Asthma Flashcards
1
Q
Asthma
Definition
A
Chronic inflammatory disorder of the airways.
- Many cells and cellular elements involved
- Airway hyper-responsiveness
- Caused by reversible generalized narrowing of the airways
- Periodic ↑ contraction of airway smooth muscle and hypersecretion of bronchial mucus in response to internal or external stimuli
2
Q
Asthma
Epidemiology
A
- 24 million people in USA
-
Most common chronic childhood disease ⇒ ~ 5 million kids
- Boys > Girls
- Women > men (over age 40)
- Prevalence rate ↑ 1%/yr
- Mortality rates ↑ in late-half of 20th century
- Highest risk population ⇒ urban minorities living in poverty areas
3
Q
Asthma
Risk Factors
A
- Genetics
-
Atopy ⇒ genetic tendency to develop allergic diseases
- Typically associated with heightened immune responses to common allergens, especially inhaled and food allergens
-
Atopy ⇒ genetic tendency to develop allergic diseases
- Environmental cigarette smoke exposure
- House dust mite exposure
- Cockroach allergen
- RSV infection
4
Q
Asthma
Bronchial Changes
A
5
Q
Bronchial Wall
Comparison
A
6
Q
Asthma
Histological Changes
A
- Thickened basement membrane
- Edema
- Inflammatory infiltrates
- Prominence of eosinophils in bronchial wall and sputum
- Hypertrophy of bronchial wall smooth muscle
- Mucus gland proliferation
7
Q
Asthmatic Sputum
A
Sputum can include:
- Curshmann spirals ⇒ dried out mucus
- Charcot Leyden crystals ⇒ eosiniphil breakdown product
- Bronchial casts
8
Q
Mucus Histology
A
9
Q
Airway Inflammation
A
Causes obstructive lung disease by four mechanisms:
- Acute bronchoconstriction
- Swelling and edema of the airway walls
- Airway remodeling
- Mucus plug formation
10
Q
Asthma Phenotyping
A
- Asthma is not one disease
- Several pathologic phenotypes lead to same sx manifestations
- Characterizing phenotype ⇒ more customized asthma threatment
- Increasing importance w/ new biologic treatments
11
Q
Airway
Hyper-responsiveness
A
Exposure to specific and nonspecific irritants cause airways to become narrow and obstructed.
Level of airway responsiveness correlates with severity of disease.
12
Q
Airway
Inflammation
A
-
Asthmatics usually have increased leukocytes
- Activated eosinophils
- Mast Cells
- MΦ
- T-cells
- Cells may be present when pt clinically asymptomatic
- E/O asthma phenotypes with similar disease manifestations
- Many inflammatory mediators involved
13
Q
Allergic Asthma
A
Asthma exacerbation precipitated by exposure to allergens in many patients.
Atopic mechanism.
Binding of Ag to cell-bound IgE stimulates mediator release from mast cells, MΦ, and basophils.
Preformed vs non-preformed mediators.
14
Q
Preformed Mediators
A
-
Histamine and serotonin
- Bronchoconstriction, swelling, edema
-
Proteolytic enzymes and histamine
- Disrupt or destroy pulmonary lining
- Allows fluid to leak in
- Leads to swelling, edema, obstruction
- Removes barrier to inhaled irritants
- Easier to trigger another attack
- Allows fluid to leak in
- Disrupt or destroy pulmonary lining
15
Q
Non-preformed Mediators
A
Formed at time of activation from arachidonic acid.
-
Lipoxygenase products
-
Leukotriene B4
- Chemoattractant for inflammatory cells
-
Leukotriene C4
- Bronchoconstriction
-
Leukotriene D4
- Bronchoconstriction
-
Leukotriene B4
-
Cycooxygenase products
-
Prostaglandin D2
- Potent bronchoconstrictor
-
Prostaglandin D2
16
Q
Non-allergic Asthma
A
Airway epithelial cells can respond to injury or irritants by releasing cytokines.
