Introduction Acute Asthma Monitoring the Child with Acute Asthma The Very Severe Asthma Attack Follow Up Fatal Asthma Attack

Introduction

The South African Childhood Asthma Working Group (SACAWG) of the Allergy Society of South Africa convened on 26-27 September 1992 to review current approaches to the management of acute asthmatic attacks in children and to develop guidelines which would be appropriate for children living in South Africa.

The objective of this consensus statement is to reduce morbidity and deaths from acute attacks of asthma in children. This document deals with approaches to management from the onset of the attack (usually at the patient’s home) until the child is admitted to a hospital intensive care unit (ICU) or high-care ward. It does not concern itself with sophisticated management within the ICU.

The most important causes of preventable illness and death from asthma remain under-diagnosis and under-treatment of the condition. Most severe attacks can be prevented. The single most important step in the prevention of life-threatening acute attacks is the implementation of adequate maintenance therapy, as detailed in our statement on the management of childhood and adolescent asthma.

The approach to the management of the acute attack in children is outlined in Fig 1. which should be studied with reference to accompanying notes.

Acute asthma

Acute asthma is defined as an acute exacerbation of wheezing, unresponsive to usually effective therapy and necessitating care in an emergency room or hospital ward. An acute asthma attack is characterised by airways narrowing and inflammation, hyperinflation, impairment of pulmonary function, alterations in alveolar ventilation and hypoxaemia.

Severity of the attack

Acute exacerbations of asthma may be classified as mild, moderate or severe according to the specifications given in Table 1.

Table 1. Classification of acute exacerbations of asthma

	Mild	Moderate	Severe
Arterial O2 saturation	>95%	91-95%	<91%
Peak expiratory flow rate*	70-90%	50-70%	<50%
Carbon dioxide pressure	<35 mmHg	<40 mmHg	>40 mmHg
Pulsus paradoxus	<10 mmHg	10-20 mmHg	20-40 mmHg
Wheezing	Expiratory	Expiratory+Inspiratory	Breath sounds soft
Respiratory rate	<40	>40	>40
Additional signs		Speaks normally	Unable to speak
		May be alert	Confusion
		Difficulty with feeding	Possible cyanosis
		Intercostal retractions	Use of accessory muscles

Measurement of the above indices may assist the clinician in recording the severity of the disease at any point. Children whose indices do not improve are likely to end up being admitted to hospital or ICU. It is important repeatedly to assess the child clinically and to assess his response to treatment.

Responder v non-responder

An initial assessment of the response of the child to properly administered B-2 agonists is essential in the planning of further treatment. Patients are classified as responders or non-responders as follows:

• For children able to use a peak expiratory flow meter an improvement of the peak expiratory flow rate (PEFR) to more than 80% of predicted values for the child’s height (or the patient’s best previously recorded PEFR), is considered a satisfactory response.
• In children unable to use a peak expiratory flow meter, the respiratory rate is regarded as the single most important measurement. A respiratory rate above 40/min is indicative of respiratory distress. In addition the presence of rib or sternal retractions, impaired speech or difficulties with feeding (in infants) also indicates an inadequate response to therapy. Chidlren who have not responded to two properly administered B-2 agonsits at home require further management in an emergency room. Children who have responded to B-2 agonists should maintain their response for 1 hour before being classified as responders.

Oxygen

The single greatest danger to children suffering an acute attack of asthma is hypoxaemia and not C02 retention. One hundren per cent oxygen should be given by means of a face mask or nasal progs (cut off) at 3-4 litres/min. This will supply about 40% oxygen. Oxygen must be used when B-2 aganost bronchodilators are given by nebuliser in the emergency room. It is not necessary to humidify oxygen. Children who have arterial oxygen saturations of below 90% are regarded as hypoxaemic. When monitoring arterial oxygen saturation, aim to maintain the saturation as close to 95% as possible. If more than 40% oxygen is required this can be given by means of a head box in the small child. It is also dangerous to give too much oxygen and thesaturation should not be pused much higher than 95%.

B-2 agonist bronchodilators

Inhaled B-2 aganosists are the mainstay of treatmetn of the acute attack. These may be given by metered dose inhaler (MDI) in older children or by means of a spacer device in younger children. If a spacer is used, give 3 or 4 puffs into the spacer and allow the child to breathe normally for 20 seconds. For the smaller or the very distressed child, if spacer devices are not available, B-2 agonsits should be given via a nebuliser, with oxygen. A paper cup attached to the mouthpiece of the MDI is a useful way of administering inhaled B-2 agonsits to young children.

