Adventures in GP-Land: “Asthma”

Posted on January 20, 2012

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It’s been a whopping 5 days since I took the plunge and immersed myself in general practice, and I have to say there’s been an astonishing lack of coughs and colds and whatever else people expect to see a lot of in a GP’s surgery. In fact, I’ve been quite surprised at the variety of things that have presented over the week, but I suppose that is the specialism of generalism and the art of the GP. There’s been musculoskeletal problems, consultations on contraception, mental health issues, and a whole host of skin rashes in every possible place you could conceive. As well as that, there’s been quite a bit of asthma, which is fortuitous given that we covered asthma in my study group earlier this week (and so on this I have been uncharacteristically well informed). Rather than talk about the pathophysiology of asthma in great detail, I’ve decided to look mainly at its treatment as that’s what I’ve seen in action over the week.

The British Thoracic Society (BTS) reviewed their guidelines for asthma treatment in 2011, and you can access the quick reference guide HERE.

ASTHMA: AN OVERVIEW

Fig. 1: The Asthma Triangle

So in a nutshell, asthma is characterised by dyspnoea, wheeze and cough, as a result of REVERSIBLE airway obstruction. Airway obstruction is caused by 3 factors (see my beautifully constructed Figure 1):

  • Bronchial muscle contraction
  • Swelling and inflammation of the mucosa (due to degranulation of basophils and mast cells and the release of inflammatory mediators)
  • Increased mucous production
A peak flow diary will show diurnal variation, with a decrease in peak flow usually in the morning. Precipitants include cold air/exercise, house dust mite, pollen, animal dander, smoking etc.

ASSESSMENT OF SEVERITY OF ASTHMA ATTACK (from BTS guidelines)

Moderate Exacerbation:

No features of acute severe asthma. Increased symptoms compared to usual. PEFR >50-70%

Acute Severe Asthma:

Cannot complete sentences. Pulse >110, Resp >25, PEFR 33-50% of predicted/best.

Life Threatening Asthma:

Any one of:

PEFR 33% of predicted/best; Oxygen stauration <92%  (pO2 <8kPa); silent chest; bradycardia, dysrythmia; hypotension; exhaustion; confusion, agitation; poor respiratory effort; cyanosis.

TREATMENT

There are a quite a few drugs used in asthma treatment:

  • Short acting Beta-2 agonists (eg salbutamol) for treatment of exacerbations
  • Long acting Beta-2 agonists
  • Inhaled corticosteroids (eg Beclametasone) for disease management
  • Combined steroid/Beta-2 agonist inhalers
  • Plus: inhaled antimuscarinics (eg ipatropium), leukotriene modifiers, theophylline, oral corticosteroids (eg prednisolone)

Treatment is stepwise:

STEP 1:

Mild, intermittent asthma- short acting Beta-2 agonist (eg salbutamol) when required

STEP 2:

Asthma requiring regular preventative therapy- Beta 2 agonist prn + corticosteroid bd.

Steroid therapy should be considered for patients with exacerbation in the last 2 years, use of inhaled beta 2 agonist 3 times a week or more, or those symptomatic 3 times or more a week/waking with symptoms at night once a week.

STEP 3:

Add inhaled long acting Beta2 agonist (eg salmeterol) to short acting Beta2 agonist and corticosteroid.

Assess control- if good with long acting Beta2 agonist: continue. If some benefit but control still inadequate: continue long acting Beta2 agonist but increase steroid dose. If no response to long acting Beta2 agonist, cease, increase corticosteroid and move on to step 4.

STEP 4:

For those with persistent poor control, add leukotriene receptor antagonist (eg montelukast) and increase inhaled cotricosteroid dose. Also use slow release theophylline and a Beta2 agonist tablet.

STEP 5:

Add a daily steroid tablet at lowest dose necessary to provide adequate control. Maintain high dose of inhaled corticosteroid.

REFER FOR SPECIALIST CARE.

TREATING SEVERE ASTHMA

Start oxygen therapy, reassess patient and measure peak flow, O2 saturation. Begin nebulised salbutamol 5mg administered 4 hourly. Add nebulised ipraptropium to nebulised salbutamol. Administer IV hydrocortisone 4 hourly for 24 hours. Arterial blood gases should be measured, if PaCO2 is >7kPa consider ventilation. A chest X-ray can rule out pneumothorax. Prednisolone can be continued orally for 24 hours.

So there you have it. Asthma treatment in a nutshell. This has all been based on the BTS guidelines, so check them out for more information.

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