Inline air humidifier, a system for humidifying air and methods related thereto

In preferred aspects the invention provides an in-line humidifier, a system using such a humidifier and methods related thereto, a method for infusing a gas into an eye during retinal detachment surgical procedure and a method for treating a retinal tear. The method for infusing gas includes providing an in-line humidifier, humidifying the gas in the in-line humidifier by flowing the gas there through and infusing the humidified gas into the eye. The in-line humidifier includes a housing and a humidifier section disposed within the housing, the humidifier section including a hydroscopic material that releasably retains liquid therein. The housing includes an inlet and outlet connection in fluid communication with the housing interior. The humidifier section is disposed within the housing so the gas entering through the inlet connection flows through the humidifying section, where small quantities of the releasably retinal liquid is released by the hydroscopic material to the flowing gas, and so the humidified gas exits the housing via the outlet connection.

FIELD OF INVENTION 
The present invention relates to in-line air humidifiers and systems using 
such humidifiers, in particular to in-line humidifiers and systems using 
same in connection with medical procedures and techniques and more 
particularly to medical procedures and techniques involving the eye and 
eye surgery (e.g., retinal tear or detachment surgery). 
BACKGROUND OF THE INVENTION 
Retinal tears can occur when the vitreous, a clear gel-like substance that 
fills the centers of the eye, pulls away from the retina thereby leaving 
behind a tear or hole in the retina. Rhegmatogenous retinal detachments 
can result if the retinal breaks, i.e. tears or holes in the retina of an 
eye are not treated. With retinal breaks, fluid from the vitreous 
apparently seeps through the retinal break and accumulates under the 
retina. The degree of detachment is measured by the volume of subretinal 
fluid as well as the area of the retina involved. Some symptoms of retinal 
detachment include the presence of floaters, flashes, shadows or blind 
area, decreased visual acuity and metamorphopsia. 
A number of techniques are employed for treating retinal detachments 
including using a scleral buckle, pneumatic retinopexy, cryopexy (i.e., 
freezing) and photocoagulation using a laser or xenon arc light source. 
These techniques may be used alone or in combination with each other to 
treat the retinal detachments for example, a combination of using a 
scleral buckle and photocoagulation. Additional retinal tears with little 
or no nearby detachment can be treated using photocoagulation or cryopexy. 
In the photocoagulation technique when using a laser, the retinal break is 
surrounded with one or more rows of a plurality of laser burns or laser 
heat spots. These laser heat spots or burns produce scars, which prevents 
fluid from passing through and collecting under the retina. In the 
photocoagulation procedure, a gas is exchanged for the vitreous fluid 
being aspirated from within the eye so the gas is intraocular when 
performing photocoagulation. Typically, the gas is air from a tank that 
may be filtered and sterilized before it is infused into the eye. 
Such air infusion of into the eye, however, can be quite problematic. For 
example, the infused air often can cause the lens of a patient's eye to 
become cloudy and dry, complicating the surgical procedure and creating 
conditions that can result in injury to the patient. 
It thus would be desirable to have improved devices, systems and methods 
for infusing a gas, particularly air, to a patient's eye during eye 
surgery procedures. It would be particularly desirable to have improved 
devices, systems and methods for infusing air or other gas to a patient's 
eye during surgery wherein the eye lens remains substantially clear and 
moist. 
SUMMARY OF THE INVENTION 
We have now produced new devices and methods that enable infusing air or 
other gases into a patient's eye during surgical procedures whereby the 
eye remains quite clear and moist. 
More particularly, the present invention provides a humidifier device and a 
system using such a humidifier, in particular a system configured for use 
in eye surgery, such as retinal tear and/or detachment surgery. The 
invention also provides related methods for humidifying air and infusing 
air during eye surgical procedures as well as a method for treating a 
retinal tear or detachment. 
The methods of the invention in generally comprise providing a humidifier 
device, humidifying (i.e. adding moisture) to gas via the device and 
infusing the humidified gas to a patient's eye typically during an eye 
surgery procedure. The humidifier device is typically in-line, i.e. 
positioned in a gas flow path between the gas source and the patient's 
eye. 
