Appeal 2007-2516
Application 10/302,553
indicates that the arterial oxygen partial pressure (PaO2) [of]
rats having respiratory distress syndrome (animal models)
which was 500-550 mm hg decrease to values of 50-110 mm
Hg whereas animals in control group which are not treated with
lung surfactant remain with their PaO2 at these low values.
From these teachings of H[a]fner, one of ordinary skill in the
art would expect instantly claimed oxygen index percentages.
(Answer 5-6).
Appellants challenge the Examiner’s conclusion, asserting that the
step of “decreasing an oxygen index of a patient by at least 20%” as recited
in claim 1 would not have been obvious to one of ordinary skill in the art
(Amended Br. 13).
We agree with the Examiner. Hafner expressly teaches that inhaled
surfactants advantageously increase PaO2 in an animal model for ARDS in a
dose-related manner (Hafner ‘970, col. 6, ll. 53-55; cols. 7-8, Tables 1 and 2;
Findings of Fact 8-9; Answer 6). PaO2 is inversely proportional to the
oxygen index.1 An increase in PaO2 would therefore lead to a decrease in
the oxygen index. Thus, it would have been expected from Hafner’s
teaching that surfactant administration would decrease the oxygen index, the
same result recited in claim 1. The difference between Hafner and claim 1 is
that the claim requires that the oxygen index be decreased by a specific
amount: by at least 20%. In our opinion, it would have been obvious to
persons of ordinary skill in the art at the time the invention was made to
have optimized administration of a surfactant composition to achieve an
effective decrease in oxygen index (or rise in PaO2 levels) for treating
1 Oxygen index = %O2 x MAP (mean airway pressure)/PaO2 (partial pressure
of oxygen in arterial blood (torr or mmHg). Specification 5: 10-16.
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