Bronchial Asthma
Dr.omar Y. Ali C.A.B.PDefinition of Asthma
Asthma is a chronic inflammatory condition of the lung airways resulting in episodic airflow obstruction.Etiology:
environmental exposures and inherent biologic and genetic susceptibilities. In the susceptible host, immune responses to common airway exposures (e.g.,respiratory viruses, allergens, tobacco smoke) can stimulate prolonged, pathogenic inflammation and aberrant repair of injured airways tissues.Epidemiology:
Asthma is a common chronic disease, causing considerable morbidity. 15% of boys Vs 13% of Girls have asthma. Childhood asthma is more prevalent in modern metropolitan locales and more affluent nations, and is strongly linked with other allergic conditions. In contrast, children living in rural areas and farming communities with domestic animals are less likely to experience asthma and allergy.Early Childhood Risk Factors for Persistent Asthma
Parental asthma Allergy:( Atopic dermatitis ,Allergic rhinitis, Food allergy). Severe lower respiratory tract infection( Pneumonia, Bronchiolitis requiring hospitalization). Male gender Low birthweight Environmental tobacco smoke exposure Reduced lung function at birth Formula feedingEarly childhood risk factors for persistent asthma
Major : parental asthma Eczema inhalant allergen sensitization Minor : allergic rhinitis.wheezing apart from colds. ≥4% peripheral blood eosinophils.food allergen sensitization
Pathogenesis:
Airway obstruction is the result of: Bronchial muscle constriction. Edema due to increase capillary permeability and fluid leak. cellular inflammatory infiltrate and exudates consists of eosinophils, mast cells and other inflammatory cell types, can fill and obstruct the airways. mucous gland hypertrophy, and mucus hyper secretion.Types of Childhood Asthma
recurrent wheezing in early childhood, primarily triggered by common respiratory viral infections, usually resolves during the preschool/early school years. chronic asthma in early school children associated with allergy that persists into later childhood and often adulthood.CLINICAL MANIFESTATIONS
Intermittent dry coughing expiratory wheezing shortness of breath chest tightness Nocturnal worsening of symptomes Exersize or play induced symptomes symptomatic improvement with bronchodilatorsLack of improvement with bronchodilator and corticosteroid therapy is inconsistent with underlying asthma.quick resolution (within 10 min) or improvement in symptoms and signs of asthma with administration of a short-acting inhaled β-agonist (SABA; e.g., albuterol) is supportive of the diagnosis of asthma.
Common asthma triggers
Common viral infections of the respiratory tractINDOOR ALLERGENS• Animal dander• Dust mites• Cockroaches• MoldsSEASONAL AEROALLERGENS• Pollens Environmental tobacco smokeSTRONG ODORS OR FUMES• Perfumes, hairsprays• Cleaning agentsCold dry airExerciseCrying, laughter, hyperventilationCOMORBID CONDITIONS• Rhinitis• Sinusitis• Gastroesophageal refluxDRUGS• Aspirin and other nonsteroidal antiinflammatory drugs• β-Blocking agentsIn severe exacerbations,there is inspiratory and expiratory wheezing, prolongation of expiration, poor air entry, suprasternal and intercostal retractions, nasal flaring, and accessory respiratory muscle use. In extremis, airflow may be so limited that wheezing cannot be heard(silent chest)
On Examination:
Expiratory wheezing and a prolonged exhalation phase can usually be appreciated by auscultation. Decreased breath sounds in some of the lung fields, commonly the right lower posterior lung field, are consistent with regional hypoventilation. Rhonchi and crackles (or rales ) can sometimes be heard, resulting from excess mucus production and inflammatory exudate in the airways.
