Asthma

Question 1

Asthma

Answer 1

Characterised by paroxysmal and reversible obstruction of the airways. It is increasingly understood as an inflammatory condition combined with bronchial hyper-responsiveness

Question 2

What does acute asthma involve

Answer 2

• Bronchospasm (smooth muscle spasm narrowing airways).
• Excessive production of secretions (plugging airways).
Triggers unleash an inflammatory cascade within the bronchial tree, leading to the typical symptoms of asthma - eg, wheeze, shortness of breath, chest tightness, cough.

Question 3

What happens to undertreated asthma patients

Answer 3

Patients with under-treated asthma who continue to have chronic low levels of inflammation may then undergo remodelling of the airways and develop fixed airways disease, which no longer responds as well or even at all to bronchodilator therapy.
Acute severe asthma (status asthmaticus) can be life-threatening and the disease causes significant morbidity, so it is imperative to treat it energetically

Question 4

Asthma risk factors

Answer 4

• Personal history of atopy.
	• Family history of asthma or atopy.
	• Inner city environment; socio-economic deprivation.
	• Obesity.
	• Prematurity and low birth weight.
	• Viral infections in early childhood.
	• Smoking.
	• Maternal smoking.
	• Early exposure to broad-spectrum antibiotics.
	Possible protective factors include:
	• Breast-feeding[4].
	• Vaginal birth - observational studies suggest that caesarean delivery might be associated with a greater risk of asthma[5].
	• Increasing sibship.
Farming environment

Question 5

Asthma presentation

Answer 5

Features that increase the probability of asthma in adults include[7]:
• More than one of the following symptoms: wheeze, breathlessness, chest tightness and cough, particularly if:
• Symptoms are worse at night and in the early morning.
• Symptoms are present in response to exercise, allergen exposure and cold air.
• Symptoms are present after taking aspirin or beta-blockers.
• History of atopic disorder.
• Family history of asthma and/or atopic disorder.
• Widespread wheeze heard on auscultation of the chest.
• Otherwise unexplained low forced expiratory volume in one second (FEV1) or peak expiratory flow (historical or serial readings).
• Otherwise unexplained peripheral blood eosinophilia.

Question 6

Why is wheeze not present in severe asthma

Answer 6

There is insufficient air flow to cause wheeze - beware the silent chest.

Question 7

Precipitating or aggravating factors for asthma attacks

Answer 7

• Cold symptoms - upper respiratory tract infection (URTI) - frequently trigger exacerbations.
• Cold air - if this causes chest pain in an adult, it may be angina.
• Exercise - symptoms may occur during exercise but more classically after exercise. Running tends to be worse than cycling.
• Pollution - especially cigarette smoke.
• Allergens - exacerbations may occur seasonally around pollen exposure or following exposure to animals such as cats, dogs or horses.
• Time of day - there is a natural dip in peak flow overnight and in a vulnerable person this may precipitate or aggravate symptoms. It may cause nocturnal waking or simply being rather short of breath or wheezy in the morning.
Work-related - if symptoms are better at home/during holidays, asthma may be related to occupation. This has significant implications and it is sensible to refer the person to a chest physician or an occupational physician

Question 8

Relavance of inspiratory and expiratory ratio

Answer 8

Usually this can be assessed by countingoneon the way in andone, twoon the way out. This 2:1 ratio of expiratory to inspiratory phase is normal. The longer the expiratory phase compared with the inspiratory phase, the more severe the obstruction.

Question 9

What chest deformity can sometimes be present in chronic asthma

Answer 9

• Harrison’s sulci

Question 10

What can be present in small children with asthma

Answer 10

Intercostal recession with respiratory distress

Question 11

What do predominantly inspiratory rhonchi and prolongation of inspiratory phase suggest

Answer 11

This suggests that airway obstruction is outside the chest

Question 12

Diagnosis of asthma

Answer 12

Carry out spirometry using the lower limit of normal to demonstrate airway obstruction, provide a baseline for assessing response to initiation of treatment and exclude alternative diagnoses. Obstructive spirometry with positive bronchodilator reversibility increases the probability of asthma. Normal spirometry in an asymptomatic patient does not rule out the diagnosis of asthma

