11/14/24, 10\:38 AM Viral Induced Wheeze and Asthma

Viral Induced Wheeze and Asthma

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Key points ⚡
Succinct notes to superpower your revision
Wheezing in children\: Common in paediatrics; caused by illnesses like bronchiolitis, viral-induced wheeze, and asthma.
Viral-induced wheeze vs asthma\: Di
wheeze-free by age 6. Recent trends diagnose asthma earlier with recurrent wheeze, atopy, and poor control between
episodes.
Common viral triggers\: RSV, rhinovirus, coronaviruses, parain
Risk factors for acute wheeze\: exposure to cigarette smoke, parental history of asthma, maternal smoking during
pregnancy, daycare/nursery/school attendance.
Symptoms\: upper respiratory tract infection symptoms (cough, coryza, blocked/runny nose, sneezing, sore throat), fever,
lethargy, poor feeding, wheezing, tachypnoea, increased work of breathing, di
Clinical
accessory muscle use.
Classi
Mild\: slight tachypnoea, expiratory wheeze, minimal work of breathing, full sentences/cry, oxygen saturations >95%, normal
heart rate.
Moderate\: tachypnoea, expiratory/inspiratory wheeze, moderate work of breathing, oxygen saturations 92-95%,
phrases/short cry, mild-moderate tachycardia.
Severe/life-threatening\: agitated/drowsy, marked tachypnoea, severe work of breathing, inspiratory/expiratory wheeze,
silent chest, oxygen saturations ≤90%, marked tachycardia/bradycardia.
Impending respiratory failure\: cyanosis, reduced respiratory e
respiratory acidosis.
Di
abnormalities (e.g., mediastinal mass), cardiac/immune/gastrointestinal disorders.
Investigations\:
Consider chest x-ray for focal signs despite treatment (pneumonia/foreign body).
Venous/capillary blood gas in severe cases (acid/base status, CO2, lactate, potassium).
Chest x-ray for severe/life-threatening cases (exclude pneumonia/pneumothorax).
Management\: Follow local guidelines.
Mild\: salbutamol via spacer, burst therapy (3 doses, 20 minutes apart), frequent reassessment, oral steroids (1-2mg/kg for 1-
3 days).
Moderate\: salbutamol burst therapy, stretch doses to 3-hourly, consider ipratropium, oxygen, oral prednisolone.
Severe\: early senior involvement, burst salbutamol/ipratropium, oxygen, intravenous steroids, possible magnesium
sulphate/aminophylline/salbutamol, consider higher-level care.
Discharge and follow-up\: Discharge if stable on 3-hourly salbutamol, arrange follow-up, provide education. Admit if not
meeting criteria; transfer to tertiary care/PICU if severe.
Complications\:
Treatment-related\: salbutamol (tachycardia, hypokalaemia), steroids (hypertension, stunted growth, weight gain), invasive
ventilation (pneumothorax).
Disease-related\: pneumonia, pneumothorax, respiratory failure.
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Article 🔍
A comprehensive topic overview

Introduction

Wheezing in children is a common clinical presentation in paediatrics. It can be caused by a spectrum of illnesses
including bronchiolitis, viral-induced wheeze and asthma.
Wheezing due to viral-induced wheeze or acute viral-induced asthma is caused by narrowing of the airways due to
mucus production and bronchoconstriction. Other conditions can present with wheeze, and these are outlined in the
di

Aetiology

Common precipitants of viral-induced wheeze and viral exacerbation of asthma include RSV, rhinovirus, coronaviruses,
parain

Viral induced wheeze vs asthma

The question often arises ‘is this asthma or viral-induced wheeze?’
.
Approximately 50% of children have had at least one episode of wheezing in early childhood, however, most of these are
wheeze-free by age six.
1
This is due to a combination of increased exposure to viruses in early childhood and smaller airway anatomy that is more
prone to cause wheezing due to Poiseuille’s law (small reduction in airway radius increases resistance to air
inversely proportional to the fourth power of the radius).
The diagnosis of asthma previously has been deferred until the child was able to perform objective testing (e.g.
spirometry), typically from age 5 onwards.
However, there is a recent shift to diagnose asthma earlier in children who have recurrent episodes of wheezing along with
atopic history and a pattern of symptoms indicating poor control between acute events.
2

Risk factors

Risk factors for acute wheeze with viral infections include\:
Exposure to cigarette smoke
Parental history of asthma
Maternal smoking during pregnancy
Daycare/nursery/school attendance (due to increased risk of exposure to viruses)

