Updated: 4/25/2019

Asthma

Topic
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Questions
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Evidence
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Snapshot
  • A 5-year-old is brought to his pediatrician’s office by his parents because he cannot keep up with his friends while playing outside because he is short of breath. His parents report that they notice him occasionally coughing at night but he is otherwise healthy. On physical exam, respiratory rate is within normal limits and slight end expiratory wheezing is appreciated diffusely.
Introduction
  • Clinical definition
    • a reversible, intermittent obstructive disease of the small airways characterized by inflammation and hyperresponsiveness
  • Epidemiology
    • can present at any age
    • most common chronic pediatric disease
    • risk factors
      • atopy
        • strongest identifiable factor
        • atopic dermatitis
        • food allergies
        • allergic rhiniti
      • family history
      • smoking
      • obesity
      • air pollution
  • Pathogenesis 
    • acute, subacute, or chronic inflammation
    • an elevated level of IgE binds mast cells and triggered by an antigen to release histamine and initiate an inflammatory cascade
      • common triggers
        • allergies (house dust mites)
        • upper respiratory infection
        • cold air
        • exercise
    • obstruction secondary to airway hyperresponsiveness, edema, mucus plugging, and smooth muscle hypertrophy
  • Classification based on daytime and nighttime symptoms
 
Asthma Classification
Severity Symptom Frequency
Pulmonary Function Test
Intermittent
  • ≤2 days/week
  • ≤2 nights/month
  • FEV1 > 80% of predicted
Mild persistent
  • >2/week but <1/day
  • >2 nights/month
  • FEV1 ≥ 80% of predicted
Moderate persistent
  • Daily daytime
  • >1 night/week
  • FEV1 60-80% of predicted
Severe persistent
  • Continual daytime
  • Frequent nighttime
  • FEV1 <60% of predicted

Presentation
  • Symptoms 
    • often worse in the early morning and at night 
    • wheezing
    • productive cough
    • shortness of breath
    • chest tightness
  • Physical exam
    • chronic asthma
      • possibly normal
      • wheezing
    • acute exacerbation
      • wheezing
      • accessory muscle usage
      • paradoxical breathing
      • decreased breath sounds
      • prolonged expiratory phase
      • tachypnea
      • pulsus paradoxus 
      • hyperresonance
  • Special presentations
    • Samter triad
      • aspirin and nonsteroidal anti-inflammatory drug sensitivity, asthma, and nasal polyps
    • exercise induced bronchoconstriction
      • only associated with exercise
    • cough variant
      • only cough symptoms 
Studies
  • Diagnostic testing
    • diagnostic approach
      • in acute exacerbation of asthma
        • provide supportive care and lifesaving treatments first
        • use peak expiratory flow rate to monitor
        • pulmonary function test as an outpatient later
    • imaging
      • chest radiograph 
        • may be normal
        • hyperinflammation if severe
    • studies
      • pulmonary function tests 
        • gold standard
      • peak expiratory flow rate
        • can be used at home to monitor obstruction
        • < 50% of personal best indicates a severe obstruction 
      • arterial blood gas
        • mild hypoxia with early respiratory alkalosis due to tachypnea 
        • normalization of PCO2 could indicate fatigue and impending respiratory failure
          • interpret in the context of the overall clinical picture
        • if severe, respiratory acidosis due to CO2 retention 
  • Diagnostic criteria
    • pulmonary function tests
      • an obstructive pattern of FEV1/FVC <70% is consistent with diagnosis
        • if consistent with obstructive lung disease, reverse with a beta-agonist
          • increase of ≥12% from baseline and ≥200 mL
        • if normal in a well patient but high clinical suspicion, induce with a methacholine challenge
          • decrease of ≥20% from baseline
      • increased residual volume and TLC
      • normal DLCO 
Differential
  • Anaphylaxis
    • distinguishing factors
      • swollen mouth, hypotension, and gastrointestinal symptoms
  • Foreign object lodged in the respiratory tract
    • distinguishing factors
      • foreign object visualized on chest radiograph
  • Post nasal drip
    • distinguishing factors
      • sore throat and excessive mucus
  • Congestive heart failure
    • distinguishing factors
      • volume overload visualized on chest radiograph and physical exam
  • Gastroesophageal reflux disease
    • distinguishing factors
      • sour taste, regurgitation, and burning sensation
Treatment of Acute Exacerbations
  • Management approach
    • administer lifesaving treatments and monitor serially with for signs of respiratory failure
      • physical examinations
      • peak expiratory flow rate 
      • ABG
  • Medical
    • first-line 
      • humidified O2
      • β2-agonists via metered dose inhaler, or nebulizer
    • second-line
      • intravenous methylprednisone
        • indication
          • if poor response to first-line treatment
  • Interventional
    • non-invasive positive pressure
      • indication
        • if poor response to medical management above
        • only appropriate for alert patients with intact airway
    • intubation 
      • indications
        • if continued threat of airway obstruction despite first-line and second-line treatment
        • if unable to protect airway due to reduced consciousness
        • if PCO2 normalizes or is elevated (patient should be hyperventilating leading to low PCO2, if the patient becomes fatigued, PCO2 will begin to increase)
Treatment of Chronic Asthma
  • Management approach
    • based on a step-wise approach building upon existing therapy
    • all patients should have a short-acting β2-agonists as needed
  • Therapy based on the classification 
    • intermittent
      • treat with short-acting β2-agonists as needed
      • no daily long-term treatment needed
    • mild persistent
      • add low-dose inhaled corticosteroid
        • predisposes to oral candidiasis ("thrush") 
    • moderate persistent
      • add long-acting β2- agonist to inhaled low-dose corticosteroid
      • alternative: add leukotriene modifier or theophylline
      • alternative: inhaled medium-dose corticosteroid only
    • severe persistent
      • inhaled medium- or high-dose corticosteroid with long-acting inhaled β2-agonist 
      • if continued poor control, consider oral corticosteroids or omalizumab (anti-IgE)
  • Other medical management strategies 
    • cromolyn
      • indication
        • exercise prophylaxis
    • montelukast
      • indication
        • exercise prophylaxis or aspirin-induced asthma 
    • inhaled β2- agonists
      • indication
        • prior to exposure to triggers such as exercise
  • Lifestyle modifications including allergy avoidance
Complications
  • Acute respiratory failure
  • Status asthmaticus
  • Atelectasis
  • Pneumothorax
  • Use of non-specific β-blockers (i.e., blocking β2) can close airways leading to death
 
