2.2 Anaesthesia for lung resection

Question 1

HistoRY A 78-year-old female is booked for bunion operation. She complains
of chest pain on her right side, cough, and weight loss.

Answer 1

What is the most obvious finding
on the cXR in Figure 2.4?

Question 2

What are the differential
diagnoses?

Answer 2

infection
* Tuberculosis, abscess

inflammation
* Lymphadenopathy

neoplasm
* Primary bronchogenic carcinoma
* Metastatic neoplasm
* Lymphoma

other
* Pulmonary artery aneurysm

Question 3

How would you decide what it is?

Answer 3

History, examination, bloods, CT, bronchoscopy, and biopsy

It is diagnosed as a nonsmall cell carcinoma, and she is now posted for
a lung resection.

Question 4

How do you preassess her?

Answer 4

History
* Anaesthetic history,
paying particular attention to cardiac and respiratory function
* Smoking history

Examination
* Signs of weight loss and cachexia
* Cardiovascular and respiratory examination

Investigations
* Routine bloods, cross matching

• Arterial blood gas
• Lung Spirometry, diffusion capacity (DLCO),
  predicted postoperative FEV1
• Cardiopulmonary exercise testing (CPET)

Question 5

What is DLco, and how do
you measure it?

Answer 5

DLCO is the diffusion capacity and is calculated by measurement of carbon
monoxide taken up by patient in unit time. It is a gross estimate of alveolar/
capillary function.

Question 6

How do you predict
postoperative FeV1?

Answer 6

The predicted or estimated postoperative (epo) values of FEV1, FVC, and
diffusion capacity can be obtained by consideration of the lung volume
removed at surgery.

For lobectomy, the simple calculation uses the number of bronchopulmonary
segments removed compared with the total number (19) in both lungs.

Example: Consider a patient with a preoperative FEV1 of 1.6 litre, which is
80% of predicted normal. For right middle lobectomy (two segments),

epo-FEV1 = 1.6 × 17/19 = 1.43 litre
ppo-FEV1% = 80% × 17/19 = 71%

often a V/Q scan is used to measure how much the lung that will not be
operated on contributes to lung function and then combine with a formula to
calculate postoperative FEV1.

Question 7

What values of the lung function tests would you accept before proceeding to surgery?

Answer 7

Routine Lung Function Test

FEV1 > 1.5 litre suitable for lobectomy
FEV1 > 2.0 litre suitable for pneumonectomy

FEV1 < 1.5 litre (Lobectomy)
< 2.0 litre (Pneumonectomy)
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Quantitative Lung Scan ===> %ppo FEV1 > 40% %ppo TLCO > 40% =
proceed

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% ppo FEV1 < 40%
% ppo TLCO < 40%
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Exercise Testing
VO2 max > 15ml kg-1min-1

<15 = Consider other options

Answer 8

The flow chart in Figure 2.5 is an amalgamation of the British Thoracic
Society and American College of Chest Physicians’ guidelines.

The initial screening tool is of preoperative measured FEV1 with >2 litre
required for pneumonectomy and >1.5 litre for lobectomy. If there is no
diffuse lung disease and no comorbidity, achievement of the appropriate lung
volume is sufficient.

___________________________________________

When these threshold lung volumes are not present, full respiratory function
testing allows calculation of the predicted postoperative FEV1 and DLCO

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If both are >40% and the oxygen saturation is >90% on air,

the patient is in an average risk group.

If either (or both) the predicted postoperative
FEV1 or DLCo are <40%,

the patient should undergo formal CPET.

The threshold Vo2 max of 15 ml/kg/min
delineates between high- and medium risk patients.

Question 9

What are your airway options?

Answer 9

For thoracotomy, one lung ventilation is desired and hence you can use a
double lumen tube (DLT) or bronchial blocker.

Question 10

How would you choose and insert a DLt?

Answer 10

1. Commonly used tube is left-sided Mallinckrodt.
   Size 39–41 for male and 37 for female.
2. • Insert with stylet, pass vocal cords,
     then remove stylet, and rotate the
     tube to 90 degrees and advance.

once resistance is felt, inflate tracheal
cuff and check both lungs.

3. • Then inflate bronchial cuff and clamp off tracheal lumen.
     Confirm single lung ventilation.
     Repeat on opposite side.

• Gold standard:
  Check with fibreoptic scope before and after positioning.

On the left side, blue bronchial cuff should just be visible below carina;

on the right side, also check that right upper lobe corresponds to opening
“slit” in distal bronchial lumen.

Question 11

What are the pain relief options postop?

Answer 11

• Systemic
• Paracetamol, NSAIDs, IV opioids
• Neuraxial

° Epidural—
Gold standard but failure rate and hypotension from bilateral
sympathetic blockade.

° Intrathecal—Not often used.

° Paravertebral—Getting more popular, can be placed by surgeon by
direct vision or anaesthetist. Single-side blockade makes for less
incidence of hypotension.

° Intercostal and intrapleural—Can be used but the limited effectiveness
makes its use not as popular.