A change that probably isn’t a change

Recently a report came across my desk from a patient being seen in the Tracheomalacia Clinic. The clinic is jointly operated by Cardio-Thoracic Surgery and Interventional Pulmonology and among other things they stent airways. The patient had been stented several months ago and this was a follow-up visit. Given this I expected to see an improvement in spirometry, which had happened (not a given, BTW, some people’s airways do not tolerate stenting), but what I didn’t expect to see was a significant improvement in lung volumes and DLCO.

When I took a close look at the results however, it wasn’t clear to me that there really had been a change. Here’s the results from several months ago:

Observed: %Predicted: Predicted:
FVC: 1.19 50% 2.38
FEV1: 0.64 35% 1.79
FEV1/FVC: 53 71% 76
TLC: 3.21 76% 4.22
FRC: 2.34 96% 2.43
RV: 2.11 113% 1.85
RV/TLC: 66 150% 44
SVC: 1.15 48% 2.37
IC: 0.87 48% 1.80
ERV: 0.25 41% 0.58
DLCO: 6.59 38% 16.18
VA: 1.78 43% 4.12
IVC: 1.04

Change_that_isnt_change_2015_FVL_redacted_2

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