Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a diffuser drape for providing
a clean work area, such as, for example, the wound site of a surgical opera-
tion.
It has been proposed in the past to provide a clean area by posi-
tioning clean air diffusers to diffuse clean air over a work surface and it has
further been proposed to provide a clean air diffuser in a surgical drape.
The previous experimental attempts to provide a practical diffuser
drape, however, met with tifficulties in integrating the diffuser into a drape
in a fashion which provided the necessary clean air pattern without at the
same time getting in the operator's way. Furthermore, with earlier proposals,
the diffused air pattern frequently broke down because of regular activities
by the operator.
According to the present invention a diffuser drape comprises a drape
member having an aperture therein; inflatable clean air duct means attached to
said drape and surrounding said aperture; said clean air duct means having dif-
fuser means therein surrounding said aperture and shaped to diffuse, in opera-
tion, low velocity clean air radially through said diffuser means inwardly
across said aperture from opposite sides thereof to produce a resultant flow
away therefroms and at least two clean air inlets for said clean air duct
means on the underside of said drape member. According to a preferred feature
of the invention the flow of clean air from the duct means is also outwardly
of the periphery of the diffuser.
Another problem encountered with earlier experimental diffusers
was how to avoid the jetting of air at the point where an inlet hose, or the
like, encountered the diffuser and, according to a preferred feature of the
invention, the clean air inlets comprise sleeve means which are widened as
they approach the duct means and merge therewith.
Yet a further problem encountered with earlier proposals was to
provide even distribution of air and, preferably, the clean air duct means is
formed in a substantially elliptical shape. Preferably also the clean air
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inlet sleeve means are flared to merge substantially tangentially into the
duct means.
According to a further feature of the invention the clean air
inlets, which comprises sleeve means, are obliquely inclined to the longitud-
inal or transverse axis of the aperture and, in diffuser drapes used for
abdominal surgery and the like, the sleeve means are preferably inclined at
an angle of between 22 and 35 to the longitudinal axis of the aperture and
preferably at an angle of 27 thereto.
The following is a tescription by way of example of one embodiment
of the present invention, reference being had to the accompanying drawings in
which: -
Figure 1 is a di?gramtic underside plan view of a diffuser drape
showing the diffuser means attached to the drape; and
Figure 2 is a cross-section of the line II - II of Figure 1, look-
ing in the direction of the arrows.
Referring now to the drawings, drape 10, which may be a surgical
drape, is provided with an aperture 11 therein. The aperture 11 may be of
square or round shape but as shown, i5 elliptical.
An inflatable clean air duct means 12 is sewn into the drape so as
to become integral therewith and surrounds the aperture. The clean air duct is
itself of substantially elliptical shape. ~ne duct has a diffuser 13 therein
~shown in dotted outline in Figure 2) and the diffuser is shaped so that, in
operation, it will provide a current of clean air radially inwardly across the
aperture as indicated by the arrows 14 in Figure 2. In the preferred config-
uration, a current of clean air is also provided outwardly of the periphery of
the diffuser, as indicated by the arrows 15 in Figure 2. The air pattern from
the diffuser across the work space 16, from opposite sides thereof, which is
the case of a surgical drape would be a patient's body, results, in known
fashion, in an outwardly flow 18 of air away from the work surface 16.
The diffuser duct portion 12a is made of a similar material to the
-
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material of the drape 10 whilst the diffuser 12b tdotted in Figure 2) may suit-
ably be of a different material. The material of the duct portions 12a may be
cotton of 140 to 180 threads per inch and the diffuser means 12b may be of a
plain weave cotton material weighing 5.2 oz/yd sold under the Dominion Textiles
trade name TQWN AND COUNTRY and having 50 threads per inch in the warp and 43
threads per inch in the weft.
With this configuration, and particularly when the duct portion 12a
is of cotton about 140 threads per inch, a very slight diffusion (almost in the
form of a leakage) takes place radially through the duct portion 12a as indi-
cated by the arrows 13a. This minor diffusion can have beneficial effects in
some applications. If unwanted, this minor diffusion may be reduced by doub-
ling the number of layers of material or by making the material less permeable.
So that the air pattern will not break down in the event of the
operation (perhaps a surgeon) leaning on the diffuser duct during operation,
at least two inlets, or mouths 20, are provited integrally with, and of the
same material as, the tuct portion 12a. The inlets comprise a widened sleeve
portion merging with the diffuser duct, and in the elliptical configuration
shown the widened sleeve means merge tangentially at 21 with the diffuser
duct. The inlets continue outwardly at 22 from the aperture, on the underside
of the drape. If the surgeon, or operator, collapses the diffuser means 13 by
placing a hand or instrument on it at one point, air will still be provided to
the diffuser as a whole because of the second inlet. For some types of func-
tion it may be necessary to supply a third, or even a fourth, inlet.
Air is normally supplied by means of hoses from a clean air source
which hoses are inserted into the upstream extensions 25 of the sleeves where
the sleeves are tied by means of ties 26 around the hoses. The clean air
source, which is positioned remotely from the drape, is of a type known ~ se.
It delivers clean air through the diffuser such that the air flow from the work
space 16 is at about 100 ft/min (fpm). The velocities often used in the clean
air art are 90 fpm plus or minor 20 fpm. In small diffusers such as shown,
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the range may be 90 fpm plus or minus 40 fpm. With an elliptical diffuser
drape as seen in Figures 1 and 2 having a work space 16 of about 2 sq. ft.,
the volume of clean air supplied would be about 200 cfm.
The widening of the inlet to provide a smooth merging with the duct-
ing is an important preferred feature of the invention because it provides for
the smooth diffusion of air into the duct means. Furthermore, the substantial-
ly elliptical shape of the diffuser and the duct means is also an important
preferret feature because unlike a rectangular configuration it provides for a
smooth and even flow of air and an even distribution of air through the diffuser.
As shown in Figure 1 the drape 10 is a surgical drape for abdominal
surgery the sleeve means 22 are inclined at the oblique angle to the longitud-
inal axis 28 and the traverse axis 29 of the aperture 11. This also is an
important preferred feature of the invention for this type of use because it
provides a configuration in which the clean air can be delivered to the aper-
ture ll without the hoses getting in the way of the operator.
It has been found that for abdominal surgery the angle o~ of the
center line of the sleeve from the longitudinal axis should be between 22
and 35 and with the optimum angle being 27.
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