the
interlobular spaces, and the axial interstitium to the mediastinum.
The liquid agent remained in the interstitial space for 30 days
without complications. Pneumomediastinum generally is self-limited,
and it requires no additional therapeutic measures beyond those for
asthma exacerbation (Ba-Ssalamah, 1999).
Emphysema can occur in the subdural space, especially in children.
Air moves posteriorly from a pneumomediastinum into the
intervertebral foramina and further into the most nondependent
potential spaces adjacent to the brain coverings (Caramella, 1997).
Spinal epidural emphysema is also described in asthmatics, tracking
along the great vessels bound by the mediastinal pleural layers
(Tsuji, 1989). As reported, these events typically have no
Pneumopericardium is uncommon and more likely to occur in younger
persons because their pericardial layers are more loosely apposed
than those in adults (van der Klooster, 1998). As with
pneumomediastinum, pneumopericardium generally has a benign course.
Pneumothorax, pneumomediastinum, pneumoretroperitoneum,
pneumorrhachis (ie, spinal epidural air), and extensive subcutaneous
emphysema are more likely to occur with episodes of coughing or
increased intrathoracic pressure that accompany the recruitment of
expiratory muscles when normal airflow is substantially reduced (van
der Klooster, 1998).
More serious is subarachnoid hemorrhage, which developed in a
patient with status asthmaticus who received ventilation with
permissive hypercapnia. This technique minimizes the overall
delivered minute ventilation and airway pressures to maintain
adequate oxygenation. However, because of elevated CO2 partial
pressures, it also led to cerebral vasodilatation and increased
intracranial pressure; when combined with coughing spells and other
forms of transmitted intrathoracic pressure, the ventilation was
believed to promote cerebral edema and limit cerebral venous
drainage (Rodrigo, 1999).
Noisy breathing may mask potential physical findings in pneumothorax,
pneumomediastinum, and pneumonia; therefore, CXR should be performed
prior to the use of mechanical ventilation.
Today's asthma treatments are extremely safe and effective. The
doctor will work closely with you to devise a treatment plan that is
tailored to your individual needs.
The mainstay of your treatment will be with preventive drugs, known
as preventers, which are designed to quell swelling and inflammation
in the airways and reduce mucus. This reduces the sensitivity of the
airways and so minmises potential damage.
The protective effect is built up gradually over a period of about a
fortnight. Your medication must be taken daily to maintain
protection, even if you are not experiencing symptoms. Most
preventers are based on corticosteroids, usually known simply as
steroids. These are completely different from the anabolic steroids
sometimes used by body builders and athletes. Most common type of
preventer are inhaled steroids. These can include beclomethasone,
There are other non-steroid preventers, usually used for children,
such as sodium cromoglycate and nedocromil sodium. They are usually
taken 3-4 times a day, and are not generally as effective as
Potential side effects
Many people worry about the side effects of steroids. High doses of
steroids taken over a long period can have significant side effects.
For this reason, doctors will be careful to prescribe the lowest
possible dose needed to control your asthma.
The main side effects are hoarseness and an increased risk of mouth
and throat infections caused by thrush, a yeast that lives normally
on the body's mucus membranes. Using the inhaler before brushing
your teeth and rinsing your mouth out well afterwards helps to avoid
this. Using a 'spacer' makes it easier to inhale the drug, and so
helps reduce the risks of steroids being absorbed into your body.
Relievers are drugs which relax and open up the airways - medically
known as bronchodilators. These are prescribed for the relief of
asthma symptoms during an actual asthma attack, when peak flow
readings are low and before exercise or activity to reduce the risk
of an attack. Because these drugs do not reduce swelling and
inflammation of airways, you may also need to take a preventer.
Some relievers alleviate symptoms virtually instantly (rescue
relievers). Others have a longer lasting action (long lasting
relievers). The latter may be prescribed if wheezing, breathing
difficulties and coughing persist despite using preventer and a
rescue reliever - or if symptoms come on in the night (nocturnal
Common rescue relievers are salbutamol and terbutaline. Another type
of reliever (most often prescribed for babies under two and for
older people), called ipratropium bromide, takes about 45 minutes to
Long lasting relievers include oxitropum, salmeterol, and
eformoterol, all of which are inhaled. Ocassionally theophylline-based
drugs are taken by mouth, so tablets may be prescribed.
Potential side effects
Side effects are usually mild and pass away quickly. The main ones
are a slightly increased heartbeat which may cause muscle trembling,
especially in the hands. Some oral relievers may cause dry mouth,
blurred vision, difficulties passing urine, or constipation.
Theophyllin-based drugs can occasionally cause nausea, more rapid
heartrate, a nettle-like rash, dizziness, nervousness, headaches,
irritability, or restlessness. Always report any unusual symptoms to
How asthma treatments are taken
Most asthma treatments are inhaled using a device called an inhaler.
There are several different types, but the main ones are aerosol
inhalers called puffers and dry powder inhalers:
'Puffers' - aerosol inhalers, metered dose inhalers, and
breath-actuated inhalers. These are the most commonly used devices
for treating asthma. The medication is mixed into a liquid and
forced under pressure into a small aerosol canister. Once activated
(usually by pushing down the canister), the liquid evaporates
leaving the active ingredient which you inhale. A measured dose of
the drug is released every time the canister if pushed down. Both
relievers and preventers can be given via a puffer.
Dry powder inhalers - the drug which comes in dry powder former is
contained in a capsule. When the device is activated the capsule
breaks and the powder may be inhaled. In some the poswder is
contained inside a disk or compartment.
Because it can be hard to co-ordinate your breathing with an
inhaler, you may be prescribed a spacer. This is a device that
allows more medication to enter your lungs than would be possible
using inhaler alone. It's usually a large canister in two halves
that click together with a mouthpiece at one end, and at the other,
a hole which is attached to an aerosol spray.
When you inhale, the drug is trapped in the space which is placed
over the mouth - or the nose and mouth in the case of 'babyhalers.'
A nebuliser is a machine in which air or oxygen is forced through
the liquid form of a drug, creating a mist - which is then inhaled
through a mask or mouthpiece. It is used to administer high doses of
reliever in an emergency and sometimes for children who are too
young to use inhaler. With the large number of inhalers and spacers
now available, nebulisers are much less frequently used than they
used to be. However they may be prescribed if you have severe,
There are a number of medicines which are taken in pill form,
including leukotriene receptor antagonists and steroid tablets. Your
doctor will be able to advise you about when and why these are
necessary for you.
Complementary treatments can play a part in the management of
chronic asthma. However, because asthma is a potentially
life-threatening condition, they should only ever be used as an
adjunct to conventional medical treatment and never as the first
line in an acute asthma attack. Homeopathy, Western herbalism,
acupressure and acupuncture, and Chinese herbalism may all be
Because asthma is a complex condition it is advisable to consult a
qualified practitioner rather than trying to treat yourself. You
should also make sure that your orthodox doctor is aware that you're
having complementary treatment.
A variety of techniques to improve posture, encourage relaxation and
improve breathing and strengthen the respiratory system may be
useful, especially when used at the beginning of an attack to help
calm you - or your child - and ease breathing. These include the
Alexander technique, yoga, and a system of breathing known as
Buteyko which unblocks the nose and stops mouth breathing and trains
people with asthma not to overbreathe.
Taken From http://www.bbc.co.uk/health/asthma/
with upper lobe atelectasis