Respiratory Medicine

Question 1

Respiratory Drugs: Short Acting Beta Agonists

Examples: salbutamol, terbutaline. What is the mechanism, indications and adverse effects of **short acting beta agonists. **

Answer 1

1. Mechanism: selective beta 2 agonists have both **bronchodilating **and vasodilating effects
2. Indications: see asthma and COPD pathways
3. Adverse effects:
   
   1. **​Common **(usually with high dose): fine tremor, palpitations, nervous tension, headache, cramps
   2. Occasional: tachycardia, arrythmia, peripheral vasodilation, myocardial ischaemia
   3. Uncommon: hypoxaemia** (vasodilation -> transient hypoxaemia - give with O₂ in acute asthma),hypokalaemia** (particulaly if nebulized, potentiated with theophylline, corticosteroids and hypoxia therefore monitor in sever asthma)

Question 2

Respiratory drugs: Long Acting Beta Agonists

Examples: salmeterol, formoterol. What is the mechanism, indications and adverse effects of short acting beta agonists.

Answer 2

1. Mechanism: as beta agonists (vaso- and broncho-dilation)
2. Indications: asthma and COPD - as treatment pathway
3. Adverse effects: similar to beta agonists. Specific concern of LABA - increased risk of asthma exacerbations: 2006 meta-analysis showed some risk, unclear if 2^o to poor control on inhaled steroids, as poorly compliant patients may only take LABA on symptomatic days, and skip steroids on “good” days. If specific concerns re: compliance, **symbicort **inhaler useful (combines formeterol and budesonide)

Question 3

Respiratory Drugs: Long Acting Beta Agonists

What specific rules should be followed for safe useage of LABA (with possible increased risk of hospitalization if poorly steroid compliant in mind)

Answer 3

1. Add only if regular use of standard dose corticosteroids has failed to achieve adequate control
2. Do not start if asthma rapidly deteriorating
3. Introduce at low dose, monitor effect before increasing
4. Stop if no evidence of benefit
5. Review and step down when good control achieved.

Question 4

Respiratory Drugs: Antimuscarinics

Examples: ipratroprium bromide (short acting) and tiotropium (long acting). What is the mechanism and indications of antimuscarinincs?

Answer 4

1. Mechanism: antagonise ACh mediated effects on smooth muscle and secretory glands, decreasing bronchoconstriction in asthma and COPD
2. Indication:
   
   1. Short-term relief in chronic asthma, but beta₂ agonists quicker and preferred; Added to standard treatment in life-threatning asthma, or if acute asthma fails to improve with standard therapy.
   2. Note: **tiotropium **is long acting and used in COPD, but not asthma.

Question 5

Respiratory drugs: Antimuscarinics

What are the adverse effects and interactions of antimuscarinics (ipratropium bromide, tiotropium)

Answer 5

1. Adverse effects
   
   1. Common: dry mouth common, nausea and headache occasional
   2. Uncommon: constipation, tachycardia, urinary retention, blurred vision, angle-closure glaucoma. Used cautiously if prostatic hyperplasia
2. Interactions: use of >1 drug with antimuscarinic effects increases risk of S/E, particularly in elderly. Decreased risk if inhaled

Question 6

Respiratory Drugs: Inhaled Corticosteroids

Example: beclomethasone. What are the indications and adverse effects of inhaled corticosteroids

Answer 6

1. Indications:
   
   1. Asthma: if beta₂ agonist required > 2 weekly, or symptoms disturb sleep > 1 weekly.
   2. COPD: see treatment pathway
2. Adverse effects: systemic risk from inhaled steroids low, but increases with high doses for prolonged periods)
   
   1. Oral candidiasis and hoarseness; decreased risk with spacer and correct rinsing
   2. Adrenal suppression - should consider corticosteroid replacement during severe intercurrent illness / operation
   3. ?Increased LRTI in older patients with COPD. Controversial
   4. Decreased bone mineral density -> osteoporosis
   5. Decreased growth velocity in children (but no effect on adult height)
   6. Glaucoma and cataracts (small risk)

Question 7

Respiratory Drugs: Leukotriene Receptor Antagonists

Example: Montelukast, Zafirlukast. What is the mechanism, indications and adverse effects of leukotriene receptor antagonists?

