In 2002 the International Society for Heart and Lung Transplantation (ISHLT) modified the 1993 criteria for the bronchiolitis obliterans syndrome (BOS, obliterative bronchiolitis).
Differences from the 1993 Criteria:
(1) separation BOS Stage 0 into 2 groups, with the introduction of an at-risk subset ("potential")
(2) use of FEV(25-75)
Parameters:
(1) current FEV1
(2) baseline FEV1
(3) current FEV(25-75)
(4) baseline FEV(25-75)
FEV1 as percent of baseline =
= (current FEV1) / (baseline FEV1) * 100%
FEV(25-75) as percent of baseline =
= (current FEV25_75) / (baseline FEV25_75) * 100%
FEV1 as Percent of Baseline
FEV(25-75) as Percent of Baseline
BOS Severity
Stage
>= 90%
> 75%
none or not significant
0
81 - 90% OR
OR <= 75%
potential (at risk)
0-p
66 - 80%
mild
1
51 - 65%
moderate
2
< 50%
severe
3
where:
• FEV(25-75) tends to deteriorate before FEV1 in patients with early onset BOS.
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