Pediatric Obstructive Diseases of Lower Airway - AUG 02 PDF

Pediatric Obstructive Airway Diseases Josy Naty M. Venturina-Fano, MD, DPPS, DPAPP ASTHMA  Asthma Airway obstruction that is reversible (but not completely so in some patients) either spontaneously or with treatment Airway inflammation Increased airway responsiven...

Pediatric Obstructive Airway Diseases Josy Naty M. Venturina-Fano, MD, DPPS, DPAPP ASTHMA  Asthma Airway obstruction that is reversible (but not completely so in some patients) either spontaneously or with treatment Airway inflammation Increased airway responsiveness to a variety of stimuli  Definition of asthma Heterogeneous disease Chronic airway inflammation History of respiratory symptoms such as wheeze, shortness of breath, chest tightness and cough that vary over time and in intensity, together with variable expiratory airflow limitation GINA 2017  Pathogenesis Non-immunologic stimuli Immunologic stimuli (viral (antigen) infections,physical and Cell activation chemical stimuli Mast cells Epithelial cells Macrophages Eosinophils Lymphocytes Autonomic nervous system Inflammatory mediators - Axon reflex Smooth muscle contraction - Neuropeptides Chemotaxis Autonomic nervous Inflammatory mediators system Smooth muscle contraction - Axon reflex Chemotaxis - Neuropeptides Granulocytic responses: Neutrophils Eosinophils Activated mononuclear cells Macrophages Lymphocytes Airway edema Cellular infiltration Subepithelial fibrosis Inflammatory mediators Mucous secretion Mucosal and vascular permeability Airway hyperresponsiveness ASTHMA  What happens in an asthma attack? Normal Bronchiole Asthmatic Bronchiole Relaxed smooth muscles Contracted smooth muscle Thin lining Inflammation of lining and walls Airway open Increased mucus secretion Minimal mucus Narrowed airway and air trapping  RISK FACTORS Parental Asthma Allergy (atopic dermatitis, allergic rhinitis, food allergy, inhalant /allergen sensitization) Severe lower respiratory tract infection (pneumonia, bronchiolitis requiring hospitalization) Wheezing apart from colds Male gender Low birthweight Environmental tobacco smoke exposure Possible use of acetaminophen Exposure to chlorinated swimming pools Reduced lung function at birth  ASTHMA PREDICTIVE INDEX Major Criteria Minor Criteria Parents with asthma Allergic rhinitis Eczema Wheezing apart from colds Inhalant allergen Eosinophils > 4% sensitization Food allergen sensitization TRIGGERING FACTORS House dust mites Pets Rodents Cockroach TRIGGERING FACTORS Molds Pollen Food additives Polluted environment TRIGGERING FACTORS Smoking Exercise Viral URTI  Diagnosis of asthma Based on: – A history of characteristic symptom patterns – Evidence of variable airflow limitation, from bronchodilator reversibility testing or other tests  Diagnosis of asthma – symptoms Increased probability that symptoms are due to asthma if: – More than one type of symptom (wheeze, shortness of breath, cough, chest tightness) – Symptoms often worse at night or in the early morning – Symptoms vary over time and in intensity – Symptoms are triggered by viral infections, exercise, allergen exposure, changes in weather, laughter, irritants such as car exhaust fumes, smoke, or strong smells  Diagnosis of asthma – symptoms Decreased probability that symptoms are due to asthma if: – Isolated cough with no other respiratory symptoms – Chronic production of sputum – Shortness of breath associated with dizziness, light- headedness or peripheral tingling – Chest pain – Exercise-induced dyspnea with noisy inspiration (stridor) Features suggesting asthma in children ≤5 years Feature Characteristics suggesting asthma Cough Recurrent or persistent non-productive cough that may be worse at night or accompanied by some wheezing and breathing difficulties. Cough occurring with exercise, laughing, crying or exposure to tobacco smoke in the absence of an apparent respiratory infection Wheezing Recurrent wheezing, including during sleep or with triggers such as activity, laughing, crying or exposure to tobacco smoke or air pollution Difficult or heavy Occurring with exercise, laughing, or crying breathing or shortness of breath Reduced activity Not running, playing or laughing at the same intensity as other children; tires earlier during walks (wants to be carried) Past or family history Other allergic disease (atopic dermatitis or allergic rhinitis) Asthma in first-degree relatives Therapeutic trial with Clinical improvement during 2–3 months of controller treatment low dose ICS and as- and worsening when treatment is stopped needed SABA Diagnosis of asthma – physical examination Physical examination in people with asthma – Often normal – Most frequent finding: expiratory wheezing on auscultation, especially on forced expiration Wheezing may be absent during severe asthma exacerbations (‘silent chest’) GINA 2014 Differential diagnoses in children ≤5 years Recurrent viral respiratory infections Gastroesophageal reflux Foreign body aspiration Tracheomalacia or bronchomalacia Tuberculosis Congenital heart disease  Differential Diagnoses in older children Chronic upper airway Vocal cord dysfunction cough syndrome Hyperventilation, Inhaled foreign body dysfunctional breathing Bronchiectasis Congenital heart disease Primary ciliary dyskinesia Cystic fibrosis Bronchopulmonary dysplasia  Diagnosis of asthma Based on: – A history of characteristic symptom patterns – Evidence of variable airflow limitation, from bronchodilator reversibility testing or other tests GINA 2014  Tests to assist in diagnosis in children ≤5 years Lung function testing Children 4–5 years of age capable of performing reproducible spirometry if coached by an experienced technician and with visual incentives Exhaled nitric oxide Fractional concentration of exhaled nitric oxide (FENO) can be measured in young children with tidal breathing Risk profiles Asthma Predictive Index (API), based on the Tucson Children’s Respiratory Study  Tests to assist in diagnosis in children ≤5 years Therapeutic trial At least 2–3 months with as-needed short-acting beta2- agonist (SABA) and regular low dose inhaled corticosteroids (ICS) Tests for atopy Skin prick testing or allergen-specific immunoglobulin E Chest X-ray May help to exclude structural abnormalities (e.g. congenital lobar emphysema, vascular ring) chronic infections such as tuberculosis, an inhaled foreign body, or other diagnoses  Chest X-ray Hyperinflation Peribronchial thickening Subsegmental / Lobar atelectasis Spirometry Normal Values for FEV1/FVC ratio: Adults: > 0.75 to 0.80 * Children: > 0.90* *Any values less than these = airflow limitation  Typical spirometric tracings Volume Flo Normal w FEV1 Asthma (after BD) Normal Asthma (before BD) Asthma (after BD) Asthma (before BD) 1 2 3 4 5 Volume Time (seconds) Note: Each FEV1 represents the highest of three reproducible measurements GINA 2014 © Global Initiative for Asthma Peak Flow Meter Measures PEFR Predicted normal PEFR for Filipino children Males (Ht. in cm - 100)5 +175 Females (Ht. in cm - 100)5 +170  Tests to assist in diagnosis in adolescents and children 6–11 years Documented excessive The greater the variations, or the more variability in lung function occasions excess variation is seen, (one or more of the tests the more confident the diagnosis below) AND documented airflow At least once during diagnostic limitation process when FEV1 is low, confirm that FEV1/FVC is reduced (normally >0.75 – 0.80 in adults, > 0.90 in children) Positive bronchodilator (BD) Children: increase in FEV1 of >12% reversibility test* (more likely predicted to be positive if BD medication is withheld before test: SABA ≥ 4 hours, LABA ≥ 15 hours)  Tests to assist in diagnosis in adolescents and children 6–11 years Excessive variability in Children: average daily diurnal PEF twice-daily PEF over 2 variability >13% weeks* Positive exercise Children: fall in FEV1 of >12% challenge test* predicted, or PEF >15% (usually only performed in adults)  Tests to assist in diagnosis in adolescents and children 6–11 years Positive bronchial Fall in FEV1 from baseline of ≥ 20% challenge test (usually with standard doses methacholine or only performed in histamine, or ≥ 15% with adults) standardized hyperventilation, hypertonic saline or mannitol challenge Excessive variation in Children: variation in FEV1 of >12% lung function between or >15% in PEF between visits(may visits* (less reliable) include respiratory infections)  Classification of Asthma Severity by Clinical Features Before Treatment Intermittent Persistent Mild Moderate Severe Daytime < 1x/week > 1x/week but Daily Daily Symptoms less than daily Affects daily Limits daily activities activities Nighttime < 2x/month > 2x/month > 1x/week > 1x/week Symptoms PEFR > 80% > 80% 60-79% < 60% predicted predicted PEFR < 20% 20-30% > 30% > 30% Variability FEV1 > 80% > 80% 60-79% < 60% predicted predicted *The worst feature determines the severity classification  Categories of asthma medications Controller medications – regular maintenance treatment – reduce airway inflammation, control symptoms, and reduce future risks such as exacerbations and decline in lung function Reliever (rescue) medications – for as-needed relief of breakthrough symptoms, including during worsening asthma or exacerbations – recommended for short-term prevention of exercise- induced bronchoconstriction  Categories of asthma medications Add-on therapies for patients with severe asthma – may be considered when patients have persistent symptoms and/or exacerbations despite optimized treatment with high dose controller medications (usually a high dose ICS and a LABA) and treatment of modifiable risk factors  Drug therapy in asthma Short – acting β2 agonist (SABA) MOA: relax the airway smooth muscles, enhance