pathophysiology of asthma and COPD

Complete pathophysiology of asthma and COPD

1. Pathophysiology Bronchial Asthma & COPD RVS Chaitanya Koppala

2. Asthma Common and chronic inflammatory condition of the airways, whose cause is not completely understood Common symptoms are Hyper-responsive airways (coughing, wheezing, chest tightness and shortness of breath) Broncho contriction Asthma means laboured breathing refer to a disorder of the respiratory system that leads to episodic difficulty in breathing Chronic disorder of the airways associated with variable airflow obstruction and an increase in the airway response to a variety of stimuli

3. Epidemiology Exact prevalence of asthma remains uncertain because of differing ways in which airway restriction is reported Diagnostic uncertainty (children under 2 yrs.) overlaps with chronic obstructive pulmonary disease (COPD) Over 5 million people in UK , around 300 million worldwide Mortality is estimated around 1400 deaths/ yr 5-12% in children with a higher occurrence in boys than girls or parents have a allergic disorder 30-70% of children become symptom free by adulthood

4. COPD vs Asthma In  COPD , both the airways and lung parenchyma are affected by the disease and airflow limitation is progressive. COPD  is predominantly diagnosed in patients >40 years old & In Asthma   only the airways are affected. Asthma  is usually present from childhood  

5. Aetiology Two main causes of symptoms are Airway hyperresponsiveness (?) Bronchoconstriction(?). Trigger factors is the allergen in faeces of the house dust mite (bedding carpets and soft furnishing.) Pollen from grass (seasonal asthma) Increased industrialization (occupational asthma) Drug induced asthma (Beta blocker drugs and prostaglandin synthetase inhibitors) ex: Aspirin and other NSAIDS (?)

6. Pathophysiology Eosinophilic Non Eosinophilic Extrinsic Asthma Intrinsic Asthma Causative factor is allergen Causative factor is Virus More common in children More common in Adults Dust mite, IgE antibodies, Rhinovirus (during first 3 yrs of life) Non allergic factors, viral infection , irritants like epithelial damage , mucosal inflammation, emotional upset, parasympathetic input Triggers activated Th2 lymphocytes and mast cells Triggers epithelial cell damage and Macrophages Effected cells are eosinophil Effected cells are neutrophils Causes airway inflammation Causes airway inflammation Airway hyperesponsiveness , irritation, Oedema , mucous plugging, remodeling Airway hyperesponsiveness , irritation, Oedema , mucous plugging, remodeling

7. Cellular mechanism involved in airways

8. Clinical manifestation Persistant cough Dyspnoea Wheezing (a high pitched noise due to turbulent airflow/ narrowed airway) Reversible airflow obstruction Atopy Allergic rhinitis

9. Acute severe asthma Requires Hopitalization Immediate emergency treatment Bronchospasm (breathless at rest, cardiac stress) Breathlessness Cannot talk or cannot lie down Air trapped Peak flow rate >100L/min Air beneath mucosal inflammation Pulse rate >110beats/min Hyperexpansion of thoracic cavity Lowering of diaphragm Rapid breathing (>30 breath/min) Lower oxygen saturation (SpO2 <92%) Fatigued, cyanosed, confused, lethargic Hypercapnia (High PaCO2 level)

10. Investigations Function of the lung can be measured to help diagnose and monitor various respiratory diseases FEV ( Forced Expiratory V olume )– spirometer (inhales deeply and exhales forcibly) FVC ( Forced Vital C apacity )– max volume of air exhaled with maximum capacity) PEF ( Peak E xpiratory F low )—the maximum flow rate that can be forced during expiration assess the improvement of deterioration and effectiveness of treatment.