Preferred humidifier devices of the invention generally include a housing 
and a humidifying section disposed within the housing. The housing 
comprises an inlet and an outlet connection or port that fluidly 
communicates with the interior of the housing. The humidifying section is 
located within the housing so air entering the housing via the inlet 
connection passes through the humidifying section and thence out through 
the outlet connection, thereby humidifying the flowing air. 
The humidifying section preferably includes material (preferably 
hydroscopic) that can be hydrated (e.g., initial charged with a liquid, 
such as a sterile saline solution) and selectively release moisture to the 
gas as it passes through the humidifying section. Preferably, the material 
also is a bacteriostatic material. Alternatively, the humidifying section 
is treated with a germicide or other agent. In general aspects, the 
humidifying section is any type of reservoir that allows for efficient 
humidification of the gas flowing therethrough. Also, in general aspects 
the hydroscopic material includes any one of a number of materials known 
in the art, including but not limited to cellulose, absorbent synthetic 
materials, papers including corrugated paper, and the like. Additionally, 
the humidifying section can have a variety of structural configurations 
and shapes including a cylinder that permits the passage of air between 
the inlet and outlet connections. In a particular embodiment, the 
humidifying section is a cylinder of concentric layers of corrugated paper 
or other absorbent material configured to maintain a desired shape and 
integrity of the air flow passage after the corrugated absorbent material 
has absorbed a desired quantity of liquid. Such a preferred cylinder 
design is suitably configured to allow the air to flow along the long axis 
of the cylindrical humidifying section. 
The device housing may be suitably constructed of any one of a number of 
materials known in the art that is appropriate for the intended use 
including maintaining structural integrity while being exposed to the 
humidified air. More particularly, the housing is constructed of a plastic 
material such as a rigid polypropylene, polyethylene and the like. In a 
preferred embodiment, the housing includes a visual port or is 
constructed, at least in part, of a clear plastic material that allows a 
surgeon or other device user to observe the condition of the hydroscopic 
material of the humidifying section within the housing. 
In one aspect of the invention, the device housing is constructed to form a 
one-piece structure in which is disposed the humidifying section. In 
another aspect of the invention the housing is constructed so as to have 
two or more members that are releasably secured to each so a single 
structure is formed when the humidifier is assembled for use. 
A humidifying system of a device of the invention suitably will be in 
communication with a source of flowing gas (particularly air) and an 
in-line humidifier as described above. Such a system can further include 
an air filter that filters the air before it passes through the 
humidifier. In a more specific embodiment, the filter or system further 
includes the capability to sterilize the air. The system typically 
includes tubing that interconnects the various components that form the 
system. The source of air that flows through the system and is infused 
into a patient's eye suitably can be a commercially available pressurized 
tank of air or the like. 
Other aspects and embodiments of the invention are discussed below.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the various figures wherein like reference characters 
refer to like parts, FIG. 1 depicts a preferred system 10 for humidifying 
air according to the present invention in which air is infused into an eye 
2 during, for example a retinal detachment surgical procedure. Although 
the illustrated system is for infusing air into the eye the system of the 
present invention is not limited to such a use. It is within the scope of 
the present invention for such a humidifying system to be used in 
conjunction with other medical procedures, particularly other surgical 
procedures involving the posterior segment of the eye and/or phakic 
fluid/gas exchange, particularly those involving prolonged infusion of a 
gas. 
System 10 includes gas supply 12, filter 14, in-line humidifier 20 and 
interconnecting tubing 16. Gas from gas supply 12 (e.g. a pressurized air 
tank) is communicated by way of the interconnecting tubing 16 to the 
filter 14 and the filtered gas is communicated via the interconnecting 
tubing to in-line humidifier 20. The filtered and humidified gas is then 
communicated via the interconnecting tubing 16 to a surgical instrument, 
for example a gas inflow instrument 4 or cannula used in retinal 
detachment surgery that infuses air into an eye. 
