Respiratory: Bronchiolitis; Viral Wheeze; Asthma

Question 1

Describe what is meant by bronchiolitis [1]
What is the most common cause? [1]

Answer 1

Bronchiolitis describes inflammation and infection in the bronchioles, the small airways of the lungs.

This is usually caused by a virus. Respiratory syncytial virus (RSV) is the most common cause.

Question 2

Describe the pathophysiology of bronchiolitis [1]

Answer 2

When a virus affects the airways of adults, the swelling and mucus are proportionally so small that it has little noticeable effect on breathing.

The airways of infants are very small to begin with, and when there is even the smallest amount of inflammation and mucus in the airway it has a significant effect on the infants ability to circulate air to the alveoli and back out. This causes the harsh breath sounds, wheeze and crackles heard on auscultation when listening to a bronchiolitic baby’s chest.

Question 3

Describe the presentation of bronchiolitis [+]

Answer 3

Symptoms noramlly usually get worse for 3-5 days, then improves

Coryzal symptoms - These are the typical symptoms of a viral upper respiratory tract infection:
* running or snotty nose, sneezing, mucus in throat and watery eyes.
* Signs of respiratory distress
* Dyspnoea (heavy laboured breathing)
* Tachypnoea (fast breathing)
* Poor feeding
* Mild fever (under 39ºC)
* Apnoeas are episodes where the child stops breathing
* Wheeze and crackles on auscultation

Signs of Resp. Distress:
* Raised respiratory rate
* Use of accessory muscles of breathing, such as the sternocleidomastoid, abdominal and intercostal muscles
* Intercostal and subcostal recessions
* Nasal flaring
* Head bobbing
* Tracheal tugging
* Cyanosis (due to low oxygen saturation)
* Abnormal airway noises

TOM TIP: You should become very confident in listing and spotting the signs of respiratory distress. This is very important when treating children, to distinguish between a well child and an unwell child. Your examiners will expect you to know the signs like the back of your hand.

Question 4

TOM TIP: You should become very confident in listing and spotting the signs of respiratory distress. This is very important when treating children, to distinguish between a well child and an unwell child. Your examiners will expect you to know the signs like the back of your hand.

What are they? [+]

Answer 4

Signs of Resp. Distress:
* Raised respiratory rate
* Use of accessory muscles of breathing, such as the sternocleidomastoid, abdominal and intercostal muscles
* Intercostal and subcostal recessions
* Nasal flaring
* Head bobbing
* Tracheal tugging
* Cyanosis (due to low oxygen saturation)
* Abnormal airway noises

Question 5

Describe the course of bronchiolitis [3]

Answer 5

Bronchiolitis usually starts as an upper respiratory tract infection (URTI) with coryzal symptoms.

From this point around half get better spontaneously.

The other half develop chest symptoms over the first 1-2 days following the onset of coryzal symptoms.

Symptoms are generally at their worst on day 3 or 4. Symptoms usually last 7 to 10 days total and most patients fully recover within 2 – 3 weeks.

Children who have had bronchiolitis as infants are more likely to have viral induced wheeze during childhood.

Question 6

Which patients should you admit w/ bronchiolitis? [+]

Answer 6

• Aged under 3 months or any pre-existing condition such as prematurity, Downs syndrome or cystic fibrosis
• 50 – 75% or less of their normal intake of milk
• Clinical dehydration
• Respiratory rate above 70
• Oxygen saturations below 92%
• Moderate to severe respiratory distress, such as deep recessions or head bobbing
• Apnoeas
• Parents not confident in their ability to manage at home or difficulty accessing medical help from home

Question 7

Describe the managment plan for bronchiolitis [+]

Answer 7

Typically patients only require supportive management. This involves:
* Ensuring adequate intake. This could be orally, via NG tube or IV fluids depending on the severity. It is important to avoid overfeeding as a full stomach will restrict breathing. Start with small frequent feeds and gradually increase them as tolerated.
* Saline nasal drops and nasal suctioning can help clear nasal secretions, particularly prior to feeding
* Supplementary oxygen if the oxygen saturations remain below 92%
* Ventilatory support if required
* There is little evidence for treatments such as nebulised saline, bronchodilators, steroids and antibiotics.

