Respiratory Flashcards
?In what circumstances might an ABG be used over VBG/CBG in paediatrics?
When able to use umbilical artery (cord – 2 arteries, 1 vein)
Unusual to do ABG from peripheral vein: Arterial line post cardiac surgery, PICU
Wheeze vs. Stridor
Wheeze: a continuous, coarse, whistling sound produced in the respiratory airways during breathing.
Stridor: a high-pitched extra-thoracic breath sound resulting from turbulent airflow through narrowed upper airways.
What is bronchiolitis?
Bronchiolitis describes inflammation and infection in the bronchioles, the small airways of the lungs
What most bronchiolitis?
Respiratory syncytial virus (RSV) is the most common cause.
What aged children are affected by bronchiolitis?
Bronchiolitis is generally considered to occur in children under 1 year.
It is most common in children under 6 months.
It can rarely be diagnosed in children up to 2 years of age, particularly in ex-premature babies with chronic lung disease.
Why do viral illnesses cause more respiratory symptoms in young children than in adults?
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.
Presentation of bronchiolitis?
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 respiratory 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 (wheezing, grunting, stridor)
Abnormal airway noises
Wheezing is a whistling sound caused by narrowed airways, typically heard during expiration
Grunting is caused by exhaling with the glottis partially closed to increase positive end-expiratory pressure
Stridor is a high pitched inspiratory noise caused by obstruction of the upper airway, for example in croup
Typical course of RSV?
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.
Most infants with bronchiolitis can be managed at home with advice about when to seek further medical attention. Reasons for admission include what?
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
Management of bronchiolitis?
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.
As breathing gets harder, a child with bronchiolitis may get more tired and less able to adequately ventilate themself. They may require ventilatory support to maintain their breathing. This is stepped up until they are adequately ventilated.
What are the management options?
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.
Assessing Ventilation in children
Capillary blood gases are useful in severe respiratory distress and in monitoring children who are having ventilatory support.
The most helpful signs of poor ventilation are:
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.Assessing Ventilation
What are the most helpful signs on blood gas of poor ventilation?
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.Assessing Ventilation
Palivizumab and bronchiolitis prevention?
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.
Which children are given monthly palivizumab and why?
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
In paediatric BLS, if the patient is not breathing, you must give rescue breaths first. Why?
Because cardiac arrest in children is more likely to be caused by respiratory pathology than cardiac.
How should artificial surfactant be given?
via intratracheal instillation
Artificial surfactant needs to be given directly into the lungs to be of benefit
Why do small children (typically under 3 years) experience virally-induced wheezes and respiratory distress?
When the small airways encounter a virus they develop a small amount of inflammationg and odema, swelling the walls of the airways and restricting the spay for air to flow. This inflammation also triffers 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.
Viral-induced wheeze vs asthma?
Viral: presenting before 3 years, 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.
How does a virally induced wheeze present?
Evidence (fever, cough, coryzal symptoms) of viral illness for 1-2 days preceding onset of:
SOB
Signs of respiratory distress
Expiratory wheeze throughout the chest
What does a focal wheeze indicate?
Focal airway obstruction such as inhaled foreign body or tumour
Requires urgent senior review
Neither viral-induced wheeze or asthma cause a focal wheeze.
How does the management of a viral wheeze differ from the management of acute asthma in a child?
Managed the same way
What is meant by an acute exacerbation of asthma?
An acute exacerbation of asthma is characterised by a rapid deterioration in symptoms. This could be triggered by any of the typical asthma triggers such as infection, exercise or cold weather.
How does an acute exacerbation of asthma present?
SOB - progressively worsening
Use of accessory muscles
Tachypnoea
Symmetrical expiratory wheeze on auscultation
‘‘Tight’’ sounding chest on auscultation with reduced air entry
Moderate acute asthma PEFR?
50-75% of predicted
Features of severe acute asthma
PEFR 33-50% predicted
RR:
> 40 in 1-5 years
> 30 in > 5 years
HR:
> 140 in 1-5 years
> 125 in > 5 years
Unable to complete sentences in one breath
Saturations <92%
Severe acute asthma PEFR?
33-50% predicted
Life threatening acute asthma PEFR?
<33%
Features of life threatening acute asthma?
PEFR <33%
Sats <92%
Exhaustion + poor respiratory effort
Hypotension
No wheeze. This occurs when the airways are so tight that there is no air entry at all. This is ominously described as a “silent chest”.
Cyanosis
Alterned conciousness/confusion
What grade of acute asthma is the absence of a wheeze and why?
'’Silent chest’’ occurs when the airways are so tight there is no air entry at all
ABGs in acute asthma?
Initially patients will have a respiratory alkalosis as tachypnoea causes a drop in CO2.
A normal pCO2 or hypoxia is a concerning sign as it means they are tiring and indicates life threatening asthma.
A respiratory acidosis due to high CO2 is a very bad sign in asthma.
