Management of asthma

Clinical triad: wheezes (polyphonic and high-pitched), dyspnoea and cough (e.g. at night, this may be the only symptom)

Have a peak flow meter at hand and determine whether asthma attack is severe, moderate or mild.

1. Severe asthma attack

Do peak expiratory flow rate (PEFR; this is closely related to FEV1, see below) and compare with standard PEFR (you need patient’s height and gender), if PEFR is < 50% of predicted value you are dealing with a severe asthma attack and if PEFR is < 33% of predicted value the patient’s condition is life threatening!!!

Features:

- too breathless to complete sentences in one breath

- use of accessory respiratory muscles

- pt may be distressed, exhausted, confused, obtuse, or may present with impaired level of consciousness (these signs are due to raising CO2)

- respiration rate (RR) > 25 breaths/minute

- heart rate (HR) > 120 beats/minute

- systolic blood pressure (BP) < 100 mmHg

- on auscultation breaths sounds (BS) may be very soft or in the worst scenario chest will be silent

- oxygen saturation may be decreased; < 95 % is considered abnormal, however this measurement is not reliable, e.g. pt has got cold extremities or is peripherally shut down, always go according to the clinical presentation together with PERF

If diagnosis of severe asthma is established inform doctor on call, ICU and get an urgent CxR.

Treatment:

- sit pt up

- give oxygen at the highest flow rate

- give nebulized ß2-agonists, salbutamol 5 mg or terbutaline 10 mg, administered via oxygen and repeat up to every 30 minutes

- add ipratropium bromide 0.5 mg to nebulizer together with ß2-agonists

- obtain i.v. access

- start steroids: 200 mg of hydrocortisone i.v.

- give antibiotics (amoxycillin, doxycyclin; in severe cases try co-amoxiclav) if evidence of chest infection (abnormal CxR, fever, increased WBC)

- ensure adequate hydration: 2-3l/24 hrs, this may prevent mucous plugging

Monitor pt regularly!! Do pre- and post nebulizer PERF. If there is no improvement or frank deterioration:

- continue oxygen and nebulized ß2-agonist up to ½ hourly

- start salbutamol infusion: loading dose 100-300 µg over 10 minutes, maintenance infusion 5-20 µg/min (5 mg in 500 ml saline at 1-3 ml/min). Be aware of side effects such tremor, tachycardia, hypokalaemia and hyperglycaemia. Measure K+ and replace as necessary!

or alternatively

- start aminophylline infusion: loading dose 250 mg (4-5mg(kg) i.v. over 20 minutes, maintenance infusion 0.5-0.9 mg/kg/hr (250 mg in 1000 ml saline at 2-4 ml/kg/hr). Do not give aminophylline in patients who have been on oral treatment!! Half the dose in patients with liver cirrhosis, CCF or those receiving erythromycin, cimetidine or ciprofloxacin!!

- if still no improvement give adrenaline 0.1 mg s.c., repeat up to three times at 30 minutes interval

- if all the above fails pt needs to be ventilated!

Ongoing therapy when patient is better:

- continue with ß2-agonist and ipratropium bromide at fixed intervals: ß2-agonist 4-hourly and prn after 24 hrs and ipratropium bromide 6-hourly for the next 24 hrs and then stop

- PERF needs to be measured before and after every nebulizer

- continue steroids: hydrocortisone 200 mg 6-hourly for the next 24 hrs and then carry on orally with prednisolone 30-60 mg for 10-14 days

The pt is ready for discharge if PERF is > 75 %, without morning dipping and nocturnal symptoms and without requirement for nebulizers for the last 24 hrs!!!

Drugs on discharge:

- prednisolone p.o. 30-60 mg OD for 1-3 weeks (dose needs to be reduced gradually if treatment > 14 days!)

- inhaled ß2-agonists (2 puffs QDS) and corticosteroids (2 puffs BD, after inhalation of ß2-agonist!) at regular intervals

- review patient in chest clinic after one month

2. Moderate asthma attack

None of the above mentioned severe features and PERF is 50-75% of predicted value.

Treatment:

- administer nebulized ß2-agonist and ipratropium bromide (see above) and give oral prednisolone 30-60mg

- reassess after 30 minutes. If PERF < 50% of predicted value, then admit and assess as above for severe asthma. If PERF 51-75% of predicted value, repeat nebulizer and observe for further 60 minutes.

- discharge pt when stable after 1-2 nebulizers and PERF > 75%. If after the second nebulizer and a further 60 minute observation, the pt is clearly improving and PERF > 60%, you may consider discharge. All other patients need admission!

- drugs on discharge: oral prednisolone (30-40 mg OD for seven days), regular inhaled corticosteroids and prn inhaled ß2-agonists.

3. Mild asthma attack

None of the above mentioned severe features and PERF > 75% of predicted value.

Treatment

- give two puffs of inhaled ß2-agonist

- observe for 60 minutes. If PERF remains > 75% of predicted value, discharge on regular inhaled corticosteroids and prn inhaled ß2-agonist. If PERF deteriorates, treat as above.

Generally: advice pt to stop smoking and avoid all ß-blockers and NSAIDs, they can worsen asthma!

4. Follow up visits

Measure functional lung volume at least once. Obstructive spirometry implies that forced respiratory volume in first second (FEV1) is reduced more than the forced vital capacity (FVC). Causes are asthma, COPD (see below) and tumours. Restrictive spirometry implies a small FVC, often associated with a normal (~ 70%) or increased ratio of FEV1:FVC. Causes are chest wall stiffness, pulmonary oedema/effusion and lung fibrosis.

CxR in chronic asthma may show hyperinflation.

Differential diagnoses: pulmonary oedema (wheezes together with bilateral crepitations), COPD (often co-exists, see below), large airway obstruction (may cause stridor) e.g. foreign body or tumour, superior vena cava obstruction (fixed JVP), pneumothorax (no breath sounds), pulmonary embolism (history), bronchiectases (purulent sputum), obliterative bronchiolitis (esp. in the elderly with possible asthma).

Titrate treatment according to symptoms. If pt comes in because of an acute attack treat as above!

Consider 5 different steps of asthma treatment for outpatients. Start at the step most appropriate to severity, moving up if needed or down if control is good > 3 months. Rescue courses of oral prednisolone may be needed and given at any time (see above).

Step 1: occasional short-acting inhaled ß2-agonist as needed for symptom relief. If used > once daily (i.e. in chronic asthma) and inhaler technique is good go to step 2. Maximum dose of inhaled Salbutamol 800 µg QDS

Step 2: add inhaled beclomethasone 100-400 µg/12 hrs

Step 3: increase inhaled beclomethasone up to 2000 µg/12 hrs or alternatively add salmeterol 50 µg/ 12 hrs. Beware of oral candidiasis! Encourage pt to gargle with antiseptic solution after using high-dose inhaled corticosteroids. Above 1500 µg/12 hrs of beclomethasone systemic absorption occurs and the pt should use a volume spacer (one could use a cut open plastic bottle).

Step 4: add one of: inhaled long-acting ß2-agonist, slow-release theophylline, inhaled ipratropium, long-acting ß2-agonist tablets, high-dose inhaled bronchodilators, cromoglicate, nedocromil (in order) to step 3.

Step 5: check compliance; add regular oral prednisolone (one daily dose)