Chapter: Medicine Study Notes : Respiratory


Is chronic and obstructive, but not usually categorised with CORD



·        Is chronic and obstructive, but not usually categorised with CORD




·        Viral infections likely to trigger asthma

·        Night time cough and low peak flow can be asthma, ?hay-fever, a cold or bronchitis

·        Ask about:

o  Living situation

o  Occupation

o  Allergies, any pets?

o  Seasonal

o  Cold air

o  Irritants (eg fumes)

o  Exercise

o  Night cough

o  History of atopy: eczema

·        Classic symptoms: SOB, wheeze, cough, tightness (like in angina)




·        Always do peak flow. Not the same as FEV1, which is more accurate. FEV1 of 50% of predicted = PF of 70% predicted


·        If can‟t get a wheeze on auscultation, then take a big breath and blow out fast to elicit wheeze (=Forced  End Expiratory Wheeze).  Also listen to heart to ensure it‟s not a cardiac cause


·        Can you demonstrate reversible bronchial constriction? If peak flow (or FEV1 if spirometry available) ­ by 15% (60 – 70 litre/min) following bronchodilator. Do best of 3 peak flows, then repeat 15 minutes (= peak response time) after >= 2 doses of a reliever


·        There will be significant pathology even if mild: pseudo stratified epithelium gone, thickened basement membrane, ­eosinophils, hypertrophy of smooth muscle and glands, ­mucus

·        High-risk asthmatic (markers of ­ risk of death):

o   Hospital admission in last 12 months

o   Previous life threatening attack

o   Repeated self-administration of high doses of reliever (eg requesting 2 or more reliever prescriptions per month)


·        Precipitating factors in a life-threatening attack:

o   In kids (80%) and adults (30%): viral URTI.  Most commonly rhinoviruses and coronaviruses

o   („common cold‟)      

o   Allergen exposure in a sensitised individual

o   Drug sensitivity, eg aspirin

·        If severe, then ?other causes: PE, pneumothorax, etc


Classification of severity


·        How they feel (ie breathlessness) does NOT correlate to severity (as measured by FEV1). Due to temporal adaptation – if chronically breathless, body turns off perception of breathlessness (cf don‟t hear trains if living by a railway line). Unless you MEASURE lung function, you CANNOT assess severity. However, in kids have to rely on symptoms as peak flow unreliable


·        Key time to measure peak flow is when asthma is getting worse. No one will do it all the time so don‟t ask them to

Asthma in Young Children


·        especially for Medication and Spacer Use

·        3rd most common reason for admission (after Bronchiolitis and URTI/Otitis media).

·        Much much less common in < 1 years (NB bronchiolitis causes wheezing in young). Peak in 2 – 4 years


·        Peak flow very unreliable under age 7 (and most bad asthmatics diagnosed from 2 – 5) ® have to rely on history


·        History:


o  Symptoms: waking at night with cough/wheeze, after exercise, how often are attacks, had time off school/kindy as a result, how long does preventer last

o  Environmental factors: smokers, pets, damp, obvious triggers 

o   Current treatment: medicines, do the family understand the difference between reliever and preventer, assess technique and compliance, is spacer accepted by child and is it washed

·        2 patterns on history: 

o  Episodic (intermittent): viral URTI ® cough and wheeze.  No interval symptoms 

o  Persistent (with exacerbations): interval symptoms (with exercise, at night), exacerbations with viral infection, interferes with everyday life

·        Symptoms in a toddler:

o  Cough, often worse at night 

o  May vomit with cough (NB exclude pertussis: cough ® choke ® vomit ® OK for an hour. In asthma, cough again straight away) 

o  Usually wheezy with URT infection 

o  Diagnosis difficult in an infant unless recurrent, strong immediate family history or evidence of atopy

·        Physical findings in a toddler:

o  Often normal chest exam

o  If severe chronic symptoms:

§  Hyperinflated chest (­ AP diameter)

§  Harrison‟s sulcus: dip in chest wall where diaphragm attaches

§  Eczema

§  Reduced growth (if severe)

o  Stethoscope can be confusing

·        Diagnosis: 

o  Cough is very common in kids (8 – 10 per year). But more during the day than at night. Won‟t slow them down when running

o  Is it asthma, bronchitis, bronchiolitis?

