Chapter 4.5.2 Asthma

Asthma is a chronic inflammatory condition with reversible airways obstruction. It is characterized by recurrent episodes of wheezing, often with cough, which respond to treatment with bronchodilators and anti-inflammatory drugs. Antibiotics should be given only when there are signs of pneumonia.

Diagnosis

Hisotry of recurrent episodes of wheezing, often with cough, difficulty in breathing and tightness in the chest, particularly if these are frequent and recurrent or are worse at nigh and in th early morning.  Findings on examination may include:

  • rapid or increasing respiratory rate
  • hyperinflation of the chest
  • hypoxia (oxygen saturation < 90%)
  • lower chest wall indrawing
  • use of accessory muscles for respiration (best noted by feeling the neck muscles)
  • prolonged expiration with audible wheeze
  • reduced or no air intake when obstruction is life-threatening
  • absence of fever
  • good response to treatment with a bronchodilator.

If the diagnosis is uncertain, give a dose of a rapid-acting bronchodilator. A child with asthma will usually improve rapidly with such treatment, showing signs such as slower respiratory rate, less chest wall indrawing and less respiratory distress.  A child with severe asthma may require several doses in quick succession before a response is seen.

Treatment

A child with a first episode of wheezing and no respiratory distress can  usually be managed at home with supportive care. A bronchodilator is  not necessary.

If the child is in respiratory distress (acute severe asthma) or has recurrent wheezing, give salbutamol by metered-dose inhalerand spacer device or, if not available, by nebulizer.  If salbutamol is not available, give subcutaneous adrenaline.

Reassess the child after 30 minutes to determine subsequent treatment:

If respiratory distress has resolved, and the child does not have fast breathing, advise the mother on home care with inhaled salbutamol from a metered dose inhaler and spacer device (which can e made locally from plastic bottles).

If respiratory distress persists, admit to hospital and treat with oxygen, rapid-acting bronchodilators and other drugs, as described below.

Severe life-threatening asthma

If the child has life-threatening asthma, is in severe respiratory distress with central cyanosis or reduced oxygen saturation < 90%, has poor air entry (silent chest) is unable to drink or speak or is exhausted and confused, admit to hospital and treat with oxygen, rapid-acting bronchodilators and other drugs, as described below.

In childre admitted to hospital, promptly give oxygen, a rapid-acting bronchodilator and a first dose of steroids.

Oxygen

Given oxygen to keep oxygen saturation >95% in all children with asthma who are cyanosed (oxygen saturation 90%) or whose difficulty in breathing interferes with talking, eating or breastfeeding.

Rapid acting bronchodilators

Give the child a rapid-acting bronchodilator, such as nebulized salbutamol or salbutamol by metered-dose inhaler with a spacer device.  If salbutamol is not available, give subcutaneous adrenaline, as described below.

Nebulized salbutamol

The driving source for the nebulizer must deliver at least 6–9 litres/min. Recommended methods are an air compressor, ultrasonic nebulizer or oxygen cylinder, but in severe or life-threatening asthma oxygen must be used. If these are not available, use an inhaler and spacer. An easy-to-operate foot pump may be used but is less effective.


Put the dose of the bronchodilator solution in the nebulizer compartment, add 2–4 ml of sterile saline and nebulize the child until the liquid is almost all used up. The dose of salbutamol is 2.5 mg (i.e. 0.5 ml of the 5 mg/ml nebulizer solution).

If the response to treatment is poor, give salbutamol more frequently.

In severe or life-threatening asthma, when a child cannot speak, is hypoxic or tiring with lowered consciousness, give continuous back-to-back nebulizers until the child improves, while setting up an IV cannula. As asthma improves, a nebulizer can be given every 4 h and then every 6–8 h.

Giving salbutamol by metered-dose inhaler with a spacer device

Spacer devices with a volume of 750 ml are commercially available.

Introduce two puffs (200 μg) into the spacer chamber. Then, place the child’s mouth over the opening in the spacer and allow normal breathing for three to five breaths. This can be repeated in rapid succession until six puffs of the drug have been given to a child < 5 years, 12 puffs for > 5 years of age. After 6 or 12 puffs, depending on age, assess the response and repeat regularly until the child’s condition improves. In severe cases, 6 or 12 puffs can be given several times an hour for a short period.

Some infants and young children cooperate better when a face mask is attached to the spacer instead of the mouthpiece.