Clinical features

History

Typical symptoms of a viral-induced wheeze or viral-induced asthma include\:
Upper respiratory tract infection including cough, coryza, blocked/runny nose, sneezing, sore throat
Fever
Lethargy and fatigue
Poor feeding
Wheezing sound
Tachypnoea and increased work of breathing
Complaints of di
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It is important to ask about prior wheezing episodes. If a previously higher level of support was required, there is greater
suspicion for risk of deterioration.
Speci
Needing admission to hospital vs outpatient therapy
Needing intravenous therapy on previous occasions
Requiring respiratory support (such as CPAP, intubation)
Requiring paediatric intensive care unit treatment
Atopic history (including eczema, allergic rhinitis, food allergies)
Family history of atopy

Clinical examination

A systematic examination should be performed, with an ABCDE approach.
Typical clinical
Tachypnoea
Hypoxia
Wheezing (typically expiratory wheeze, but maybe heard throughout)
Prolonged expiratory phase
Reduced air entry
Accessory muscle use/retractions (also referred to as increased work of breathing)

Classi

Local guidelines should be followed regarding the classi
the Royal Children's Hospital Melbourne\:
Mild\: alert, slight tachypnoea, expiratory wheeze, minimal work of breathing, speaking in full sentences or long cry,
oxygen saturations above 95% and normal heart rate
Moderate\: alert, slight tachypnoea, wheezing during expiration with or without inspiratory wheeze, mild to moderate
work of breathing, oxygen saturations 92-95%, able to speak in phrases or shortened cry and mild to moderate
tachycardia
Severe and life-threatening\: agitated/drowsy/confused, marked tachypnoea, moderate to severe work of breathing,
inspiratory and expiratory wheeze with prolonged expiratory phase (though wheeze may be absent in a silent chest if
there is little or no air entry), oxygen saturations 90% and below (cyanosis is very concerning), and marked tachycardia (or
bradycardia)
Impending respiratory failure\: may be signalled by cyanosis, reduced respiratory e
alertness (lethargic or agitated), oxygen saturations less than 90% and respiratory acidosis (rising CO2 on
venous/capillary blood gas)
Unlike asthma in adults, recording peak does not form a part of the initial acute assessment in children.

Di

Wheeze is a common symptom of viral-induced wheeze and asthma exacerbation but can also re
underlying diagnoses that must be considered.
Di
2
Anaphylaxis\: must be considered, especially if associated with sudden onset wheeze and respiratory distress
Foreign body aspiration\: history of inhalation or aspiration, non-responsiveness to treatments, radiographic evidence of
foreign body or air trapping due to a ball-valve mechanism
Other pulmonary disorders\: for example, cystic , laryngomalacia and tracheomalacia
Anatomical abnormalities\: congenital or acquired (e.g. mediastinal mass in leukaemia/lymphoma)
Less commonly, cardiac, immune and gastrointestinal disorders may present in similar ways.
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Investigations

Investigations for acute viral-induced wheeze or acute viral-induced asthma should be considered to help distinguish
between di
additional diagnosis.
For example, a chest x-ray would be considered if there are focal signs on auscultation despite treatment, to exclude
pneumonia/foreign body.
3
In addition, investigations are used in the assessment of severe or life-threatening asthma to aid in the monitoring of the
condition.
Arterial blood gasses are not used routinely in children. If required, a venous blood gas or capillary blood gas can provide
information regarding acid/base status, CO2 level, lactate and potassium.
3
In the case of severe or life-threatening cases, consider a chest x-ray to ensure no additional treatable diagnoses (e.g.
pneumonia or pneumothorax).

Management

Management of acute viral induced wheeze and viral exacerbation of asthma is dependent on the severity.
Escalating therapy might be required if a patient who presents as lower severity deteriorates or does not respond to initial
therapy, this may require input from a senior clinician.
Local management guidelines should be followed. The management below is based on a guideline by the Royal
Children's Hospital Melbourne\:

Mild

Management of mild severity includes\:
Commence a trial of salbutamol via spacer and mask (\<6 years old = 6 pu
A ‘burst therapy’ may be considered, which involves 3 doses of the above, each 20 minutes apart
Frequent reassessment to ensure adequate response and need for further dosages
Oral steroids may be considered (prednisolone dosage 1-2mg/kg once daily) for 1-3 days (see note below on steroid use
in viral-induced wheeze) depending on history and response to therapy

Moderate

Management of moderate severity includes\:
Commence inhaled salbutamol as ‘burst therapy’ via spacer and mask with 3 doses, 20 minutes apart
Attempt to stretch doses of salbutamol to a minimum of 3 hourly to consider discharge home
Consider adding in ipratropium, either as a single dose (\<6 years = 4 pu
minutes apart)
Oxygen may be required
Oral prednisolone 1-2 mg/kg daily for 1-3 days. If unable to stretch doses of salbutamol, consider escalating therapy (see
below)

