What’s the Airway Inflammation and AHR (Airway Hyper Reactivity)
- Airway Inflammation and AHR
AHR is closely related to airway inflammation, although it’s not exclusively dependent on it. Inflammation in the airways leads to swelling, increased mucus production, and hypersensitivity of the airway smooth muscles.
Whats Asthma
Asthma is a chronic respiratory condition characterized by airway hyper-reactivity (AHR), which is a key component of the disease. Airway hyper-reactivity refers to the tendency of the airways to constrict excessively in response to various triggers, such as allergens, irritants, or exercise, which usually do not affect individuals without asthma
Whats atopy? And how’s it linked to asthma
Atopy and Allergic Reactions
Atopy is the genetic tendency to develop allergic diseases, and it is strongly linked to asthma. Individuals with atopy are prone to producing Immunoglobulin E (IgE) antibodies in response to common allergens.
How does asthma occur due to allergins
When an allergen is inhaled into the airway, it triggers an early-phase and late-phase bronchoconstrictor response. The early-phase response happens almost immediately and involves the release of mediators like histamine, leading to quick bronchoconstriction (narrowing of the airways). The late-phase response occurs hours later and involves the recruitment of additional inflammatory cells to the airway, causing sustained bronchoconstriction and inflammation. These allergic mechanisms are also involved in certain cases of occupational asthma, where exposure to allergens at the workplace leads to asthma symptoms.
Aspirin-Sensitive Asthma
In some individuals with asthma, the ingestion of aspirin or other non-steroidal anti-inflammatory drugs (NSAIDs) can exacerbate their condition. This is due to the inhibition of cyclo-oxygenase (COX) enzymes by these drugs, which shifts the metabolism of arachidonic acid towards the lipoxygenase pathway. This pathway leads to the production of cysteinyl leukotrienes, which are potent bronchoconstrictors that can worsen asthma symptoms.
What are the typical symptoms of asthma
- Recurrent Wheezing: A high-pitched whistling sound during breathing, particularly during exhalation, is common in asthma patients.
- Chest Tightness: Patients often describe a sensation of tightness or pressure in the chest.
- Breathlessness: Difficulty breathing, which may vary in intensity from mild to severe.
- Cough: This can be persistent and may worsen at night or early in the morning. In some cases, cough may be the primary symptom, leading to what’s termed “cough-variant asthma.”
List common triggers of asthma
- Exercise: Particularly in cold weather, physical activity can provoke asthma symptoms.
- Airborne Allergens or Pollutants: These include dust, pollen, smoke, and chemicals.
- Viral Infections: Upper respiratory tract infections, such as the common cold, can exacerbate asthma.
Pets
Contraceptive Drugs
Aspirin
Nsaids
Beta Blockers even in some eye drops
How do you diagnose asthma
Asthma diagnosis begins with a thorough clinical history, focusing on the presence of characteristic symptoms such as recurrent episodes of wheezing, breathlessness, chest tightness, and cough. These symptoms, especially if they vary in intensity and frequency, suggest asthma. In patients with a compatible history, lung function tests and other supportive evidence are then used to confirm the diagnosis.
- Spirometry:
- Spirometry is the gold standard for diagnosing asthma. It measures the Forced Expiratory Volume in one second (FEV1) and the Forced Vital Capacity (FVC). These measurements help identify airflow obstruction, determine its severity, and establish a baseline for assessing the response to bronchodilators.
- Bronchodilator Reversibility:
- A significant increase in FEV1 after administering a bronchodilator indicates asthma. Specifically, an increase of 12% or more and at least 200 mL in FEV1 is considered diagnostic. Greater diagnostic confidence is achieved with an increase of over 15% and 400 mL.
- Peak Expiratory Flow (PEF):
- When spirometry is unavailable, PEF can be used. Patients measure their PEF twice daily (morning and evening) to detect diurnal variations. A diurnal variation of more than 20% suggests asthma, with the lowest PEF typically recorded in the morning. This variability also correlates with the severity of the disease.
- Exercise-Induced Asthma:
- In cases where symptoms are triggered by exercise, a decrease in FEV1 of 15% or more after six minutes of exercise supports the diagnosis of asthma.
- Airway Hyperreactivity (AHR) Tests:
- For patients with normal lung function but symptoms suggestive of asthma, tests to demonstrate AHR, such as methacholine or histamine challenge tests, may be conducted. AHR has a high negative predictive value; however, positive results can also be seen in other respiratory conditions like COPD, bronchiectasis, and cystic fibrosis.