GM-CSF ⇒ stimulate eosinophils and mast cells
17
Q
Neutrophilic Asthma
A
Some asthmatics have a predominantly Th1 type inflammation ⇒ neutrophils
- High levels of PMNs can be found in pts with severe asthma or during acute exacerbations
- Correlated with lower FEV1
-
Do not respond as well to therapy
- Corticosteroids do not reduce PMNs
- Most therapy targeted at eosinophils
- Linked to fatal asthma
18
Q
Bronchoconstriction
A
Caused by contraction of circular smooth muscle within bronchial walls.
-
Bronchoconstriction
- Inflammatory mediators
- PNS ⇒ irritant or cold air may trigger a parasympathetic vagal reflex ⇒ constriction
-
Bronchodilation
-
SNS
- NE/Epi ⇒ cAMP ⇒ relaxation
-
Non-adrenergic, non-cholineric inhibitor nerves
- Releases NO ⇒ potent bronchodilator
-
SNS
19
Q
Mucus Plugs
A
- Produced by glands located below epithelial lining
-
Asthma ⇒ ↑ production
- Inflammatory mediators
- PNS stimulation
- Can plug up airways causing further narrowing
20
Q
Airway Remodeling
A
- Inflammation & cytokines (TGF-β) ⇒ myofibroblast activation
- Myofibroblasts ⇒ collagen and fibronectin production
-
Results in airway remodeling ⇒ fixed obstruction
- Not reversed by bronchodilators
- Leads to residual obstructive lung disease despite max therapy
21
Q
Asthma
Etiologies
A
- Environmental
- Viral infection
- Sinusitis
- Exercise induced
- GERD ⇒ vagal response
- ASA induced
- Sampter’s triad: a chronic condition defined by asthma, sinus inflammation with recurring nasal polyps, and aspirin sensitivity
- Obesity
- Occupational
- Farmers ⇒ dust, hay, chemicals
- Painters ⇒ isocyanite asthma
- Cleaners ⇒ household products
22
Q
Aggrevating Factors
A
23
Q
Asthma
Presentation
A
- Any age group
- 75% dx prior to age 7
- Some show remission during adolescence
- Recurrent episodes
- Wheezing
- Breathlessness
- Chest tightness/pain
- Coughing
- Sputum production
- Particularly at night or early morning
- Widespread and variable airflow obstruction
- Often reversible either spontaneously or with treatment
24
Q
Asthma
Clinical Work-Up
A
- H&P
- PFTs
- FENO
- Bronchoprovocation testing
- Peak flow monitoring
- CBC and sputum for eosinophils
- CXR
25
Asthmatic History
* **Recurrent episodes of cough, wheezing, or SOB**
* **Return of function between episodes**
* Atopic history?
* Family history?
* Symptoms triggered by usual asthma triggers
* Exercise, allergens, airborne irritants, seasonal changes, after illness
26
Conditions That Mimic Asthma
27
Physical Findings
Varies with intensity of asthma.
May have no signs between attacks.
* Asthma exacerbations
* Tachycardia
* Tachypnea
* Fragmented speech
* Accessory muscle use
* Diaphoresis
* Mild asthmatics
* Persistent cough
* ± Wheezing
* Severe asthmatics
* **Quiet chest** ⇒ no wheezing and minmal breath sounds; implies minimal air flow
* **± Larger chest volume** ⇒ hyperinflation d/t air trapping
28
Asthmatic
Pulmonary Function Tests
* _Spirometry_
* Obstructive lung disease
* **FEV-1% \< 70% or lower limit of normal**
* May be normal between attacks
* **Improvement after trial of bronchodilator therapy**
* _Peak flow meters_
* Measures initial flow rate with forced expiratory effort
* **Absolute reduction in peak flow**
* **Variability in peak flow of more than 20%**
29
Bronchodilator Response
Defined as:
**12% improvement in FEV-1 & at least 200 cc improvement**
or
**12% improvement in FVC & at least 200 cc improvement**
or
**30% improvement in FEF 25-75%**
30
Peak Flow Meters
* **May be 1st sign of worsening asthma**
* Have pt do 3 times and take their best number
* Pt should know their "personal best"
* _Clinical relavence_
* Used with asthma action plan to improve health outcomes
* Triage severity of asthma exacerbation
* Used to determine triggers
31
FeNO
* **Marker of eosinophilic inflammation of the lungs**
* **Measures exhaled NO**
* Levels decrease with inhaled corticosteroids (ICS)
