The following question is based on the shown pulmonary function tests (PFTs). Assume in each case that the test result is adequate and reproducible.
Key:
FVC |
L |
Forced Vital Capacity |
FEV1 |
L |
Forced Expiratory volume in 1 second |
FEV1/FVC |
% |
Ratio of the above |
RV |
L |
Residual volume at end expiration |
TLC |
L |
Total Lung Capacity |
DLCO corr |
ml/min/mmHg |
Diffusing capacity for carbon monoxide, corrected for Hb |
You are asked to evaluate a previously well, 36-year-old male who has presented to Emergency Department (ED) with shortness of breath and increased work of breathing. This has been progressive over the past week. He has had PFTs performed recently as an outpatient:
Predicted |
Actual |
% Predicted |
Post Bronchodilator |
% Change |
|
FVC (L) |
4.20 |
3.15 |
75 |
3.62 |
+15 |
FEV1 (L) |
3.40 |
2.14 |
63 |
2.56 |
+20 |
FEV1/FVC (%) |
80 |
68 |
71 |
+4 |
|
RV (L) |
2.31 |
3.03 |
131 |
||
TLC (L) |
6.41 |
6.53 |
102 |
Obstructive, reversible, evidence of gas trapping but not hyperinflation (1 mark)
At risk of dynamic hyperinflation, may need high inspiratory pressures, low PEEP, long expiratory time (3 Marks)
Formal pulmonary function tests have also been asked about in Question 21.2 from the first paper of 2014 and the identical Question 9.1 from the first paper of 2011.
To approach this systematically:
The ventilation strategy for somebody with such an obstructive pattern of respiratory function and such propensity to hyperinflation resembles that which might be used for status asthmaticus, and would consist of the following strategies:
Pellegrino, Riccardo, et al. "Interpretative strategies for lung function tests."European Respiratory Journal 26.5 (2005): 948-968.
The American Thoracic Society has a page which features an excellent bibliography of the articles which support their interpretation standards.