Wednesday, January 4, 2017

Asthma

Asthma
Pulmonology makes up 12% of the PANCE and between 10-15% of the End of Rotation Examinations. This means that topics like Asthma, which are found on every topic blueprint, are likely to pop up. This makes it essential for you to know the ins-and-outs of asthma treatment plans, including triggers, signs and symptoms, diagnostic studies, severity index, and stepwise therapy.  


Before we begin, I want to point you in the right direction. Check out the guidelines by the NIH and the National Asthma Education and Prevention Program (NAEPP), which most PA schools teach.
  1. Asthma Action Plan (English) (Spanish)

And don't forget, for more practice questions, visit TrueLearn.com/DoseOfPA


Now onto the basics of Asthma...

  1. Characteristics
    1. Airway inflammation
    2. Airway hyperresponsiveness
    3. Reversible airflow obstruction
  2. May begin at any age
  3. Dyspnea common when exposed to rapid changes in temperature and humidity
Extrinsic
Intrinsic
  • Atopic: produce IgE to environmental triggers (eczema, hay fever)
  • Become asthmatic at young age
  • Not related to atopy or environmental triggers
  • PFTs (obstructive): decreased expiratory flow, low FEV1, and decreased FEV1/FVC ratio
    • Increased FEV1 > 12% with albuterol
    • Decrease in FEV1 >20% with methacholine or histamine
    • Increase in diffusion capacity of lung for carbon monoxide (DLCO)
General
Signs and Symptoms
Diagnostics
Therapy 1
Therapy 2
Triggers: pollens, house dust, molds, cockroaches, cats, dogs, cold air, viral infections, tobacco smoke, meds (BB, aspirin), exercise
Intermittent: SOB, wheezing, chest tightness, cough
-Occurs in 30 mins to exposure to triggers
-Symptoms worse at night
-Wheezing (inspiration AND expiration) is most common finding
-CXR: for first time wheezers
-PFTs: required to DX
-Spirometry before and after bronchodilators: increase in FEV1 or FVC by 12%

-SABA (albuterol) for acute attacks
  • Onset 2-5 min, duration is 4-6 hours
-LABA (salmeterol) for nighttime asthma and exercise induced asthma
-Inhaled Corticosteroids: mod to severe asthma
  • Use regularly to decrease airway hyperresponsiveness and exacerbations
-Montelukast: prophylaxis for mild exercise induced asthma and control of mild-mod
  • Allows for reduction in steroid and B2

-Cromolyn sodium: prophylaxis before exercise

AVOID Beta-BLOCKERS in asthmatics
Acute Asthma Exacerbation
Tachypnea
Sweating, wheezing, speaking in incomplete sentences, use of accessory muscles

-Paradoxical movement of the abdomen and diaphragm on inspiration
-Peak exp flow: low
  • Severe <60
-ABG: increased A-a gradient
-CXR: r/o pneumonia, pneumothorax
-Inhaled B2 agonist via nebs or MDI
-Corticosteroids: IV or orally
-IV magnesium: can help prevent bronchospasm

Complications:
-Status asthmaticus: does not respond to standard meds
-ARDS: resp muscle fatigue
-Pneumothorax, atelectasis, pneumomediastinum


Monitor peak flow (peak expiratory flow rate) - measures airflow obstruction
  • Adult normal ranges: 450-650 L/min (men) vs. 350-500 L/min (women)
  • Mild >300, Mod-Severe 100-300, Severe <100
  • Mild persistent asthma: monitor periodically, increase dose of inhaled steroid if peak flow decreases
  • Moderate persistent asthma: daily monitoring required. Increase dose of inhaled steroid if peak flow decreases
  • Severe persistent: daily monitoring; initiate prednisone if peak flow decreases


Severity
Long-term Control Medications
Mild intermittent (symptoms <=2 times/week)
None
Mild persistent (symptoms 2+ times/week, not everyday)
Low dose inhaled corticosteroid
Moderate persistent (daily sx, frequent exacerbation)
Daily inhaled corticosteroid (med dose) or cromolyn/nedocromil, methylxanthine, or antileukotriene
Severe persistent (continued sx, frequent exacerbation, limited physical activity)
Daily corticosteroid (high dose)
+ LABA or methylxanthine
+ oral corticosteroids


