Peds Asthma

DEFINITION OF ASTHMA: 

DEFINITION OF ASTHMA ASTHMA is a chronic inflammatory disorder of the airways in which many cells, in particular mast cells, eosinophils, and T lymphocytes, and their products (mediators, cytokines) play a role; The inflammation causes an increase in airway responsiveness to a variety of stimuli widespread but variable airflow limitation that is at least partially reversible either spontaneously or with treatment. Clinical symptoms: recurrent episodes of wheezing, breathlessness, chest tightness, and cough particulary at night and/or in the early morning. .

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The reasons for the increase in the prevalence of ASTHMA changes in indoor environment higher exposure to HDM high quantities of cockroaches increasing humidity (prevention of heat loss) changes in outdoor environment urbazniztion heavy pollution ‘Hygenic hypothesis’ of asthma/atopy development - less infections (hygenic style of life, vaccination) lead to decrease stimulation of TH1 population of lymphocytes and predominance of TH2 population; this population responsible for overproduction of IgE and atopic background

PATHOGENESIS OF ASTHMA: 

PATHOGENESIS OF ASTHMA AIRWAY INFLAMMATION ABNORMAL NEURAL CONTROL HORMONAL IMBALANCE PSYCHOLOGICAL DISTURBANCES TYPES OF ASTHMA ALLERGIC = ATOPIC = EXTRINSIC ASTHMA IgE - DEPENDENT Th2 LYMPHOCYTE DEPENDENT MECHANISMS NONALLERGIC = NONATOPIC = INTRINSIC ASTHMA IgE - INDEPENDENT Th2 LYMPHOCYTE DEPENDENT MECHANISMS

AIRWAY INFLAMMATION IN ASTHMA: 

AIRWAY INFLAMMATION IN ASTHMA A pivotal role in the generation of an immune response is activation of T lymphocytes by antigen presented by APC (dendritic cells, macrophages, B lymphocytes). T lymphocytes initiate immunological cascade. Their products - CYTOKINES - modulate the function of large number of target cells. Cytokines are responsible for differentiation, migration, accumulation and activation of inflammatory cells such as: eosinophils, mast cells, neutrophils, B lymphocytes. Cells activated by cytokines release mediators and other cytokines. Mediators contributes to the development of the characteristic pathological events that occur in asthma.

PATHOLOGICAL CHANGES IN ASTHMA: 

PATHOLOGICAL CHANGES IN ASTHMA SWELLING OF THE AIRWAY WALL OEDEMA CELLULAR INFILTRATION CONTRACTION OF SMOOTH MUSCLE MUCUS PLUG FORMATION EPITHELIAL CELL DAMAGE AND SHEDDING (CELL DEBRIS) INCREASED MUCUS SECRETION EXUDED SERUM PROTEINS AIRWAY WALL REMODELLING - increase in smooth muscle - vascular proliferation - collagen deposition - increase in bronchial glands

ABNORMAL NEURAL CONTROL OF AIRWAYS: 

ABNORMAL NEURAL CONTROL OF AIRWAYS autonomic nerves influence the tone of the airway smooth muscle, airway secretion, blood flow, mikro- vascular permeability and the migration and release of inflammatory cells the autonomic nervous system consists of: sympathetic, parasympathetic and non-adrenergic non-cholinergic (NANC) nervous system several nonspecific stimuli provoke reflex bronchoconstriction by activating the sensory receptors; in asthmatic patients the airway response develops at lower level of stimulation and the intensity of the airflow limitation response is more severe

FACTORS THAT EXACERBATE ASTHMA - TRIGGERS : 

Genetic background Environmental factors FACTORS THAT EXACERBATE ASTHMA - TRIGGERS ALLERGENS RESPIRATORY INFECTIONS EXERCISE AND HYPERVENTILATION WEATHER SULFUR DIOXIDE FOODS, ADDITIVES, DRUGS ASTHMA DEVELOPMENT

