One-Lung Ventilation

Question 1

A 72-year-old male patient is listed for a right upper lobectomy for lung malignancy. He is a smoker and is on ramipril for hypertension. He weighs 71kg.
What are the indications for one-lung ventilation?

Answer 1

Absolute:
* When a healthy lung needs to be isolated from the contralateral side affected by any pathological process (air, blood and pus) e.g. lung abscess and pulmonary haemorrhage.
* To facilitate ventilation e.g. bronchopleural fistula.
* To allow for washout of a single lung e.g. cystic fibrosis.

Relative
* Surgical access e.g. pneumonectomy/lobectomy,oesophageal surgery, and aortic surgery.

Question 2

How can one-lung ventilation be achieved?

Answer 2

• Double-lumen tube.
• Bronchial blocker.
• Endobronchial intubation of a normal endotracheal tube.

Question 3

How do right and left-sided double-lumen tubes differ?

Answer 3

• Both right- and left-sided double lumen tubes have separate tracheal and bronchial aspects.
• However, right-sided double-lumen tubes have a Murphy’s eye in the bronchial lumen due to the anatomy of the right upper lobe.

Question 4

What size double-lumen tube would you choose for this patient?

Answer 4

• The patient’s height is the most accurate predictor for the size of the double-lumen tube used:
• Less than 155 cm: 35 French.
• 155–165 cm: 37 French.
• 165–175 cm: 39 French.
• More than 175 cm: 41 French.
• The size of the tube required can also be estimated based on direct measurements of the major bronchi on CT scans.

Question 5

How would you intubate this patient with a double-lumen tube?

Induction:

Answer 5

• Preparation for the anaesthetic includes patient consent; a team brief and completion of the WHO checklist; drawing up of routine and emergency drugs; insertion of intravenous access and placement of AAGBI monitoring.
• Given the patient’s comorbidities and the major procedure, an arterial line should be inserted with vasopressor agents primed and attached to the patient for use during induction (anticipating cardiovascular instability secondary to anaesthetic agents).
• A senior thoracic anaesthetist and trained assistant should be present.
• Cardiostable induction of anaesthesia with doses of propofol and fentanyl slowly titrated to effect and rocuronium.

Question 6

How would you intubate this patient with a double-lumen tube?

Intubation:

Answer 6

• Ensure that a left-sided, appropriately sized double-lumen tube has been checked and lubricated appropriately, with the stylet inserted.
• Use a videolaryngoscope to view the vocal cords.
• Insert the tube through the glottis and remove the stylet to prevent injury. Rotate the tube 90 degrees anticlockwise. Advance the tube until 29–30 cm (28–29 cm in women) and resistance is felt.
• Connect to the anaesthetic circuit.

Question 7

How would you intubate this patient with a double-lumen tube?

Verification of tube position:

Answer 7

• Inflate the tracheal cuff and ventilate. Bilateral chest rise should be noted, with breath sounds bilaterally on auscultation.
• Clamp and disconnect the tracheal lumen, inflate the bronchial cuff and auscultate to ensure left-sided ventilation only.
• Unclamp and reconnect the tracheal lumen and recommence bilateral lung ventilation.
• The double-lumen tube position should always be confirmed using a fibreoptic bronchoscope following clinical checks.

Question 8

What are the advantages of using a bronchial blocker over a double-lumen tube?

Answer 8

• Can be used in paediatric patients (bigger range of sizes).
• Can be used in patients with single-lumen endotracheal tube in situ e.g. patients on the intensive care unit, where exchange of tubes is not desirable due to potentially difficult or swollen airways, with a high risk of aspiration of gastric contents.
• Decreased risk of airway injury e.g. nerve damage and palsy.
• Less challenging insertion in certain patient groups e.g. patients with poor mouth opening, tracheostomy patients, and laryngectomy stoma patients.

Question 9

What are the causes of hypoxia during one-lung ventilation?

Answer 9

• The main cause of hypoxia during one-lung ventilation is secondary to movement of the double-lumen tube. Other equipment-related causes include failure of oxygen delivery and anaesthetic circuit disconnection or blockage.
• Increased airway pressures can also cause hypoxia secondary to bronchospasm, pneumothorax, coughing or anaphylaxis.
• Shunt.

Question 10

The patient desaturates to 82% during the procedure. How do you proceed?

Answer 10

• Ensure that the patient is on 100% oxygen.
• Inform the surgeons and theatre team, and call for help.
• Equipment check: oxygen supply, ventilator and circuit.
• Check the position of the double-lumen tube.
• Maintain adequate cardiac output with fluid, vasopressors and
  inotropes if required.
• Suction the dependent lung.
• Apply CPAP to the non-dependent lung (however, this minimises the
  surgical view, so may not be possible). Apnoeic oxygenation could
  also be used at this stage e.g. low-flow oxygen via a suction catheter.
• Recruitment manoeuvres and increase PEEP to the dependent lung, with lower tidal volumes. Given the patient’s medical history, aim for sats of 88%–92% (PO2 of 8 kPa).
• Surgeons to clamp pulmonary artery.
• Two-lung ventilation/consider abandoning procedure if severe hypoxia continues.