Renmin Hospital, Wuhan University Ding Xuhong (丁续红) Asthma Renmin Hospital, Wuhan University Ding Xuhong (丁续红)

DEFINITION A clinical syndrome of unknown etiology characterized by three distinct components (1) Recurrent episodes of airway obstruction that resolve spontaneously or as a result of treatment (clinical manifestation)

(2)An exaggerated bronchoconstrictor response to stimuli that have little or no effect in nonasthmatic subjects, a phenomenon known as airway hyperresponsiveness (Pathophysiologically) (3) Inflammation of the airways as defined by a variety of criteria (Pathogenesis)

PATHOLOGY Constriction of airway smooth muscle Airway epithelium thickening Mucus plugging

Lung Hyperinflation in Asthma

Thick bronchi with Mucous plugs

Mucous plug in asthma

Asthma - Microscopically Patchy necrosis of epithelium Sub-mucosal glandular hyperplasia Hypertrophy of bronchial smooth muscle Eosinophils, mast cells, lymphocytes (Th2) infiltration

Asthma Microscopic Pathology Obstructed Inflammed Bronchi

PATHOGENESIS OF ASTHMA

Asthma Pathogenetic Types Extrinsic (Allergic/Immune) Atopic - IgE Occupational - IgG Allergic Bronchopulmonary Aspergillosis - IgE Intrinsic (Non-immune) Aspirin induced Infection induced

Risk Factors that Lead to Asthma Development Predisposing Factors Atopy Causal Factors Indoor Allergens Domestic mites Animal Allergens Cockroach Allergens Fungi Outdoor Allergens Pollens Occupational Sensitizers Contributing Factors Respiratory infections Small size at birth Diet Air pollution Outdoor pollutants Indoor pollutants Smoking Passive Smoking Active Smoking

Airway Hyperresponsiveness Genetic Inducers Allergens,Chemical sensitisers, Air pollutants, Virus infections INFLAMMATION Airflow Limitation SYMPTOMS Cough Wheeze Dyspnoea Triggers Allergens, Exercise, Cold Air, SO2 Particulates

DIAGNOSIS OF ASTHMA History and patterns of symptoms Physical examination Measurements of lung function

PATIENT HISTORY Has the patient had an attack or recurrent episodes of wheezing? Does the patient have a troublesome cough, worse particularly at night, or on awakening? Does the patient cough after physical activity (e.g playing)? Does the patient have breathing problems during a particular season (or change of season)?

Do the patient’s colds ‘go to the chest’ or take more than 10 days to resolve? Does the patient use any medication (e.g. bronchodilator) when symptoms occur? Is there a response? If the patient answers “YES” to any of the above questions, suspect asthma

Physical Examination Wheeze -Usually heard without a Remember - stethoscope Dyspnoea Rhonchi heard with a stethoscope Use of accessory muscles Remember - Absence of symptoms at the time of examination does not exclude the diagnosis of asthma

Blood Finding Blood eosinophilia, elevated serum level of sIgE Arterial blood gases: PaO2 between 55 and 70mmHg PaCO2 between 25 and 35mmHg

Radiographic finding In severe asthma, hyperinflation, pneumomediastinum or pneumothorax may be detected

ECG Sinus tachycardia (usually), right axis deviation, right bundle branch block, “P pulmonale”, ST-T wave abnormalities (severe asthma)

Diagnostic testing Diagnosis of asthma can be confirmed by demonstrating the presence of reversible and variable airway obstruction using Peak Flow Meter

Bronchial challenge test: PC20<8mg/mL Reversibility test: FEV1 increase more than 12% after inhalation of salbutamol, the absolute value of increase >200ml Variability of PEF diurnally ≥20%

Differential diagnosis Chronic bronchitis Heart failure (“cardiac asthma”) Hypersensitivity pneumonia Lung cancer

Goals to Be Achieved in Asthma Control Achieve and maintain control of symptoms Prevent asthma episodes or attacks Minimal use of reliever medication No emergency visits to doctors or hospitals Maintain normal activity levels, including exercise Maintain pulmonary function as close to normal as possible Minimal (or no) adverse effects from medicine

Tool Kit for Achieving Management Goals Relievers Preventers Peak flow meter Patient education

What Are Relievers? (also known as rescue medication) Bronchodilator (beta2 agonist) Quick relief of symptoms (within 2-3 minutes) Used during acute attacks Action lasts 4-6 hrs Not for regular use

Relievers Short acting 2 agonists Salbutamol (万托林) Anti-cholinergics Ipratropium bromide（爱全乐） Xanthines Theophylline Adrenaline injections

What are Preventers? Anti-inflammatory Takes time to act (1-3 hours) Long-term effect (12-24 hours) Only for regular use (whether well or not well)

Prevent future attacks Long term control of asthma Prevent airway remodeling

Preventers Corticosteroids Anti-leukotrienes Prednisolone, Betamethasone Montelukast, Zafirlukast Beclomethasone, Budesonide Fluticasone Xanthines Theophylline SR Long acting 2 agonists Mast cell stabilisers Bambuterol, Salmeterol Sodium cromoglycate Formoterol COMBINATIONS Salmeterol/Fluticasone Formoterol/Budesonide

Patient Education in the Clinic Explain nature of the disease (i.e. inflammation) Explain action of prescribed drugs Stress need for regular, long-term therapy Allay fears and concerns Peak flow reading Treatment diary / booklet

Status Asthmatic FEV1 < 40%pred with treatment, PaCO2 increases, developing major complication such as pneumothorax Close monitoring Frequent treatments with inhaled β2-agonists, intravenous aminophylline, high-dose intravenous steroid Oxygen supplement Antibiotics – if infection exist If indicated, intubation of the trachea and mechanical ventilation

The Pregnant Asthmatic No departure from the ordinary management of asthma No unnecessary medication should be administered Systemic steroid should be used sparingly Tetracycline, atropine, terbutaline(博利康尼?), iodine-containing mucolytics should be avoided

Key Messages Asthma is a common disorder It produces recurrent attacks of cough with or without wheeze Between attacks people with asthma lead normal lives as anyone else In most cases there is some history of allergy in the family

Asthma can be effectively controlled, although it cannot be cured Effective asthma management programs include education, objective measures of lung function, environmental control, and pharmacologic therapy A stepwise approach to pharmacologic therapy is recommended. The aim is to accomplish the goals of therapy with the least possible medication

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