mucociliary clearance, decrease vascular permeability, and may modulate mediator release from mast cells and basophils Onset of action: 5 minutes (peak: 60 minutes) Duration of action: 4-6 hours Role in Therapy : acute exacerbation, pretreatment of exercise-induced asthma, control episodic bronchoconstriction Side effects: cardiovascular stimulation, skeletal muscle tremor, hypokalemia  Drug therapy in asthma Long Acting β2 agonist MOA: Same as SABA; longer duration of action (12 hours or more) Role in therapy: Chronic treatment improves symptom score, decreases nocturnal asthma, prevents exercise-induced asthma, improves lung function and decreases the use of SABA Side effects: cardiovascular stimulation, skeletal muscle tremors, hypokalemia and irritability  Drug therapy in asthma Ipratropium bromide MOA: bronchodilators that block postganglionic efferent vagal pathways  reduce intrinsic vagal tone to the airways; block reflex bronchoconstriction caused by inhaled irritants Role in therapy: valuable in patients intolerant of inhaled B2 agonist Side effects: dryness of mouth, bad taste  Drug therapy in asthma Systemic Corticosteroids MOA: inhibits production of inflammatory cytokines; inhibits the lymphocytic, eosinophilic airway mucosal inflammation of asthmatic airways; restore B-adrenergic responsiveness Role in therapy: reserved for patients who require urgent treatment, those who have not improved adequately with bronchodilators or who experience worsening symptoms despite maintenance therapy Side effects: Short term: mood disturbances, gastrointestinal irritation, increase appetite Long term: osteoporosis, hypertension, diabetes, HPA suppression, muscle weakness, cataracts, obesity, skin thinning  Drug therapy in asthma Inhaled Corticosteroids Role in Therapy: effective in improving all indices of asthma control; reduces or eliminates the need for systemic corticosteroids Side effects: oropharyngeal candidiasis, dysphonia, coughing, significant decrease in bone mineral density, HPA suppression with dose of >400ug/day in children  Drug therapy in asthma Leukotriene receptor antagonist (LTRA) MOA: antagonizes leukotriene activity at specific receptor sites in the airways, thereby reducing inflammation Role in therapy: Controls symptoms of asthma but less effective than low dose ICS; used for patients with both asthma and allergic rhinitis, or if patient will not use ICS Side effects: headache, abdominal pain, rashes, elevation of liver enzymes  Drug therapy in asthma Methylxanthine (Theophylline, Aminophylline) MOA: Inhibit the enzyme phosphodiesterase resulting in smooth muscle relaxation Inhibit cell surface receptors for adenosine Anti-inflammatory action Role in therapy: should not be used in the management of asthma exacerbations Side effects: nausea, vomiting, tachycardia and arrhythmia, seizures  Drug therapy in asthma Magnesium Sulfate MOA: decrease the uptake of calcium by bronchial smooth muscles leading to bronchodilation Role in therapy: not recommended for routine use in asthma exacerbations; adults and children who fail to respond to initial treatment and have persistent hypoxemia; and children whose FEV1 fails to reach 60% predicted after 1 hour of care Side effects: cardiac arrhythmias, hypotension, flushing, sweating, depression of reflexes, CNS depression  Asthma flare-ups (exacerbations) Acute or sub-acute progressive increase in symptoms of shortness of breath, cough, wheezing or chest tightness and progressive decrease in lung function (PEF or FEV1) May occur in patients with a pre- existing diagnosis of asthma or, occasionally, as the first presentation of asthma GINA 2014 SEVERITY OF ASTHMA EXACERBATIONS MILD or MODERATE SEVERE OR LIFE THREATENING CHILDREN Breathless, agitated Any of the following: ≤ 5 years old Pulse rate ≤ 200 bpm (0-3 Unable to speak or drink years) or ≤ 180 bpm (4-5 Central cyanosis years) Confusion or drowsiness Oxygen saturation ≥ 92% Marked subcostal and subglottic retractions Oxygen saturation 200 bpm (0-3 yrs)or >180bpm (4-5yrs) MILD or MODERATE OLDER Talks in phrases Talks in words CHILDREN and Prefers sitting to lying Sits hunched forward ADOLESCENTS Not agitated Agitated Respiratory rate Respiratory rate >30/min increased Accessory muscles being Accessory muscles not used used Pulse rate >120 bpm Pulse rate 100-200 bpm O2 saturation (on air) O2 saturation (on air) 90- 50%)  Prevention Hand hygiene with antimicrobial soap or an alcohol-based rub No vaccine exists for the prevention of RSV infection RSV immune globulin (RSV-IG) Palivizumab  Disease course Mild URTI during the first few days of illness  lower respiratory tract involvement (or bronchiolitis)  wheezing, crackles, and varying degrees of respiratory distress Mean duration of illness: 15 days Period of resolution: within 3 to 4 weeks  Long term sequelae Bronchiolitis obliterans Allergic sensitization Asthma