Perioperative Management of the child with asthma Flashcards
Learning objectives
By reading this article, you should be able to:
1 Understand the pathophysiology and classification of asthma.
2 List the common medications used to treat acute
and chronic asthma in children.
3 Assess and anaesthetise a child with asthma for
elective surgery.
4 Describe the management of a child with an
acute exacerbation of asthma and bronchospasm
under anaesthesia
Key points
1 Asthma is an umbrella term for a heterogeneous
group of reactive airway disorders that have a
common clinical presentation.
2 Management should focus on symptom control;
the majority of patients achieve control with
regular inhaled corticosteroids.
3 Poorly controlled asthma is the biggest risk factor
for intraoperative bronchospasm and postoperative complications.
4 Understanding asthma in children will help to
reduce perioperative complications.
Incidence
Improvements?
A total of 1.1 million children in the UK are treated for asthma,
and the worldwide prevalence is increasing.
Children with asthma have a higher risk of perioperative
respiratory adverse events (PRAEs)
Identifying and optimising asthma control in
children presenting for elective surgery will reduce harm.
Admissions to hospital for asthma are highest in preschool children,
Definition
Asthma is an umbrella term used for a group of heterogeneous
disorders characterised by
chronic airway inflammation
In susceptible patients this leads to
airway hyperreactivity,
mucus plugging and bronchospasm
causing variable airflow limitation,
reversible airway obstruction and
Respiratory distress
Clinical symptoms
Clinical symptoms include
dyspnoea, cough
(often nocturnal or exercise-induced)
and
chest tightness.
Signs include wheeze,
increased work of breathing,
hypoxia and, in life-threatening cases,
cyanosis and reduced consciousness.
Pathophysiology
Asthma is a multifactorial disease resulting from interactions
between genetic, host (e.g. obesity, prematurity, low birth
weight) and environmental factors.
Similar clinical manifestations
(phenotypes) can have different underlying
pathophysiological pathways, which can result
in differing responses to
treatment.
Thus endotypes, the mechanisms underpinning
phenotypes, are now being elucidated to help individualised
treatments.
Endotypes in severe asthma can be classified into
Th2 (atopic, aspirin exacerbated respiratory disease [AERD] and
late-onset asthma)
and non-Th2 (non-atopic).3
Th2 atopic accounts for >85% of paediatric asthma endotypes where sensitisation to aeroallergens cause CD4 activation leading to
interleukin (IL)-4, IL-5, IL-13 release causing prolonged eosinophil survival, mucus hyper-secretion, smooth muscle contraction and airway hyperreactivity
The diagnostic challenge
Children present a unique challenge in the diagnosis of asthma
because the diagnosis relies on history, examination, which can
differ depending on age, and additional tests, which require a
cooperative mature child.
a formal diagnosis of asthma are of school age because they can comply with
spirometry
Forty percent of children have one wheezy episode
in childhood, but only 25% of children with intermittent cough,
wheeze or exerciseinduced symptoms have asthma
A child with recurrent wheeze
who is failing to thrive, has unusual features in the history or
examination should be referred to a paediatrician
Preoperative assessment
Preoperative assessment should include questions about the
child’s general health, growth, exercise tolerance/ability to keep
up with their peers, atopy, birth history, significant family history and social history including tobacco smoke exposure.
wheeze is
auscultated in the preoperative visit, there are clinical signs of
respiratory distress or abnormal vital observations, consider
rescheduling and refer to a paediatrician or the emergency
department.
Preoperative investigations in children with asthma
requested by anaesthetists have not been shown to reduce the
incidence of PRAEs
DDX
When encountering a child with recurrent wheeze, consider
the following differential diagnoses. Consider bronchiolitis if the
child is aged <12 months, the wheeze is seasonal, particularly in
the autumn or winter and associated with coryzal symptoms,
fever and poor feeding.
Consider cardiac causes in the child with
recurrentwheeze associatedwith failure to thrive, heartmurmur
or hepatomegaly.
. In a child with wheeze associated with focal
chest signs and signs of infection, consider pneumonia.
Laryngomalacia or a vascular ring can present as inspiratory wheeze
or stridor usually from birth, particularly when crying or feeding.
Adolescents, particularly girls, who report
wheezy episodes not responsive to bronchodilator treatment but
are otherwise well may have vocal cord dysfunction.
Investigations and classification of
perioperative relevance
Tests
Spirometry and peak expiratory flow rate (PEFR) require a
compliant child, usually of school age, who can follow instructions.
Reversibility is defined by an improvement in FEV1 >12%.
FEV1/FVC<0.8 and reversibility suggests asthma.6
Normal spirometry does not exclude asthma, with sensitivity and
specificity of 52% and 73%, respectively.
Peak expiratory flow rate is the maximal rate of expiration
after a full inspiration, measured in litres per minute. It reflects larger airway calibre, muscle strength and voluntary
effort. The relationship between PEFR and FEV1 is complex,
with some studies showing reasonable correlation; however,
PEFR has been shown to underestimate the degree of airflow
obstruction in severe disease
Fraction of exhaled nitric oxide (FeNO) is recommended by
the National Institute of Health and Care Excellence (NICE) to
diagnose asthma in school-aged children with a value of >35
parts per billion supporting the diagnosis of asthma
reflects airway eosinophillic inflammation and is closely
linked to atopic status
Investigations and classification of
perioperative relevance
Tests
Spirometry and peak expiratory flow rate (PEFR) require a
compliant child, usually of school age, who can follow instructions.
