Bronchial Asthma

Bronchial Asthma - the chronic inflammatory disease of the airway

Bronchial asthma is characterised by chronic airway inflammation, bronchial hyperreactivity and reversible airway obstruction (bronchoconstriction, mucosal oedema, increased mucus production)

Status asthmaticus is a refractory state of acute severe asthma that does not respond to standard therapy

2. Asthma is more common in children but there has been a rapid increase in adult-onset asthma lately. Males are more likely to affected than females.

3. Various trigger factors contribute to asthma.

Allergens - dust mites, pollen, dander

Bronchial infection

Cold air

Exercise

Drugs - aspirin, NSAIDs, beta-blockers

Emotions and stress

Various food

Hormones

Irritants - smoke, perfumes, smell, wood dust, etc

Extrinsic (allergic) asthma develops in patients who are prone to develop IgE antibodies.

Intrinsic (non-allergic) asthma is a manifestation in response to RTI or physosocial stressors.

4. The chief complaints are typically: cough, tightness, wheezing, dyspnoea. The symptoms often worsen at night which result in frequent awakening. If etiology is present, it worsens the symptoms. There is usually a medical history of allergies or atopies. Family history of asthma or other atopy must be noted.

Patients who smoke should be advised to stop smoking.

5. Physical examination is important to determine the severity of exacerbation. The patient may present with tachypnoea, tachycardia, usage of accessory muscles and pulsus paradoxus. On chest examination, there is hyperinflation of the chest, hunch shoulders and deformities - Harrison sulcus, pectus carinatum. Auscultation of the lungs - wheezing, prolonged expiratory phase

Be aware of dangerous signs of status asthmaticus such as paradoxical abdominal and diaphragmatic movements, pulsus paradoxus, altered mental status and silent chest (absence of wheezing). The patient may be also cyanotic and febrile. At a later stage there may be bradycardia and hypotension

6. The diagnosis of bronchial asthma is done via history taking, physical examination and confirmation through spirometry. A demonstration of reversibility more than 12% post-bronchodilator administration is diagnostic of asthma.

Pulse oximetry is monitored for oxygen saturation and supplemental oxygen given, aim to achieve >90% saturation.

Blood tests like FBC may reveal leukocytosis and eosinophilia.

Severe attacks of asthma, ABG may be needed to evaluate arterial pH levels, hypoxaemia and hypercarbia. In severe attacks, there is usually acidosis secondary to hypoventilation.

Chest X-rays are not recommended unless there is suspicion of complications.

Other tests that may be of help to identify trigger factors include bronchial provocation test and skin prick test.

7. The principles of management is to choose the treatment based on the severity. A stepwise approach to managing asthma is meant to assist decision-making.

In summary,

i. SABA prn

ii. + low dose ICS

iii. + low dose ICS and LABA

iv. + medium dse ICS and LABA

v. + high dose ICS and LABA

vi. + high dose ICS, LABA and oral corticosteroid

Consider monoclonal antibodies in step 5 and above if available (omalizumab)

Alternatives may be used in lower steps - theophylline, cromolyn

In children, leukotrine antagonists such as montelukast and zafirlukast is effective.

Patients are also educated on avoidance of trigger factors, warm-up exercise or SABA administration 5 minutes pre-exercise or LABA usage prior to exercise.

About one third of the patients fail to respond to treatment because of wrong technique. All patients should be re-educated on proper usage of and techniques.

8. Status asthmaticus is a medical emergency. Upon diagnosis of severe asthma,

i. oxygen supplementation 8L/min by mask is given to maintain SpO2 above 95%.

ii. high dose salbutamol or continuous nebulized 0.5% salbutamol

iii. IV prenisolone 250mg

iv. measure ABG, CXR for complications

v. if no improvement, IV MgSO4 25-100mg/kg over 20 minutes

vi. still no improvement, intubation with PPV

9. The complications of asthma include increased risk of influenza, pneumonia, pneumothroax, pneumomediastinum, COPD and iatrogenic Cushing syndrome.