Bronchospasm
Jan 23, 2025
🌬️Bronchospasm: Who, What, When, Where, Why and How?🌬️
Who does it happen to?
Bronchospasm can occur in isolation, or as a component of a much more serious incident such as anaphylaxis ⚠️.
Reactive airways disease such as asthma 🌬️ and chronic obstructive pulmonary disease (COPD) place patients at a higher risk of bronchospasm during anaesthesia, however, the incidence rate is still quite low.
Smoking 🚬 (or exposure to tobacco smoke), atopy 🧬 - which is a genetic tendency to develop allergic diseases, or viral upper respiratory tract infections 🤧 can all increase the chances of a patient developing bronchospasm during anaesthesia.
There are many occurrences of bronchospasm during anaesthesia in patients that have no reactive airway disease history at all – basically, it can happen to anyone! 🌍
What is bronchospasm?
Bronchospasm is caused by increased smooth muscle contraction around the bronchioles, usually as a result of a chemical or mechanical irritant 💉, which leads to constriction and airflow obstruction in the lower respiratory tract. It is characterised by a long expiratory phase ⏳.
When/ Where is it likely to occur?
Most commonly occurs during the induction 🛠️ and maintenance 🧑⚕️ phases of anaesthesia (occurrence rates are equal). Less likely to occur in emergence 🏃♀️ and recovery periods 🏥 (although not absolute).
Bronchospasm during the induction phase is most likely caused by airway irritation related to the process of intubation 🔪.
Bronchospasm during the maintenance phase of anaesthesia is likely a result of serious drug allergy 💊 or anaphylaxis ⚠️, or inadequate depth of anaesthesia 😴.
Other considerations that may mimic bronchospasm are mechanical obstruction of the breathing circuit 🔌, laryngospasm 👄, and airway soiling (increased secretions 💧, aspiration) in patients that are not intubated.
Why is it important?
Left untreated, bronchospasm leads to hypoxaemia 💔, hypotension 💦, and potential respiratory and cardiac arrest.
How do we spot it?
Bronchospasm is seen during the expiratory phase of ventilation 🌬️, with prolonged expiration characterised by a “shark fin” capnography waveform 📉 and increased peak airway pressures ⬆️.
An expiratory wheeze 🎶 may also be auscultated or heard in the breathing circuit 🎧. Bearing in mind that airway sounds such as a wheeze require movement of air through the airways 🌪️, so in severe cases of bronchospasm with complete airway obstruction, the airway will be silent. 🤐
How do we treat it?
🚑Management involves administration of 100% oxygen 💨 and calling for help early.
💊🩸Stop any potential ongoing triggering agents such as antibiotics or blood products.
🔧Troubleshoot airway circuit to rule out mechanical obstruction.
💔Reverse hypoxaemia and treat bronchoconstriction:
😴Deepen anaesthesia (propofol and volatile agents such as sevoflurane can produce bronchodilatory effect).
💨1st line therapy: Salbutamol (via MDI and in-line adapter, nebulised or intravenous).
💊 2nd line therapy includes ipratropium bromide, magnesium sulphate, hydrocortisone, ketamine, and adrenaline (in extreme cases)
⚠️Ongoing consideration of differential diagnoses or identification of cause such as anaphylaxis, acute pulmonary oedema, or aspiration.
Secondary management includes ongoing pharmacotherapy and investigation into the cause, including radiography and blood testing and increased monitoring and surveillance in the postoperative period.
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References:
Abd-Elsayed, A., Eapen, J.J., Bang, J. (2023).'Management of Bronchospasm. in Alaa Abd-Elsayed (ed.), Advanced Anesthesia Review. https://doi.org/10.1093/med/9780197584521.003.0110
Loosely, A. (2011) Management of bronchospasm during general anaesthesia. Update in Anaesthesia. https://e-safe-anaesthesia.org/e_library/05/Bronchospasm_during_anaesthesia_Update_2011.pdf
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