Answer 7

1. Mechanism: block the effects of cysteinyl leukotrienes in airways, bronchodilating and anti-inflammatory effects
2. Indications:
   
   1. not more effective than corticosteroids, but has an additive effect - indicated for add-on therapy in patients on steroids.
   2. may be particularly effective in exercise-induced asthma, rhinitis, aspirin induced asthma.
3. Adverse effects:
   
   1. Occasional: abdominal pain, thirst, headache
   2. Rare: Churg Strauss syndrome (eosinophilia, vasculitis rash, worsening pulmonary symptoms, cardiac complications, peripheral neuropathy)

Question 8

Respiratory Drugs: Theophylline

What is the mechanism, indications and adverse effects of theophylline

Answer 8

1. Mechanism: methylxanthine; non-specific adenosine antagonist for A1, -2, -3 receptors almost equally (cardiac and bronchodilating)
2. Indications: asthma and stable COPD (as treatment pathway). Not effective as exacerbations of COPD. Combined with ethylenediamine as aminophylline, may be used by slow I.V infusion for acute asthma
3. Adverse effects: tachycardia, arrhythmia, palpitation, nausea and GI disturbance, headache, insomnia, convulsions if given rapidly by IVI.

Question 9

Respiratory Drugs: Theophylline

What are the pharmacokinetics of theophylline?

Answer 9

1. Narrow therapeutic window; 10-20mg/litre usually gives satisfactory bronchodilation, but adverse effects may occur within this range.
2. Metabolised in the liver by saturatable mechanism (zero order); considerable plasma variation partiularly in smokers and alcoholics (decreased), hepatic impairment or heart failure (increased)
3. Note: many drug interactions; check before prescribing.

Question 10

Chronic Obstructive Pulmonary Disease

Which treatments reduce mortality in COPD?

Answer 10

1. Smoking cessation
2. Domicillary oxygen for patients with persistent hypoxaemia (stable PaO2 < 7.3KPa)
3. **Lung reduction surgery **(only applicable to small numbers of patients.

Note: drug treatment improves symptoms, but has no proven effect on mortality.

Question 11

Chronic Obstructive Pulmonary Disease

What is the NICE recommended treatment pathway for COPD for patients with:

1. Breathlessness and exercise limitation
2. Exacerbations or persistent breathlessness
3. Persistent exacerbations or breathlessness

Answer 11

Question 12

Chronic Obstructive Pulmonary Disease: Acute Exacerbation

What are the management steps for a patient with an acute exacerbation of COPD?

Answer 12

1. ​High dose SABA, often with SAMA. Nebulize with air, not oxygen
   
   1. Ipratropium 500 micrograms 6hrly.
   2. Salbutamol 2.5 - 5 mg 4-6 hourly
2. Oral steroids: prednisolone 30mg for 7-14 days; improves lung function and symptoms
3. Antibiotics: co-amoxiclav only if sputum is purulent or signs of consolidation.
4. Oxygen:
   
   1. subgroup with severe disease at risk of CO2 retention and acidosis if given high dose oxygen - high admission bicarbonate a useful clue. In this situation aim for 88-92%
   2. most acutely ill and COPD patients NOT at risk of hypercapnic respiratory failure target 94-98%.
   3. Mark target oxygen sats on drug chart.

Question 13

Chronic Obstructive Pulmonary Disease

What management options are available if oxygen supplementation fails for control respiratory distress?

Answer 13

1. I.V Aminophylline if poor response to initial therapy
2. Noninvasive positive pressure ventilation (NIV): used in decompensated hypercapnic ventilatory failure - indicated if ongoing resp. acidosis (pH <7.35) despite medical and O₂ therapy
3. Invasive ventilation: decide ceiling of care before NIV initiated; resuscitation decision is ideally consultant-led with patient, family and ITU and includes background functional status, co-morbidity, chance of reversibility, and patient wishes

Question 14

Chronic Obstructive Pulmonary Disease

Which investigations are indicated in a patient presenting with an acute exacerbation of COPD that requires hospital management?

Answer 14

1. CXR
2. ABG
3. ECG
4. FBC, U&E
5. Theophylline level (if taking at admission)
6. Sputum MC&S if purulent

Question 15

Asthma Management

What is the BTS guideline for management of adults with asthma?

Answer 15