History

John, a 30-month-old boy was admitted to our Paediatric ward via Accident and Emergency Department for wheezy attack. He had symptoms of upper respiratory tract infection for two days with progressive increase in shortness of breath despite oral treatment from his family doctor. His parents brought him to Accident and Emergency Department. After a dose of nebulized bronchodilator, he was still tachypnoeic with diffuse wheezing and was thus admitted.

Question 1:

How to assess the severity of this wheezy episode if you are the paediatric medical officer admitting the child?

Answer

The severity of the exacerbation helps to determine the treatment to be administered. There are several severity scores adopted in different guidelines. Essentially the score include clinical signs like degree of breathlessness, use of accessory muscle, amount of wheezing, degree of agitation and conscious level but they correlated poorly with degree of airway obstructions. Vital signs are more objective and include pulse rate, respiratory rate and in particular, oxygen saturation detected by pulse oximetry. Peak expiratory flow rate (for children older than 5 years) has also been included but this may not be reliable if the child has never used a peak flow meter. Pulsus paradoxicus is not recommended in British Thoracic Society BTS guideline due to pragmatic reasons. It must be emphasized that some of these criteria in these scores are arbriturarily defined and thus the score serve as an initial guide to management rather than an ultimate dictum of the severity of exacerbation.

Figure 4.4-1 Severity of Asthma Exacerbations*

Mild Moderate Severe Respiratory arrest imminent

Breathless Walking

Can lie down Talking infant- softer shorter cry; difficulty feeding

Prefers sitting At rest
Infant stops feeding

Hunched forward

Talks in Sentences Phrases Words

Alertness May be agitated Usually agitated Usually agitated Drowsy or confused

Respiratory rate Increased Increased Often > 30/min

Normala rates of beathing in awake children:

Age
<2 months
2-12 months
1-5 years
6-8 years

Normal rate
<60/min
<50/min
<40/min
<30/min

Accessory muscles and suprasternal retractions Usually not Usually Usually Paradoxical thoraco-abdominal movement

Wheeze Moderate, often only end expiratory Loud Usually loud Absence of wheeze

Guide to limits of normal pulse rate in children:
Infants	2-12 months-Normal Rate	<160/min
Preschool	1-2 years	<120/min
School age	2-8 years	<110/min

Pulse paradoxus Absent < 10mm Hg May be present 10-25 mm Hg Often present
>25 mm Hg (adult)
20-40 mm Hg (child) Absence suggests respiratory muscle fatigue

PEF after initial bronchodilator % predicted or % personal best Over 80% Approx. 60-80% < 60% predicted or personal best (<100L/min adults) or response lasts <2hrs

PaO₂ (on air)⁺

and/or PaCO₂⁺ Normal Test not usually necessary

< 45mm Hg > 60 mmHg

< 45 mm Hg < 60 mm Hg

Possible cyanosis

>45 mm Hg;
Possible respiratory failure (see text)

SaO₂% (on air) > 95% 91-95% < 90%

Hypercapnea (hypoventilation) develops more readily in young children than in adults and adolescents.

* Note: The presence of several parameters, but no necessarily all, indicateds the general classification of the exacerbation.
⁺Note: Kilopascals are also used internationally; conversion would be appropriate in this regard.

GINA2007

Table 4 Levels of severity of acute asthma exacerbations (BTS guideline on severity of asthma attack 2007)
Near fatal asthma	Raised PaCo2 and/or requiring mechanical ventilation with raised inflation pressures 223-225
Life threatening asthma	Any one of the following in a patient with severe asthma: - PEF < 33% best or predicted - SpO2 < 92% - PaO2 < 8kPa - normal PaCO2 (4.6-6.0 kPa) - silent chest - cyanosis - feeble respiratory effort - bradycardia - dysrhythmia - hypotension - exhaustion - confusion - coma
Acute severe asthma	Any one of: - PEF 33-50% best or predicted - respiratory rate = 25/min - heart rate = 110/min - inability to complete sentences in one breath
Moderate asthma exacerbation	- Increasing symptoms - PEF > 50-75% best or predicted - no features of acute severe asthma
Brittle asthma	- Type 1: wide PEF variability (>40% diurnal variation for > 50% of the time over a period > 150 days) despite intense therapy - Type 2: sudden severe attacks on a background of apparently well controlled asthma

Table 6 Clinical features for assessment of severity for children aged over 2 years old (BTS guideline 2007)
Acute severe	Life threatening
Can’t complete sentences in one breath or too breathless to talk or feed Pulse > 120 in children aged > 5 years > 130 in children aged 2-5 years Respiration > 30 breaths/min aged >5 years > 50 breaths/min aged 2-5 years	Silent chest Cyanosis Poor respiratory effort Hypotension Exhaustion Confusion Coma

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