Pulmonary emphysema and the crossover point

In 13 healthy subjects and 34 patients with chronic obstructive lung disease (COLD) (23 patients without and 11 patients with emphysema) the breath number at crossover point, using He and SF6 as test gases, and some pulmonary functions (spirometry, body plethysmography and washout curves) were investigated. Although the patients with emphysema did show a more severely impaired lung function than the patients without emphysema, no clear lung function pattern for patients with emphysema was demonstrated in comparison to the patients without emphysema. The pattern of the breath number at crossover point was unpredictable. Most probably this breath number is more related to the severity of impaired gas mixing than to the degree of emphysema. So the clinical diagnosis of emphysema in patients with COLD remains difficult, in spite of the use of advanced technology for fast and accurate analysis by mass spectrometry.