Diagnosis
Pulmonary function test:Spirometry usualy done in children ˃ 5 yearsIt involve measurements of FEV1, FVC, & FEV1/FVC ratio And comparing to reference values of same age and sex.FEV1 and FVC normally ˃ 80% of reference value .FEV1/FVC ratio should be ˃ 0.8Low FEV1 and FEV1/FVC ratio ˂ 0.8 indicate reduction in airflow (obstructive airway disease)Improvement of FEV1 ˃ 12% with inhaled bronchodilators (albuterol) or worsening FEV1 ˃ 15% after exersize is consistant with asthma
Peak expiratory flow (PEF) monitoring devices provide simple and inexpensive home-use tools to measure airflow. PEF monitoring should be done at morning and evening (best of 3 attempts) for several weeks to determine personal best and normal AM PM variation. Diurnal variation in PEF >20% is consistent with asthma
Exhaled Nitric Oxide (FeNO)
noninvasive measure of allergic airways inflammation. Nitric oxide (NO) is a marker of allergic/eosinophilic inflammation that is easily measured in exhaled breath. value of >20 ppb supports the clinical diagnosis of asthma in children.2. Chest radiograph: CXR often is normal in asthma apart from hyperinflation and peri_ bronchial thickening. It is not done routinely.
allergy (skin prick)testing to assess sensitization to inhalant allergens 88% of asthmatic patients had inhalant allergen sensitization.
Treatment
Optimal goal: well controlled asthma Reduce impairement: Prevent chronic symptomes Prevent sleep disturbance Infrequent SABA requirement Maintain near normal lung function Maintain normal activity 2. Reduce risk: Prevent exacerbations Reduce exacerbation severity /duration Minimal medications adverse effects
Treatment
1-Regular Assessment and Monitoring: assessing asthma severity directs the initial level of therapy. The 2 general categories are intermittent asthma and persistent asthma( mild, moderate, and severe) asthma control refers to the degree to which symptoms & functional impairments are minimized(well, not well, or very poorly controlled),Children with well-controlled asthma have daytime symptoms ≤2 days/wk and need a rescue bronchodilator ≤2 days/wk; an FEV1 of >80% of predicted (and FEV1 /FVC ratio >80% for children 5-11 yr); no interference with normal activity; and <2 exacerbations in the past year.
2- Patient Education:Explain basic facts about asthma:• normal vs asthmatic airways • Long-term-control and quick-relief medications• potential adverse effects of asthma pharmacotherapyTeach, demonstrate, and have patient show proper technique for:• Inhaled medication use (spacer use with metered-dose inhaler)• Peak flow measuresInvestigate and manage factors that contribute to asthma severity:• Environmental exposures• Comorbid conditions
Provide an asthma management plan (regular asthma medications, how to manage worsening, signs of exacerbations, when to contact doctor)Encourage adherence to treatment.Regular follow-up visits:• Twice yearly (more often if asthma not well controlled)• Monitor lung function at least annually
3- Control of Factors Contributing to Asthma Severity: Eliminating and Reducing Problematic Environmental Exposures: Control of dust mites:
Use dehumidifier Encase mattress and pillows in dust proof covers Wash all bedding and blankets in hot water at least once weekly Replace wool or feathered bedding with synthetic materials Use damp mop instead of dry cloth to remove dust mites Use vaccum cleaner
Other important measures
Avoid smoking inside home.Annual influenza vaccineAvoid strong perfumes.Do not use kerosine heaters or wooden stoves.Replace stuffed or fabric toys with plastic ones or wash them in hot water weekly or freeze overnight.Keep windows closed to avoid pollens.Don’t keep pets that have fur or feathers inside home.Use cocroaches exterminators.Aspirin and related drugs should be avoided.B. Treating comorbid conditions: GER(Occult GER should be suspected in individuals with difficult-to-control asthma, especially patients who have prominent symptoms while eating or sleeping(in a horizontal position)) Rhinitis sinusitis
4- Asthma Pharmacotherapy:The goals of therapy are to achieve a well-controlled state by reducing the chronic and troublesome symptoms, allowing infrequent need of quick-reliever medications, maintaining “normal” lung function, maintaining normal activity levels including physical activity and school attendance
Two groups of medications are used to treat asthmatic child: Quick Relievers Long term controllers
Quick Relievers(rescue medications)
are used in the management of acute asthma symptoms. They include: (SABAs, inhaled anticholinergics, and short-course systemic corticosteroids)SABAs (albuterol, levalbuterol, terbutaline) duration of action 4-6 hr bronchodilation by inducing airway smooth muscle relaxation. use of 1 MDI/m indicate inadequate asthma control. Overuse of β-agonists is associated with an increased risk of death episodes from asthma.
