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Asthma

Asthma. Definition. Chronic inflammatory disorder of the airway involving many cell types Causes recurrent episodes of wheezing, breathlessness, chest tightness, cough (especially @ night or early am) Associated with widespread / variable airflow limitation which is at least partly reversible

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Asthma

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  1. Asthma

  2. Definition • Chronic inflammatory disorder of the airway involving many cell types • Causes recurrent episodes of wheezing, breathlessness, chest tightness, cough (especially @ night or early am) • Associated with widespread / variable airflow limitation which is at least partly reversible • Associated increase in airway responsiveness to various stimuli NHLBI/WHO

  3. Why do we care??? • Overall prevalence of Asthma is increasing • Affects up to 3% of population

  4. Why do we care??? • 5600 patients die of asthma each year in the US (about 15 people per day or 1-7%) • In 1998 17.7 million people (adults) with asthma • African Americans are 3 times more likely to suffer a fatal attack • Hispanics and Women are more likely to suffer fatal attacks

  5. COST • $12.7 billion in 1998 • 500,000 hospitalizations/year • >10 million school/work days missed/year • Accounts for up to 1.9 million ER visits/yr • # of children dying from Asthma increased 3 Fold 1979--->1996

  6. DiagnosisNot as easy as we think • Classic triad: Persistent wheeze Chronic cough Chronic dyspnea • Other Presentations: Cough (with or without bronchorrhea) Chest pain or tightness Hyperventilation Hemoptysis (Churg-Strauss, aspergillosis)

  7. There’s more • Intermittent seasonal waxing and waning • nocturnal episodes • exacerbation on exposure to stimuli (exercise, cold air, allergens, pollution, URI, strong odors) • Forget: age, gender, fam hx, race for diagnosis PV is unknown

  8. History • History of “wheezing”, SOB, cough • Age at onset of asthma • Use of steroids • History of hospitalization / intubation • Duration of current exacerbation • Associated symptoms (CP, fever)

  9. Leaving us with the Physical • Wheeze • Widespread, high or multi- pitched, musical are characteristic but not specific • Occur at various points in cycle • Different from a wheeze with a definite pattern (ie. Wheeze at end expiration = ILD) (Upper airway noises distinguished by listening over neck)

  10. But alas; • The presence or absence of wheezing is a poor predictor of severity • Need spirometry or peak flow measures to quantify severity • Accessory muscle use, pulsus paradoxus are found only during acute attacks (insensitive, ie:useless)

  11. Exam beyond the wheeze • Speech pattern • air movement, I:E ratio • Retractions, accessory muscle use • Diaphoresis • Cyanosis • Altered Mental Status = No O2 • pulse >120

  12. Other Physical Clues • Hives • eczema • allergic rhinitis • nasal polyps with or without ASA sensitivity • clubbing is not asthma

  13. PFTs • Must be part of the diagnosis of asthma • peak flow (PEFR) established by patients personal best • patient performs PEFR 2X/day for 2 weeks when asymptomatic (not on steroids) • Measurement is used to develop an asthma plan

  14. Severity • Mild: >80% of predicted • Moderate: 50-80% of predicted • Severe: <50% of predicted

  15. Spirometry • FEV1 (Forced expiratory volume) used to assess the degree of obstruction if obstructed reassess after bronchodilator • FVC (Forced Vital Capacity)

  16. Bronchoprovocation • Uses a stimulus to provoke airway narrowing and measures FEV1

  17. What about? • CXR almost always normal • Blood tests not effective (could maybe detect eosinophilia) • Allergy Testing sometimes helpful • ABG if acute attack, status • Pulse Ox (does not correlate w/severity)

  18. Always remember a differential • GERD • post-viral tussive syndrome • autoimmune disease • COPD • cardiac disease (CHF) • Medication induced • Malignancy • unusual infection (pertussis, etc) • Allergic disease

  19. Mild Asthma • symptom free most days • Awakened from sleep 1/wk or less • near normal lung function (FEV1>75%) • maintains asthma control using B-agonist (no more than 8 canisters/yr) * use of more than 8 canisters (200puffs each) is associated with worsening asthma

  20. Mild Intermittent Asthma • Actually the mildest form • require treatment on an as needed basis (exercise induced) • B-agonist treatment only • studies show no advantage to scheduled regular dosing

  21. Mild Persistent Asthma • Asthma symptoms occur regularly but infrequently • Awakened from sleep 3-4X/month • Typically not restricted in daily activities • Lung function is Normal between episodes but is abnormal (<FEV1) during attacks • Treatment: B-agonist +/- steroid inhaler

  22. Moderate Persistent Asthma • Symptoms occur on a daily basis • Disease limits there daily activities • Awakened 2 or more nights/week • chronic FEV1 60-75% predicted • unable to maintain normal lung function using 6-7 puffs B-agonist/day • requires controller medication to improve function

