Aidan at 01:21, 5 October 2020

2020-10-05T01:21:58Z

Aidan: Text replacement - "Clinical Presentation" to "Clinical Manifestations"

2020-07-14T23:43:45Z

Text replacement - "Clinical Presentation" to "Clinical Manifestations"

← Older revision		Revision as of 23:43, 14 July 2020
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	* Parental asthma (RR=2)		* Parental asthma (RR=2)

	== Clinical ~~Presentation~~ ==		== Clinical Manifestations ==

	* Trigger-induced wheeze, dyspnea, cough, or chest tightness		* Trigger-induced wheeze, dyspnea, cough, or chest tightness

Maintenance script: Imported from text file

2020-07-04T01:17:24Z

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New page

== Differential Diagnosis ==

* Bronchopulmonary dysplasia
* Cystic fibrosis and other causes of bronchiectasis
* Eosinophilic granulomatosis with polyangiitis (eGPA): asthma, eosinophilia, and granulomatous vasculitis
* Vocal cord dysfunction: recurrent or severe 'asthma' with normal PFTs, needs laryngoscopy for diagnosis
* Allergic bronchopulmonary Aspergillosis (ABPA)
* Reactive airway dysfunction syndrome (RADS): irritant-induced asthma following a single high-intensity exposure
** Treat like asthma exacerbation, usually resolves over 3 months

== Risk Factors ==

* Parental asthma (RR=2)

== Clinical Presentation ==

* Trigger-induced wheeze, dyspnea, cough, or chest tightness
** Trigger can include exercise, cold, seasonal allergies
* Chronic cough

== Diagnosis ==

* Requires both of:
** ''Variable respiratory symptoms'': wheeze, dyspnea, chest tightness, or cough that vary over time
** ''Variable expiratory airflow limitations'': documentation by PFTs with either bronchodilator response or methacholine challenge, or possibly peak flows and exercise

=== Variable expiratory airflow limitations ===

* Document FEV1/FVC below the lower limit of normal at least once to document airflow limitation
* PFTs may be normal at time of initial assessment

==== Bronchodilator reversibility ====

* Improvement of FEV1 by 12% ''and'' 200 mL 10-15 minutes after 200-400 mcg salbutamol
* Better as a rule-out test than a rule-in test

==== Methacholine challenge ====

* Minimum concentration of methacholine required to produce a 20% decrease in FEV1 (PC20)
* Asthma diagnosed with PC20 <4 mg/mL
* Asthma excluded with PC20 >16 mg/mL

==== Exercise challenge ====

* Decrease in FEV1 of >10% ''and'' 200 mL from baseline following exercise

==== Peak expiratory flow (PEF) ====

* Twice daily peak flows over 2 weeks that have average daily diurnal variability >10%

==== Response to empiric treatment ====

* Improvement in FEV1 by >12% ''and'' 200 mL (or peak flow by >20%) after 4 weeks of empiric treatment

==== Repeated PFTs ====

* Excessive variation in FEV1 between visits >12% ''and'' 200 mL

== Classification ==

=== Uncontrolled Asthma ===

* Poor symptom control, or
* 2+ exacerbations requiring oral steroid in the past year, or
* One serious exacerbation requiring hospitalization in the past year, or
* Sustained FEV1 <80% of personal best

==== Severe Asthma ====

* Asthma requiring high-dose ICS with another puffer for the past year, or
* Oral steroids needed for 50% of the past year, or
* Uncontrolled asthma despite these therapies

== Investigations ==

* Pulmonary function tests, methacholine challenge
** Reversible airway obstruction: used for its NPV rather than PPV for asthma
* Peak expiratory flow

=== Severe Asthma ===

* Total IgE
* CBC for peripheral eosinophils
* Sputum eosinophils and FeNO, where available

== Management ==

=== Non-pharmacologic ===

* Confirm diagnosis
** Don't forget to rule out ABPA (allergic bronchopulmonary aspergillosis) if they have difficult-to-control asthma
* Environmental control and education
** Including inhaler technique, adherence, trigger avoidance, and management of comorbidities
** [https://asthma.ca/get-help/asthma-3/control/asthma-action-plan/ Asthma Action Plan]
* Weight loss and exercise
* Allergen/trigger avoidance and consider allergen immunotherapy
* Smoking cessation
* Vaccinations
* Avoid NSAIDs (and also non-selective beta blocker if possible)
* Manage comorbidities such as GERD, PND, and obesity

=== Pharmacologic ===

* Step-up management
*# SABA prn, or ICS/LABA prn if age >12
*# Add inhaled corticosteroid (ICS)
*# Add LABA if age >12
*# Add leukotriene receptor antagonist (LTRA)
* Before stepping up therapy, confirm inhaler technique and adherence!
* If they have had symptom control for 2 months and are at low risk of exacerbation, consider stepping down therapy
* If severe asthma, refer to Respirology

==== Specific Inhalers ====

* ICS decreases exacerbations, hospitalizations, and symptoms, and increases quality of life and lung function
** Decreases asthma-related mortality
* LTRA: only appropriate for first-line if they cannot tolerate ICS or has allergic rhinitis
* For step-up from low-dose ICS, ICS-LABA better than ICS-LTRA

==== Specific Populations ====

* Seasonal allergic asthma: start ICS as soon as symptoms begin, and continue until four weeks after the relevant pollen season ends
* Exercise-induced: salbutamol pre-exercise, then LTRA pre-exercise, then scheduled ICS
* Pregnancy:
** 1/3 improve, 1/3 stable, 1/3 worsen
** Exacerbations more common in second trimester
** Most evidence for budesonide, but treat as you would anyone else
* Aspirin-induced respiratory disease (Samter's triad): avoid ASA/NSAIDs, and treat as normal but often responds well to LTRA. Can try desensitizing to ASA.

=== Severe Asthma ===

* Should be referred on to Respirology
* Needs total IgE levels, CBC for eosinophils, and sputum eosinophils or FeNO (where available)
* Step-up therapies, in order of evidence (I believe):
** Can add tiotropium (LAMA) mist inhaler to ICS/LABA
** Can add chronic azithromycin to ICS/LABA
** Can add low-dose oral steroid
* Can add biologic
** Anti-IgE (omalizumab): for severe allergic asthma with IgE 30-700
** Anti-IL5 (mepolizumab, reilzumab, benralizumab): severe eosinophilic asthma (eos >300)
** Anti-IL4/IL13 (dupulimumab): severe eosinophilic asthma

== Asthma Control ==

* Having asthma control is defined as having ''all'' of the following:
** Daytime symptoms <4 days/week
** Nighttime symptoms <1 night/week
** Physical activity is normal
** Mild and infrequent exacerbations
** No abscence from work or school due to asthma
** <4 doses/week of rescue inhaler are needed
** FEV1 or PEF ≥90% of personal best
** PEF diurnal variation <10-15%
** <2-3% sputum eosinophils
* If all of the above conditions are ''not'' met, the patient does not have asthma control and medication should be titrated up
* If all of the above conditions ''are'' met and they are stable for several months, consider titrating down their medication

== Further Reading ==

* Lougheed MD, ''et al''. [https://dx.doi.org/10.1155%2F2012%2F214129 Canadian Thoracic Society 2012 Guideline Update: Diagnosis and Management of Asthma in Preschoolers, Children and Adults: Executive Summary]. ''Can Resp J''. 2012;19(6):e81-e88.

[[Category:Respirology]]

Asthma - Revision history

Aidan at 01:21, 5 October 2020

Aidan: Text replacement - "Clinical Presentation" to "Clinical Manifestations"

Maintenance script: Imported from text file