Bronchoprovocation test - useful when asthma suspected, but PFTs non-diagnostic
  • Measures lung function before and after inhalation of increasing doses of methacholine; hyperresponsive airways → obstruction at low doses


Chest XR - severe asthma reveals hyperinflation
  • Only get with severe asthma to r/o pneumonia, pneumothorax, pneumomediastinum, foreign body


Arterial Blood Gas (ABG) - if significant respiratory distress
  • Hypocarbia (common) with hypoxemia
  • If PaCO2 normal or increased, respiratory failure may ensue - asthmatics have increased respiratory rate, which should cause PaCO2 to DECREASE


Treatment
Acute Mild
PEF ≥ 70% pred or best
Dyspnea only with activity
SABA x 1-2 puffs (spacer, VHC, nebulizer)
First time wheezing – chest x-ray
Possible short course oral steroids
SABA prn: Albuterol
Acute Moderate
FEV1/PEF 40-69% pred or best
Dyspnea with normal activity
Requires office or ED visit
SABA x q 20 min (VHC, nebulizer) – 1 hr
SABA x q 60 min – 3 hrs; decide admit
Oral steroids
O2 if needed (SaO2 ≥ 90%)
Low dose inhaled corticosteroid: Fluticasone (Flovent)
Acute Severe
FEV1/PEF <40% pred or best
Dyspnea with conversation
Requires ED/hospitalization
High dose SABA (VHC) + anticholinergic (nebulizer, MDI) x q 20 min – up to 4 hr
Systemic Steroids – PO or IV
O2 if needed (SaO2 ≥ 90%)
Low dose ICS + LABA : Advair + Symbicort
Medium dose ICS + LABA
Advair or Symbicort
Life-Threatening
PEF <25% pred or best
Too dyspneic to speak
Requires ED/hospitalization/ICU
Possible Intubation and Mechanical Ventilation
Treatment as above; hourly/continuous SABA
IV Systemic Steroids
O2 if needed (SaO2 ≥ 90%)
High dose ICS + LABA + oral steroids
Advair or Symbicort + Prednisone


Sample Questions Provided by TrueLearn
Question 1: A 16 year old female presents to the ER in severe respiratory distress. She complains of persistent cough, dyspnea and chest tightness. Physical exam reveals a decreased inspiratory to expiratory duration, accessory muscle use, tachypnea, tachycardia, and decreased breath sounds. Upon further auscultation you hear the breath sound in the exhibit. What is the best next step in management of this patient’s condition?


  1. Montelukast
  2. Zafirlukast
  3. Cromolyn
  4. Albuterol
  5. Theophylline


Explanation:
The most likely diagnosis is asthma. Asthma is a reversible airway obstruction secondary to bronchial hyperreactivity, airway inflammation, mucous plugging and smooth muscle hypertrophy. Patients often present with cough, episodic wheezing, dyspnea, and chest tightness. Symptoms often worsen at night or early in the morning. Physical exam reveals wheezing, prolonged expiratory duration (decreased inspiratory to expiratory ratio), accessory muscle use, tachypnea, tachycardia, decreased breath sounds (late sign), decreased oxygen saturation (late sign), hyperresonance and possible pulsus paradoxus. Arterial blood gases demonstrate mild hypoxia and respiratory alkalosis. Normalizing PCO2, respiratory acidosis and more severe hypoxia in an acute exacerbation warrant close observation as they may indicate fatigue and impending respiratory failure. Spirometry may show a decreased FEV1/FVC ratio. Eosinophilia may be seen on a CBC while a CXR shows signs of hyperinflation. Asthma can be definitively diagnosed with a methacholine challenge test. Treatment in general includes avoiding allergens and potential triggers, beta-2 agonists, corticosteroids, muscarinic antagonists, methylxanthines, cromolyn and antileukotrienes. Treatment is dependent on classification. Asthma is divided into 4 types: mild intermittent, mild persistent, moderate persistent and severe persistent. Acute treatment of an asthma attack involves supplemental oxygen, bronchodilators such as albuterol and muscurinic antagonists such as ipratropium.


Answers A & B: Montelukast and zafirlukast are antileukotrienes that work by blocking leukotriene receptors thereby preventing bronchoconstriction. Zileuton is a 5-lipoxygenase inhibitor that blocks the conversion of arachidonic acid to leukotrienes thereby blocking bronchoconstriction. These medicines are not used in the acute treatment of asthma, they are used to prevent asthma attacks.