Any of the following inhaled B-2 agonists may be used. These may be nebulised with 1 ml saline over 5 minutes and are appropriate for most children.

• Salbutamol 0.15 mg/kg/dose at 20-minute intervals with a maximum dosage of 5 mg/dose. Salbutamol nebuliser solution concentration is 5 mg/ml.
• Fenoterol 0.02 mg/kg/dose also at 20-minute intervals. Nebuliser solution concentration is 1 mg/ml.

The usual starting dose for these and other agents, e.g. hexoprenaline, in most young children is about 0.5 ml/dose.

Patients who fail to respond adequately to two properly administered inhaled doses of B-2 agonists are regarded as non-responders and ipratropium bromide should be added to the patients treatment.

Where B-2 agonists are not available or where nebulisation is difficult, or if the child is unco-operative, subcutaneous adrenaline (0.01 ml/kg) 1:1000 may be used. A maximum of 0.3 ml may be given subcutaneously and this may be repeated a maximum of 3 times after 20 minutes.

It is important to inform patients that if they have not responded to two nebulisations at home, they should go to hospital. In hospital, for the severe asthmatic child, B-2-agonists may also be carefully administered as a continuous intravenous infusion of 0.2 ug/kg/min is given. The dose may be increased by 0.1 ug/kg every 15 minutes to a maximum of 4 ug/kg/min.

In patients on intensive regular B-2-agonist treatment it is important to monitor the serum potassium level because of the risk of hypokalaemia. Oral potassium chloride is effective for treatment of hypokalaemia in this situation.

Ipratropium bromide (Atrovent)

Recent studies indicate that ipratropium bromide given with a B-2-agonist can be used to augment and sustain bronchodilatation in acute asthmatics. It is therefore suggested that Atrovent should be added to the regimen of all children who are classified initially as non-responders. The recommended dose for children is 1 ml in 1 ml saline per dose given 4-hourly. Alternatively the dose may be determined according to the child’s weight (0.1 ml/kg 4-hourly).

Spacer devices

Spacer devices are highly effective in facilitating delivery of B-2-agonists to the airways. The simplest device is a plastic 2-litre cola bottle which can be used even in rural areas where facilities may be limited. To achieve optimal bronchodilation 5 puffs from a metered dose inhaler should be given through the cola bottle. Alternatively commercial spacer devices may be used.

Steroids

Oral:

Oral steroids should be given to all non-responders. Steroids should be given early in the attack. Prednisone or prenisolone 2 mg/kg/d should be given as a single daily dose for 7 days. The dose may be tapered down over a further 7 days and a maintenance alternate-day or daily dose of prednisone will be required in some patients. The use of long-acting steroid preparations such as Celestone syrup is still controversial but is acceptable if given only as a “one-off” treatment with a dose of betamethasone 0.1 mg/kg during an acute attack. Repeated courses of Celestone syrup are strongly discouraged.

Intravenous:

The use of intravenous steroids as a bolus dose is currently considered to be of debatable value. If Solu-Medrol is given intravenously it should be administered in no more than 3 doses of 1-2 mg/kg. Alternatively dexamethasone 0.4 mg/kg may be given as a bolus dose.

Monitoring the child with acute asthma

• It is important to measure indices of severity to assist in the assessment of progress, particularly one the child is admitted to hospital.
• Improvements in the PEFR or forced expiratory volume (FEV1) are the most objective indices of response in children over the age of 5 years.
• The importance of monitoring of the respiratory rate cannot be overstressed, particularly in children under the age of 5 years. A respiratory rate of less than 40/min is desirable. Repeated monitoring of the respiratory rate is a simple measurement of progress in the patient’s condition and should always be recorded by medical and nursing staff.
• If facilities are available for the measurement of arterial oxygen saturation this should be used in all non-responders.
• Apart from the respiratory rate, the quality of the cry, the ability to fee and the level of consciousness are important indices of improvement in small children.
• Monitoring of PcO2, percentage saturation and pH is useful in the child with a severe attack. A rise in the PcO2 indicates respiratory fatigue. A fall in saturation to below 91% indicates severe hypoxaemia and the presence of a pH below 7.25 indicates serious respiratory failure.

