Note: the following material is for personal use only see below for
Download 3.95 Mb.
|
- Navigate this page:
- Reactive Airway Disease (Asthma)
- Epidemiology
- Static lung volumes and capacities
- Remove/avoid : environmental triggers, aspirin
- B-agonists
- Anticholinergics (
- Leukotriene modifiers
- Mild intermittent
Pulmonary Cystic DiseaseReal vs. paracysts / < 3 mm in size emphysema bronchiectasis honeycombing basilar: IPF, RA, scleroderma, asbestosis apical: Langerhans (20-40 yrs, upper>lower), Sarcoid (peripheral or bronchovascular), LAM (women) Reactive Airway Disease (Asthma) [NEJM] Intrinsic: physical or infections Extrinsic: inhalants or (rarely) food Early: 10-20 mins / 1 to 2 hrs / IgE Late: 3 to 4 hrs / 12 hrs / inflammatory infiltrates / reversible bronchoconstriction / viral, allergens, stress, parasympathetic response to rhinitis, reflux (GERD) or other Epidemiology: most common pulmonary disease in children / most common reason for pediatric hospitalization / 90% of RAD present < 6 yrs Presentation: may have history of wheezing with URI’s and exercise, nighttime, early AM coughing Common precipitates: cigarette smoke, pet dander, dust, mites, weather changes, and seasonal or food allergies Exam (during acute asthma attack): cough, dyspnea, wheezing, tachypnea, subcostal retractions, nasal flaring, tracheal tugging and a prolonged expiratory phase, pulsus paradoxus, hypoxemia, decreased I/E / mental status changes, hypercarbia indicate impending respiratory arrest CXR: normal to hyperinflation / lung markings commonly increased (more in chronic) / atelectasis most often affects RML / flattening of the diaphragm / exacerbations may see segmental atelectasis Diagnosis: clinical +/- confirmatory tests (PFT’s vs. methacholine) 12 to 20% ↑ FEV1 w/ bronchodilators considered significant / absence of response to single bronchodilator exposure does not preclude benefit to maintenance therapy methacholine challenge causes bronchoconstriction in 95% of patients with RAD (20% decrease in FEV1) / can reverse it faster with B2 agonists / false positives may occur in 7% of general population and also CHF, allergic rhinitis, viral URI, COPD, CF Peak flow meter – take level for body size (set at 100%): 80% is significant / 50% is an emergency PFT: degree of airway obstruction and disturbance in gas exchange, measure response to inhaled allergens and chemicals, quantify response to drugs, follow patients over the long term Static lung volumes and capacities reveal various abnormalities, although these may not be detected when mild disease is in remission. Total lung capacity, functional residual capacity, and residual volume are usually increased. Vital capacity may be normal or decreased. Labs: eosinophilia (> 250 to 400 cells/µL) / degree of eosinophilia often correlates with severity of asthma / reduction can reflect adequate treatment with corticosteroids Ddx (see below for more): viral pneumonia, bacterial pneumonia. foreign body aspiration, anaphylaxis/angioneurotic edema, bacteremia/sepsis Treatment: Mental Education: peak flow monitoring (peak flow decreases to < 80% of personal best go to twice-a-day monitoring; diurnal variation > 20% indicates airway instability and need to adjust regimen Remove/avoid: environmental triggers, aspirin (esp. with nasal polyposis, can also have this with NSAIDS rarely, tartrazine or yellow no. 5), sulfites (shrimp, red wine, beer), B-blockers Anxiety may be extreme in many stages of asthma because of hypoxia and the feeling of asphyxiation. Treatment of the underlying respiratory problems, including judicious use of O2 therapy, is the preferred approach, especially when conducted by calm, attentive, supportive medical personnel. The use of sedatives in nonintubated patients is associated with increased mortality and the need for mechanical ventilation Medications B-agonists relax bronchial smooth muscle, modulate mediator release (by increasing c-AMP), protect from many bronchoconstrictors, inhibit microvascular leakage, increase mucociliary clearance / side effects more common for oral agents because higher doses required (useful for nocturnal asthma) albuterol 2.5 mg in 3cc nebs q 2 hrs (short acting) Anticholinergics (ipratropium bromide) competitively inhibiting muscarinic cholinergic receptors / block reflex bronchoconstriction due to irritants or to reflux esophagitis Solumedrol 25 mg IV q 6 hrs (long acting) Cromolyn to stabilize mast cell membrane (who will take medicine QID besides kids) Corticosteroids block late response (not the early response) to inhaled allergens and lead to subsequent bronchial hyperresponsiveness (bronchial hyperresponsiveness gradually decreases with long-term therapy) oral inhaled corticosteroids – 4-6 hours onset, 5 day course recommended to decrease inflammation and reactivation, long-term use has a 5-10% incidence of oral candidiasis (use of spacer helps, rinse throat with water and spit) Theophylline (a methylxanthine) relaxes bronchial smooth muscle and has modest anti-inflammatory activity. Mechanism unclear / inhibits intracellular calcium release decreasing microvascular leakage, inhibits late response, decreases eosinophils and T lymphocyte infiltration, increases myocardial and diaphragmatic contractility. Used for long-term control as adjunct to B-agonists / long-acting theophylline useful for nocturnal asthma / narrow therapeutic index and can cause severe adverse reactions (keel levels 10 - 15 µg/mL (56 and 83 µmol/L). Leukotriene modifiers: montelukast and zafirlukast (Singulair), selective competitive inhibitors of LTD4 and LTE4 receptors, and zileuton, a 5-lipoxygenase inhibitor. Taken PO for long-term control and prevention of symptoms in patients / zileuton may cause a dose-related increase in ALT or AST / montelukast does not. With zafirlukast, drug interactions mediated by cytochrome P-450 enzymes Mild intermittent short acting B2 agonists/ACh blockers PRN Mild persistent (> 2/wk) long acting B2 agonists (has come under debate) /ACh blockers / add inhaled steroids or cromolyn Moderate persistent (daily) B2 agonists (short and long) + inhaled steroids Severe persistent B2 agonist + oral steroids Acute RAD hospitalization 5 day PO steroid course nebulized epinephrine (B2 agonist) – immediate bronchodilation Note: during severe respiratory distress, an elevated and rising PaCO2 would indicate impending respiratory failure. During tachypnea, a PaCO2 not well below 40 indicates poor ventilation. Recent Studies Salmetrol/Fluticasone – combination better than single agent Fluticasone – meta-analysis of 1377 patients, 7% increased FEV1, no adverse effects Fluticasone – 4-24 weeks lung function >> nedocromil, theophylline, montelukast, 8% oral candidiasis, no significant HPA suppression Leukotriene inhibitors – montelukast is good (Zafirkulast is not good)
Download 3.95 Mb. Share with your friends:
|