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
Elective surgery
Children with well-controlled or mild asthma can proceed
with elective surgery at district general hospitals as day cases.
Ideally, all children should have nurse-led preoperative
assessment.
Any patient with STRA or a previous exacerbation
requiring mechanical ventilation should be assessed by a
consultant anaesthetist.
This helps to establish rapport,
manage expectations,
discuss the risks and alternatives to GA,
referral to relevant specialties and organisation
of a postoperative high-dependency bed
The perioperative plan for children with moderate to severe asthma may include recommendation for perioperative
oral steroids or temporarily increasing the ICS dos
Steroids
If the child has been receiving >15 mg m2 hydrocortisone
equivalent for more than 1 month,
steroid replacement should be considered
Children on high ICS doses are at risk of adrenal
suppression after surgery, and all anaesthetists should be able
to diagnose and treat this as a medical emergency
Children
with diagnosed adrenal insufficiency should have a perioperative steroid replacement plan by a paediatric endocrinologist. Steroid dosing equivalents can be found in the British
National Formulary for Children (BNFC) and from NICE
Day of surgery
On the day, reassess and confirm the child is fit for surgery.
Ensure the child has their usual asthma medications
and inhaled or nebulised salbutamol before induction of anaesthesia.
Preoperative anxiety should be managed holistically
with play specialist input, distraction and, if necessary,
sedative premedication.
Induction
Induction of anaesthesia can be i.v. or
via inhalation.
Observational studies have suggested i.v. induction is
associated with a reduced incidence of PRAE;
Common agents include
sevoflurane,
ketamine and
propofol
Ensure adequate depth of anaesthesia
before proceeding with
airway manoeuvres or painful procedures.
Airway
Consider whether airway instrumentation is required at all.
If airway support is necessary,
supraglottic airway devices are associated
with lower incidences of laryngo and bronchospasm
than tracheal intubation and,
if used, consider maintaining spontaneous ventilation.
If tracheal intubation is performed,
ensure bilateral air entry without wheeze.
Use a cuffed tracheal tube to minimise leak,
optimise ventilation and monitor cuff pressure
to reduce the risk of PRAE’s
intraoperative
Intraoperative ventilator settings should be changed
only if the child is having an acute attack
Before extubation,
if a neuromuscular blocking drug is used,
ensure return of the
train of four ratio and use a reversal agent as required
Analgesia
Intraoperative multimodal analgesia should include
simple analgesics including paracetamol and NSAIDs
as per age and weight dosing regimens,
and regional anaesthesia or wound infiltration.
Most children with asthma can take NSAIDs
NSAIDs should be avoided in children who have a personal
or a significant family history of NSAIDs exacerbating asthma
symptoms. If opioids are required in certain patients,
particularly those with STRA or previous bronchospasm under GA, synthetic opioids or ketamine are preferable as
morphine causes more histamine release. Intravenous magnesium may be a useful analgesic adjunct
Post op
Postoperatively, if the child is well and meets day-case
discharge criteria, they can go home with safety-netting
advice.
Specific anaesthetic agents in asthma
There is little evidence for agents other than ketamine and
volatiles in asthma.
Table 2 presents some of the commonly
used drugs and their adverse effects that
may affect bronchial reactivity.
There is limited evidence for propofol and remifentanil
TCI during surgery in children with asthma, but they
can be used to maintain anaesthesia or sedation in ICU. All
opioids cause respiratory depression and histamine release, and
there is some evidence to suggest an increase in asthma/chronic
obstructive pulmonary disease (COPD) in the adults with regular
opioid exposure
The use of i.v. lidocaine is controversial; lidocaine is
thought to decrease airway responsiveness to agents causing
bronchoconstriction, however, it itself might increase airway
tone, as shown in one small study in adults utilising i.v. lidocaine
infusion.19 Furthermore, aerosol and i.v. lidocaine has been
associated with an increase in PRAE in children.20 On balance,
we would recommend using other agents first.
Severe bronchospasm
Incidence
Pathophys
The risk of bronchospasm under GA in patients with asthma is
between 0.21% and 20%.21
Intraoperative bronchospasm can
be isolated or as a symptom of anaphylaxis
The pathophysiology of bronchospasm under GA is multifactorial
and likely secondary to change in
airway tone,
vagal stimulation secondary to airway instrumentation,
impairment of diaphragmatic function,
mucociliary clearance
and the cough reflex.
