Nitric oxide diffusing capacity versus spirometry in the early diagnosis of emphysema in smokers

van der Lee, I.; Gietema, H.A.; Zanen, P.; van Klaveren, R.J.; Prokop, M.; Lammers, J.-W.J.; van den Bosch, J.M.M.

doi:10.1016/j.rmed.2009.06.005

« Previous Next »Respiratory Medicine
Volume 103, Issue 12 , Pages 1892-1897, December 2009

Nitric oxide diffusing capacity versus spirometry in the early diagnosis of emphysema in smokers

I. van der Lee
- Spaarne Hospital, Department of Pulmonary Diseases, Hoofddorp, The Netherlands
- Correspondence to: I. van der Lee, Spaarne Ziekenhuis, Department of Pulmonary Diseases, PO Box 770, 2130 AT Hoofddorp, The Netherlands, Tel.: +31 23 8907220; fax: +31 23 8907221.
H.A. Gietema
- University Medical Center, Department of Radiology, Utrecht, The Netherlands
P. Zanen
- St Antonius Hospital, Department of Pulmonary Diseases, Nieuwegein, The Netherlands
- University Medical Center, Department of Pulmonary Diseases, Utrecht, the Netherlands
R.J. van Klaveren
- Department of Pulmonology, Erasmus Medical Center, Rotterdam, The Netherlands
M. Prokop
- University Medical Center, Department of Radiology, Utrecht, The Netherlands
J.-W.J. Lammers
- University Medical Center, Department of Pulmonary Diseases, Utrecht, the Netherlands
J.M.M. van den Bosch
- St Antonius Hospital, Department of Pulmonary Diseases, Nieuwegein, The Netherlands

Received 5 August 2008; accepted 8 June 2009. published online 08 July 2009.

Summary

The diffusion capacity for nitric oxide (DLNO) is independent of pulmonary capillary blood volume and equals the membrane diffusing capacity. Therefore the DLNO could be more sensitive in detecting alveolar destruction than the DLCO.

We measured flow-volumes curves, DLNO, DLCO, the transfer coefficients KNO (DLNO/VA) and KCO (DLCO/VA) and performed computed tomography (CT) scans in 263 randomly selected heavy smokers. Subjects with areas ≥1% of the total lung volume showing an attenuation <−950 Hounsfield Units were considered to have emphysema.

In 36 subjects emphysema was diagnosed with CT, a low KNO was present in 94 subjects, and in 95 subjects a FEV1/FVC ratio <70% was seen. The area under the ROC curve for detection CT-based emphysema was 0.894 for the KNO, 0.822 for the KCO and 0.795 for FEV1/FVC, meaning that the KNO has a slightly higher sensitivity to detect emphysema than the KCO and FEV1/FVC. The positive predictive value of KNO however was low (34.7%), while the negative predictive value of KNO was very high (98.2%), indicating an emphysema exclusion test. The DLNO/DLCO ratio is significantly higher in the study group compared to normal subjects.

Keywords: COPD, Emphysema, Diffusion capacity, Spirometry, Nitric oxide