- Atopy and Inflammatory Markers:
- Atopy, a predisposition to developing allergic reactions, is often associated with asthma. It can be identified through skin-prick tests or by measuring total and allergen-specific IgE levels.
- Fractional Exhaled Nitric Oxide (FENO):
- FENO levels of 40 parts per billion or more in a glucocorticoid-naïve adult are indicative of eosinophilic airway inflammation, supporting an asthma diagnosis.
- Peripheral Blood Eosinophilia:
- An elevated eosinophil count in the blood can also support the diagnosis of asthma, particularly in the presence of other suggestive findings.
- Chest X-Ray:
- While often normal in asthma, a chest X-ray may reveal complications such as lobar collapse due to mucus plugging a large bronchus.
- High-Resolution CT Scan (HRCT):
- HRCT is useful for detecting bronchiectasis, a possible complication in severe or long-standing asthma,
The diagnosis of asthma involves a combination of clinical evaluation, lung function tests, and supportive investigations. Spirometry with bronchodilator reversibility testing is key in identifying variable airflow obstruction. PEF monitoring is helpful in detecting diurnal variations, while additional tests like AHR, atopy assessment, and imaging studies can further support the diagnosis, particularly in complex or unclear cases.
Asthma management is typically guided by a stepwise approach, where treatment is escalated or de-escalated based on the severity and control of the patient’s symptoms. The goal is to achieve and maintain control of the disease, minimizing symptoms and preventing exacerbations.
In this initial step, treatment is aimed at patients with mild intermittent asthma. These are individuals who experience symptoms less than once a week over three months and have fewer than two nocturnal episodes per month. For these patients, the occasional use of inhaled short-acting β2-agonists (SABAs) like salbutamol or terbutaline is usually sufficient.
For patients who require more than occasional relief from symptoms, regular preventer therapy is introduced. This usually involves the daily use of inhaled corticosteroids (ICS) to control underlying inflammation, which is a key component of asthma.
Indications for Starting Regular Preventer Therapy:
- Recent Exacerbation: Any patient who has had an asthma exacerbation in the last two years should start on regular preventer therapy.
- Frequent Use of SABAs: Patients who use inhaled β2-agonists three times a week or more should be considered for preventer therapy.
- Frequent Symptoms: If the patient reports asthma symptoms three times a week or more, regular ICS should be introduced.
- Nocturnal Symptoms: Waking up at least once a week due to asthma symptoms also indicates the need for regular preventer therapy.
Medication Choices and Dosing:
- Inhaled Corticosteroids (ICS): The first-line choice for regular preventer therapy includes ICS such as beclometasone, budesonide, fluticasone, mometasone, or ciclesonide.
NOTE IT’S ICS + SABA
- Adherence: Ensure the patient is taking their medication as prescribed.
- Inhaler Technique: Verify that the patient is using their inhaler correctly, as improper technique can significantly reduce the effectiveness of the medication.
- Exposure to Aggravating Factors: Identify and minimize any ongoing exposure to triggers, such as allergens, pollutants, or irritants.
- ICS Dose Increase: Some patients may benefit from a higher dose of inhaled glucocorticoids, but beyond a certain point (800 µg/day of BDP or equivalent), increasing the dose further provides diminishing returns and may lead to more side effects.
- LABA Addition: Adding a long-acting β2-agonist (LABA), such as formoterol or salmeterol, to the ICS regimen generally provides better asthma control than simply increasing the ICS dose. This combination is effective because LABAs provide prolonged bronchodilation, complementing the anti-inflammatory effects of ICS.
- Convenience and Adherence: Fixed-combination inhalers that include both a glucocorticoid and a LABA improve adherence because they simplify the treatment regimen.
- Safety: These combinations also prevent the use of LABAs as monotherapy, which has been associated with an increased risk of severe asthma attacks or even asthma-related death.
For patients who still exhibit poor control despite being on a moderate dose of inhaled glucocorticoids and add-on therapy, the treatment plan may be escalated further.
- High-Dose ICS: The dose of inhaled glucocorticoids can be increased up to 2000 µg/day of BDP or budesonide (BUD) or an equivalent dose of another ICS. This is a high dose and is usually reserved for patients with severe, persistent asthma.
- Nasal Glucocorticoids: These may be beneficial for patients who also have significant upper airway symptoms, such as those associated with allergic rhinitis.