Although generally less preferred, devices of the invention may omit filter 
element 14. In such a design, gas from the gas supply 12 is communicated 
directly to the humidifier 20 by means of the interconnecting tubing 16. 
The gas supply 12 in an illustrative embodiment is a pressure tank, 
however, the gas supply can be any of a number of means for storing and 
distributing a gas into a feed line including a pressure regulated gas 
supply system. Alternatively, the gas supply 12 can be the gas supply 
system of a facility or a structure in which the system is located. For 
example, the gas supply can be the compressed air system in a hospital or 
other medical facility. In an exemplary use, the gas supply 12 is a source 
of dry filtered air and more particularly a source of sterile, dry 
filtered air. The gas being supplied includes air, sulfur hexafluorine, 
perfluoro propane and any other gas known to those skilled in the art that 
can be infused into an eye. Typically, the gas is supplied at a pressure 
sufficient to maintain the shape of the eye without injury, for example 
between about 0 and 100 mm Hg or more particularly, between about 20-40 mm 
Hg. 
Filter 14 filters the gas to remove particulate matter and infectious 
material such as bacteria in the micron and sub-micron range. The filter 
14 also is preferably configured to sterilize the gas or air as it passes 
there through. In an exemplary embodiment, the filter 14 is a MILLEX-GS 
manufactured by the Millipore Corporation. 
As further shown in FIGS. 2-3, the in-line humidifier 20 includes a housing 
22, having an inlet and outlet connection 26a, b and a humidifying element 
24 disposed therein. As shown in FIG. 2, housing 22 preferably includes at 
least an area 28 that is translucent or clear so the user can observe the 
condition of the humidifying element 24. Alternatively, the entire 
housing, or a substantial portion of the housing (60%, 70%, 80% or 90% or 
more of the housing surface area) may be constructed of a translucent or 
clear material to enable observation of humidifying element 24. 
In one embodiment as shown in FIG. 2, the housing 22 forms a one-piece 
structure in which is disposed the humidifying element 24. In a second 
embodiment, as shown in FIG. 3, the housing 22 includes two subsections 
30a, b that are releasably secured to each other so as to form a single 
housing like that shown in FIG. 2 when assembled together. In the 
illustrated embodiment, one subsection 30a includes a male threaded 
connection 32a and the other section a female threaded connection 32b to 
threadably secure the subsections 30a, b together. The subsections 30a, b, 
however, can be configured with other connecting means, e.g., press fit, 
etc. Preferably, the subsections 30a, b also are configured so the gas 
flows through the humidifying element 24 and does not escape the housing 
22. 
The housing's inlet connection 26a and outlet connection 26b are any one of 
a number of suitable connections, e.g. male/female luer lock connections 
or slip-on tubing connections (e.g., tubing slipped over a spigot). The 
inlet and outlet connections 26a, b are arranged so the gas or air flows 
through the humidifying element 24 in a manner best suited for releasing 
moisture that is retained in the humidifying element to the flowing gas. 
In one embodiment, the inlet connection 26a is disposed in one end cap 34 
and the outlet connection 26b is disposed in the other end cap so the gas 
passing through the humidifier 10 flows along the long axis of a 
cylindrical humidifying element 24. In an alternative embodiment, the end 
connections 27a, b are diametrically opposed on the shell of the housing 
22 as shown in phantom in FIG. 2. 
Housing 22 is suitably constructed from a variety of materials. For 
example, plastics will be suitable, preferably rigid materials, such as a 
polypropylene or high-density polyethylene. Polyfluorocarbons also can be 
employed such as an extruded teflon housing. Stainless steel or other 
metal also can be employed, although may be less preferred for cost 
reasons. Typically, housing 22 is constructed of one or more materials 
that can be shipped in a sterile condition from a manufacturer to a remote 
facility (e.g., hospital) for later use. 
