Lung Isolation

Question 1

What are the 3 legs of prethoracotomy respiratory assessment?

Answer 1

1. Respiratory mechanics 2. Cardiopulmonary reserve 3. lung parenchymal function (gas exchange)

Question 2

What is the most effective test for prediction of post-thoracotomy respiratory complications?

Answer 2

Predicted post-operative FEV1 % (ppoFEV1 %) = preoperative FEV1 % x (100 - % of functional tissue removed/100)

Question 3

What respiratory mechanics predict low risk of lung resection?

Answer 3

ppoFEV1 > 60% and ppoDLCO > 60%

Question 4

When do you need to perform noninvasive additional tests before lung resection? What are those tests?

Answer 4

If ppoFEV and ppoDLCO are 30-60%, then you should perform stair climbing altitude > 22m or shuttle walk distance > 400m

Question 5

When do you need to perform additional cardiopulmonary tests before lung resection? What are those tests?

Answer 5

If ppoFEV and ppoDLCO are both < 30% OR if between 30-60% but they fail stair climbing test or the shuttle walk test; need to do a peak O2 consumption test = if it is >20 mL/kg/min (or 75% predicted), then low risk; if <10 mL/kg/min (or 35% predicted), then high risk

Question 6

Does the diameter of the cricoid ring ever exceed that of the glottis?

Answer 6

No, the cricoid ring diameter is never larger than that of the glottis; therefore if you have issues passing a DLT through the glottis, it will be tough to pass through the cricoid ring

Question 7

What is the major risk with a right-sided DLT?

Answer 7

Low margin of safety, especially for the right upper lobe = higher risk of RUL obstruction or inadequate isolation

Question 8

What are relative indications for right-sided DLTs?

Answer 8

Distorted anatomy of left mainstem (i.e. via tumor or descending TAA) + left-sided pneumonectomy + left-sided tracheobronchial disruption + left-lung transplantation

Question 9

Is auscultation alone reliable for confirmation of proper DLT placement?

Answer 9

No

Question 10

How does perfusion change with one lung ventilation?

Answer 10

Hypoxic pulmonary vasoconstriction limits blood flow to the non-ventilated lung, decreasing the shunt

Question 11

What is the most common cause of desaturation during OLV?

Answer 11

DLT malposition

Question 12

What are some common risk factors for hypoxemia while on OLV?

Answer 12

Higher % of perfusion/ventilation to operative lung on preop V/Q scan + poor PaO2 during two lung ventilation in lateral position + right-sided thoracotomy + restrictive lung disease + supine position with OLV

Question 13

When is gas exchange during OLV most optimal (at what lung volume or capacity)?

Answer 13

At functional reserve capacity (FRC) which is when PVR is the lowest in both the large and small pulmonary vessels