Initial ABG in acute asthma
Respiratory alkalosis (tachypnoea causes a drop in CO2)
What does a normal pCO2 or hypoxia in an ABG of a patient with acute asthma indicate?
A normal pCO2 or hypoxia is a concerning sign as it means they are tiring and indicates life threatening asthma.
Most concerning sign on ABG in acute astham?
A respiratory acidosis due to high CO2 is a very bad sign in asthma.
How can you monitor response to treatment in acute asthma?
Respiratory rate
Respiratory effort
Peak flow
Oxygen saturations
Chest auscultation
What should be additionally monitored when using salbutamol to treat acute asthma?
Serum potassium and HR
Salbutamol causes potassium to be absorbed from the blood into the cells
Salbutomol causes tachycardia
What HR indicates a severe acute asthma exacerbation in a child between 1-5 years?
> 140
What HR indicates a severe acute asthma exacerbation in a child older than 5 years?
> 125
What RR indicates a severe acute asthma exacerbation in a child between 1-5 years?
> 40
What RR indicates a severe acute asthma exacerbation in a child over 5 years?
> 30
Staples of management in acute viral induced wheeze or asthma are?
Supplementary oxygen if required (i.e. oxygen saturations less than 94% or working hard)
Bronchodilators (e.g. salbutamol, ipratropium and magnesium sulphate)
Steroids to reduce airway inflammation: prednisone (orally) or hydrocortisone (intravenous)
Antibiotics only if a bacterial cause is suspected (e.g. amoxicillin or erythromycin)
What bronchodilators may be used in acute asthma (in order of stepping up)
Inhaled or nebulised salbutamol (a beta-2 agonist)
Inhaled or nebulised ipratropium bromide (an anti-muscarinic)
IV magnesium sulphate
IV aminophylline
How are mild cases of acute asthma managed?
Mild cases can be managed as an outpatient with regular salbutamol inhalers via a spacer (e.g. 4-6 puffs every 4 hours).
Mod - severe acute asthma management
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
If you haven’t got control by this point the situation is very serious. Call an anaesthetist and the intensive care unit. They may need intubation and ventilation. This call should be made earlier to give the best chance of successfully intubating them before the airway becomes too constricted.
Once control of acute asthma is established: you can gradually work your way back down the ladder as they get better - how?
Review the child prior to the next dose of their bronchodilator.
Look for evidence of cyanosis (central or peripheral), tracheal tug, subcostal recessions, hypoxia, tachypnoea or wheeze on auscultation.
If they look well, consider stepping down the number and frequency of the intervention.
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.
It is also worth noting that salbutamol causes tachycardia and a tremor.
When might you discharge a child admitted of an asthma exaccerbation and what steps might you consider?
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.
A few other steps to consider:
Finish the course of steroids if these were started (typically 3 days total)
Provide safety-net information about when to return to hospital or seek help
Provide an individualised written asthma action plan
What are ‘‘atopic conditions’’
Asthma
Eczema
Food alergies
Hay fever
Patients with one of these conditions are more likely to have others. These conditions characteristically run in families, so always ask about family history and don’t be surprised if their brother, mother or “everyone in the family” has asthma, eczema and allergies.
Bronchoconstriction in asthma?
Asthma is a chronic inflammatory airway disease leading to variable airway obstruction.
The smooth muscle in the airways is hypersensitive, and responds to stimuli by constricting and causing airflow obstruction.
This bronchoconstriction is reversible with bronchodilators such as inhaled salbutamol.
Presentation Suggesting a Diagnosis of Asthma
Episodic symptoms with intermittent exacerbations
Diurnal variability, typically worse at night and early morning
Dry cough with wheeze and shortness of breath
Typical triggers
A history of other atopic conditions such as eczema, hayfever and food allergies
Family history of asthma or atopy
Bilateral widespread “polyphonic” wheeze heard by a healthcare professional
Symptoms improve with bronchodilators
What wheeze is heard in chronic asthma?
Bilateral widespread ‘’ polyphonic ‘’ wheeze
Presentation Indicating a Diagnosis Other Than Asthma?
Wheeze only related to coughs and colds, more suggestive of viral induced wheeze
Isolated or productive cough
Normal investigations
No response to treatment
Unilateral wheeze suggesting a focal lesion, inhaled foreign body or infection
Typical triggers of chronic asthma?
Dust (house dust mites)
Animals
Cold air
Exercise
Smoke
Food allergens (e.g. peanuts, shellfish or eggs)
Diagnosing asthma in children?
A diagnosis is made clinically based on a typical history and examination.
When there is a low probability of asthma and the child is symptomatic, consider referral to a specialist for diagnosis.
When there is an intermediate or high probability of asthma, a trial of treatment can be implemented and if the treatment improves symptoms a diagnosis can be made.
