Post-op lung resection calculation (PPO)

Question 1

How to calculate for % PPO FEV1 & % PPO DLCO for lung resection?

Answer 1

2 ways to calculate:
1) Anatomic method
2) Perfusion method

Question 2

What I need to have to calculate the PPO? (2)

Answer 2

1) % of pt’s FEV1 or DLCO from lung function test
2) Need to know the number of segments to be removed in anatomic method, and the % of perfusion to be removed in perfusion method

Question 3

Example of % PPO calculation for anatomic method

Answer 3

Pt’s FEV1: 66% predicted, DLCO 61% predicted

If segments to be removed are RML & RLL,
So
RML & RLL (2 +5 segments = 7 segments to be removed)

Segments left post resection of RML & RLL = 19 – 7 = 12
So 12/19 segments = 63% will be left post-op

So,
% PPO FEV1 = 63% out of 66% = 0.63 x 0.66 = 42%
% PPO DLCO = 63% out of 61% = 0.63 x 0.61 = 38%

Or..
Count the percentage straight from how many segments are left:
% PPO FEV1 = 12/19 x 66% = 41.68%
% PPO DLCO = 12/19 x 61% = 38.5%

Question 4

Example of % PPO calculation for perfusion method

Answer 4

Pt’s FEV1: 66% predicted, DLCO 61% predicted
Pt’s perfusion scan result:
R side: RUZ 18%, RMZ 20%, RLZ 5%
L side: LUZ 15%, LMZ 30%, LLZ 12%

If segments to be removed are
RML & RLL,

% of RMZ & RLZ to be removed = 20% + 5% = 25%
% of perfusion left after the RMZ and RLZ are removed = 100% - 25% = 75%

So
% of PPO FEV1 = 75% x 66% = 50%
% of PPO DLCO = 75% x 61% = 46%

Or..
Calculate the % from what % of perfusion that are left
e.g.
25% removed (from RML + RLL = 20+5%)
Thus 75% left behind
PPO FEV1 = 0.75 x 66% = 49.5%
PPO DLCO = 0.75 x 61% = 45.75%

Question 5

What is the American College of Chest Physician (ACCP 2013) guideline for lung resection says about risk for lobectomy or pneumonectomy?

Answer 5

1) If % PPO FEV1 AND % PPO DLCO are >60% –> low risk
2) If % PPO FEV1 AND/OR % PPO DLCO >30 – 60% –> proceed with stair climb or shuttle walk test
3) If % PPO FEV1 OR % PPO DLCO <30% –> proceed with CPET

For stair climb and shuttle walk test:
- If stair climb is > 22m, or shuttle walk test >400m –> low risk.
- If <22m or <400m –> proceed with CPET

For CPET:
- If VO2 max is >20ml/kg/min OR >75% –> low risk (<1% mortality risk & sufficient functional reserve)
- If VO2 max is 10-20ml/kg/min OR 35-75% –> mod risk (benefit of op outweighs mortality risk)
- If VO2 max is <10ml/kg/min –> high risk (>10% mortality risk thus contraindicated for surgery

Question 6

How many lung segments?

Answer 6

RUL: 3
RML: 2
RLL: 5

LUL: 5
LLL: 4

Total: 19 segments