Exacerbations of Asthma
Asthma exacerbations represent a significant worsening of the disease’s symptoms, including increased shortness of breath, wheezing, and coughing. These exacerbations are often accompanied by a deterioration in lung function and heightened airway inflammation. Understanding the triggers, progression, and management of these exacerbations is crucial for preventing severe outcomes and maintaining control over the condition
The exacerbation of asthma is offen caused by? How can mild to moderate exacerbation be handled?
Especially with someone with Brittle Asthma: A more unpredictable form, where exacerbations can occur suddenly with little or no warning.
Pollens
Air pollution ( smoke, dust, chm pollutants)
Viral infections like rhinovirus
- Use of ‘Rescue’ Glucocorticoids:
Short Courses of Oral Glucocorticoids: To regain control during an exacerbation, short courses of oral glucocorticoids, such as prednisolone (30–60 mg daily), are often required. This treatment helps to quickly reduce inflammation and improve lung function.
**(Doubling the dose of inhaled glucocorticoids (ICS) is generally not effective in preventing an impending exacerbation.) **
- Worsening Symptoms and PEF: If symptoms and peak expiratory flow (PEF) progressively worsen day by day, particularly if PEF falls below 60% of the patient’s personal best, rescue glucocorticoids are indicated.
- Sleep Disturbance: The onset or worsening of sleep disturbances due to asthma is a key indicator that an exacerbation is occurring and may warrant rescue glucocorticoids.
- Morning Symptoms: Persistence of morning symptoms, lasting until midday, indicates worsening asthma control, necessitating rescue treatment.
- Reduced Response to Inhaled Bronchodilators: A progressively diminishing response to inhaled bronchodilators, such as short-acting β2-agonists (e.g., salbutamol), is a sign of an exacerbation that requires more intensive treatment.
- Severe Symptoms: If symptoms are severe enough to require nebulized or injected bronchodilators, this indicates a significant exacerbation, and rescue glucocorticoids should be administered.
Management of acutely severe asthma
Managing acute severe asthma is a medical emergency that requires prompt and effective intervention to prevent life-threatening complications. This involves both immediate assessment and aggressive treatment strategies.
- Measurement of Peak Expiratory Flow (PEF):
- PEF should be measured as a key indicator of the severity of airway obstruction. It is expressed as a percentage of the predicted normal value or the patient’s best previous value when they were on optimal treatment.
- If the patient is too ill to perform PEF, this indicates a severe condition requiring urgent attention.
- Arterial Blood Gas (ABG) Analysis:
- Essential to assess the level of PaCO2 (partial pressure of carbon dioxide in arterial blood).
- A normal or elevated PaCO2 level is particularly concerning as it suggests that the patient’s respiratory muscles may be tiring, potentially leading to respiratory failure.
- Chest X-ray:
- Not immediately necessary unless there is a clinical suspicion of complications like pneumothorax (air in the pleural space that can compress the lung) or other causes of acute respiratory distress.
- High Concentrations of Oxygen:
- Administer high concentrations of oxygen to maintain oxygen saturation (SaO2) above 92%.
- Oxygen should be humidified if possible to prevent drying of the airways.
- Even if the PaCO2 is normal or elevated (indicating a potentially life-threatening attack), the concentration of oxygen should not be reduced. Instead, the elevated PaCO2 should serve as a warning that the situation is critical and requires aggressive management.
- If appropriate oxygenation is not achieved, it may indicate the need for assisted ventilation.
- Short-Acting β2-Agonists:
- These are the first-line bronchodilators and should be administered promptly.
- In a hospital setting, they are typically given via a nebulizer driven by oxygen for rapid and effective delivery.
- In primary care settings, multiple doses of salbutamol delivered via a metered-dose inhaler (MDI) with a spacer device can provide equivalent bronchodilation.
- Ipratropium Bromide:
- An anticholinergic bronchodilator that can be added to salbutamol, especially in severe or life-threatening asthma attacks, for additional bronchodilation.
- Reducing Inflammation:
- Glucocorticoids are crucial in managing the inflammation associated with acute severe asthma. They help to reduce the inflammatory response and speed up the resolution of the exacerbation.
- Oral Prednisolone: Often used if the patient can swallow and is not vomiting.
- Intravenous Hydrocortisone: Used if the patient is vomiting, unable to swallow, or if a more rapid effect is needed.
