Bronchospasm
Overview:

Bronchospasm is an abnormal and rapid contraction (spasm) of the smooth muscle of the bronchi (airway leading to the lungs), resulting in a narrowing and obstruction of the airway. A cough, with generalized wheezing, usually indicates bronchospasm. Bronchospasm is a major characteristic of asthma, and bronchitis. Bronchospasm can present on its own, or as part of anaphylaxis, or some other underlying pathology.
Process:

The bronchial muscle goes into a state of contraction (bronchospasm), which narrows the bronchus. The mucosa become swollen and inflamed, which further reduces the bronchial diameter. Additionally, bronchial glands produce excessive amounts of sticky mucus, which is difficult to cough out, and which may form plugs in the bronchus, further obstructing the flow of air.

When bronchi become obstructed, greater pressures are needed to push air through them, in order to meet the body’s requirement for oxygen. This necessitates greatly increased muscular effort. Breathing, during bronchospasm, requires more effort than normal breathing.

The excessive amounts of sticky mucus, caught in the bronchi, are irritating, and often trigger coughing.

Causes:
Signs:
Notes:
1. When intubated, ventilation may become difficult, or there may be a rise in airway pressure. In severe cases, silent chest may occur ie, so little gas flow in or out that no sound is heard during auscultation.
2. Absolute bronchospasm may be difficult to distinguish from oesophageal intubation.
3. Airway obstruction can produce a "shark fin" capnograph (prolonged expiration and narrow airway).
4. A blocked circuit, or blocked or misplaced ETT can mimic bronchospasm.

5. General causes of wheeze during general anaesthesia: 5. Causes of increased peak airway pressure during IPPV: 6. Bronchospasm occurs equally during intubation and maintenance phases of GA. During induction, bronchospasm usually occurs due to airway irritation (eg, laryngoscopy). During maintenance phase, bronchospsm usually occurs due to allergic reaction.
Risk factors:
Symptoms:
Treatment (intra-operative):
In extreme cases, give Adrenaline infusion.

Note: Ketamine is the only IV anaesthetic agent with bronchodilating properties.

Safe Anaesthesia