Question 8

Describe the different types of ventilatory support might have to give a child w bronchiolitis [3]

Answer 8

High-flow humidified oxygen via tight nasal cannula (i.e. “Airvo” or “Optiflow”). This delivers air and oxygen continuously with some added pressure, helping to oxygenate the lungs and prevent the airways from collapsing. It adds “positive end-expiratory pressure” (PEEP) to maintain the airway at the end of expiration.

Continuous positive airway pressure (CPAP). This involves using a sealed nasal cannula that performs in a similar way to Airvo or Optiflow, but can deliver much higher and more controlled pressures
.
Intubation and ventilation. This involves inserting an endotracheal tube into the trachea to fully control ventilation.

Question 9

What are the best indicators of resp. failure? [2]

Answer 9

Rising pCO2, showing that the airways have collapsed and can’t clear waste carbon dioxide.

Falling pH, showing that CO2 is building up and they are not able to buffer the acidosis this creates. This is a respiratory acidosis. If they are also hypoxic, this is classed as type 2 respiratory failure.

Question 10

Which babies might be given monthly injections to protect agaisnt bronchiolitis? [2]
What injection would recieve? [1]

Answer 10

Palivizumab is a monoclonal antibody that targets the respiratory syncytial virus. A monthly injection is given as prevention against bronchiolitis caused by RSV. It is given to high risk babies, such as ex-premature and those with congenital heart disease.

It is not a true vaccine as it does not stimulate the infant’s immune system. It provides passive protection by circulating the body until the virus is encountered, as which point it works as an antibody against the virus, activating the immune system to fight the virus. The levels of circulating antibodies decrease over time, which is why a monthly injection is required.

Question 11

Describe what causes viral induced wheeze and why it occurs [3]

Answer 11

Viral-induced wheeze:
- describes is an acute wheezy illness caused by a viral infection.
- Small children (typically under 3 years) have small airways. When these small airways encounter a virus (commonly RSV or rhinovirus) they develop a small amount of inflammation and oedema, swelling the walls of the airways and restricting the space for air to flow.
- This inflammation also triggers the smooth muscles of the airways to constrict, further narrowing the space in the airway.

This swelling and constriction of the airway caused by a virus has little noticeable effect on the larger airways of an older child or adult, however due to the small diameter of a child’s airway, the slight narrowing leads to a proportionally larger restriction in airflow. This is described by Poiseuille’s law, which states that flow rate is proportional to the radius of the tube to the power of four. Therefore, halving the diameter of the tube decreases flow rate by 16 fold.

Air flowing through these narrow airways causes a wheeze, and the restricted ventilation leads to respiratory distress. For some reason, certain children are much more prone to this airway swelling than others. There seems to be a hereditary element, so when assessing a wheezy child ask about a family history of viral-induced wheeze. These children are at higher risk of developing asthma in later life.

Question 12

How do you differentiate between viral induced wheeze and asthma? [3]

Answer 12

The distinction between a viral-induced wheeze and asthma is not definitive. Generally, typical features of viral-induced wheeze (as opposed to asthma) are:
* Presenting before 3 years of age
* No atopic history
* Only occurs during viral infections
* Asthma can also be triggered by viral or bacterial infections, however it also has other triggers, such as exercise, cold weather, dust and strong emotions. Asthma is historically a clinical diagnosis, and the diagnosis is based on the presence of typical signs and symptoms along with variable and reversible airflow obstruction.

NB: majority of children will improve - but some will develop asthma.

Question 13

What are the presenting features of viral induced wheeze? [3]

What is the management? [1]

Answer 13

• Shortness of breath
• Signs of respiratory distress
• Expiratory wheeze throughout the chest
• TOM TIP: Neither viral-induced wheeze or asthma cause a focal wheeze. If you hear a focal wheeze be very cautious and investigate further for a focal airway obstruction such as an inhaled foreign body or tumour. These patients will require an urgent senior review.

Management
* Management of viral-induced wheeze is the same as acute asthma in children.