o  Trial of therapy (preventative as well as relievers) and review

·        Criteria for admission:

o  Pulse rate > 1.5 * normal

o  Respiratory rate > 70 minute 

o  ­Chest movements

o  Restlessness/apathy/CNS depression or cyanosis/pallor [signs of exhaustion]

·        Treatment:


o  Avoid triggers: passive smoking, pets, house dust mite (dehumidifiers don‟t work), pollens, cold, exercise, damp houses, certain foods (overstated)

o  Infrequent episodic asthma:

§  Consider no therapy, avoid triggers


§  If distressed with attacks: use bronchodilators + spacer only. Start during URTI phase. No preventative

o  Frequent Episodic Asthma (only get it with a cold):

§  Intervals between attacks < 6 weeks

§  Bronchodilator as needed with URTIs

§  Prophylaxis:

§  Sodium cromoglycate (Vicrom + spacer).  ?Evidence of poor efficacy

§  Nedocromil (Tilade + spacer)

§  Inhaled steroids: if it makes no difference then stop

·        Persistent Asthma

o   Male: female = 4:1 

o   Preventative. If mild try Vicrom or Tilade. Moderate or severe use inhaled steroids (takes 2 – 3 months for maximal effect). Titrate back once controlled

o   Bronchodilators as required 

o   Poor control: consider ­dose, check inhaler device and technique, poor compliance, environmental triggers


·        Other treatment options:


o   Long-acting b-agonists: salmeterol (Serevent), eformoterol (Foradil, Oxis)

o   Theophylline (Nuelin, Theodur): 3rd line, gut ache ® poor compliance

o   If severe: alternate day oral prednisone treatment – reduced side effects (short and fat), and reasonable asthma control

·        Protocol for an acute attack:

o   Salbutamol dose: up to 5 years: 6 puffs via space.  Over age 5: 12 puffs via space

o   For severe add ipratropium (Atrovent)

o   For moderate and severe, give doses at 0, 20, 40 and 60 minutes and review at 75 minutes 

o   Oral Steroid for all except minor attacks: 1 mg/Kg/day ® ¯relapse



Principles of management


·        Asthma self-management plans are recommended as essential in the long-term treatment of adult asthma. Those with formal management plans have half the morbidity of those without them, despite the same treatment


·        Also need to establish, avoid and control triggers

·        Factors associated with asthma deaths:

o   Long term:

§  Lack of appreciation of chronic asthma severity and risk

§  Poor compliance

§  Discontinuity of medical care

§  Under utilisation of inhaled steroids

o   Fatal attack:

o   Delay in seeking medical help

o   Inability to recognise severity

o   Over-reliance on bronchodilator

o   Insufficient systemic steroid use

o   Lack of written information


·        If the management plan is too complicated for the patient, modify (eg just the point at which to see the doctor)


·        Compliance is critical Þ ownership of treatment by the patient is fundamental – negotiate and educate



·        Status asthmaticus: severe acute asthma that does not respond to treatment.


·        Most important part is use of inhaled corticosteroid. Patient may favour reliever (it obviously does something – reinforce that preventer stops it happening to start with)

·        Inhaled Corticosteroids:


o  Action:  Anti-inflammatory and ¯hyper-reactivity

o  Effect: ­lung function, ¯symptoms, ¯admissions (only drug to do this)

o  If using a b-agonist most days then should be on an inhaled steroid

o  Doses:


§  200 to 1000 mg/day of Beclomethasone Dipropionate (BDP/Becotide) or Budesonide (BUD/Pulmicort), or


§  100 to 500 mg/day of Fluticasone Propionate (Flexatide - only difference is potency, not efficacy, ?¯side effects)


§  Starting dose: if steroid naïve, better to start low and step up not start high and step down – too hard to wind it back


§  Back titration: in stable patients back titration may be attempted. ½ dose as a one off. If cut too far too fast can rebound within a month. Stopping treatment altogether is likely to cause a relapse


o  Doses by severity:


§  Stable: inhaled steroid bd, b agonist prn. If well controlled can take total steroid dose once a day at night rather than bd ® better compliance


§  Unstable: inhaled steroid qid, b agonist prn. If still not controlled then oral theophylline at night or long acting b agonist