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CLINICAL MANIFESTATION Natural history of asthma ASTHMA EXACERBATION ASTHMA FREE PERIOD REMISSION SYMPTOMS dry cough feeling of chest tightness audible musical wheezing followed by dyspnoea (patient describes dyspnoea as both expiratory and inspiratory) increased work of breathing difficulties in walking, even talking duration - minutes, hours, days the expectoration of viscous sputum

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ONSET: acute or insidious SIGNS sitting position, leaning forward using the arms paleness, cyanosis sweat hyperinflation of the chest tachypnoe, tachycardia pulsus paradoxus - reduction in pulse volume during inspiration use of accessory muscles of respiration increased percussion note auscultation: prolonged expiration, wheezing, rhonchi, silent lung barrel chest deformity, Harrison sulci, clubbing of the fingers

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ASTHMA EQUIVALENT COUGH VARIANT ASTHMA - the cough at night or induced by exercise, cold air or laughter COUGH PREDOMINANT ASTHMA WHEEZY BRONCHITIS

ASTHMA IN EARLY LIFEINFANTILE ASTHMA: 

ASTHMA IN EARLY LIFE INFANTILE ASTHMA significant number of asthmatic children demonstrates first obstructive episodes early in life 30% < 1yr of age 50-55% < 2 yr of age 80% < 5 yr of age

ASTHMA IN EARLY LIFEINFANTILE ASTHMA: 

ASTHMA IN EARLY LIFE INFANTILE ASTHMA wheezing - associated lower respiratory tract illnesses in infants and young children are extremly common; a large number of anatomical and physiological factors predisposes to obstruction but only part of infants develops recurrent symptoms; there are many causes of recurrent and persistent wheezing but their prevalence is low; however before asthma diagnosis is establish other alternative diagnoses should be excluded.

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Infantile asthma - criteria of diagnosis 3 wheezy episodes (independent of atopy) 2 wheezy episodes with atopic background (positive family or individual history) 1 wheezy episode induced by exposure to allergen GINA recommendation recurrent wheezing (wheezy bronchitis) other causes excluded positive response to therapy

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DIAGNOSIS OF ASTHMA

1. Case history: 

1. Case history characteristics of asthma episode, frequency, duration, severity types of triggers (precipitating, agravating) the onset of the disease atopic history environmental history previous and current therapy response to medication impact of disease on child, family, school attendence psychosocial evaluation of patient/family general medical history of child 2. Physical examination

3. lung function tests: 

3. lung function tests considerable (more than 20%) variabilty of peak flow rate or FEV1 over short period of time daily variability= response to bronchodilator when obstruction (improvement of at least 15-20% in PEF or FEV1) measurement of bronchial hyperresponsiveness (decreasing of at least 15-20% in PEF or FEV1 after non-specific provocation) basic spirometry - assessment of degree of obstruction x 100 PEF evening - PEF morning 1/2 (PEF even. + PEF morn.)

4. assessment of allergy: 

4. assessment of allergy SERUM IgE measure of the allergy predisposition and their degree the concentration is age dependent total concentration specific IgE level - against specific antigens; not more sensitive than skin test, results independent of therapy, skin lesions, dermographism, no risk of excessive (allergic/anaphylactic) reaction normal values does not exclude allergy

4. assessment of allergy: 

SKIN TESTS background - recovery of IgE on the surface of patient mast cells; interaction between allergen and IgE leads to releasing of histamine and other mediators, which acts on specific receptors in small vessels, causing increasing permeability and dilatation and axon reflex stimulation technique: prick/puncture or intradermal, small quantity of allergenic extract is introduced into the skin 4. assessment of allergy

4. assessment of allergy: 

SKIN TESTS two control tests should be always performed: negative control - for exclusion of nonspecific reaction on pricking or solution used in production of extracts; positive control - for assessment of skin reactivity size of skin weal recorded after 15 min. - measuring the mean diameter, positive test - a wheal at least 3 mm greater than negative control 4. assessment of allergy

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Allergen SPECIFIC IgE The advantages: - safety - high degree of precision - standardization - lack of dependence on the skin reactivity and medication The disadvantages: - lack of immediately available results - high costs

5. other tests: 