Subcutaneous adrenaline
If the above two methods of delivering salbutamol are not available, give a subcutaneous injection of adrenaline at 0.01 ml/kg of 1:1000 solution (up to  a maximum of 0.3 ml), measured accurately with a 1-ml syringe. If there is no improvement after 15 min, repeat the dose once.

Steroids

If a child has a severe or life-threatening acute attack of wheezing (asthma) give oral prednisolone, 1 mg/kg, for 3–5 days (maximum, 60 mg) or 20 mg for children aged 2–5 years. If the child remains very sick, continue the treatment until improvement is seen.

Repeat the dose of prednisolone for children who vomit, and consider IV steroids if the child is unable to retain orally ingested medication. Treatment for up to 3 days is usually sufficient, but the duration should be tailored to bring about recovery. Tapering of short courses (7–14 days) of steroids is not necessary. IV hydrocortisone (4 mg/kg repeated every 4 h) provides no benefit and should be considered only for children who are unable to retain oral medication.

Magnesium sulfate

Intravenous magnesium sulfate may provide additional benefit in children with severe asthma treated with bronchodilators and corticosteroids. Magnesium sulfate has a better safety profile in the management of acute severe asthma than aminophylline. As it is more widely available, it can be used in children who are not responsive to the medications described above.

Give 50% magnesium sulfate as a bolus of 0.1 ml/kg (50 mg/kg) IV over 20 min.

Aminophylline

Aminophylline is not recommended in children with mild-to-moderate acute asthma. It is reserved for children who do not improve after several doses of a rapid-acting bronchodilator given at short intervals plus oral prednisolone. If indicated in these circumstances:

Admit the child ideally to a high-care or intensive-care unit, if available, for continuous monitoring.
Weigh the child carefully and then give IV aminophylline at an initial loading dose of 5–6 mg/kg (up to a maximum of 300 mg) over at least 20 min but preferably over 1 h, followed by a maintenance dose of 5 mg/kg every 6 h.

IV aminophylline can be dangerous at an overdose or when given too rapidly.

• Omit the initial dose if the child has already received any form of aminophylline or caffeine in the previous 24 h.
• Stop giving it immediately if the child starts to vomit, has a pulse rate > 180/ min, develops a headache or has a convulsion.

Oral bronchodilators

Use of oral salbutamol (in syrup or tablets) is not recommended in the treatment of severe or persistent wheeze. It should be used only when inhaled salbutamol is not available for a child who has improved sufficiently to be discharged home.

Dosage:

  • Age 1 month to 2 years: 100μg/kg (maximum, 2mg) up tof our times daily
  • Age 2–6 years: 1–2 mg up to four times daily

Antibiotics

Antibiotics should not be given routinely for asthma or to a child with asthma who has fast breathing without fever. Antimicrobial treatment is indicated, however, when there is persistent fever and other signs of pneumonia (see section 4.2)

Supportive care

Ensure that the child receives daily maintenance fluids appropriate for his or her age (see section 10.2).  Encourage breastfeeding and oral fluids. Encourage adequate complementary feeding for the young child, as soon as food can be taken.

Monitoring

A hospitalized child should be assessed by a nurse every 3 h or every 6 h as the child shows improvement (i.e. slower breathing rate, less lower chest wall indrawing and less respiratory distress) and by a doctor at least once a day. Record the respiratory rate, and watch especially for signs of respiratory failure – increasing hypoxia and respiratory distress leading to exhaustion. Monitor oxygen therapy as described in Section 10.7.

Complications

If the child fails to respond to the above therapy, or the child’s condition worsens suddenly, obtain a chest X-ray to look for evidence of pneumothorax. Be very careful in making this diagnosis as the hyperinflation in asthma can mimic a pneumothorax on a chest X-ray. Treat as described in Chapter 4.3.3.

Follow-up care

Asthma is a chronic and recurrent condition.

Once the child has improved sufficiently to be discharged home, inhaled salbutamol through a metered dose inhaler should be prescribed with a suitable (not necessarily commercial) spacer and the mother instructed on how to use it.

A long-term treatment plan should be made on the basis of the frequency and severity of symptoms. This may include intermittent or regular treatment with bronchodilators, regular treatment with inhaled steroids or intermittent courses of oral steroids. Up-to-date international or specialized national guidelines should be consulted for more information.