Question 14

Describe the clinical dx of asthma [+]

Answer 14

Spirometry - The NICE guidelines suggest offering spirometry to children aged over 5-years-old if a diagnosis of asthma is being considered:
- (FEV1:FVC) ratio of less than 70% is suggestive of obstructive airway disease

Bronchodilator reversibility:
* For children aged 5 to 16-years-old, an improvement in FEV1 of >12% is suggestive of asthma
* For children aged 17 years-old and older, an improvement in FEV1 of >12%, plus an increase in volume of >200mL, is suggestive of asthma

FeNO:
- A fraction exhaled nitric oxide level of greater than 35 parts per billion (ppb) is suggestive of asthma

Peak Flow:
* The NICE guidelines suggest monitoring peak flow variability for 2-4 weeks if there is any diagnostic uncertainty
* Greater than 20% variability is considered a positive test, suggestive of asthma
* After diagnosis and treatment, peak expiratory flow can also be used as an indicator of treatment effect and a marker of clinical improvement/deterioration

Question 15

Describe the features of moderate, severe and life threatening asthma in children [+]

Answer 15

Moderate:
- Peak flow > 50 % predicted
- Normal speech
- No features listed across

Severe:
* Peak flow < 50% predicted
* Saturations < 92%
* Unable to complete sentences in one breath
* Signs of respiratory distress
* Respiratory rate: > 40 in 1-5 years; > 30 in > 5 years
* HR: > 140 in 1-5 years; > 125 in > 5 years

Life Threatening:
* Peak flow < 33% predicted
* Saturations < 92%
* Exhaustion and poor respiratory effort
* Hypotension
* Respiratory rate:
* Silent chest
* Cyanosis
* Confusion

Question 16

Describe the management plan for acute asthma in children aged 5-16 [+]

Answer 16

Mild cases can be managed as an outpatient with regular salbutamol inhalers via a spacer (e.g. 4-6 puffs every 4 hours).

Moderate-severe:
1. SABA

2. SABA + paediatric low-dose inhaled corticosteroid (ICS)
3. SABA + paediatric low-dose ICS + leukotriene receptor antagonist (LTRA)
4. SABA + paediatric low-dose ICS + long-acting beta agonist (LABA) (Don’t stop the LRTA like in adults)
5. SABA + switch ICS/LABA for a maintenance and reliever therapy (MART), that includes a paediatric low-dose ICS
6. SABA + paediatric moderate-dose ICS MART
   OR consider changing back to a fixed-dose of a moderate-dose ICS and a separate LABA
7. SABA + one of the following options: increase ICS to paediatric high-dose, either as part of a fixed-dose regime or as a MART OR a trial of an additional drug (for example theophylline) OR seeking advice from a healthcare professional with expertise in asthma

double check - as asthma guidelines may have changed

Question 17

Describe the management plan for acute asthma in children aged < 5 [+]

Answer 17

One. SABA

Two:. SABA + an 8-week trial of paediatric MODERATE-dose inhaled corticosteroid (ICS)
* After 8-weeks stop the ICS and monitor the child’s symptoms:
* if symptoms did not resolve during the trial period, review whether an alternative diagnosis is likely
* if symptoms resolved then reoccurred within 4 weeks of stopping ICS treatment, restart the ICS at a paediatric low dose as first-line maintenance therapy
* if symptoms resolved but reoccurred beyond 4 weeks after stopping ICS treatment, repeat the 8-week trial of a paediatric moderate dose of ICS

Three. SABA + paediatric low-dose ICS + leukotriene receptor antagonist (LTRA)

Four. Stop the LTRA and refer to an paediatric asthma specialist

Question 18

What are the different definitions for low, moderate and high doses for ICS in asthma? [3]

Answer 18

<= 200 micrograms budesonide or equivalent = paediatric low dose

200 micrograms - 400 micrograms budesonide or equivalent = paediatric moderate dose

> 400 micrograms budesonide or equivalent= paediatric high dose.

Question 19

How do you treat acute moderate asthma in children > 5?

Answer 19

Supplementary oxygen if required (i.e. oxygen saturations less than 94% or working hard)

Question 20

How do you treat acute severe asthma in children > 5?

Answer 20

Moderate to severe cases require a stepwise approach working upwards until control is achieved:
* Salbutamol inhalers via a spacer device: starting with 10 puffs every 2 hours
* Nebulisers with salbutamol / ipratropium bromide
* Oral prednisone (e.g. 1mg per kg of body weight once a day for 3 days)
* IV hydrocortisone
* IV magnesium sulphate
* IV salbutamol
* IV aminophylline

Question 21

How would you treat life threatening acute asthma in a child > 5?