5. other tests CHEST X - ray - normal in asymptomatic asthma, necessary to exclude other diseases acute asthma - hyperinflation and diagnosis of complication BLOOD EOSINOPHIL COUNT - increased count in about 50% of astma patients predictive for responsiveness to therapy measure of the severity, indicates steroid requirement SPUTUM EOSINOPHILIA positive > 20% of the total leucocytes usually present in symptomatic asthma

5. other tests: 

5. other tests DIFFERENTIAL DIAGNOSIS

Classification of asthma severity: 

Classification of asthma severity Intermittent asthma intermittent symptoms < 1 time a week brief exacerbation nightime asthma symptoms 1- 2 times a month asymptpmatic and normal lung function between exacerbation: PEF variability < 20% FEV1 > 80% predicted Mild persistent asthma symptoms 1 time a week or more, but < 1 time per day exacerbation may affect activity and sleep nightime asthma symptoms > 2 times a month PEF variability 20-30%, FEV1 > 80% predicted

Classification of asthma severity: 

Classification of asthma severity Moderate persistent asthma symptoms daily exacerbations affect activity and sleep nightime asthma symptoms >1 time a week PEF variability > 30%, FEV1 60 - 80% predicted Severe persistent asthma continous symptoms frequent exacerbations frequent nightime asthma symptoms PEF variability > 30%, FEV1 <60% predicted

Asthma management program: 

Asthma management program Educate patients to develop partnership in asthma management Assess and monitor asthma severity with both symptoms reports and measurements of lung function Avoid and control asthma triggers Establish individual medication plans for long term management Establish plans for managing exacerbation Provide regular follow up care

Goals for successful management of asthma: 

Goals for successful management of asthma Achieve nad maintain control of symptoms Prevent asthma exacerbations Maintain pulmonary function as close to normal level possible Maintain normal activity levels, including exercise Avoid adverse effects from asthma medications Prevent development of irreversible airflow limitation Prevent asthma mortality

General principles of long term asthma therapy: 

General principles of long term asthma therapy Chronic therapy Dependence of intensity of therapy on severity of asthma Priority of anti-inflammatory drugs Short acting bronchodilators as first line rescue medication Long acting bronchodlators associated with anti-inflamatory therapy in moderate and severe asthma

General principles of long term asthma therapy: 

General principles of long term asthma therapy Priority of inhaled medication Establishment of individual therapy Written instruction Complementary function of antihistamines

Asthma medication – preventers: 

Asthma medication – preventers Inhaled corticosteroids (potential side effects in high doses) Sodium cromoglycate (very safe but only weakly antiinflammatory) Nedocromil sodium

Asthma medication - controllers: 

Asthma medication - controllers Leukotriene antagonists (good safety profile, responders and non-responders) Slow release theophylline (narrow therapeutic window) Long acting inhaled (or oral) beta2 agonists ????????? (not antiinflammatory, but steroid sparing)

Asthma medication - relievers: 

Asthma medication - relievers Short acting beta 2 agonists Muscarinic receptor antagonists - anticholinergics Systemic corticosteroids Rapid release teophylline (short acting)

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Choice of therapy EPISODIC asthma b2 agonist as needed * prevention of EIA - GKS ih b2 agonists Anti- leukotriens cromones GINA NHLBI/WHO Report 2002

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Choice of therapy MILD asthma b2 agonist as needed * chronic antiinflammatory therapy Cromones Anti-leukotriens Slow released theophylline budezonid up to 400ug GINA NHLBI/WHO Report 2002

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Choice of therapy MODERATE asthma b2 agonists as needed * budezonid 400 - 800ug + Anti - leukotriens Long acting b2 agonists Slow released theophylline or budezonid > 800 ug

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Choice of therapy SEVERE Asthma b2 agonists as needed * budezonid > 800 ug + Anti-leukotriens Slow-released theophylline GKS systemic + + + + Long acting b2 agonists

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Asthma exacerbation Short acting beta 2 agonists Systemic corticosteroids Muscarinic receptor antagonists Theophylline Monitoring Oxygen Hydratation