Bronchospasm presentation
Bronchospasm can present as an
increase in peak inspiratory pressure (PIP),
decrease in tidal volumes,
change in endtidal CO2
(‘shark-fin’ trace or loss of end-tidal CO2)
and wheeze
Mx
Management includes follows the
Association of Anaesthetists’ quick reference guide
for the management of bronchospasm and
- includes calling for help,
- stopping surgery when safe,
- giving 100% Fio2,
- auscultate to exclude tracheal tube obstruction,
displacement or pneumothorax - Switch to hand ventilation, .
which will give you an impression of lung compliance.
- Exclude anaphylaxis by looking for associated features.
Meds Mx Severe bronchospasm
- Consider deepening anaesthesia
(if suitable, consider switching from TIVA or desflurane to sevoflurane).
- For isolated bronchospasm,
treat first line with salbutamol either within
the anaesthetic circuit with an MDI or nebuliser
- Second-line treatments include nebulised ipratropium,
i.v. salbutamol,
magnesium,
hydrocortisone
and, in extremis, i.v. adrenaline 1 mg kg1 titrated to response.
Bronchospasm under GA requiring i.v. therapies
should be treated as severe asthma,
and ventilator management is suggested below.
Vent management
Mechanical ventilation in a child with
acute severe asthma is challenging.
Liaise early with PICU or the retrieval team for
strategies to improve gas exchange.
Use a ventilator that is familiar,
ideally one with flow-volume loops
and the ability to perform breath holds
to help assess lung compliance,
the degree of airflow limitation and auto-PEEP.
There are proponents for low PEEP (4-5 cmH2O) to
matched PEEP, based on an expiratory hold.
Targets include Spo2 >90%,
pH >7.2.
The points listed below are some suggestions.
Vent management strats
- Ensure the patient remains under full neuromuscular
block (consider a vecuronium infusion). - Choose a ventilation mode that is familiar and available
on your ventilator. - Choose a PEEP (4e5 cmH2O) e discuss with local PICU/
retrieval team. - If using pressure-controlled modes, set PIP to <40
cmH2O. If on a volume control mode, set the PIP limit to - Be guided by plateau pressures which should be kept
<30 cmH2O. - Aim for tidal volumes 5e7 ml kg1
- Consider the relationship of the inspiratory to PIP to
achieve adequate tidal volumes. High PIP risks barotrauma. - Increase expiratory time and aim for an I:E ratio of
1:3-1:4.
This can be done by reducing the ventilatory
frequency
(e.g. 10-15 min/1 for children aged >10 yrs).
- Allow for permissive hypercapnia (pH 7.2)
- Multiple methods could be used to assess breath
stacking, which can include using the flow trace and
ensuring the flow reaches baseline at the end of expiration. If the end-tidal CO2 trace does not reach plateau, this
suggests incomplete expiration. - Refrain from manually decompressing the chest as
this can precipitate a cardiac arrest. - Consider further i.v infusions of salbutamol,
aminophylline, adrenaline or ketamine in addition to
sevoflurane.
Conclusions
Paediatric asthma is a common condition and good perioperative care requires a multidisciplinary approach involving
primary care, and in severe asthma, secondary and tertiary
care. A good understanding of the pathophysiology of asthma,
knowledge of the medications used, and national guidelines
for the management of asthma and bronchospasm are integral to safe perioperative care.