Severe

Management of severe severity includes\:
Early senior involvement in the case of deterioration
Burst salbutamol and ipratropium via spacer or nebuliser. Nebulised salbutamol can be given continuous or 20 minutes
apart (as a burst). Ipratropium cannot be given continuously (can only be given as a burst with 3 doses 20 minutes apart)
Supplemental oxygen may be required
Intravenous rather than oral steroids (intravenous hydrocortisone or methylprednisolone) are given
If contemplating giving intravenous magnesium sulphate, aminophylline or salbutamol, a senior should be involved
immediately and consider retrieval to a higher-level facility/PICU
4
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Inhalers vs nebulisers
A 2013 Cochrane review found that metered-dose inhalers (MDI) via spacer performed at least as well as
nebulisation.
This applied to mild-moderate wheezing episodes, as severe and life-threatening episodes may still require
nebulisers.
The bene
ability to deliver ipratropium with salbutamol and the ability to give back-to-back nebulised salbutamol.
5

Discharge and follow up

Decisions around discharge depend on severity and response to therapy administered.
Discharge home may be considered if the patient is clinically stable on 3-hourly salbutamol, clinical signs are within
normal limits for age, early follow up plans have been arranged and education has been delivered to parents including an
asthma action plan and safety-netting.
3
The parents must be comfortable with the discharge plan and feel con
Admission will be required to the ward for ‘stretching of salbutamol’ if the patient does not meet the above criteria.
Transfer to tertiary care or PICU in cases of severe or life-threatening, requiring IV infusions or respiratory support (such as
CPAP or intubation).

Use of steroids

The role of steroids in viral-induced wheeze is debated.
Steroids certainly have a role in acute asthma exacerbation, and there is recent evidence that steroids may decrease the
length of hospital stay for younger children with mild-moderate viral-induced wheeze (severe and life-threatening were
excluded from the study).
Further research is yet to conclude the role of steroids in community-managed viral-induced wheeze.
6

Complications

Complications can occur because of the underlying disease or treatment.
Treatment-related complications include\:
7
Salbutamol\: tachycardia and hypokalaemia
Steroid use\: hypertension, stunted growth, weight gain
Invasive ventilation\: pneumothorax
Disease-related complications include\:
8
Pneumonia
Pneumothorax
Respiratory failure (potentially fatal)

References

Beigelman, Avraham, and Leonard B Bacharier. Infection-Induced Wheezing in Young Children. T h e J o u r n a l o f A l l e r g y a n d
C l i n i c a l I m m u n o l o g y , U.S. National Library of Medicine, Feb. 2014, Available from\: [LINK]
Oo, Stephen, and Peter Le Souëf. RACGP - The Wheezing Child\: an Algorithm. A u s t r a l i a n F a m i l y P h y s i c i a n , vol. 44, no. 6,
2015, pp. 360–364., Available from\: [LINK]
https\://app.geekymedics.com/notebook/2658/ 5/611/14/24, 10\:38 AM Viral Induced Wheeze and Asthma
The Royal Children's Hospital Melbourne. A c u t e a s t h m a . Dec. 2020. Available from\: [LINK]
Cochrane. I n t e r v e n t i o n s f o r A c u t e S e v e r e A s t h m a A t t a c k s i n C h i l d r e n \: a n O v e r v i e w o f C o c h r a n e R e v i e w s . Available from\: [LINK]
5 Aug. 2020,
Cates, CJ, et al. H o l d i n g C h a m b e r s ( S p a c e r s ) v e r s u s N e b u l i s e r s f o r D e l i v e r y o f B e t a-A g o n i s t R e l i e v e r s i n t h e T r e a t m e n t o f a n
A s t h m a A t t a c k . Sept. 2013. Available from\: [LINK]
Davis, Tessa. S t e r o i d s f o r P r e-S c h o o l W h e e z e . Don't Forget The Bubbles, 26 Feb. 2020. Available from\: [LINK]
Howell, J., S e v e r e A s t h m a E x a c e r b a t i o n s i n C h i l d r e n Y o u n g e r t h a n 1 2 Y e a r s . 2021. Available from\: [LINK]
Sawicki, G., Haver, K,. A s t h m a E x a c e r b a t i o n s i n C h i l d r e n Y o u n ge r t h a n 1 2 Y e a r s . 2021. Available from\: [LINK]

Reviewer

Dr Hemani Sharma
Paediatric fellow

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Contents

Introduction
Aetiology
Risk factors
Clinical features
Di
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