1. Patient cannot hold still for scan. 

   • Younger patient who has failed feed and wrap or sedation.

   • Older patient who is non-compliant.

2. Scan requires breath holds and patient cannot comply with breathing instructions.

Anaesthesia may be induced via either an IV or gas/inhalation method.

Gas/inhalation method:

• Less distress for children (no needles).

• Useful if IV access is difficult.

Intravenous method:

• Less perioperative complications

Once induced the patient may be given an laryngeal airway (LMA) or an endo tracheal tube (ETT). 

When the scan requires inspiratory or expiratory breath holds, an ETT is needed. 

Prior to starting a GA list we will perform a 'huddle' with the team. The team may include:

• Radiographers

• Radiologists/interventionalists

• Radiology nurses 

• Anaesthetics team - anaesthetists and technicians

We will introduce our names and roles, then discuss requirements for each case such as:

• Patient positioning

• IV access

• Breath holds

• Any other concerns

A main reason we perform GA imaging is to obtain good inspiratory breath holds on patients who cannot comply with breathing instructions awake. This is to ensure we can scan the lungs without any collapse and see each part of the lung clearly for pathology. 

When a patient is being put under GA their lungs can undergo atelectasis (collapse). The longer they are under GA the more prominent this can be. This is due to the patient being muscle relaxed, relying on artificial ventilation and lying supine.

Atelectasis appears as hyperdensity in the lungs often in the posterior aspect. We obtain a single slice called a control scan through the inferior lungs prior to imaging to ensure there is limited atelectasis and we will be able to see lung tissue clearly. 

If there is atelectasis (top image), we ask the anesthetist to recruit the lungs. This helps to increase the intrathoracic pressure to reduce any atelectasis. We may need to repeat this process a few times until we are happy with lung condition (middle and bottom image). 

Once we are happy with the lung condition (bottom image) on the control scan we then proceed to actual CT. This helps to reduce the dose to our patients by only obtained the true CT when we have ideal lung expansion. 

Lists frequently change times, but we currently run:

• Tuesdays PM - CT GA Respiratory List (every 2 months)

• Thursdays PM - CT GA List

The Medical Imaging Work-In lists are shared lists between MRI/CT/Intervention/PET.