Answer C: Cromolyn prevents the release of vasoactive mediators from mast cells. It is useful for exercise-induced bronchospasm. It if effective only for the prophylaxis of asthma and is not used in an acute asthma attack.


Answer E: Theophylline likely caused bronchodilation by inhibiting phosphodiesterae thereby decreasing cAMP hydrolysis by increased cAMP levels. It use is limited because of its narrow therapeutic window. Toxicity may manifest as cardiac or neurologic symptoms.


Bottom Line: Acute asthma exacerbations are treated with supplemental oxygen, beta-2 agonists and muscarinic antagonists. Exams are moving toward adding more and more media clips in the form of pictures, video or audio. You need to be able to diagnose many conditions based on common physical exam signs. In addition to lung sounds, you should try and learn to recognize how to diagnose murmurs based on what they sound like.


Question 2: A 12 year old female presents to the ER in severe respiratory distress. She complains of persistent cough, dyspnea and chest tightness. Physical exam reveals a decreased inspiratory to expiratory duration, accessory muscle use, tachypnea, tachycardia, and decreased breath sounds. Upon further auscultation you hear the breath sound in the exhibit below. What is the most likely diagnosis?


  1. Asthma
  2. Inhaled foreign body
  3. Lobar pneumonia
  4. Interstitial pneumonia
  5. Pleuritis


Explanation:
The most likely diagnosis is asthma. Asthma is a reversible airway obstruction secondary to bronchial hyperreactivity, airway inflammation, mucous plugging and smooth muscle hypertrophy. Patients often present with cough, episodic wheezing, dyspnea, and chest tightness. Symptoms often worsen at night or early in the morning. Physical exam reveals wheezing, prolonged expiratory duration (decreased inspiratory to expiratory ratio), accessory muscle use, tachypnea, tachycardia, decreased breath sounds (late sign), decreased oxygen saturation (late sign), hyperresonance and possible pulsus paradoxus. Arterial blood gases demonstrate mild hypoxia and respiratory alkalosis. Normalizing PCO2, respiratory acidosis and more severe hypoxia in an acute exacerbation warrant close observation as they may indicate fatigue and impending respiratory failure. Spirometry may show a decreased FEV1/FVC ratio. Eosinophilia may be seen on a CBC while a CXR shows signs of hyperinflation. Asthma can be definitively diagnosed with a methacholine challenge test. Treatment in general includes avoiding allergens and potential triggers, beta-2 agonists, corticosteroids, muscarinic antagonists, methylxanthines, cromolyn and antileukotrienes.


Answer B: An inhaled foreign body may present with stridor. Stridor is a high pitched wheezing that is caused by the obstruction of the trachea either by inflammation or an object. Just enough air passes the obstructed point to cause a high-pitched whining wheeze. An inhaled foreign body may become lodged in the trachea or mainstem bronchus. Radiographs may show signs of hyperinflation. Treatment consists of rigid bronchoscopy.


Answer C: Lobar pneumonia may present with rales, whispered pectoriloquy or egophony on physical exam. It can be acute in onset and caused by various organisms depending on certain patient demographics.


Answer D: Interstitial pneumonia may present with rales, whispered pectoriloquy or egophony on physical exam. It can be acute in onset and caused by various organisms depending on certain patient demographics.


Answer E: Pleuritis is inflammation of the pleural lining of the lung. It can present with pleuritic chest pain which is defined as a knife-like pain on inspiration and may be caused by a number of disorders such as a PE or infection. It often presents with a pleural friction rub on physical exam. Pleural Friction Rubs are created when the visceral and parietal pleurae become inflamed and roughened. The inflamed membranes will stick together. As the therapist auscultates the chest wall, the rubbing together of the inflamed membranes will cause the patient to experience pain and stop breathing - a maneuver called splinting. The pain is caused by the sticking together of the membranes and the pulling apart of those membranes with continued breathing. Once the membranes slip past one another and break free from the sticking point, then the patient is pain-free and inhalation or exhalation can continue. The sound that a pleural friction rub makes is a leather-on-leather type of sound. These sounds can be heard at the same points in the inhalatory and the exhalatory cycles.


