January 15, 2016 - Clinical Asthma

Question 1

Asthma in Canada

Answer 1

About 8% of the population has asthma. (5-10% prevalence)

About 50% of people with asthma is poorly controlled.

Question 2

Most Common Non-Communicable Pediatric Disease

Answer 2

Asthma

Question 3

Asthma Economics

Answer 3

It is the inverted pyramids.

10% of people with severe or uncontrolled asthma make up 54% of the cost spent on asthma. 70% of people with mild or controlled asthma make up only 13% of the cost.

If you can keep asthma under control, you will decrease cost.

Question 4

Pathophysiology of Asthma

Answer 4

Early stage has to do with mast cells and constriction of the airways.

Late stage has to do with infiltrates of lymphocytes, neutrophils, and eosinophils.

Can cause inflammation and edema, mucus and plasma exudation, smooth muscle contraction, and epithelial damage/shedding.

Question 5

Asthmatic Airways

Answer 5

Asthmatic airways often have increased vasculature, are inflamed, and are edematous. These result in a compromise in airspace lumen.

Question 6

Correlation of Atopic Diseases

Answer 6

Asthma often correlates with other types of allergies. It os common to have overlap with allergic rhinitis and eczema.

If the patient has these, you want to get these under control first as they can be an excaberating factor.

Question 7

Early and Late Asthmatic Response

Answer 7

Early phase is due to mast cell release.

Late phase is due to cellular infiltration.

Question 8

Potential Asthma Triggers

Answer 8

Infections - particularly viral respiratory

Irritants - tobacco and air pollution, noxious chemicals, cold air/exercise

Allergens - cats, dogs, dust, aspergillus, suphites, MSG

Drugs - aspirin/NSAIDs, beta-blockers

Miscellaneous - strong emotional response

Question 9

Clinical Presentation of Asthma

Answer 9

Variable wheezing, dyspnea, chest tightness, cough.

May be worse at night or in the morning.

Question 10

Demonstrating Varible Airflow Obstruction

Answer 10

Spirometry: for adults - less than 75% FEV1 and an increase of 12% or more after a bronchodilator has been applied with more than 200mL of increase. For children, less than 80% with an increase of 12% with bronchodilator.

Question 11

Methacholine Challenge

Answer 11

Patient is exposed to increasing concentrations of methacholine.

You are looking for a 20% drop in FEV1, and the concentration where FEV1 drops 20% is known as the PC₂₀.

PC₂₀ <4mg/mL - consistent with asthma

PC₂₀ >16mg/mL not consistent with asthma

PC₂₀ >4-16mg/mL is indeterminate

Question 12

Diagnostic Testing for Asthma

Answer 12

Pulmonary function testing - spirometry/peak flow as well as methacholine challenge is useful to aid in diagnosis

CBC - may show eosinophilia

IgE level - may be elevated

Question 13

Asthma vs. COPD

Answer 13

Age of onset - asthma may be at any age but tends to be younger, and most cases of COPD are in patients over the age of 50

Smoking Hx - asthma may or may not have, but COPD is almost invariably a current smoker or an ex-smoker

Cough - asthma is often nocturnal, while COPD is often in the morning

Wheeze & Dyspnea - asthma is usually episodic, while COPD is more gradual and progressive

Peak Flow - Reduced and variable in asthma, while it is usually reduced and consistent in COPD

Bronchodilator trial - asthma often shows an increase in FEV1 while COPD will usually have no change

Steroid trial - asthma shows a good response, and COPD shows minimal