- Fluid Replacement:
- Although there is no direct evidence for their use, intravenous fluids may be beneficial as many patients are dehydrated due to increased insensible water loss (water loss through the skin and respiratory tract).
- Potassium Supplementation:
- Repeated doses of salbutamol can cause a decrease in serum potassium levels, which may necessitate supplementation to prevent hypokalemia (low potassium levels in the blood).
- Additional Bronchodilation:
- Magnesium sulfate can provide additional bronchodilation in patients with severe asthma, particularly if the PEF is below 30% of the predicted value. It is considered when other treatments do not achieve sufficient control.
- Possible Benefit:
- Aminophylline, a methylxanthine bronchodilator, may benefit some patients. However, due to its potential cardiac side effects, it requires close cardiac monitoring during administration.
- PEF Monitoring:
- PEF should be recorded every 15–30 minutes initially and then every 4–6 hours to monitor the patient’s response to treatment and detect any deterioration.
- Pulse Oximetry:
- Continuous monitoring with pulse oximetry ensures that SaO2 remains above 92%. However, if the initial PaCO2 levels were normal or raised, or if the patient’s condition deteriorates, repeat arterial blood gas analysis is necessary to reassess PaO2 (partial pressure of oxygen) and PaCO2.
- Intubation and IPPV:
- Required if the patient fails to improve despite aggressive medical treatment, particularly if they exhibit signs of respiratory failure, such as worsening hypoxia (low blood oxygen levels), hypercapnia (elevated blood carbon dioxide levels), or exhaustion.
The management of acute severe asthma involves a structured approach beginning with the immediate assessment of severity through PEF measurement and arterial blood gas analysis. Treatment focuses on rapidly reversing bronchoconstriction with high-dose inhaled bronchodilators, maintaining adequate oxygenation, and reducing inflammation with systemic glucocorticoids. Continuous monitoring and reassessment are critical, with escalation to more intensive interventions, such as intravenous magnesium or aminophylline, and potential mechanical ventilation if initial treatments fail. This approach aims to stabilize the patient quickly and prevent progression to life-threatening respiratory failure.
SLIDES
WHAT’S Brittle Asthma and the types
.
- Description: A rare but severe form of asthma characterized by wide variations in peak expiratory flow (PEF).
- Type 1: Consistent, severe, and poorly controlled despite treatment.
- Type 2: Intermittent, sudden drops in lung function that can lead to life-threatening asthma attacks.
Classification of Asthma
Asthma can be classified based on the age of onset, response to treatments, severity of symptoms, and underlying causes. Here’s a breakdown of these classifications:
- Description: Asthma that begins in childhood and continues into adulthood. It often persists throughout life.
- Triggers: Many children with this type of asthma are allergic to inhaled antigens, which can include common allergens like dust mites, pollens, animal danders, and fungi.
- Characteristics: These patients frequently experience recurrent symptoms triggered by allergen exposure.
- Description: Asthma that develops in adults, typically without a clear allergic cause.
- Triggers: This type of asthma may be triggered by chemical exposures in the workplace (also referred to as occupational asthma). However, in some cases, no clear environmental triggers are identified.
- Characteristics: More common in middle-aged adults and can be harder to control compared to childhood-onset asthma.
- Description: Asthma that does not respond well to corticosteroid treatment. This can be challenging to manage as corticosteroids are the mainstay of asthma treatment.
- Characteristics: These patients require alternative therapies and may have a more complicated disease course.
- Description: A form of asthma where the main symptom is a chronic cough rather than the typical wheezing or shortness of breath.
- Characteristics: It is often misdiagnosed as another respiratory condition like chronic bronchitis or postnasal drip.
Asthma can also be classified based on the severity of symptoms:
- Acute Severe Asthma: Sudden onset of severe symptoms, requiring emergency treatment.
- Life-Threatening Asthma: Severe form where respiratory function deteriorates, requiring immediate intervention.
- Allergic Asthma: Triggered by allergens such as dust, pollen, or pet dander.
- Non-Allergic Asthma: Triggered by factors not related to allergens, such as infections or stress.
- Seasonal Asthma: Symptoms occur during certain times of the year, often associated with seasonal allergens like pollen.
- Occupational Asthma: Triggered by exposure to irritants or chemicals in the workplace.
- Exercise-Induced Asthma: Triggered by physical activity and characterized by shortness of breath during or after exercise.
Each type of asthma has its unique triggers, treatment strategies, and management approaches based on individual patient needs.
