Asthma: Everything there is to know
What is asthma?
Asthma is an inflammatory disease of the respiratory tract (bronchi and bronchioles), characterized by reversible airflow obstruction leading to recurrent episodes of coughing, wheezing, dyspnea (shortness of breath) and tightness in the chest.
It is a chronic disease, interspersed with acute episodes with symptoms ranging from simple respiratory discomfort to exacerbations (called flare-ups or asthma attacks) which correspond to the onset of symptoms over several days requiring hospitalization, sometimes in intensive care.
When we breathe, air enters the bronchial tubes and reaches the lungs. In a person with asthma, there is a thickening (edema) and inflammation of the mucous membrane (lining) of the bronchial tubes. Because of this constant inflammation, the bronchial tubes are hyper-reactive to certain substances, causing the muscles around the bronchial tubes to contract (bronchial spasm) and thus causing symptoms.
There are two types of asthma:
- Early-onset asthma, most often allergic, which often develops in childhood: patients are atopic, meaning they are predisposed to the development of allergies to the allergens they breathe in (dust mites, animal hair, mold, pollen, etc.). Their skin hypersensitivity tests (prick tests) therefore come back positive to these different allergens. These patients generally have a family history of other allergic conditions such as eczema or hay fever.
- Late-onset asthma, often non-allergic, which is not triggered by the presence of an allergen and whose causes and treatments are not yet clearly understood today. These asthmas are commonly associated with the presence of polyps in the nose.
How common is asthma?
Asthma is a very common condition: 339 million people live with asthma worldwide.
The number of asthma patients is increasing, with more than 25 million asthmatics in the US ( 7.7% of American adults).
Asthma is responsible for over 9.8 million doctor's office visits, 188,968 discharges from hospital inpatient care, 1.8 million emergency department visits, and over 3,500 deaths each year.
Symptoms and complications of asthma
Asthma symptoms can be intermittent or prolonged and are usually worse at night or in the morning.
The main symptoms of asthma are:
- Persistent dry cough often during exertion or at night) that persists
- Shortness of breath and difficulty breathing deeply
- Tightness in the chest or rib cage
Other more distressing symptoms may appear during an exacerbation (or attack):
- Feeling of suffocation
- Difficulty filling and emptying the lungs
- Wheezing or a high-pitched whistling sound
The duration of an attack can vary considerably depending on the individual, the triggering circumstances (duration of exposure and concentration of the triggering factor), and the nature and onset of treatment. It may last a few hours or several days.
Between episodes, breathing is usually normal.
Asthma can affect patients' quality of life, causing sleeplessness, reduced physical activity and absenteeism from school or work.
Causes and risk factors of asthma
Asthma is caused by a combination of genetic predisposition and environmental factors.
Some of the triggers for asthma symptoms are:
- Tobacco smoke, including second-hand smoke
- Air pollution
- Chemical irritants (cleaning products and/or cosmetics)
- Rapid temperature change (especially to cold, dry air)
- Respiratory infections, especially viral infections (flu, recurrent bronchitis, non-allergic rhinitis or common colds, etc.)
- Strong emotions (stress, etc.)
- Physical exercise (exertion)
- Hormones, especially in cases of premenstrual asthma
Allergens are also part of the triggering factors. These are most often household allergens, which are found in the home: dust mites in particular, but also animal dander and molds. Pollen and food are less often involved.
In addition, in allergic rhinitis (also called seasonal allergies or hay fever) or sometimes in non-allergic rhinitis, nasal polyps are also an aggravating factor for asthma. Asthma is more often destabilized in patients who also have allergic rhinitis. This is due to the continuity between the mucous membranes of the nose and the bronchi. So when an allergen comes into contact with one of these mucous membranes, it causes the same type of inflammation in the other.
Allergic (or atopic) background is a major risk factor for asthma in children. When only one parent has allergies, the risk of the child also developing allergies is 20-30%. If both spouses have allergies, the risk rises to 40-60%. Thus, although it is common to find a family predisposition for the development of asthma, the transmission of asthmatic disease from parents to their children is by no means automatic.
