Appeal No. 2003-1548 Page 5
Application No. 08/786,957
suits the purpose of measuring airway pressure including the use of a chamber having
a highly pliant exterior wall as taught by Lee” (answer, page 4).
Appellant argues (1) that, since Lee is directed to a “catheter-tip” gauge-pressure
transducer and not specifically to an endotracheal tube, it would not have been obvious
to use Lee’s pressure transducer system in combination with an endotracheal tube and
(2) that, even if combined, the invention recited in claim 1 would not result. In light of
Lee’s reference to pressure measurement using catheter-tip pressure transducers for
measuring pressure within a patient’s blood stream or within some other conduit or
vessel in the body (column 1, lines 39-42) and McGrail’s teaching (column 1, lines 9-24)
of the interchangeable use in the medical art of the terms “catheters” and “tubes” and
the use of the term “catheter” to describe a variety of devices, such as endotracheal
tubes, we agree with the examiner that one of ordinary skill in the art would have
recognized the applicability of Lee’s catheter-tip gauge-pressure transducer system in
combination with an endotracheal tube. In our view, it would have been obvious to one
of ordinary skill in the art to modify the configuration of McGrail’s lumen 40 so as to
communicate the distal end thereof with the external wall of the tube and to provide a
diaphragm and transducer at said distal end and to conduct air at atmospheric pressure
to the “back” or “reference pressure” side of the diaphragm, with electrical leads running
from the transducer through the lumen 40 to an external electronics package, as taught
by Lee to achieve the calibration advantages identified by Lee. Nevertheless, the
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