Asthma Flashcards
What is asthma?
Paroxysmal, recurrent attacks of cough, wheeze and dyspnea due to reversible airways narrowing with inflammation and hyper-responsiveness
Asthma risk factors and triggers?
- Genetic predisposition
- Often precipitated by environmental triggers
- Hormonal factors
- Gastrointestinal Reflux
- Stress
- Drugs: beta-blockers, NSAIDs
- Occupational Asthma
State environmental triggers of asthma?
- Allergens
e.g. dust, pets, pollens, occupational - Infections
e.g. viral - Environmental pollutants
e.g. smoke, dust - Physical factors
e.g. cold air, exercise, hyperventilation
What is occupational asthma?
it is characteristically associated with symptoms at work with relief on weekends and holidays
- If removed from exposure within the first 6 months of symptoms, there is usually complete recovery
Describe the hormonal asthma trigger?
- Some women show premenstrual worsening of asthma, which can occasionally be very severe
- are related to a fall in progesterone and in severe cases may be improved by treatment with high doses of progesterone
What is the pathophysiology of asthma?
- genes predisposing to allergies + lack of early Th1 stimulation = increase Th2 expression
- Th2 releases IL-4 and IL-3
- B cells are activated and release IgE antibodies
- mast cells are activated by the IgE antibodies and allergens
- mast cells release histamine, leukotrines and cytokines
- there is a hyperactive response - bronchospasm, edema, airway obstruction
- there is chronic inflammation and tissue remodeling
Roles of Th1 and Th2?
Th1 - protective immunity
Th2 - allergic disease e.g. asthma
Factors favoring Th1 phenotype?
- presence of older sibling
- early exposure to day care
- TB, measles, hepatitis A infection
- rural environment
Factors favoring Th2 phenotype?
- widespread use of antibiotics
- western lifestyle
- urban environment
- diet
- sensitization to house dust mites and cockroaches
Clinical features?
- Episodic breathlessness
- cough
- expiratory wheezing
- Specific triggers (clinical history!)
What 2 clinical tests will show you characteristic features of asthma?
- peak flow diary
- spirometry
Peak flow diary in asthma?
- normal PEFR is 300-700 litres/min
- shows >20% diurnal variation on > / = 3 days in a week for two weeks
Explain the diurnal variation in the peak flow diary?
in the morning our bronchioles are more constricted so that’s when asthma patients usually have their exacerbations
Spirometry features in asthma?
decrease in FEV1 > 15% in response to stimulus challenge
e.g exercise, histamine, metacholine
Note: FEV1 improves by ≥ 12% and ≥ 200mls with bronchodilators
What is the skin pricktest for asthma?
a medical provider pricks your skin using a needle with a small amount of allergen
- if you are allergic the spot will get red, swollen and itchy
How does spirometry work?
a spirometer measures the amount of air you can breathe out in one second and the total volume of air you can exhale in one forced breath
- these measurements will be compared with the expected normal result for someone of your age, height and sex
Classification of drugs for asthma?
- bronchodilators
- leukotriene antagonists
- mast cell stabilizers
- corticosteroids
- anti Ig-E antibody
Bronchodilator classses and drugs?
- Beta-sympathomimetics
- salbutamol, terbutaline, bambuterol, salmeterol - methyl xanthines
- theophylline, aminophylline - anticholinergics
- ipatropium bromide, tiotropium bromide
Leukotriene antagonist drugs?
- montelukast
- zafirlukast
Mast cell stabilizer drugs?
- sodium chromoglycate
- ketotifen
Corticosteroids drugs?
- systemic
- hydrocortisone, prednisolone - inhalational
- bevlomethasone, budesonide, fluticasone, flunisolide
Anti Ig-E antibody?
omalizumab
Features of mild asthma?
- undistressed
- RR < 25
- HR > 110bpm
- O2 stats > 97%
- PEFR > 75% predicted
Treatment of mild asthma?
- 5mg salbutamol nebulizer
OR - salbutamol 4-10 puffs pMDI
- repeat every 20 mins and reassess in 1 hr
- discharge if stable
Features of moderate asthma?
- distressed but no signs of severe asthma - can complete a sentence
- PEFR 50-75%
Treatment of moderate asthma?
- salbutamol 4-10 puffs pMDI or spacer
- repeat every 20 mins for 1 hr
OR - 5mg salbutamol nebulizer
- repeat after 15-20 mins - prednisolone 40mg PO od
- observe overnight
What do you discharge mild and moderate asthma on?