Asthma is suggested with an obstructive
spirometry pattern and FEV1/FVC ratio <70%,
a bronchodilator
reversibility on spirometry of >12%, or both
Normal spirometry does not exclude asthma, with sensitivity and
specificity of 52% and 73%, respectively.
Peak expiratory flow rate is the maximal rate of expiration
after a full inspiration, measured in litres per minute. It reflects larger airway calibre, muscle strength and voluntary
effort. The relationship between PEFR and FEV1 is complex,
with some studies showing reasonable correlation; however,
PEFR has been shown to underestimate the degree of airflow
obstruction in severe disease
Fraction of exhaled nitric oxide (FeNO) is recommended by
the National Institute of Health and Care Excellence (NICE) to
diagnose asthma in school-aged children with a value of >35
parts per billion supporting the diagnosis of asthma
reflects airway eosinophillic inflammation and is closely
linked to atopic status
Classification
Classification of paediatric asthma is conventionally based on
spirometry and PEFR. However, their limitations do not
exclude asthma, and these tests cannot be performed by children aged <5 yrs; thus, alternative methods of classification
may be more useful in the perioperative period.
. Take a history
of the child’s level of control over the preceding weeks to
months and inhaler use, particularly the short-acting beta
agonist (SABA) salbutamol (patients may refer to this as the
‘reliever’ or ‘blue’ inhaler). Using salbutamol more than three
times per week or one inhaler per month suggests poor control
and warrants review by a paediatrician.
A history of triggers for attacks is also
useful. Triggers could include exercise, cold weather, secondhand smoke or aero-allergens (e.g. dust, pollen). Airway
instrumentation during GA may also be a trigger.
Completely controlled asthma
Completely controlled asthma means that the patient is
free from day and nighttime symptoms, no asthma attacks,
no need for salbutamol and no activity limitations in the
preceding month
Mild asthma
Mild asthma includes symptoms two to three times per week with
FEV1 80% without limiting physical activity
and unremarkable vital observations, proceed with elective
cases.
Moderate Asthma
Children with moderate asthma have daily or nightly
symptoms with FEV1 between
60% and 80% predicted;
these children may have reduced exercise capacity compared with
their peers. It may be difficult to assess control and consider
each case on the risks of proceeding against optimising control.
If the child has been well over the past month, compliant
with treatment, with good school attendance and a recent
paediatrician or primarycare review, ideally within the past
month, there is reassurance that it would be safe to proceed
with elective surgery
severe asthma
In In severe asthma children have persistent daytime or
nighttime symptoms with spirometry FEV1 <60%.6 Severe
asthma affects approximately 5% of patients with asthma but
accounts for the majority of its health burden. children have persistent daytime or
nighttime symptoms with spirometry FEV1 <60%.6 Severe
asthma affects approximately 5% of patients with asthma but
accounts for the majority of its health burden.
s ‘asthma which requires treatment with high dose of inhaled corticosteroids
(ICS) plus a second controller and/or systemic corticosteroids
to prevent it from becoming “uncontrolled” or which remains
uncontrolled despite this therapy
review
preceding elective cases to ensure optimisation of medical
management and a plan for perioperative care would be prudent to help reduce perioperative complications.
For severe
asthma consider performing procedures in a centre with a
paediatric high dependency unit (HDU) or paediatric ICU (PICU)
facility. If the child requires more than low to moderate dose
ICS (>400 mg day
Asthma and comorbidities
Comorbidities in asthma may be coincidental but for children
with poorly controlled asthma treatment of comorbidities,
including obesity, atopy(e.g., rhinosinusitis, eczema and food
allergies), and reducing second-hand smoke exposure may
improve control. The effect of treating children with symptomatic reflux or sleep apnoea is unclear.
Management
Chronic management
Good management of asthma requires a multidisciplinary,
multimodal approach with medications as outlined in Table 1
All children diagnosed with asthma in the UK should have a
printed asthma action plan.
It is useful to ask to review this in
preoperative assessment as it details their medications,
last review and asthma emergency plan.
In children the preferred method of inhaled drug delivery is
via a metered dose inhaler (MDI) and spacer with an appropriately sized facemask for toddlers, or a mouthpiece for
children aged >4 yrs, for maximal drug delivery.
Meds
Children with
mild asthma are prescribed low dose ICS or
leukotriene receptor antagonists (LRAs)
with SABA.
Those with moderate asthma require ICS with LRA or long-acting beta
agonists (LABAs) and severe asthma are prescribed ICS, LRA
and LABA under specialist respiratory input.
Treatment is usually started at the most appropriate level for initial severity
to achieve good control titrated based on symptoms and attacks. Monoclonal antibodies may be initiated under specialist
Acute attacks
Acute treatment of asthma aims at relieving
bronchoconstriction and airway inflammation
and includes oxygen,
SABA,
ipratropium bromide,
corticosteroids (i.v. or oral)
and
i.v. medications including magnesium, SABA and aminophylline
Asthma and anaesthesia
Risk factors for an asthma attack under GA
Theoretically any child with asthma has an increased risk of a
PRAE.
Patient factors increasing the risk include
- previous exacerbations under GA,
- moderate to severe asthma,
- respiratory tract infection within the past 4 weeks,
- age <5 yrs and having previously received artificial ventilation for asthma.
- Anaesthesia-related factors include airway
instrumentation particularly tracheal intubation
and positive pressure ventilation and
- surgical factors include
prolonged procedures and
airway surgery