 

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Questions (7)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
Calculator

(M2.PL.4799) A six-year-old boy with a history of asthma currently uses an albuterol inhaler as needed to manage his asthma symptoms. His mother brings him into your office because she feels she has had to increase the patient’s use of his inhaler to four times per week for the past month. She also reports that he has woken up three times during the night from his symptoms this month. The boy reports that he is upset because he can’t always keep up with his friends in the playground. His past medical history is significant for allergic rhinitis. The patient’s temperature is 98°F (36.6°C), blood pressure is 110/70 mmHg, pulse is 88/min, and respirations are 18/min with an oxygen saturation of 98% O2 on room air. Auscultation of his lungs reveals bilateral late expiratory wheezes.

What changes should be made to his current asthma treatment regimen? Review Topic

QID: 109291
1

Maintain current therapy

0%

(0/25)

2

Add cromolyn prior to exercise

4%

(1/25)

3

Add fluticasone daily

80%

(20/25)

4

Add salmeterol twice daily

16%

(4/25)

5

Add zileuton twice daily

0%

(0/25)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

(M2.PL.4799) A 55-year-old female patient comes to your office complaining of white spots on her tongue. She reports that she first noticed them about one week ago. She denies pain or difficulty swallowing. Her past medical history is significant for asthma, hepatitis C, and heroin abuse. She had previously been homeless and only recently went to the doctor one month ago for the first time in over five years. At that time, her primary care physician prescribed sofosbuvir, an albuterol inhaler, and daily inhaled fluticasone, which she has been using as directed. She is sexually active with one male partner. Her last HIV test was negative, and she does not have a history of sexually transmitted diseases. She denies current alcohol or intravenous drug use. She smokes a pack a day of cigarettes and reports she has been smoking since she was 16. On physical examination, you note lesions on her oral mucosa that are easily scraped off, as shown in Figure A.

Which of the following is the best treatment for this patient’s most likely diagnosis?
Review Topic

QID: 109290
FIGURES:
1

Acyclovir

0%

(0/40)

2

Nystatin suspension

85%

(34/40)

3

Smoking cessation

5%

(2/40)

4

Surgical removal

8%

(3/40)

5

Topical betamethasone

0%

(0/40)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

(M2.PL.4799) A 26-year-old male comes into your clinic complaining of worsening asthma symptoms. He reports that when he was first diagnosed with asthma, he experienced shortness of breath and chest tightness around twice a month. Then last month he began to get short of breath three times a week. He uses his albuterol inhaler during these episodes with temporary improvement of his symptoms. He denies nighttime awakenings due to his symptoms, but he does complain that his symptoms are interfering with his marathon training. His past medical history is significant for type I diabetes. His current medications include insulin and his albuterol inhaler. When asked about over-the-counter medications, he reports that he takes a multivitamin and aspirin, which he has been using for muscle soreness associated with his increased training schedule. A review of systems is also notable for headaches, nasal congestion, rhinorrhea and anosmia. The patient’s temperature is 99°F (37.2°C), blood pressure is 120/78 mmHg, pulse is 84/min, and respirations are 14/min with an oxygen saturation of 98% O2 on room air. On physical exam, you note bilateral expiratory wheezing and lesions within the nasal cavity, shown in Figure A.

Which of the following is the best initial treatment for this patient’s symptoms? Review Topic

QID: 109289
FIGURES:
1

Aspirin desensitization

33%

(18/55)

2

Montelukast

36%

(20/55)

3

Omalizumab

9%

(5/55)

4

Salmeterol

20%

(11/55)

5

Theophylline

2%

(1/55)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 2

(M2.PL.192) A 48-year-old male with a history of rhinitis presents to the emergency department with complaints of shortness of breath and wheezing over the past 2 days. He reports bilateral knee pain over the past month for which he recently began taking naproxen 1 week ago. Physical examination is significant for a nasal polyp and disappearance of bilateral radial pulses on deep inspiration. Which of the following is the most likely cause of this patient's physical examination findings? Review Topic

QID: 104198
1

Pulmonary hypertension

33%

(1/3)

2

Interstitial lung fibrosis

0%

(0/3)

3

Asthma

33%

(1/3)

4

Pulmonary embolism

0%

(0/3)

5

Cardiac tamponade

33%

(1/3)

M2

Select Answer to see Preferred Response

PREFERRED RESPONSE 3
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