Question 13

Approach to patients with a high probability of asthma

Answer 13

• Record the patient as likely to have asthma and commence a carefully monitored initiation of treatment (typically six weeks of inhaled corticosteroids).
• Assess the patient’s status with a validated symptom questionnaire, ideally corroborated by lung function tests (FEV1 at clinic visits or by domiciliary serial peak flows).
• With a good symptomatic and objective response to treatment, confirm the diagnosis of asthma and record the basis on which the diagnosis was made.
• If the response is poor or equivocal, check inhaler technique and adherence, arrange further tests and consider alternative diagnoses.
In years to come it may be possible to identify patients with asymptomatic asthma and hence underlying inflammation by using more sensitive tests (eg impulse oscillometry or challenge testing) as equipment becomes available in a clinical setting rather than just in a pure research setting.

Question 14

What is FeNO

Answer 14

FeNO tests measure the levels of nitric oxide in the breath. Increased levels are thought to be related to lung inflammation and asthma

Question 15

Asthma differentials in children

Answer 15

• Bronchiolitis
• Cystic fibrosis
• Other congenital problems such as congenital heart disease
• Vocal cord dysfunction mimics steroid refractory asthma
• GORD
  Inhalation of a foreign body
• Postnasal drip(causes a cough which is worse at night)
• Inspiratory stridor and wheeze –> laryngeal disorder including croup
• Focal signs may suggest bronchiectasis or TB

Question 16

Distnguishing between COPD and Asthma

Answer 16

• Reversibility distinguishes asthma from COPD, although the reversibility is relative rather than absolute
• People with severe asthma may never achieve completely normal parameters for lung function and COPD is rarely totally refractory to medication.
• People with asthma who have been undertreated or non-compliant (not necessarily with severe asthma) may develop remodelling of the airways due to chronic inflammation and therefore may not show significant reversibility.
• Almost all patients with COPD do smoke or have smoked in the past. People with asthma can also develop COPD. Whether or not this reflects disease progression or comorbidity is debatable.
Asthma-COPD overlap syndrome is characterised by persistent airflow limitation with several features usually associated with asthma and several features usually associated with COPD

Question 17

Asthma differentials in adults

Answer 17

• COPD
• Heart failure can cause nocturnal cough and cardiac asthma
• Coronary heart disease - chest tightness or pain, especially on meeting a stiff wind on a cold morning may be asthma or angina
• GORD can cause nocturnal cough and a postnasal drip may cause more coughing when lying down
• Vocal cord dysfunction
• Pulmonary fibrosis, ILD, recurrent pulmonary embolism and TB
• Distinguish wheezing from shortness of breath on exertion - this can be due to heart failure, severe anaemia and obesity, often aggravated by lack of physical fitness.

Question 18

Asthma investigations

Answer 18

• Peak flow using wright’s peak flow meter
• Lung function tests with either peak flow or spirometry
• CXR should not be used routinely in assessment of asthma but consider cxr in any patient presenting with an atypical history or with atypical findings on examination

Question 19

Interpretation of peak flow results

Answer 19

Expected PEFR increases with increasing height and it varies with age, reaching a peak in the early 20s and then gradually declining. Current normative charts are criticised for being outdated and not encompassing ethnic diversity.
A patient’s peak flow can be compared with that listed normal for their age, sex and height. However, it is often more helpful in a patient with asthma to compare changes with an individual’s best peak flow, recorded in a clinically stable period on optimal treatment. Thus, a patient with asthma may have a ‘predicted’ PEFR of 500 L/minute but know that a peak flow of 400 L/minute indicates reasonable control and that, where it falls to 300 L/minute, appropriate action is required

It is normal for peak flow to fall slightly overnight and these ‘nocturnal dips’ may be accentuated in asthma. A marked diurnal variation in peak flow (>20%) is significant

However peak flow variability is not specific to asthma

Question 20

Spirometry interpreation

Answer 20

• Preferred over peak flow
• Spirometry measures the whole volume that may be expelled in one breath (vital capacity). It also permits calculation of the percentage exhaled in the first second - the FEV1
• • Spirometry may be normal in individuals currently asymptomatic and does not exclude asthma, and should be repeated, ideally when symptomatic. However, a normal spirogram when symptomatic does make asthma an unlikely diagnosis.
  • It also offers good confirmation of reversibility in subjects with pre-existing obstruction of the airways where a change of >400 mL in FEV1 is found after short-term bronchodilator/longer-term corticosteroid therapy are trialled.