Answer 21

Question 22

Describe a typical step down regime of inhaled salbutamol in children from acute asthma? [1]

Answer 22

A typical step down regime of inhaled salbutamol is 10 puffs 2 hourly then 10 puffs 4 hourly then 6 puffs 4 hourly then 4 puffs 6 hourly.

Consider monitoring the serum potassium when on high doses of salbutamol as it causes potassium to be absorbed from the blood into the cells.

Question 23

Acute asthma:
- Generally, discharge can be considered when the child well on [] puffs [] hourly of salbutamol.
- They can be prescribed a reducing regime of salbutamol to continue at home, for example [] then [] then [] as required.

Answer 23

Generally, discharge can be considered when the child well on 6 puffs 4 hourly of salbutamol. They can be prescribed a reducing regime of salbutamol to continue at home, for example 6 puffs 4 hourly for 48 hours then 4 puffs 6 hourly for 48 hours then 2-4 puffs as required.

Question 24

Which conditions can cause bronchiolitis to be more severe? [3]

Answer 24

more serious if bronchopulmonary dysplasia (e.g. Premature), congenital heart disease or cystic fibrosis

Question 25

Describe the difference in symptoms between croup, epiglottitis and inhaled foreign body [3]

Answer 25

Croup:
- Barking cough, hoarse voice and stridor

Epiglottitis:
- soft stridor
- high fever
- sore throat
- drooling
- tripod position

IFB:
- cough
- chocking
- stridor
- afebrile

Question 26

Describe the difference in timeline and management between croup, epiglottitis and inhaled foreign body [6]

Answer 26

Question 27

Lecture

Describe the management of acute wheeze [+]

Answer 27

ABCDE approach, get help early

Assess severity

Apply high-flow oxygen (initially 15 litres via non-rebreathe mask,) titrate as needed aiming for target saturations 94-98%

Start bronchodilators:
* Burst therapy of Salbutamol (via spacer if Sats > 94% or via nebulizer if needing oxygen) and Ipratropium Bromide if severe exacerbation/poor response to Salbutamol
Give steroids

Consider IV Magnesium Sulphate if poor response to initial therapy

Also, can consider IV Salbutamol and IV Aminophylline

Question 28

A potential exam scenario is discussing inhaled steroids with a parent that is worried about potential side effects. A common question is whether they slow growth.

Describe how you would discuss this answer

Answer 28

There is evidence that inhaled steroids can slightly reduce growth velocity and can cause a small reduction in final adult height of up to 1cm when used long term (for more than 12 months).
- This effect was dose-dependent, meaning it was less of a problem with smaller doses.

It is worth putting this in context for the parent by explaining that these are effective medications that work to prevent poorly controlled asthma and asthma attacks that could lead to higher doses of oral steroids being given.
- Poorly controlled asthma can lead to a more significant impact on growth and development.
- The child will also have regular asthma reviews to ensure they are growing well and on the minimal dose required to effectively control symptoms.

Question 29

Describe how you would tell a patient how to use an inhaler:
MDI technique without a spacer: [+]
MDI technique with a spacer: [+]

Answer 29

MDI technique without a spacer:
* Remove the cap
* Shake the inhaler (depending on the type)
* Sit or stand up straight
* Lift the chin slightly
* Fully exhale
* Make a tight seal around the inhaler between the lips
* Take a steady breath in whilst pressing the canister
* Continue breathing for 3 – 4 seconds after pressing the canister
* Hold the breath for 10 seconds or as long as comfortably possible
* Wait 30 seconds before giving a further dose
* Rinse the mouth after using a steroid inhaler

MDI technique with a spacer:
* Assemble the spacer
* Shake the inhaler (depending on the type)
* Attach the inhaler to the correct end
* Sit or stand up straight
* Lift the chin slightly
* Make a seal around the spacer mouthpiece or place the mask over the face
* Spray the dose into the spacer
* Take steady breaths in and out 5 times until the mist is fully inhaled

NB: Spacers should be cleaned once a month. Avoid scrubbing the inside and allow them to air dry to avoid creating static. Static can interact with the mist and prevent the medication being inhaled.