2) Anticholinergic Agents: Inhaled ipratropium used in combination with albuterol, improve lung function and reduce the rate of hospitalization in children who present with acute asthma. it is approved by the FDA for use in children >12 yr of age.
Long-Term Controller Medications
All levels of persistent asthma should be treated with daily medications to improve long-term control. include ICSs, LABAs, leukotriene modifiers, NSAI agents, and sustained-release theophylline. Corticosteroids are the most potent and most effective medications used to treat both the acute (administered systemically) and chronic (administered by inhalation) manifestations of asthma.Inhaled Corticosteroids: first-line treatment for persistent asthma. available in metered-dose inhalers (MDIs),in dry powder inhalers (DPIs), or in suspension for nebulization. Fluticasone propionate, mometasone furoate, ciclesonide, and budesonide. significant adverse effects that occur with long-term systemic corticosteroid therapy have not been seen or rarely reported in children receiving ICSs in recommended doses.
High doses (≥1,000 μg/day in children) and frequent administration (4 times/day) are more likely to have local and systemic adverse effects.Most common local adverse effect are oral candidiasis (thrush) and dysphonia (hoarse voice).these side effects can be reduced by using spacers and by mouth rinsing.
Children treated with long-term ICS therapy are likely to be about 1 cm shorter than expected as an adult, which is of little clinical significance.
2. Systemic Corticosteroids:Oral corticosteroids are used primarily to treat asthma exacerbations and, rarely, in patients with severe disease who remain symptomatic despite optimal use of other drugs.In these severely asthmatic patients, every attempt should be made to exclude any comorbid conditions and to keep the oral corticosteroid dose at ≤20 mg every other day.
Children who require routine or frequent short courses of OCSs, especially with concurrent high-dose ICSs should be screened for adverse effects as osteoporosis, hypertension, wt gain, cataract, growth suppression, and adrenal insuffeciency.
3. Long-Acting Inhaled β-Agonists:LABAs (salmeterol, formoterol) are considered to be daily controller medications.Used in combination with ICS in persistant asthma.(not as monothreapy)prolonged duration of action, at least 12 hr.LABAs are well suited for patients with nocturnal asthma and for those who require frequent use of SABA inhalations during the day to prevent exercise-induced bronchospasm (EIB), but only in combination with ICSs.
combination ICS/LABA therapy e.g fluticasone/salmeterol is superior to add-on therapy with either an LTRA or theophylline or doubling the ICS dose once a patient is well controlled on combination ICS/LABA therapy, the LABA component should be discontinued while continuing the ICS.
4. Leukotriene-Modifying Agents:LTRAs(montelukast and zafirlukast ) are recommended as alternative treatment for mild persistent asthma and as add-on medication with ICS for moderate persistent asthma.Montelukast approved ˃ 1 year once dailyZafirlukast approved ˃ 5 years twice daily
5. NSAI Agents: Cromolyn and nedocromil are considered (NSAIDs), they have little efficacy as a long-term controller for asthma. They are mainly used as alternative or add to SABA to prevent exersize induced bronchospasm. They are no longer recommended.
6.Theophylline: It has both bronchodilator and antiinflammatory properties. It was considered as an add-on agent to ICS in school-age children at Treatment Step 3 and beyond, it is rarely used in children today because of its potential toxicity. Theophylline has a narrow therapeutic window; therefore, serum theophylline levels need to be routinely monitored, especially if the patient has a viral illness or is started on a medication known to delay theophylline clearance, such as a macrolide antibiotic, cimetidine.