Question 21

Assessment and review of asthma patients

Answer 21

• Should be reviewed at least annually
• The ‘three questions’ approach of the Royal College of Physicians has been widely used and valued for its simplicity, although it is poorly validated:
  • Have you had any difficulty sleeping because of your asthma symptoms, including cough?
  • Have you had your usual asthma symptoms during the day (cough, wheeze, chest tightness of breathlessness)?
  • Has your asthma interfered with your usual activities (housework, work, school, etc)?

Question 22

Drug treatment for asthma

Answer 22

• Step 1 - for those with very mild, intermittent asthma, the occasional use of a beta2-agonist inhaler may be all that is required but all patients with asthma should be prescribed this for short-term relief of symptoms as required.
• Step 2 - start regular inhaled steroid at an appropriate dose for the severity of disease (200-800 micrograms/day beclometasone diproprionate or equivalent). Triggers for starting inhaled corticosteroids should be:
• An exacerbation in the previous two years.
• Use of a beta2-agonist inhaler more than three times per week.
• Symptomatic of asthma more than three times per week.
• Waking due to asthma more than once per week.
• Step 3 - initial add-on therapy involves the addition of a long-acting beta2agonist (LABA). Theseshould notbe used without the concurrent use of inhaled steroid. Where control is good, continue but, where there is no response, stop and increase the dose of inhaled corticosteroid (up to 800 micrograms/day beclometasone diproprionate or equivalent). With partial benefit, continue the LABA but also increase the inhaled corticosteroid dose. If this fails to provide control, trial a leukotriene receptor antagonist or sustained release (SR) theophylline.
• Step 4 - with persistent poor control, increase inhaled steroid up to 2,000 micrograms/day beclometasone diproprionate or equivalent and/or add a fourth drug (leukotriene receptor antagonist, SR theophylline or beta2-agonist tablet).
• Step 5 - continuous or frequent use of oral steroids, maintaining high-dose inhaled steroids.
Referral to a respiratory physician would be normal at Step 4-5 depending on expertise.

Question 23

Omalizumab in asthma treatment

Answer 23

NICE recommends omalizumab as an option for treating severe persistent confirmed allergic IgE-mediated asthma as an add-on to optimised standard therapy in people aged 6 years and older who need continuous or frequent treatment with oral corticosteroids (defined as four or more courses in the previous year).

Omalizumab should only be initiated by a specialist.

Optimised standard therapy is defined as a full trial of and, if tolerated, documented compliance with inhaled high-dose corticosteroids, LABAs, leukotriene receptor antagonists, theophyllines, oral corticosteroids and smoking cessation if clinically appropriate.

Question 24

Exercise-induced asthma

Answer 24

For most, exercise-induced asthma indicates poorly controlled asthma and will require regular inhaled steroid treatment beyond the anticipatory use of a bronchodilator when preparing for sport.

Where exercise poses a particular problem and patients are already on inhaled corticosteroids, consider the addition of LABAs, leukotriene inhibitors, chromones, oral beta2agonists or theophyllines

Question 25

Complications of asthma

Answer 25

Inadequate control of asthma leads to much morbidity and poor quality of life, with a high rate of working days lost and emergency hospital admissions. Complications mostly relate to acute exacerbations:
	• Pneumonia.
	• Pneumothorax.
	• Pneumomediastinum.
	• Respiratory failure and arrest.

Question 26

Hygeine hypothesis

Answer 26

The ‘hygiene hypothesis’ is currently popular. It suggests that decreased exposure to childhood infections, endotoxin and bacteria increases the risk of developing atopy.