Table 1 Medical management of asthma in children
Acute attack treatment
- SABA
- Anti-muscarinic agent
SABA
SABA
Salbutamol
b2 Agonist
Acute asthma dose:
Inhaled: 2 -10 puffs;
can be repeated every 10 mins
Nebulised:
1 month -4 yrs: 2.5 mg,
repeated every 30 mins
> 5 yrs:
5 mg repeated every 30 mins
Tachycardia
Hypokalemia
Tremor
Vasodilatation lactic acidosis
Anti-muscarinic agent
Anti-muscarinic agent
Ipatropium bromide
Non-specific muscarinic antagonist causing
bronchodilation
Corticosteroid
CS
Prednisolone
Reduction in airway
inflammation
2 mg kg 1 max of 60 mg p.o
Magnesium Sulphate
Magnesium Sulphate
Bronchial smooth muscle relaxation
2-17 years: 40 mg kg1
(max 2 g)
to be given
over 20 mins
Hypotension if injected rapidly; may
prolong neuromuscular block
Aminophylline
Aminophylline
Methylxanthine derivative,
non-selective
phosphodiesterase inhibitor
producing smooth muscle relaxation
Only in theophylline naive: 5 mg/kg max 500
mg as a slow bolus followed by an infusion
Infusion (after bolus or in patients on
theophylline):
Palpitations
Arrhythmias
Seizure
Serious hypokalaemia when used in with B2
agonists
Chronic treatment
SABA
SABA Salbutamol b2 agonist Inhaled 2
e10 puffs maximum 4 hourly as above
ICS
Budesonide
Beclometasone
Reduces airway inflammation All can be given as low, moderate or high
dose
Oral thrush
Poor dentition
Paradoxical bronchospasm (rare)
Adrenal suppression at high doses
ICS
LABA Fluticasone and Salmeterol
Reduced airway inflammation
and bronchodilation
Symbicort may be used as maintenance and
reliever (single agent) MART regimen
Relvar (>12 yrs) used once daily
As above and muscle cramps
LRA
LRA
Montelukast LRA
selectively binding to receptors for D4 and E4;
reducing airway oedema,
bronchoconstriction and
inflammation
Nightmares
Neuropsychiatric behaviours
Suicidal ideation
rh-DNAse
rh-DNAse (recombinant human deoxyribonuclease)
Dornase alpha
Used PICU/under specialist
supervision as non-evidence
based.
rh-DNAse is an enzyme that catalyses the hydrolysis
of DNA found in respiratory sections thus may reducing
mucous plugging and airway obstruction.
Omalizumab
Omalizumab
targets IgE;
used in STRA with IgE titres 3 e1500 IU/l
Anaethetic agents
Ketamine 1e2 mg kg1
Maintains airway tone
Promotes bronchodilation (BD)
through catecholamine release
Caution in volume depleted states
as may have a negative ionotropic
effect
Propofol* 2.5-4 mg kg
May promote BD
Hypotension
Sevoflurane 0e8% Promotes BD
Maintains spontaneous
ventilation
Requires an anaesthetic delivery
circuit
Desflurane may cause airway
irritability
Morphine
May cause BC through histamine
release
Respiratory depression
Remifentanil*
Skeletal muscle rigidity may
occur
Atracurium
May cause BC through histamine
release
Lignocaine
Topicalisation increases risk of
postoperative airway adverse
events11
Dexamethasone
Should not be used if the child is
already on regular steroids
Glycopyrronium bromide
Reduces airway secretions
Neostigmine
Increase airway tone
Neostigmine 50 mg kg1 May cause BC
Acute severe attack:
Sp2 =<92%
Can’t complete full
sentences
HR>140: 1–5 yrs
HR>125: >5 yrs
RR>40: 1–5 yrs
RR>30: >5 yrs
Life threatening:
SPO2 <92%
PEF<33% best
hypotension,
cyanosis, silent chest,
poor respiratory
effort, confusion
Bronchospasm algorithm
- Oxygen Target SPO2 >94%
- Bronchodilators: Salbutamol
2.5–5 mg + 250 mcg ipatropium
bromide - Magnesium: 150 mg to each
nebulised solution within the first hour
_____________________
- Steroids: Prednisolone 10 mg
<2 yrs; 20 mg 2–5 yrs; 30–40 mg >5 yrs.
If on steroids can recieve a total of
2 mg kg–1, max. 60 mg. If vomiting
consider hydrocortisone 4 mg kg–
_____________________
- I.V. Salbutamol: bolus <2 yrs
5 mcg/kg; >2 yrs 15 mcg kg–1 over 5 min.
Infusion: 1–2 mcg kg–1 min–1 - I.V. Magnesium Sulphate 40 mg kg–1
max. 2 g over 20 min
_____________________
- I.V. Aminophylline: 5 mg kg–1 bolus
over 20 min with cardiac
monitoring (if theophilline naive). I.V.
infusion 1 month–11 years:
1 mg kg h–1; 12–17 yrs:
0.5–0.7 mg kg h–1 based on plasma
theophylline level
