52. Lung Cyst

Question 1

A 62-year-old man presents for excision of a right-sided lung cyst

What are the causes of lung cysts?

Answer 1

1. Congenital
   Bronchogenic
2. Acquired
3. Abscess – e.g. tuberculosis, staphylococcal, klebsiella
   pneumonia, hydatid, septic pulmonary infarction, aspiration
4. Tumour –
   cavitating primary bronchogenic or metastatic
5. Bullae
   secondary to emphysema
6. Bronchial obstruction
   following inhaled foreign body

Question 2

This man has a right lower lobe abscess that requires resection. He has a
history of emphysema.

What are the important considerations when assessing this man

Answer 2

The pre-operative assessment would concentrate

on his respiratory function and exercise tolerance.

Concomitant medical problems such as
ischaemic heart disease are obviously also important.

Poor exercise tolerance,
obesity and the presence of cardiovascular
disease are strong indicators of a poor prognosis.

Question 3

Routine investigations should include

Answer 3

Full blood count
Electrolytes
Clotting screen
ECG
Chest X-ray
Pulmonary function tests
CT/MRI of chest

An echocardiogram may also be indicated.
Post-operative analgesia should be considered and discussed at this stage

Question 4

What would you expect the pulmonary function tests to show?

Answer 4

↓ FEV1

↓ FVC

↓ FEV1/FVC ratio

Lung volumes may be normal or increased
Transfer factor for carbon monoxide is low

Question 5

What values for FEV1 and FVC would you consider to be severe?

Answer 5

A predicted post-operative FEV1 of less than 1L will result in problems with
sputum retention and less than 0.8L is a contra-indication to lung
resection

Question 6

What is maximum breathing capacity?

Answer 6

Maximum breathing capacity (MBC) is the product of maximum respiratory
rate and tidal volume. The patient is asked to breathe in and out maximally
for 15 seconds. The results are then multiplied by four to give the MBC.
Normal is >60 l/min
Value of 25–50 l/min implies severe respiratory impairment.

Question 7

What are the options for airway management in this man?

Answer 7

It is important to isolate the infected segment as far as possible by performing
endobronchial intubation usually with a double-lumen tube.

The choice of induction may be influenced by the expected difficulty
of intubation or the request by the surgeon to perform rigid bronchoscopy
before the tube is inserted.

Acceptable techniques include awake fibre-optic intubation,
inhalational induction, rapid-sequence induction or even a
conventional intravenous induction followed by a non-depolarising relaxant.
In the latter technique,

strong positive pressure should be avoided until the infected area is isolated.

The patient should be positioned semi-sitting, ideally
with the abscess-side down for induction.

Question 8

How do you confirm correct placement of a double-lumen tube?

Answer 8

The procedure for a left-sided tube is as follows:

1. Inflate tracheal cuff (5–10 ml of air)→confirm bilateral breath sounds.
2. Open tracheal lumen to air.
3. Ventilate down bronchial lumen only (proximal clamp on tracheal lumen).
4. Inflate bronchial cuff (1–2 ml) until leak disappears (listen at open
   tracheal lumen) and breath sounds heard only on left side.
5. Unclamp tracheal lumen.
6. Clamp bronchial lumen → confirm breath sounds heard only on right side.
7. Unclamp both lumens.

NB: The procedure may be altered in the case of a lung abscess where the
infected lung needs to be isolated as soon as possible. In this case both cuffs
may be inflated before any ventilation to reduce the risk of spillover into the
good lung.

Question 9

How else should it be confirmed

Answer 9

The correct position should ideally be confirmed by the use of a fibre-optic
bronchoscope. When it is passed down the tracheal lumen of a left-sided tube,
the carina should be visible with the bronchial cuff seen within the left main
bronchus.

The right main bronchus should also be visible and the origin of the
right upper lobe bronchus may be seen

Question 10

What measures can be used to prevent or treat hypoxaemia during
one-lung ventilation?

Answer 10

Administer 100% oxygen.

Check position of DLT with fibre-optic scope.

Oxygen may be insufflated into the collapsed lung via a suction catheter.

PEEP to the dependent lung may expand collapsed alveoli.

This may necessitate the application of CPAP to the collapsed lung to
prevent a shift of blood flow secondary to the increase in pulmonary
vascular resistance in the dependent lung.

Intermittent two-lung ventilation if surgical access is compromised by the
above manoeuvres.

Clamping of the pulmonary artery supplying the collapsed lung may be
required.

Note that, in general, ventilator settings used during two-lung ventilation
need very little (if any) adjustment when one-lung ventilation is commenced.

Question 11

What are the options for post-operative analgesia?

Answer 11

Intravenous opioids
Not ideal in patients with limited respiratory reserve
Regional techniques are preferable

NSAIDs

Epidural analgesia
May need supplementing with NSAIDs for
shoulder-tip pain.

Paravertebral block May be less reliable than an epidural but fewer
haemodynamic problems.

Interpleural catheter Placed by the surgeon.

Intercostal blocks
By anaesthetist blind or by surgeon under direct
vision