Asthma is an often under-diagnosed condition. A visit to the doctor is recommended if the patient develops a persistent dry cough, wheezing, shortness of breath, tightness in the chest, waking up at night or limitations in activities due to breathing difficulties.
The diagnosis of asthma is then based on attentive discussion with the patient by the attending physician on the following subjects: family history of asthma and allergies, the symptoms experienced (attacks of breathlessness, wheezing, coughing), the frequency and intensity of respiratory discomfort, the circumstances in which they are triggered (at home, at work, during periods of heavy pollution, etc.) and the presence of any other viral infections (rhinitis, sinusitis, etc.).
To confirm the diagnosis of asthma, functional respiratory testing (FRT) is carried out by a pulmonologist. The purpose of this testing is to measure how well the lungs work and to identify the severity of the asthma.
- FEV1 (forced expiratory volume in one second) is measured with a spirometer (an electronic device with a mouthpiece into which the patient blows) and is a reference index of bronchial obstruction.
A diagnosis of an obstructive lung disease can be made when FEV1 < 80% of predicted values* or when the FEV1/CV ratio (also called Tiffeneau-Pinelli index) < 70%, with the CV (vital capacity) being the maximum amount of air that a person can expel from the lungs after a maximum inhalation. Asthma can be diagnosed if FEV1 improves by more than 200 ml and more than 12% of its baseline value after taking a fast-acting bronchodilator (albuterol).
*They take into account age, gender, height and ethnicity
Peak expiratory flow (PEF) is calculated with a peak flow meter and measures the maximum breath velocity of the asthma patient during forced exhalation.
Normal or theoretical PEF values depend on sex, age and height: they are typically 400-550 liters per minute in women and 500-650 liters per minute in men, but PEF is mainly measured for comparison with baseline.
For each patient, the best value ("baseline value"), which is achieved when the asthma is controlled, is recorded. During asthma monitoring, each new measurement of the patient's PEF is compared to the baseline value, usually in the form of a percentage (= 100 x measured PEF / baseline PEF). This is the variability of the PEF. A variation of less than 20% is considered normal.
During an attack, arterial blood gases (ABG) can be measured. Estimating the levels of oxygen and carbon dioxide in the blood helps to assess the efficiency of breathing.
Skin tests (or prick tests) should also be performed to determine whether the asthma is allergic in origin and to identify the allergens involved.
Asthma control should be measured using an asthma control questionnaire (ACQ) or asthma control test (ACT). These questionnaires are easy to complete and can be used to determine whether asthma is under control (no symptoms at all), uncontrolled (unacceptable symptoms) or acceptably controlled (some symptoms). It is the measure of asthma control that will dictate treatment.
Treatments for asthma
There are 5 successive treatment levels. When asthma requires a level 4 or 5 to be controlled, it is considered severe asthma.
Preventative measures are an integral part of asthma treatment.
These measures include:
- Limiting contact with the offending allergens
- Avoiding exposure to tobacco (active smoking or second-hand) which increases likelihood of an attack, decreases sensitivity to corticosteroids and accelerates the decline in lung function
- Avoiding toxic household products (cleaning products, volatile organic compounds, etc.), occupational toxins (silica, toxic fumes, etc.) and air pollutants (ozone, nitrogen oxide, etc.)
- Stopping medications that may trigger attacks, in case of intolerance to aspirin, non-steroidal anti-inflammatory drugs (NSAIDs), and beta blockers
Vaccination is also recommended every year for the flu and every 5 years for pneumococcus.
Treatment of exacerbations or attacks (rescue treatment)
Treatment for asthma attacks is necessary at all stages of the disease and is the same regardless of the severity of the asthma.
Since 2019, GINA (the Global Initiative for Asthma) has recommended a new strategy for symptomatic treatment of asthma symptoms and exacerbations.
It recommends the use of a combined low-dose inhaled corticosteroids (ICS) and formoterol as needed. Of these ICS (which have an anti-inflammatory effect on the bronchial tubes), the positive data obtained so far concerns the use of budesonide (Pulmicort®), but BDP or beclomethasone dipropionate (Beclovent®, Qvar®) also seems to be suitable.