* Can be used to assess compliance and predict exacerbations
* Clinically practical
32
Bronchial Provocation Testing
**Inhaling an agent that provokes an asthmatic response to establish diagnosis.**
* Non-specific agents
* **Methacholine**
* **Mannitol**
* Histamine
* Cold air challenge
* Exercise challenge
* Inhaled antigens
* **20% drop in FEV-1 is significant**
* **Excellent negative predictive value**
33
CXR
* Usually done during preliminary evaluation
* Typically normal
* Asthmatic CXR
* Hyperinflation ⇒ see more ribs
* Flattening of diaphragm
34
Asthma
Evaluation
* **Assess severity** ⇒ intermittent or persistent; mild, moderate, or severe
* **Assess likelihood for exacerbation in the future**
* **Assess for degree of asthma control using a standard metric**
* E.g. Asthma Control Test
35
Asthma
Severity
Warrants daily therapy if experiencing sx:
\> 2 days per week
\> 2 nights per month
36
Asthma Control
**Asthma Control Test**
5 questions
Score ≤ 19 means poorly controlled
37
Asthma Therapy
Goals
Outlined by NAEPP and GINA:
* Achieve and maintain symptom control
* Prevent exacerbations
* Maintain pulmonary function as close to normal as possible
* Maintain normal activity levels, including exercise
* Avoid adverse effects of asthma medications
* Prevent development of irreversible airflow obstruction
* Prevent asthma mortality
38
Asthma Therapy
Components
Recommendations based on severity, control, and responsiveness.
_Includes:_
* **Patient education**
* **Asthma Action Plan**
* How to monitor asthma on a daily basis
* What to do if they have an exacerbation
* **Avoidance of asthma triggers**
* Allergens, irritants, respiratory viruses
* **Pharmacotherapy**
* Stepwise management ⇒ goal to limit sx or rescue inhaler use \< 2 days/wk or 2 nights/month
* **Immunotherapy when appropriate**
39
Pharmacotherapy
40
Patient Education
Provide patients with the info needed to self-manage their own asthma in conjunction with physician guidance.
* **Knowledge of avoidance measures**
* Active & passive smoking
* Beta-blockers
* In patients who are sensitive:
* ASA and NSAIDS
* Occupational agents
* Dust mites
* Other common allergens
* Foods and additives
* **Knowledge of treatment modalities**
* Diagnosis
* Rescue inhalers vs controllers
* Inhaler use training
* Advice regarding prevention
* Signs that might suggest asthma is worsening and actions to take
* Training in monitoring asthma
* How and when to seek medical attention
* Written self-management plan
41
Asthma
Management
* Intermittent
* SABA only
* Persistent
* Inhaled corticosteroids
* Add LABA
* Consider LTRA
* Biologics for appropriate patients
* Consider LAMA
42
Acute Exacerbation
Management
* **Short-acting** β-**agonists**
* Albuterol ⇒ intermittent neb, continuous neb, MDI
* MDI equivalent to nebulizers if proper technique used
* **Inhaled anticholinergic**
* Ipratropium bromide (Atrovent)
* May be given with albuterol with additive effects (Duoneb)
* **Steroids**
* Prednisone, methylprednisolone, or prednisolone
* PO or IV based on severity
* Dose: 40-80 mg/day until PEF reaches 70% of predicted or personal best
* Higher doses do not appear to offer added benefit
* **Adjunctive treatments**
* Oxygen if hypoxic
* Goal: O2 sat ≥ 90% if not pregnant, ≥ 95% if pregnant
* Magnesium ⇒ 2g IV over 20 minutes
* Heliox: 70/30 mixture
* Low viscosity gas ↓ WOB
* May prevent intubation in severe asthmatics
* CPAP/BiPAP
* ↓ WOB and may prevent intubation
43
Indications for Intubation
Clinical judgement based on:
* Rising or normal pCO2
* Progressive deterioration despite aggressive treatment
* Deteriorating mental status
* Refractory hypoxia
* Hemodynamic instability
44
Asthma
Summary
* Common disease
* Diagnosis based on history and findings suggestive of inflammation and airway contriction
* Treatment geared towards bronchodilation and decreasing inflammation