Bottom Line: Wheezing is a common type of breath sound heard in patient with asthma. Exams are moving toward adding more and more media clips in the form of pictures, video or audio. You need to be able to diagnose many conditions based on common physical exam signs. In addition to lung sounds, you should try and learn to recognize how to diagnose murmurs based on what they sound like. For more information, see: http://www.uptodate.com/contents/asthma-symptoms-and-diagnosis-in-children-beyond-the-basics


Question 3: A mother brings her 10 year old son to the office for a follow-up examination to discuss pulmonary function test results that were preformed last week. You inform her that your suspicions have been confirmed and her son has asthma. She begins to tell you how she has looked up asthma on the internet and refuses to put her son on any steroids. You would then discuss the following medication as an option for long term control with the patient's mother:


  1. Albuterol
  2. Prednisone
  3. Salmeterol
  4. Theophylline
  5. Montelukast

Explanation:
Montelukast (Singulair) is a leukotriene receptor antagonist that may be used as an alternative to inhaled glucocorticoids as a long-term asthma control agent.



Answer A: Albuterol is a short-acting beta agonist and is used acute relief of asthma and is not recommended for chronic control of the illness


Answer B: Prednisone should not be started at this time because of the requests made by the patient’s mother. This would prohibit all steroids from being given at this time


Answer C: Salmeterol is a long-acting beta agonist, which can be used for the long term management of asthma. However, due to recent studies linking the long-term use of long-acting beta agonists to increased mortality, salmeterol should only be used in combination with inhaled glucocorticoids, and never as monotherapy.


Answer D: Theophylline is incorrect because is used mostly in hard-to-control asthmatics and has a high side effect profile.


Bottom Line:  Bottom Line: An alternative to steroid treatment for asthma includes leukotriene receptor antagonists such as montelukast. We cannot emphasize enough how important it is to have a clear understanding of the correct approach to managing an asthmatic patient. Asthma is an extremely high-yield topic. Remember that ABG analysis may show mild hypoxia and respiratory alkalosis. Look for decreased FEV1 on pulmonary function tests. Regarding medication protocols for the treatment of chronic asthma, disease severity can be divided into 3 basic categories: mild, moderate, and severe. Always remember to treat cases of statis asthmaticus (prolonged, non-respondable asthma attack) with aggressive bronchodilatory therapy, corticosteroids, O2, and intubation if necessary. Remember AIRWAY, AIRWAY, AIRWAY!!! Mild (infrequent exacerbations): Treat only with inhaled short-acting beta-agonists during an attack. Moderate (daily and/or occasional nighttime attacks): Treat with inhaled beta-agonist and inhaled corticosteroid with consideration of adjunct therapy with cromolyn or a leukotriene inhibitor. Severe (multiple daily and nighttime attacks): Treat with inhaled beta-agonist, inhaled corticosteroid, and multiple additional therapies including systemic steroids.


Question 4: A 16 year old female presents to your office with shortness of breath with light activity. After examination and testing, she is determined to have asthma. The pharmacologic therapy that is likely to have the biggest impact on her FEV1 is:


  1. IV epinephrine
  2. Inhaled corticosteroids
  3. Inhaled beta-2 agonist
  4. IV beta-2 agonist
  5. SQ epinephrine


Explanation:
Part of the diagnosis of asthma is a response to an inhaled B2-agonist, demonstrated by an increase in FEV1. The other medications can be used in various ways to treat asthma, but will not have nearly as profound of an effect on FEV1 as an inhaled beta-2 agonist. Incorrect: Answer (A): Epinephrine is normally reserved for cases of life-threatening, refractory asthma. It can be given subcutaneously through the use of an epipen. Incorrect: Answer (B): Inhaled corticosteroids are commonly used to treat asthma in the mild/moderate/severe persistent categories, whereas inhaled beta-2 agonists alone are usually used in mild intermittent asthma. Incorrect: Answer (D): Clinical evidence for the use of IV beta-2 agonistsis weak. Inhaled beta-2 agonists have a more local effect on the lung. Incorrect: Answer (E): Epinephrine is normally reserved for cases of life-threatening, refractory asthma. Bottom Line: Inhaled beta-2 agonists are an effective tool in treating and diagnosing asthma due to their profound effect on FEV1. Asthma is a must know topic. You need to know how to categorize asthma based on symptoms and how to treat each category.

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