The side effects of inhaled corticosteroids can include oral thrush, dysphonia (hoarseness) or sore throat. Rinsing the mouth after inhalation is therefore recommended to prevent these rare side effects.
As an alternative rescue treatment option, short-acting Beta-2-adrenergic agonists (bronchodilators) can be used at the first symptoms of an attack. Among them, the most prescribed drugs are albuterol as first-line treatment (Accuneb®, Ventolin®, Proair®, Proventil®), and terbutaline (Bricanyl®, Bethine®). Inhale 1 to 2 puffs and repeat the inhalation a few minutes later if necessary.
Beta-2-adrenergic agonists can also be used to prevent exercise-induced asthma or exposure to allergens (1-2 puffs should be inhaled 15 minutes before exercise or exposure) and in the symptomatic treatment of severe, acute asthma (inhaled by nebulization or misting).
They take effect within 2-3 minutes and persist for 4-6 hours. Side effects that may occur with these inhalants include tachycardia, shaky hands or legs, headache and throat irritation with coughing.
More rarely, inhaled anticholinergics (or muscarinic receptor antagonists, which also cause bronchial dilatation) may also be used in the symptomatic treatment of an asthma attack, such as ipratropium bromide (Atrovent®). They require the inhalation of 1 to 2 puffs, to be repeated if necessary a few minutes later.
Background (or control) treatments
The aim of background treatment is to reduce the frequency and intensity of symptoms.
It does not apply to intermittent asthma, which only requires treatment of symptoms on demand, but becomes necessary from mild persistent asthma and onwards.
For the ongoing treatment of persistent asthma in adults and severe asthma in children, the use of low-dose daily inhaled corticosteroids (ICS) is recommended: beclomethasone (Beclovent®, QVAR®, Vanceril®) ciclesonide (Alvesco®), fluticasone propionate (Flovent®), budesonide (Pulmicort®) and mometasone (Asmanex®).
The response to ICS is highly variable from one individual to another and their doses are increased according to asthma control, provided the treatment is taken properly (good compliance) and triggers are taken into account. They generally require 2 daily doses.
Another treatment option for controlling persistent asthma is leukotriene receptor antagonists (LTRAs), such as montelukast (Singulair®), which require one 10 mg tablet per day at bedtime.
Then, from moderate persistent asthma and onwards, long-acting Beta-2-adrenergic agonists (LABAs) are prescribed for the ongoing symptomatic treatment of asthma (low dose for moderate persistent and medium dose for severe persistent). They require 1 to 2 inhalations twice a day.
LABAs can have rapid onset of action, such as with formoterol (Foradil®, Perforomist®), or a delayed onset of action, such as with salmeterol (Serevent®) which reacts after 15 minutes. But all are long lasting (around 12 hours).
They are prescribed in fixed combination with low or medium dose corticosteroids: formoterol + budesonide (Symbicort®) or salmeterol + fluticasone (Advair®, AirDuo®).
Finally, for the treatment of severe persistent asthma, a combination of high-dose ICS/LABA and possibly long-acting anticholinergics such as tiotropium (Spiriva®) are used.
Biotherapies (treatments with living organisms or substances from these organisms) can also be used. These include anti-IgE antibodies such as omalizumab (Xolair®), anti-IL5/5R antibodies such as mepolizumab (Nucala®) and anti-IL4/IL13R antibodies such as dupilumab (Dupixent®). The latter 3 treatments are administered by subcutaneous injection by a medical professional. They are intended for severe asthma patients who need to be cared for by an asthma specialist.
Another innovative therapy for these patients is bronchial thermoplasty, which involves the delivery of controlled, therapeutic radiofrequency energy to the airway wall, thus heating the tissue and reducing the amount of smooth muscle present in the airway wall.
>> To learn more about biotherapy for asthma, read our article: “What is biological therapy? A special look at asthma” <<
It is sometimes still necessary to use oral corticosteroids (OCS) such as prednisolone, betamethasone or dexamethasone. The duration of treatment and the dose used should be as short as possible as they can cause numerous adverse effects (weight gain, skin fragility, muscle wasting, osteoporosis, etc.). The treatment of exacerbations is based on the use of prednisolone or prednisone for 5 days.
