Investigations of Pulmonary Function

Asthma Exacerbation

During an asthma attack, also called an asthma exacerbation, your airways become swollen and inflamed. The muscles around the airways contract and the airways also produce extra mucus, causing your breathing (bronchial) tubes to narrow. During an attack, you may cough, wheeze and have trouble breathing.

Differential diagnosis of Wheezing

Extrathoracic airway obstruction

1. Oropharynx enlarged tonsils, retropharyngeal abscess, obesity, post nasal drip.

2. Larynx laryngeal edema, laryngostenosis, laryngocele, epiglottitis, anaphylaxis, severe laryngopharyngeal reflux, and laryngospasm

3. Vocal Cords vocal cord dysfunction, paralysis, hematoma, tumor, cricoarytenoid arthritis.

Interathoracic airway obstruction

1. Tracheal obstruction tracheal stenosis, tracheomalacia, tracheobronchitis (herpetic), malignancy, benign tumor, aspiration.

2. Tracheal compression goiter, right sided aor tic arch

3. Lower airway obstruction asthma, COPD, bronchiolitis, bronchiectasis, carcinoid tumor, aspiration, malignancy

4. Parenchyma pulmonary edema

5. Vascular pulmonary embolism

Pathophysiology

1. Exacerbator of Asthma

2. Infections viral, bacterial

3. Outdoors respirable particulates, ozone, sulfur dioxide, cold air, humidity, smoke

4. Indoors smoke, dust mites, air conditioners, humidity, perfumes, scents, smoke

Non-Adherence

Clinical Features

History: History of asthma and any life threaten ing exacerbations, number of ER visits/hospital admissions in the last 6 months or ever, any ICU admissions, previous prednisone use, triggers for attacks, normal peak expiratory flow rate, change in peak flow rates, wheezing, cough, dyspnea, decreased function, exercise limitation, nocturnal symptoms, absenteeism from work/school, post nasal drip, recurrent sinusitis, GERD, occupational and work environment, past medical history, medication history, psychosocial issues, home environment (pets, heating source, filter changes).

Physical HR raised RR raised pulsus paradoxus, O2 requirement, moderate severe dyspnea, barrel chest, cyanosis, hyperresonance, decreased breath sounds, wheezing, forced expiratory time

Types of wheezing inspiratory wheeze and expiratory wheeze are classically associated with extrathoracic and intrathoracic airway obstruction, respectively. However, they are neither sensitive nor specific and cannot help to narrow differential diagnosis.

Investigation

Basic

Labs: CBCD, electrolytes, urea, Cr, troponin/CK

Microbiology sputum Gram stain/AFB/C&S

Imaging CXR

Special

ABG if acute respiratory distress

Peak flow meter need to compare bedside reading to patient’s baseline

Spirometry/PFT (non acute setting) raised FEV1 >12% and an absolute increased by 200 mL post bronchodilators suggest asthma

Methacholine challenge (non acute setting) if diagnosis of asthma not confirmed by spirometry alone. A decrease of FEV1 >20% after methacholine challenge suggests asthma. Sens 95%

Acute management

ABC O2 to keep sat >92%, IV

Bronchodilator salbutamol 2.5 5.0 mg NEB q6h + q1h PRN and ipratropium 0.5 mg NEB q6h (frequency stated is a guide, can increase or decrease on a case by case basis)

Steroid prednisone 0.5 1 mg/kg PO daily 7 14 days (may be shorter depending on response) or methylprednisolone 0.4 0.8 mg/kg IV daily (until conversion to prednisone)

Others if refractory case and life threatening, consider IV epinephrine, IV salbutamol, theophylline, inhaled anesthetics, MgSO4

Mechanical ventilation BIPAP, intubation

Long term management

Environmental control avoidance of out door/indoor allergens, irritants, and infections; home environment cleanliness (e.g. steam cleaning)

Vaccinations influenza vaccine annually and pneumococcal vaccine booster at 5 years

1. First line short acting b2 agonist (salbutamol 2 puffs PRN). Proceed to second line if using more than 2/week or 1/day for exercise induced symptoms, symptoms >2/week, any nocturnal symptoms, activity limitation or PEF

2. Second line inhaled corticosteroids plus short acting b2 agonist PRN

3. Third line inhaled corticosteroid plus long acting b2 agonist (note that long acting b2 agonist should never be used alone in asthma), leukotriene receptor antagonist (most effective in asthma complicated with sinus disease and exercise induced asthma)

4. Fourth line anti IgE therapy (omalizumab) for refractory allergic asthma, administered subcuta neously q2 4weeks, dosed by IgE level and body weight, for add on therapy or inadequately controlled moderate to severe allergic asthma despite use of high doses of inhaled corticosteroid therapy

Treatment issues

Common inhaled medications

 Short-Acting b Agonists salbutamol metered dose inhaler (MDI) 100 mg 1 2 puffs PRN or 2.5 mg NEB PRN, fenoterol MDI 100 mg 1 2 puffs PRN, terbutaline 500 µg INH PRN

1. Short-Acting Anticholinergics ipratropium MDI 20 µg 2 puffs QID or 500 mg NEB QID

2. Long-Acting b Agonists formoterol 6 24 mg INH BID, salmeterol diskus 50 µg i puff BID

3. Long-Acting Anticholinergics tiotropium 18 µg INH daily

Inhalded Corticosteroids beclomethasone 50 400 mg INH BID, budesonide turbuhaler 200 400 mg INH BID or 0.5 1 mg NEB BID, fluticasone 125 250 mg INH BID, ciclesonide MDI 100 400 mg INH daily (only indicated for asthma at this time, not COPD)

Specific Entities

Exercise Induced Aasthma

Pathophysiology mild asthma with symptoms only during exercise due to bronchoconstriction as a result of cooling of airways associated with heat and water loss

Diagnsis spirometry. Exercise or methacholine challenge may help in diagnosis

Treatments prophylaxis with salbutamol 2 puffs, given 5 10 min before exercise. Consider leukotriene antagonists or inhaled glucocorticoids if frequent use of prophylaxis

Traid Asthma (Samter’s syndrome) triad of asthma, aspirin/NSAIDs sensitivity, and nasal polyps. Cyclooxygenase inhibition decreasedprostaglandin E2 increasedleukotriene synthesis asthma symptoms. Management include ASA/NSAIDs avoidance and leukotriene antagonists (montelukast)

Allergic Bronchopulmonary Bronchopulmonary Asperogillosis (ABPA)

Pathophysiology associated with asthma and cystic fibrosis. Due to colonization of the airways by Aspergillus fumigatus, leading to an intense, immediate hypersensitivity type reaction in the airways

Clinical Features history of asthma, recurrent episodes of fever, dyspnea, and productive cough (brownish sputum). Peripheral eosinophilia. CXR findings of patchy infiltrates and central bronchiectasis

Diagnosis above clinical features plus Aspergillus extract skin test, serum IgE level, sputum for Aspergillus and/or serologic tests (IgE and IgG against Aspergillus)

Treatments systemic glucocorticoids, itraconazole