  23. Chronic Moderate AsthmaTreatment • Regular treatment with a “Controller” inhaled steroids (2 puffs BID beclometasone,flunisolide, triamcinolone) nedocromil cromolyn sodium Leukotriene interrupter (zarfirlukast) • consider long-acting B-agonist • Avoid fixed combinations (Advair)

  24. Severe Asthma • Frequent exacerbations with minimal exposures • Awakened from sleep 4-7 nights/week • FEV1 below 60% predicted • unable to achieve normal lung function despite chronic treatment (steroids @ mod/high dose or orals) • often need unscheduled medical care • should record PEFR 2X/day

  25. Treatment for Severe Asthma • With a specialist • multiple controllers adjusted frequently

  26. Acute Attack B-agonists • Treatment of choice • High doses • Inhaled, ? Continuous • No upper limit of dosing established • MDI is as effective as neb even in acute exacerbations (8 puffs = one neb) • complications: dysrhythmias, hypoK, hypomag, hypophos

  27. Steroids • Use them (whichever one you prefer) • Use in ED, decreases admissions • Use at discharge reduces relapse • Doses > 40mg/day appear to be equal in efficacy • Long taper unnecessary (usually) • Anyone on oral steroids need a MDI steroid

  28. Anti-cholinergics • Synergistic with B-agonists • No major side effects • most useful in severe asthma • probably useful in moderate exacerbations Ipratoprium bromide (Atrovent): • potent bronchodilator • slower than B-agonists, lasts longer • Severe or moderate exacerbation 500mcg added to first treatment, repeat if needed

  29. Others • Magnesium- weak bronchodilator, short half-life, ?effectiveness, use at least 2grams over 20min • Methylxanthines- weak bronchodilator, narrow therapeutic range, lots o side effects, if intubating you may consider • Heliox- one third as dense as N/O2, flows more easily through obstructed airway,consider if resp acidosis • Ketamine- bronchodilator, depressant, think of using when intubating an asthmatic

  30. Indications for intubation • Apnea/near apnea • Deteriorating physical exam • cyanosis despite O2 therapy • Altered mental status or consciousness • inability to protect airway • MI • life threatening dysryhthmia • persistent/progressive acidosis • exhaustion

  31. Technique • Preoxygenation important • Inducing agents: Benzos, Ketamine, Etomidate, Avoid barbiturates (cause histamine release) • Paralytics: Succinylcholine is contraindicated (ACh-like action), use Rocuronium or vecuronium, pavulon post intubation • Permissive hypercapnea • small TV(6-10cc/kg), Low resp rate(10-12/min), longer expiratory times, max peak pressure (under 60)

  32. Pregnancy • Asthma is the most common lung condition during pregnancy (4% at any given time) • Risk of poorly controlled asthma outweighs risk of medications used to treat asthma • Worsening tends to occur 29-36 weeks • Usually less severe during last 4 weeks • Labor and Delivery are not associated with worsening symptoms

  33. More • Patterns through one pregnancy often repeat with the next • Asthma improvement is generally gradual throughout pregnancy • Recent studies do not support worsening of asthma in women with diagnosis of severe asthma

  34. Asthma risks • Increased incidence of PIH • Increased incidence of preeclampsia • increased risk of premature delivery • Increased incidence of placenta previa • Increased risk for C-section • Increased risk for SGA newborn • Increased incidence birth defects (debatable)

  35. Pulmonary changes during Pregnancy • Enlarging uterus causes diaphragm resting position to rise but excursion is not impaired • FRC (residual capacity) decreases by 20% during latter half of pregnancy as ERV (expiratory reserve volume) and RV (residual volume) decrease

  36. More change • Increase in resting minute ventilation due to increased tidal volume • progesterone and increased metabolic requirements are thought to be the stimulant for increased TV

  37. ABG and acid-base • Arterial PCO2 falls during pregnancy to 27-32 mmHg • Respiratory Alkalosis=increased secretion of HCO3 so usually PH is 7.4-7.45 • PO2 is usually increased secondary to hyperventilation 101-108 mmHg • So… always calculate your A-a gradient when evaluating dyspnea

  38. Medications in Pregnancy

  39. Medications in Pregnancy • Most drugs are either category B or C • General consensus is to avoid epinephrine for question of vasoconstriction of UP circulation • Corticosteroids (oral) Many accusations…no proof Swedish study showed no increase in malformations using budesonide ObstGyn1990;76:803

  40. Predictors of bad outcomes(risks for near fatal attacks) • H/o severe asthma (hospitalizations, intubations) • psychiatric co-morbidities ETOHism, depression, poverty • sub-optimal therapy • poor perception of dyspnea • Race & sex

  41. Take home • Do Not stop an asthmatics steroids • Inhaled steroids reduce deaths by 58% • after discontinuation rate of death increases over first 3 months • sudden onset asphyxia is often from medications (ASA, B-Blocker)

  42. Latest & Greatest • Stage II trials of anti-IgE meds inhibits mast cells and basophils • Pre anti-IL4 trials induces T’s-->Th2 lymphs, induces IgE expression in B’s, induces endothelial cells to express VCAM • New target IL5 eotaxin/MBP

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