They require 1 dose in the morning (+ 1 in the evening if high dose) with a meal.
Finally, the transition from one stage of treatment to another is based on the level of asthma control measured by the ACQ or ACT:
- If the treatment helps to control the asthma for 3 months, there is the possibility of progressively reducing the doses or the number of molecules used;
- Conversely: if asthma is not controlled, it is possible to increase the doses of inhaled corticosteroids (ICS) or to add an additional treatment. However, before initiating a therapeutic escalation, it is advisable to check that the treatment is being taken correctly, as failures are most often due to non-compliance. This is why therapeutic patient education is essential in asthma.
Acute asthma exacerbations
In the event of sudden or rapidly progressive onset of symptoms, emergency consultation should be considered.
Treatment of acute asthma exacerbations should be started at home by the patient, taking one puff of their fast acting bronchodilator every 30-60 seconds up until 10 puffs*. If there is no improvement after 10 puffs or if the patient feels worse at any point, it should be considered as a severe asthma attack and the patient should call 911 for an ambulance. He or she should not go to hospital on their own but wait for help, restarting the repeated puffs of their reliever inhaler after 15 minutes while waiting for the ambulance.
*This routine is not appropriate for SMART or MART ((Single) Maintenance and Reliever Therapy - when you have just one inhaler containing a combination of medicines to help your asthma) medicine regimes. Make sure to ask your doctor for more information on what to do in case of a severe attack.
In the hospital, high-dose short-acting Beta-2-agonists are used as nebulizers (in a mist), with the addition of oxygen and oral corticosteroids (prednisolone).
It is then important to avoid recurrence, as it has been found that up to 30% of asthmatics relapse within a month. To do this, oral corticosteroid therapy is usually extended for 3 to 7 days. It is necessary to follow or reinforce the control treatment and it is important to ensure that one's treatment is always available and to learn how to use one's inhalation device properly.
Living with asthma
Proper use of inhalers
Each type of inhaler has a specific technique for use. The American Lung Association has a helpful series of videos explaining proper technique for each of the various types of inhalers that you can watch here.
There a few different categories of inhalation devices:
- Pressurized metered dose inhalers (pMDIs): pMDIs are the most widely used inhaler and have been used for over 40 years to deliver various types of inhaled medicines. It contains pressurized, inactive gas that propels a precise dose of medicine released in a puff when the top of the inhaler is pressed. This type of device requires good co-ordination so that the canister is pressed and a full breath is taken at the same time.
- Breath-activated inhalers: These devices are alternatives to pMDIs and follow the same principle. Some of these devices are still pressurized MDIs, but they don’t require the canister to be pressed to release a dose, the medicine is released automatically when the patient inhales.
- Dry powder inhalers (DPIs): These inhalers are also breath-activated inhalers, but they do not contain the pressurized gas that propels the medicine. As with other breath-activated inhalers, a dose is triggered by breathing in at the mouthpiece of the device, but the medicine within the device comes in the form of a dry powder. These inhalers can be single-dose (with a capsule to be inserted into the device before inhalation) or multi-dose (with a reservoir with many doses, equipped with a dose counter).
DPIs generally require less co-ordination to use, but require a fairly strong breath to draw the powder into the lungs. As they are sensitive to water, it is important to not blow into the device and to keep it dry.
- Spacer devices: These devices are used with pMDIs and fit onto the end of the inhaler. When the inhaler is pressed, the spacer holds the medicine like a reservoir and a valve near the mouth keeps the medicine from escaping until the patient breathes in. When the patient breathes out, the valve closes. Spacer devices are often helpful for young children or infants or for those who don’t have the co-ordination to operate a pMDI.
- Nebulizers: Nebulizers are devices that turn liquid asthma medicine into a fine mist, like an aerosol spray, which is then inhaled through a mask or mouthpiece.
However, there are 3 guidelines that apply to all types of inhalers:
- Breathe out fully to empty your lungs
- Breathe in deeply as you operate the inhaler
- Hold your breath for 10 seconds.
Evaluating asthma control
The nature and intensity of background treatment is determined by the level of asthma control.