§  Severe: systemic steroids, high dose b agonist, O2, medical review. Bronchodilators and inhaled steroids don‟t work so well in severe asthma as the major cause of obstruction is mucus plugging and the drugs don‟t get through. Steroid dose: start early (takes approx 12 hours to have an effect), 0.4 – 0.6 mg/kg/day = 40 mg for normal adult. In practice: 30 – 40 mg/day until PEF normal, then 20 mg/day for as many days again


o  Side-effects: Dose dependent redistribution of fat, electrolyte disturbances, hypertension (ie

o   Cushing‟s features), stunted growth in children

·        Bronchodilator:


o  Reliever.  Short acting inhaled b agonist.


o  Potent and rapid bronchodilator and a relatively low toxicity. Relaxes airway smooth muscles (plus other effects, e.g. ¯release of mast cell mediators). Adverse effects: muscle tremour and tachycardia common. Use as needed – not regularly – then becomes a guide to severity


o  Salbutamol and terbutaline sulphate common.


o  Long acting agonists for more severe asthmatics: Salmeterol and Eformoterol (similar effect but ­ potency). Peak effect 2 – 4 hours, duration 9 – 12 hours.

o  Theophylline:


§  May have additive effect with b agonist, but ­risk of side effects (including ¯K).


§  Narrow TI.


§  ­T½ in heart and liver failure, viral infections, elderly, enzyme inhibitors eg: cimitidine, erythromycin, contraceptives


§  ¯T½ in smokers, chronic alcohol, phenytoin, carbamazepine, rifampicin, and barbiturates


§  Given IV (very slowly) as aminophylline (too irritant for IM) for severe attack unresponsive to nebuliser

·        Others:


o  Sodium cromoglicate: non-steroidal preventer – less effective than steroids but fewer side effects. Single dose good for prevention of exercise induced asthma

o   Anti-leukotrienes: Leukotrienes ® ­vascular permeability, ­mucus production, ¯mucus transport, etc. Oral montelukast ® 15 % ­ in FEV1, ¯use of b agonist. Place in therapy still uncertain


·        Follow-up (eg good liaison with GP) following emergency admission is critical to preventing recurrence




·        Advantages: minimum possible dose, highly targeted, patient controls therapy


·        Inhaled steroids ® deposition in mouth. If not using spacer, need to rinse, gargle and spit otherwise risk of thrush and croaky voice. At best, 10% gets to lower airways without spacer


·        Metered dose inhalers (MDI):


o   Autohaler: shake, push lever up, suck. Lower level of suck needed than powder inhalers – but still require good suck to get lower airways deposition. As expensive as powder inhalers. OK from age 8 upwards


o   Standard MDI: (cheap, light and rapid delivery of drug, but co-ordination difficult). From age 12 onwards. Instructions for use:

§  Shake an inhaler between each puff

§  Remove cap

§  Hold it upright and pointed backwards

§  Breath out

§  Fire during 1st 25% of long slow inhalation

§  Hold breath

§  Breath out after removing inhaler from mouth

·        Inhalers through a spacer:

o   As effective as a nebuliser.  Increases LRT deposition by 4 times

o   Eliminate oral deposition of steroids and ­ lung deposition of both preventers and relievers

o   Breath-a-tech with a facemask up to 6. Remove mask as soon as you can (stops nasal filtering – try at age 4 - 5). Need smaller spacer as they have a small tidal volume

o   Volumatic without facemask. Need to be able to mouth breath well (ie try from age 2 – 3 onwards)

o   Need to inhale within 30 seconds of a puff into the space

o   One puff at a time

o   But plastic spacer ® static charge ® particles stick. So wash in detergent once a week and do not rinse bubbles off (® microfilm of detergent)

o   If using a new space without washing, need to prime it (10 puffs).  Don‟t do this in front of patient

·        Dry Powder Inhalers: ­­ oral deposition.  Use from age 5 up (good for use at school when they don‟t

·        want to lug a spacer around but their MDI technique is inadequate).  Advantages: light, quick delivery,

·        don‟t need co-ordination, CFC free.  Disadvantages: cost, require high respiratory flow

o   Accuhaler: 60 doses, easy to use, has dose meter

o   Disk haler: 6 doses

o   Turbohaler: easier to use than disk haler.  Red mark inside indicates when its empty


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