Recently a CPET report for an individual whose primary complaint was tachycardia and DOE with minimal activity came across my desk. Since the patient had had an pneumonectomy (one lung removed) about a year ago there wasn’t much doubt the results would be reduced, the question was whether they were reduced more than they should have been.
You might expect lung function to decrease by half following a pneumonectomy but because the remaining lung always expands to some extent FVC and TLC tend to be approximately 60%-65% of their pre-surgical volume. Although this increase in volume however does not increase the alveolar-capillary surface area the entire cardiac output needs to pass through the remaining lung which causes an increase in the pulmonary capillary blood volume. For this reason DLCO also tends to be about 65% of baseline.
| Observed: | %Predicted: | |
| FVC (L): | 2.08 | 62% |
| FEV1 (L): | 1.62 | 57% |
| FEV1/FVC (%): | 79 | 92% |
| TLC (L): | 2.89 | 64% |
| DLCO (ml/min/mmHg): | 11.55 | 54% |
With the exception of the DLCO the patient’s pulmonary function results were about what would be expected following a pneumonectomy. It’s hard to be sure the DLCO is anomalously low because the surgery was performed at a different hospital and we don’t have any pre-surgical pulmonary function results to compare them to. Since this is also the first time the patient had a CPET there isn’t anything to compare the current results to either.