Different tools exist to evaluate its control:
- the GINA criteria which define 3 levels of asthma control:
- Controlled asthma if all items are validated (no daytime symptoms or less than 2 occurrences per week, no nocturnal symptoms, no need for reliever/rescue treatment and a normal FEV1/PEF ratio;
- Partly controlled asthma if at least 1 measure is present in a week (more than 2 occurrences of daytime symptoms, presence of nocturnal symptoms, use of more than 2 reliever/rescue treatments per week and FEV1/PEF < 80%);
- Uncontrolled asthma when 3 or more features of partly controlled asthma are present in any week.
- The Asthma Control Test: if the score is < 20 then the asthma is considered to be uncontrolled;
- The peak expiratory flow (PEF) value: corresponds to the maximum speed of an asthma patient's breath during forced expiration;
- The number of exacerbations is also a measure of whether the asthma is controlled.
The reasons for uncontrolled asthma can be varied:
- Inadequate or insufficient background treatment
- Poor patient compliance (e.g. due to the development of side effects)
- Incorrect use of inhalation devices
- Environmental exposures to triggers
- A related ENT infection
- Being overweight or obese
PEF measurement should be carried out regularly and it is advisable to keep your vaccination schedule up to date.
Asthma during pregnancy
The majority of asthma control treatments are safe in pregnancy. Inhaled corticosteroids (ICS) and inhaled long-acting Beta-2- agonists (LABAs) have a high benefit/risk ratio in pregnancy and should be used without restriction according to GINA guidelines.
Uncontrolled asthma, on the other hand, may be associated with an increased risk of:
- Pre-eclampsia (high blood pressure and protein in the urine leading to serious complications), placenta previa (abnormal location of the placenta which may be responsible for severe bleeding), hemorrhage (bleeding);
- Caesarean section;
- Gestational diabetes;
- Low birth weight or premature birth.
Nevertheless, it is quite possible to have a child if the mother's asthma is well treated. Planning the pregnancy with one's doctor, not interrupting background treatment, monitoring symptoms of worsening asthma (reduced respiratory function) and protecting oneself from triggers or irritants (not smoking, for example), among other things, allow for a pregnancy without complications.
In children, asthma is most often caused by allergies: prick tests (skin sensitivity tests) are then carried out to identify the different types of allergies involved.
The particular objectives for asthmatic children are to maintain schooling and extracurricular activities as normal.
The treatment is the same as for adults, but the inhalation techniques are different, with the use of a spacer with mask or mouthpiece.
Classification of asthma is different for children under 36 months (depending on severity, triggers, the existence of atopy or genetic predisposition for allergies, or progression of the asthma).
Asthma and physical activity
Physical activity is recommended for asthmatics because it increases lung capacity (by strengthening respiratory muscles such as the diaphragm), ensures better asthma control and improves exercise tolerance, in addition to having a beneficial effect on morale, reducing cardiovascular risks and improving resistance to stress.
However, before starting any physical activity, it is recommended that the patient make an appointment with their doctor to check that the asthma is well controlled and to choose a suitable activity.
There is no specific sport recommended for asthmatics. It can be beneficial to engage in:
- Brisk walking, hiking, cycling or rollerblading, which improve lung capacity;
- Swimming or water aerobics;
- Yoga or tai chi, which help to control breathing;
- Team sports such as volleyball, football, etc.;
- But also tennis, dance, gymnastics, climbing, rowing, etc.
The only sports that are not recommended for people with asthma are:
- Scuba diving, because the compressed air in the tank is cold and completely dry, which can trigger an attack in someone who has asthma.
It is nevertheless possible to practice this sport in case of non-severe and well-controlled asthma following a medical diving evaluation and/or other testing;
- Skydiving and other sports that expose you to significant variations in atmospheric pressure.
30 minutes of moderate physical activity per day is recommended. And it is important to note that exercise can be part of daily life. Changes in habits also help us to keep moving and improve our breathing: taking the stairs instead of the lift or escalator, walking or cycling instead of taking transport or the car, etc.