- prednisolone 40mg PO od for 5-7 days
- prednisolone 1mg/kg (max 50 mg od) - salbutamol inhaler
- beclomethasone inhaler 2 buffs bd
- see clinic in 4-6 weeks
Signs of severe asthma?
- distressed with signs of severe asthma
- cannot complete a sentence
- RR>25
- HR>110bpm
- O2<97%
- PEFR- 33-50%
Treatment of severe asthma?
- 5 mg salbutamol nebulizer
- repeat every 20 minutes for i hr and then reassess O2 supplement (aim 93-95%) - prednisolone 40mg PO od
- magnesium sulphate 2g slow IV (over 20 mins) stat (dose 40mg/kg max 2g)
- +/- aminophylline IV (250 mg slow over 20 mins)
Signs of life threatening asthma?
- exhausted
- drowsy
- confused
- silent chest
- cyanotic O2 stats <92%
- PEFR 33%
Treatment of life threatening asthma?
- 5mh salbutamol nebulizer and repeat every 10-20 mins for reassess O2 supplement
- prednisolone 40mg PO od or IV hydrocortisone 2–mg 6-8 hrly
- magnesium sulphate 2g slow IV
- +/- aminophylline IV
- ICU review for elective intubation and mechanical ventilation
Ongoing care for severe and life threatening asthma?
- regular medical review
- if no improvement, needs ITU review
- consider pneumothorax
- chest infection
- other respiratory pathology - ensure adequate hydration
- including IV fluids
Treatment of a mild/moderate asthma attack?
- Carefully teach and monitor correct inhaler technique
- Salbutamol inhaler 4-10 puffs via a spacer device or salbutamol nebulizer repeated as required initially, then every 8 hours
- Keep under observation at least 24 hours after the attack
Clinical signs of life threatening asthma?
- Silent chest
- Central cyanosis
- Tachypnoea RR > 30
- exhaustion
- inability to speak through a sentence - Persistent tachycardia > 110 bpm
- bradycardia
- hypotension
- pulsus paradoxus - Use of accessory muscles
- Confusion, agitation, coma
- Peak flow < 33 % of predicted
What to do for life threatening asthma?
immediate hospitilization
Severe/life threatening asthma differentials?
- Acute LVF
- Pneumothorax
- PE
- Upper airways obstruction
- Massive pleural effusion
- Severe pneumonia
Severe asthma treatment?
- IV line, rehydrate with 0.9% NS
- High flow oxygen 5l/min
- Salbutamol nebuliser solution 5 mg by nebulizer
- repeat as required (every 15-30 min), then q 6 hrs
or Salbutamol MDI 4 puffs via spacer - Hydrocortisone 200mg iv q 8 hours 3-5 days
- If you use steroids > 10 days, gradually taper the dose for steroids, 10 mg per week initially, and decrease by 5 mg until you stop.
- Antibiotic: Amoxycillin 500 mg q 8 hours or Doxycycline
What to do if there is no improvement in treatment for severe asthma?
- add Aminophylline 250 mg slow over 10 min
- If no response:
- Aminophylline 250 mg over 12 hours
- Magnesium sulphate 1.2-2 g iv over 20 min
- Adrenaline 0.5-1.0 ml of 1:1000 slowly nebulised or i.m.
Management of acute asthma principles?
- Exclude other conditions:
- stridor and upper airway obstruction (inspiratory difficulty rather than expiratory wheeze of asthma)
- heart failure - Give antibiotics
- only with evidence of precipitating infection
What to do before discharge of n acut asthma attack?
Check correct use of Metered Dose Inhaler (MDI) in your patients
- use a spacer device, especially during attacks.
- Can use plastic bottle (cut hole in bottom of bottle), shake MDI before use, prime bottle with 2 puffs
Maintenance and preventive treatment of asthma?
STEP 1: Salbutamol MDI with Spacer
STEP 2: if required more than once every day add inhaled steroid (Beclamethasone 2 puffs) BID, increase to 4 puffs as required
STEP 3: Refer to specialist if not controlled
Describe assessment of symptom control?
in the past 4 weeks has the patient had:
1. daytime symptoms more than twice a week
2. any night waking due to asthma
3. SABA reliever needed more than twice a week
4. any activity limitation due to asthma
Classifying level od asthma control?
- well controlled - none
- partly controlled - 1-2 symptoms
- uncontrolled - 3-4 symptoms
Stepwise management of asthma?
- mild intermittent
- SABA - mild persistent
- SABA
- ICS low dose - moderate persistent
- SABA
- ICS low dose
- LABA - severe persistent
- SABA
- ICS high dose
- LABA - very severe persistent
- SABA
- ICS high dose
- LABA
- OCS
