4.5 Asthma + Bronchospasm

Question 1

a) List the factors that may have contributed to an increase in the prevalence of asthma in developed
countries in the last 20 years. (5 marks)

Answer 1

> > Better identification of cases,
influenced by targets for asthma
management in primary care.

> > Hygiene hypothesis:
cleaner environment associated with
increased rates
of allergy-associated asthma.

> > Obesity:
increases an individual’s risk
due to altered airway mechanics
and chronic inflammatory state.

> > Urbanisation.

> > Asthma development following
survival from premature birth.

> > Increased use of drugs such
as beta-blockers, NSAIDs, aspirin.

Question 2

b) What are the possible causes of acute bronchospasm during general anaesthesia in a patient with mild asthma? (5 marks)

Answer 2

> > Pre-existing upper respiratory tract infection,
poor asthma control, smoking.

>> Airway irritation: 
cold inspired gases, 
airway secretions, airway suctioning, 
laryngoscopy, intubation, 
extubation, aspiration, carinal
stimulation or endobronchial intubation.

> > Drugs causing histamine release,
muscarinic block or allergy.

> > Vagal stimulation:
peritoneal or visceral stretch etc.

Question 3

c) Outline the immediate management of acute severe bronchospasm in an intubated patient during
general anaesthesia. (10 marks)

Answer 3

This is an emergency situation and I would alert the theatre team, call for help and assess and manage the patient simultaneously following an ABC approach.

> > Stop surgical/drug triggers where possible.

>> A: 
Ensure ETT patent, 
ensure position is correct 
(carinal or endobronchial placement 
may have triggered bronchospasm), 

suction if required
(avoiding stimulation of trachea),
100% inspired oxygen.

>> B: Auscultate chest, 
confirm wheeze or 
even absence of breath sounds;
check SpO2, manually ventilate 
to assess compliance and apply higher,
sustained pressure for ventilation 
and longer expiratory flow time; and
increase inspired anaesthetic gas concentration.

> > C: Check heart rate and blood pressure,
increase intravenous filling as
increasing intrathoracic pressure
reduces venous return, reducing cardiac
output and causing a tamponade-type effect.

> > Drugs:
• Salbutamol MDI via airway adaptor
on breathing circuit, 10 puffs.

• Salbutamol IV 100–300 mcg bolus in
extremis/5–20 mcg/min ivi.

• Magnesium 1.2–2 g/20 min IV bolus.
• Adrenaline IV 0.2–1 mg bolus in extremis/1–20 mcg/min ivi.
• Hydrocortisone 200 mg IV.

> > Once acute situation has resolved,
monitor response with arterial blood gas,
assess whether safe to proceed with case or whether to abandon, to keep intubated and take to ICU or whether safe to wake the patient up.

> > Incident reporting.

> > Consideration of need for referral for
optimisation of asthma control.

> > Full explanation to patient and/or family, including a written explanation of what has occurred.