7.Long-Acting Inhaled Anticholinergics
Used in combination with ICS. Duration of action 24 hr. Approved for patients above 12 years old. E.g is Tiotropium
Omalizumab (Anti-IgE Antibody)
It is monoclonal antibody that binds IgE and prevents its binding to the IgE receptor, thereby blocking IgE mediated allergic responses and inflammation. It is FDA approved for patients >6 yr old with severe allergic asthma who continue to have inadequate control despite treatment with high-dose ICS and/or OCS. Omalizumab is given every 2-4 wk subcutaneouslyAllergen Immunotherapy
Allergen immunotherapy (AIT ) involves administering gradually increasing doses of allergens to a person with allergic disease to reduce or eliminate the patient's allergic response to those allergens. Conventional AIT is given subcutaneouslyManagement of intermittent asthma is simply the use of a SABA as needed for symptoms and for pretreatment in those with exercise-induced bronchospasm (Step 1 therapy)The preferred treatment for patients with persistent asthma is daily ICS therapy, as monotherapy or in combination with adjunctive therapy(long-acting inhaled β2-agonists (LABAs),leukotriene modifying agent , and theophylline(steps 2, 3, 4 )
Children with severe persistent asthma (treatment Steps 5 and 6) should receive high-dose ICS and LABA. With or without oral corticosteroids as controller therapy .
Step-Up, Step-Down” Approach Step down If a child has had well-controlled asthma for at least 3 mo, by decreasing the dose or number of the child’s controller medication(s) to establish the minimum required medications to maintain well-controlled asthma.Step up therapy if a child has not-well-controlled asthma (it is important to check inhaler technique and adherence,environmental control measures, and identify and treat comorbid conditions).
Use of SABA >2 days/wk for symptom relief (not prevention of exercise-induced bronchospasm) generally indicates inadequate control and the need to step up treatment.
Asthma Exacerbations
acute or subacute episodes of progressively worsening symptoms and airflow obstruction. Airflow obstruction during exacerbations can become extensive, resulting in life-threatening respiratory insufficiency. Often, asthma exacerbations worsen during sleep (between midnight and 8 a.m.) where airways inflammation and hyper responsiveness at the peak.Complications that can occur during severe exacerbations include atelectasis and air leaks in the chest (pneumomediastinum,pneumothorax). A severe exacerbation that does not improve with standard therapy is termed (status asthmaticus)
Manifestations of severe Asthmatic exacerbation:
Dyspnea retractions accessory muscle use tachypnea cyanosis Inability to speak Inability to lie down Marked pulsus paradoxicus mental status changes silent chest with poor air exchange (PEF or FEV1 value <50% of predicted values).Emergency Room treatment:
Continuous oxygen therapy. inhaled β-agonist every 20 min for 1 hr with or without inhaled ipratropium systemic corticosteroids either oral or intravenously.IM epinephrine may be administered in severe cases.Oxygen should be administered and continued for at least 20 min after SABA administration to compensate for possible ventilation/perfusion abnormalities caused by SABAsMonitoring of vital signs,hydration and oxygen saturationThe patient may be discharged home if there is sustained improvement in symptoms, normal physical findings, PEF >70% of predicted, an oxygen saturation >92% at room air for 4 hr. Discharge medications include inhaled β-agonist every 3-4 hr plus a 3-7 day course of an oral corticosteroid.Optimizing controller therapy before discharge.
moderate to severe exacerbations that do not adequately improve within 1-2 hr of intensive treatment, admission to the hospital, at least overnight. Other indications for hospital admission include high-risk features for asthma morbidity or death
Risk Factors for Asthma Morbidity and Mortality
Previous severe asthma exacerbation .Two or more hospitalizations for asthma in past year large diurnal variation in peak flowsUse of >2 canisters of short-acting β-agonists per monthPoor response to systemic corticosteroid therapyLow birthweightUrban environmentPovertyCrowdingHospital management:
Oxygen frequent or continuous administration of inhaled β agonist Inhaled ipratropium bromide is added every 6 hr if patients do not show a remarkable improvement.systemic corticosteroid oral or IVAdministration of fluids at or slightly below maintenance requirements.Avoid chest physiotherapy.
If no improvement with these initial measures, give:Parenteral epinephrine (im,sc,iv)β-agonists IV or SC (terbutaline)Methylxanthines IVmagnesium sulfate slow infusion IVsevere asthma exacerbation results in respiratory failure require intubation and mechanical ventilation