Radiographs

Chest radiographs are not generally indicated in the child with an acute attack, if there is a clear history of preceding asthma or a family history of allergies. If there is concern about the possibility of a pneumothorax or other air leak, chest radiographs should be done. Occasionally a chest radiography may be necessary to exclude the possibility of a foreign body.

Dangerous and unnecessary practices

Rectal theophylline is absoluted contraindicated in the management of acute asthma in children and intravenous aminophylline should only be used in selected patients in a ICU setting where blood levels can be monitored. If children are on oral theophylline they may be given their usual maintenance dose at the onset of an attack if this has not been given. There is no place for physiotherapy, mist tents or lung lavage in the management of acute attack. The administration of antihistamines to children with acute asthma has not been shown to be beneficial. Children with acute asthma attacks should not be sedated. Antibiotics are not indicated in the management of acute asthma in children.

Nebulisers

There are advantages to the selective use of home nebulisers in some asthmatic children. However, it must be remembered that a metered dose inhaler used with a spacer is just as effective as a nebuliser in deliver of the drug to the airways.) Nebulisers may have a role in small children for prophylaxis with sodium cromoglycate. Nebulised steroids also have a role in a subset of small children who are prone to very severe, near-fatal attacks of asthma. These high-risk children should be properly instructed in the use and care of the nebuliser and peak flow meter and should have a crisis plan which includes self-admission to hospital. Special care should be taken with neublisation of B-2-agonists during an attack of asthma at home since the use of B-2 agonists in a distressed child without the use oxygen can be dangerous.

The very severe asthma attack

Children who present in extremis with a very severe attack of asthma should immediately be given 100% oxygen, and adrenaline 0.3 ml subcutaneously, followed by intravenous salbutamol if they are unable to use a nebuliser. They should be admitted immediately to a high-care facility or ICU for intensive treatment. Particular care should be taken with the child who has had a previous admission to an ICU. Between 1% and 6% of all asthmatics will require admission to an ICU and less than one-third of all children with asthma admitted to an ICU will require ventilation. Signs of deterioration and impending respiratory failure include a rising PcO2 of 5-10 mm/l h or PcO2 >55 mmHg, increasing dyspnoea or fatigue or confusion, a pulsus paradoxus of more than 40 mmHg and respiratory acidosis with a pH <7.25. In modern clinical practice, with severe asthmatic patients it is important to focus on oxygenation. The decision to ventialte a patient should be made by a specialist but will largely be made on the basis of the presence of hypoxaemia and a respiratory acidosis rather than a rising PcO2.

Follow-up

After admission to an emergency room or hospital with a severe attack it is important that children should be stable on discharge medicines for at least 24 hours before discharge. They should be discharged with sufficient medication for at least 3 days. It is important that they should be given the telephone number of a contact person and that they should be properly and adequately instructed in the use of the MDI, spacer or nebuliser. PEFR measurements should be made at least 3 times a day until they are reassessed within 3 days of discharge to assess PEFR deterioration is noted. It is important that trigger factors of the acute attack should be identified and that a written plan of action should be given to the patient.

Fatal asthma attacks

A subgroup of children are at particular risk for fatal asthma attacks. Previous studies suggest that children between the ages of 15 and 20 years and disadvantaged children have a five-fold greater risk. In
addition children who have had previous life-threatening attacks or hospital admissions within the previous year are also at risk.

It is important to identify such patients and to determine known trigger factors so that avoidance measures can be applied. These children should be properly instructed in the use of their medication and fears and misconceptions must be removed. They should have a clear crisis plan as to where they should go and what they should do if they develop an attack. It is important that these children receive psychological counselling to reduce the strong dependency that some of them exhibit.

It would be useful for these children to carry an injectable adrenaline kit (e.g. Ana-Guard) and they should all wear a Medic-Alert bracelet or necklace. It is hoped that in the near future paramedics will be adequately trained to assist in the emergency management of these children.

This article was previously published in the South African Medical Journal and we thank the editor and publisher for allowing us to reprint this article here.
South African Childhood Asthma Working Group. Management of Acute Asthmatic attacks in children. SAMJ. 1993;83:286-289

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Copyright Allergy Society of South Africa