Biomedical Engineering Reference
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such as hydrogen peroxide and 8-isoprostane. (13). In a recent study,
Biernacki et al. (14) showed that at exacerbations, that were all associated
with purulent sputum, 8-isoprostane levels in exhaled breath condensate
increased markedly and then fell with antibiotic therapy at 2 weeks, though
at this time levels were not back to baseline. At a further follow up at 2
months, there was a further fall in exhaled breath 8-isoprostane, suggesting
that oxidative stress takes a significant time to recover after an exacerbation
and this may be another important factor in the reason that some exacerba-
tions take considerable time to recover or they may never recover to baseline
levels (Fig. 3).
In patients with alphal-antitrypsin deficiency, there is some evidence
for greater inflammatory load at the start of the exacerbation with higher
elastase activity and lower levels of sputum alphal-antitrypsin and secretory
leukoprotease inhibitor, than in nondeficient COPD patients (15). Biochem-
ical markers were reduced by 3 days after antibiotic therapy and took a vari-
able time to return to baseline. However, there was no difference in the time
Figure 3
(A) Exhaled 8-isprostane during a COPD exacerbation and after 2 weeks,
compared to controls. (B) Exhaled 8-isprostane in 12 patients at COPD exacerba-
tion, after 2 weeks and after 2 months. (From Ref. 14.)
