What is asthma?

Asthma is a lungs disease common among children, and it can also affect adults. In fact, an asthmatic episode can be as mild as occasional wheeze or as severe as acute, life-threatening obstruction of the airways. This disease comes along atopy such as allergic rhinitis (hay fever) and atopic dermatitis (eczema). Several factors can trigger asthma, which is characterized by hyper-responsiveness of the airways. Without doubt, if untreated, asthma is highly lethal.

What causes airway obstruction during asthma?

Occlusion of airways is the result of an infiltration of inflammatory cells, mucus over-secretion leading to mucus plugs, and the contraction of smooth muscle in the lungs. These are reversible unless there’s deposition of collagen, thickening of basement membrane, desquamation of epithelium, hypertrophy and hyperplasia of smooth muscle.

Asthma classification:

Classification is different according to whether the disease is chronic or acute.

Chronic asthma:

Intermittent: where symptoms occurs 2 times maximum per week, and nightly flares occur 2 times maximum per month.
Mild persistent: is characterized by symptoms occurrence 2 times per week, but never 2 times per day. Besides, nightly flares has an impact on activity.
Moderate persistent: where symptoms takes place on daily bases, and nightly flares lasts several days.
Severe persistent: not only symptoms occur everyday and often, it can also affect sleep and activities.

Acute asthma:

Acute severe: where a severe unexpected attack doesn’t improve after medication.
Life-threatening asthma: where breathing is very hard, and wheezing stays at night and in the morning.
Near-fatal: it features respiratory arrest or arterial carbon dioxide tension.

Causes and triggers of asthma:

The etiology behind asthma is still unclear, but genetics factors and smoking play a major role in causing the disease. Airway inflammation is the hallmark of asthma, which occurs as a result of exposure to an environmental trigger:

• An individual's or family's history of atopy
• Tobacco smoking
• Inflammatory gases or particulates inhalation
• Viral infections in the respiratory tract such as colds, flu, chronic sinusitis, and covid-19
• Medication such as beta-blockers and aspirin
• Exposure to allergens such as pollen, perfumes, mold, insect stings, dust mites, etc...
• Humidity
• Obesity
• Exercising
• Gastroesophageal reflux disease (GERD)
• Strong emotions such as stress, anxiety, sadness, laughter, etc.…
• Exposure to household fumes such as those used in paints and cleaning chemicals such as bleach
• High amount consumption of foods preserved with sulfites, including dried fruits and vegetables, wine, beer, etc.…

Asthma symptoms:

• Shortness of breath
• Coughing attacks that become intolerable during respiratory tract infection
• Wheezing sound while exhaling
• Trouble sleeping
• Chest feels tight
• Chest pain

Risk factors of asthma:

• A family history of the disease
• Atopy including hay fever and eczema
• Being obese
• Tobacco smoking or being exposed to the smoke
• Air pollution or fumes
• Exposure to chemicals

Diagnosis:

Pulse oximetry:

Using pulse oximetry, patients can determine how severe an asthma attack is or monitor any deterioration. This method measures the amount of oxygen in your blood (oxygen saturation). Indeed, it is a quick and painless test of how well oxygen is being delivered to the furthest parts of the body from the heart. To illustrate, a patient's physiological reserve and the lag time for pulse oximetry mean that a falling pO2 on pulse oximetry is a late finding, signaling a patient who is seriously ill or at risk of peri-arrest.

Peak flow:

Peak flow measurements should also be compared with nomograms and the person's normal baseline function in order to evaluate asthma. The measurements differ with each severity of acute asthma attacks, calculated as certain percentages of expected peak flow.

Laboratory testing:

Urea and electrolytes: after a repeated dose of salbutamol or a high dose, the patient should have urea and electrolytes check, since it leads to iatrogenic hypokalemia.

Eosinophil: in asthma, eosinophilic sputum is common, but eosinophil levels do not tend to correlate with asthma severity.

Serum IgE: some patients also have elevated levels of serum IgE.

Arterial blood gas: during an arterial blood gas, hypoxemia and respiratory acidosis can be identified.

Periostin: periostin is believed to be a marker for asthma, but its clinical significance is not yet understood.

ECG: the ECG can reveal tachycardia due to asthma, albuterol (salbutamol), or theophylline.

Imaging:

Chest x-ray: in patients at risk for foreign objects or infection, a chest x-ray is important.

CT scan: whenever recurrent symptoms do not respond to therapy; a chest CT scan is done on the patient.

Spirometry:

Treatment requires the asthma severity level determination, this is done by spirometry. As a matter of fact, the ratio of FEV1 to FVC is low in patients with airway obstruction, which is reversible with treatment. Short-acting beta 2 agonists inhalation reverses the airway obstruction in the patient, and then the spirometry test is repeated.

Bronchial challenge test:

If airway hyperreactivity is suspected in a patient, a methacholine/histamine challenge may be required. Also, only trained healthcare professionals should perform this test.

Exercise spirometry:

It may be possible to detect exercise-induced bronchoconstriction by using exercise spirometry.

Prevention:

• Avoiding allergens is very important to avoid attacks
• Stay away from tobacco
• Avoid obesity by controlling weight
• Follow your doctor’s plan to help with your symptoms
• Take your prescribed medication right on time and with the same dose advised
• Don’t overuse salbutamol “Albuterol” because it leads to iatrogenic hypokalemia
• Take vaccines against respiratory virus-induced diseases such as flu, covid-19 and pneumonia
• Avoid activities that cause attacks

Asthma treatment:

In treatment, symptom burden and exacerbation risk are minimized while improving asthma control.

Monoclonal antibody therapy:

Asthma patients with a positive skin test may benefit from monoclonal antibody therapy, which lowers their levels of IgE. Thus, this in turn lowers their production of histamine. The cost of the injections, however, is extremely high.

Bronchial thermoplasty:

Thermoplasty of the bronchial wall is a relatively new treatment that is supposed to reduce the stenosis of the airways by utilizing thermal energy. Moreover, studies indicate that it may reduce the frequency of hospitalizations and days off school.

Medical measures:

In normal situations: a bronchodilator such as salbutamol or ipratropium bromide, along with anti-inflammatory agents such as inhaled steroids (betamethasone usually) are first line medical treatments.
During life-threatening asthma: steroids, inhalation of high flow oxygen, nebulizer with short-acting beta 2 agonists, intravenous magnesium sulfate, and antagonists of short-acting muscarinic can save the patient.
In near-fatal asthma: intubation and mechanical ventilation are vital.

Surgery:

Indeed, no surgery can help with asthma treatment and management.

Other methods:

• Quit smoking
• Weight control
• Avoid exposure to dust mites, animals, humid closed rooms, etc....
• Self-care

Complications:

• Interference with sleep and leading to insomnia
• Reduction of quality of life including work, school and regular activities
• Air pathways narrowing
• Severe asthma attacks
• Medication side effects

Asthma hospitalization:

If no positive result occurs even after 3 doses of inhaled bronchodilator, hospitalization is necessary if the patient has:

• Severe airflow obstruction
• Little to no response to medication
• Long asthma duration
• Mental illness
• No or little support at home

References:

-Hashmi MF, Tariq M, Cataletto ME. Asthma. [Updated 2022 Feb 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-.

-D'Amato G, Vitale C, Lanza M, et al. Near fatal asthma: treatment and prevention. Eur Ann Allergy Clin Immunol. 2016;48(4):116-122.

-Webmd “study sees link between insomnia, Asthma”