There are investigations that can be used where there is an intermediate probability of asthma or diagnostic doubt:
Spirometry with reversibility testing (in children aged over 5 years)
Direct bronchial challenge test with histamine or methacholine
Fractional exhaled nitric oxide (FeNO)
Peak flow variability measured by keeping a diary of peak flow measurements several times a day for 2 to 4 weeks
From what age might a child be dianosed with asthma
Children are usually not diagnosed with asthma until they are at least 2 to 3 years old
Principles of stepwise ladder of long term management of asthma?
Start at the most appropriate step for the severity of the symptoms
Review at regular intervals based on the severity
Step up and down the ladder based on symptoms
Aim to achieve no symptoms or exacerbations on the lowest dose and number of treatments
Always check inhaler technique and adherence at each review
Chronic asthma: medical therapy in children under 5 years?
Start a short-acting beta-2 agonist inhaler (e.g. salbutamol) as required
Add a low dose corticosteroid inhaler or a leukotriene antagonist (i.e. oral montelukast)
Add the other option from step 2.
Refer to a specialist.
Chronic asthma: medical therapy in children from 5-12 years of age?
Start a short-acting beta-2 agonist inhaler (e.g. salbutamol) as required
Add a regular low dose corticosteroid inhaler
Add a long-acting beta-2 agonist inhaler (e.g. salmeterol). Continue salmeterol only if the patient has a good response.
Titrate up the corticosteroid inhaler to a medium dose. Consider adding:
- Oral leukotriene receptor antagonist (e.g. montelukast)
- Oral theophylline
Increase the dose of the inhaled corticosteroid to a high dose.
Referral to a specialist. They may require daily oral steroids.
Chronic asthma: medical therapy in children from over 12 years of age?
Same as adult therapy
Start a short-acting beta 2 agonist inhaler (e.g. salbutamol) as required
Add a regular low dose corticosteroid inhaler
Add a long-acting beta-2 agonist inhaler (e.g. salmeterol). Continue salmeterol only if the patient has a good response.
Titrate up the corticosteroid inhaler to a medium dose. Consider a trial of an oral leukotriene receptor antagonist (i.e. montelukast), oral theophylline or an inhaled LAMA (i.e. tiotropium).
Titrate the inhaled corticosteroid up to a high dose.
Combine additional treatments from step 4, including the option of an oral beta 2 agonist (i.e. oral salbutamol). Refer to specialist.
Add oral steroids at the lowest dose possible to achieve good control under specialist guidance.
How do inhaled corticosteroids affect the growth of children?
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.
Why is inhaler technique important?
Inhaler technique is a key aspect of good asthma management. The better the technique, the more medication reaches the lungs. Poor technique results in medication in the mouth or the back of the throat. This reduces the effectiveness of the medication and leads to complications such as oral thrush with steroid inhalers.
Types of inhalers
Metered dose inhaler
Dry powder inhalers - require patients to inhale quickly and deeply to draw the powder into the lungs
What can be used with an inhaler to maximised the effectiveness?
Spacer device
Metered dose inhaler (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
Metered dose 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
Alternatively exhale fully before putting making a seal with the spacer, spray the dose and take one deep breath in to inhale the mist in one breath before holding for 10 seconds.
How are spacers looked after?
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.
What is pneumonia
Pneumonia is simply an infection of the lung tissue. It causes inflammation of the lung tissue and sputum filling the airways and alveoli. Pneumonia can be seen as consolidation on a chest xray. It can be caused by a bacteria, virus or atypical bacteria such as mycoplasma.
How might pneumonia present?
Cough (typically productive)
High fever (>38.5)
Tachypnoea
Tachycardia
Increased work of breathing
Lethargy
Delirium
Signs of pneumonia, which may indicate secondary sepsis?
Tachypnoea (raised respiratory rate)
Tachycardia (raised heart rate)
Hypoxia (low oxygen)
Hypotension (shock)
Fever
Confusion
If the patient is acutely unwell and epiglottitis is suspected then investigations should not be performed. However, what will be seen if a later xray of the neck is done?
Performing a lateral xray of the neck shows a characteristic “thumb sign” or “thumbprint sign”.
This is a soft tissue shadow that looks like a thumb pressed into the trachea.
This is caused by the oedematous and swollen epiglottis.
What structural changes occur in laryngomalacia?
SHORTENED ARYEPIGLOTTIC FOLDS
There are two aryepiglottic folds at the entrance of the larynx, running between the epiglottis and the arytenoid cartilages.
They are either side of the airway and their role is to constrict the opening of the airway to prevent food or fluids entering the larynx and trachea. In laryngomalacia the aryepiglottic folds are shortened, which pulls on the epiglottis and changes it shape to a characteristic “omega” shape.
SOTENING AND REDUCED TONE IN THE TISSUE SURROUNDING THE SUPRAGLOTTIC LARYNX
The tissue surrounding the supraglottic larynx is softer and has less tone in laryngomalacia, meaning it can flop across the airway. This happens particularly during inspiration, as the air moving through the larynx to the lungs pulls the floppy tissue across the airway to partially occlude it. This partial obstruction of the airway generates the whistling sound.