In addition, it is important to be aware of the factors that contribute to exercise-induced asthma (which can occur during or after physical exertion):
- Prolonged, high-intensity exertion;
- Cold, dry air;
- Air pollution;
- Pollen, in the case of asthma caused by allergies
- Poorly controlled asthma with significant inflammation of the bronchial tubes, which makes them very reactive to triggers.
To prevent exercise-induced asthma, it is therefore important to:
- Do a progressive warm-up;
- Adapt the intensity of your exercise to your abilities and the control of your asthma
- Keep yourself hydrated during exercise;
- Do a progressive cool-down so as to not stop abruptly.
A doctor may also prescribe, if necessary, one or two puffs of asthma medication 10 to 15 minutes before exercise, to limit the risk of an asthma attack during exercise.
Traveling with asthma
A change of environment can trigger asthma symptoms. It is therefore important to take the necessary precautions before travelling: assess your asthma control, find out about the local conditions, adapt to the mode of transport and prepare your treatments properly.
Before travelling, it is advisable to make an appointment with your doctor to ensure that your asthma is well controlled. It is not recommended to leave a few days after a severe asthma attack, which indicates insufficient asthma control. It is better to delay departure so that the modified or reinforced treatment can take effect and the asthma can be stabilized.
It is important to avoid dry, cold or very hot climates, which are conducive to asthma attacks. Places at very high altitudes (above 2,500m or 8,000 feet) and highly polluted cities (such as Beijing, Mexico City, New Delhi, etc.) should be avoided. If you are allergic to pollen, it is also not advisable to go to the countryside during pollen peaks.
In addition, dusty or damp interiors should be avoided. It may be useful to bring your own bedding (dust mite mattress or pillow cover, synthetic pillow, etc.) to avoid allergies. Finally, it is wise to avoid places with animals if you are allergic (farms, riding schools, etc.).
Air travel is safe for people with well-controlled asthma. However, it is important to carry your asthma medication in the cabin. It is also advisable to close the adjustable air vents. Finally, inhaler containers should not be put in the hold as they may leak when depressurized.
When travelling by train, it is important to bring something warm to cover up with (scarf, jumper, etc.) because the temperature can be low with the air conditioning, in sharp contrast to the air outside. Seats near the windows should also be avoided as they are at the level of the ventilation grilles which stir up dust.
When travelling by car, do not overuse the air conditioning and if possible use an air conditioning system with an air filter. In highly polluted areas (suburbs, building sites, pesticide spraying, etc.), avoid opening the windows because of the dust and exhaust fumes. You should also make sure that the interior of the car is regularly dusted, avoid using air fresheners and ask others not to smoke in the car. Finally, do not leave inhaler treatments in direct sunlight as the contents could explode.
In addition, it is essential to take your various treatments with you: rapid-acting bronchodilators in case of an asthma attack (to be kept with you during the journey and when you travel), daily medications (with the packaging and instructions, and in sufficient quantity for the duration of your stay), your latest prescription from your doctor(to renew your usual treatment if necessary), corticosteroid tablets (prescribed by a doctor for severe attacks) and a peak flow meter (for patients with severe asthma). It is also possible to take an adrenaline auto-injector (epinephrine) with you for people who are likely to have major and dangerous allergic reactions (swelling and/or drop in blood pressure).
Finally, contact details for various doctors, emergency centers and local repatriation services may be useful.
In conclusion, asthma is a chronic respiratory illness that affects more and more people worldwide. If well controlled, asthma has little impact on daily life and patients can live a virtually normal life. However, care must be taken to ensure that treatment is taken correctly, as poorly controlled asthma can lead to severe attacks, which in turn can cause serious complications.
Asthma Facts and Figures, Asthma and Allergy Foundation of America
Asthma Facts, American College of Allergy, Asthma & Immunology
Asthma Diagnosis, AAFA
Lung Function Tests, American Lung Association
Asthma inhalers, Patient
Pocket Guide for Asthma Management and Prevention 2020, Global Initiative for Asthma
How to Treat and Asthma Attack, American Academy of Family Physicians
Managing Asthma, American Lung Association
Asthma Control Test, GSK
Asthma and Pregnancy, American Lung Association
Being Active with Asthma, American Lung Association
Traveling with Asthma and Allergies, AAFA
Published Mar 31, 2021