Although FIGS. 2-3 illustrate the housing 22 as having a generally 
cylindrical structure with hemispherical end caps (FIG. 2) or truncated 
conical end caps (FIG. 3) this is not a limitation as the housing can have 
any of a number of geometrical configurations or shapes or combination of 
shapes. For example, the housing 22 can be configured using cylindrically 
shaped members that are joined at an angle to each other so as to form an 
L-shaped in-line humidifier. The thickness and other details of the 
housing 22 are established based on the humidity, pressure and flow 
conditions of the intended use as well as any external forces and/or 
external environmental conditions (e.g., in situ sterilization and impact 
loads). 
In a further aspect of the invention, as shown in FIG. 4A, housing 22 can 
include one or more internal baffle(s) 36 that direct gas flow through the 
humidifying element 24 and out of the housing. Such an arrangement allows 
the inlet and outlet connections 26a, b to be positioned so as to have 
differing orientations, e.g. positioned so one connection is an end cap 34 
and the other connection in the shell of the housing (e.g., orthogonal to 
each other). Alternatively, the housing 22 includes one or more baffles 36 
and the humidifying element 24 comprises two or more sub-sections 25a, b 
so the gas makes two or more passes through the humidifying element. As 
shown in FIG. 4B, with such a design the inlet and outlet connections 26a, 
b can be disposed in the same end cap 34. 
The humidifying element 24 includes a material that preferably can be 
hydrated and which exhibits good moisture exchanging properties with a 
flowing gas. The humidifying element 24 also includes a support structure 
or capability so as to maintain the humidifying element in its desired 
configuration (e.g., cylindrical) and so the gas can flow therethrough and 
adsorb moisture from the hydrated material. As such, the humidifying 
element can include one or more elements to perform the above functions. 
In an exemplary embodiment shown in FIG. 5, the humidifying element 24 
includes a plurality of concentric layers 40 that are substantially 
parallel to the direction of flow of the gas through the housing 22 and 
the humidifying element 24. Each concentric layer 40 includes a plain 
paper sub-layer 40 having a smooth surface and a corrugated paper 
sub-layer 42 that preferably is attached thereto using any of a number of 
means known to those skilled in the art. In a more specific embodiment, 
the plain paper sub-layer 40 and the corrugated paper sub-layer 42 are 
formed as a continuous sheet and this sheet is wound about a common axis 
to form the plurality of concentric layers 40 shown in FIG. 5. 
When so formed, the corrugated paper sub-layer defines a plurality of 
passages 46 that extend along the entire length of the humidifying element 
and which are open at both ends of the element. The corrugations also 
maintain sufficient structural rigidity when hydrated so the flow passages 
46 remain open and the humidifying element 24 essentially maintains its 
structural configuration. In this way, the gas can flow along the entire 
length of the humidifying element 24 through the flow passages 46 and 
adsorb moisture from the surrounding hydrated paper of both the corrugated 
paper sub-layer 42 and the plain paper layer 40. 
The humidifying element 24 also can be constructed from a variety of other 
materials. For example, the humidifying element 24 can be made of a sheet 
of flexible plastic foam material, preferably with one surface of which is 
configured so has to have a plurality of ridges and valleys extending 
substantially parallel to each other. The ridges and valleys may form, for 
example, a saw tooth pattern, a square pulse type of pattern or a 
sinusoidal pattern. The sheet is suitably then wound about itself along a 
common axis so that the ridges and valleys cooperate to form a plurality 
of flow passages. 
In general the humidifying element 24 can be any type of reservoir that 
allows efficient humidification of a gas flowing therethrough. Also, while 
FIG. 3 depicts a preferred cylindrical shape, humidifying element 24 can 
be formed in a variety of other designs that would be appropriate for the 
specific configuration of the housing 22. For example, the humidifying 
element can be hexagonal or octagonal in shape. Other physical 
characteristics of the humidifying element 24, such as the thickness of 
the element are established so as to minimize flow and pressure losses, 
maximize available area for moisture exchange, establish the level of 
hydration required for use and the physical configuration of the housing. 
In a further embodiment, the humidifying element 24 is treated with a 
germicide or other agent so as to minimize the potential for infection and 
the like when the flowing gas is being humidified. 
Suitable dimensions of devices of the invention and the components thereof 
can vary rather widely and can be readily determined by those skilled in 
the art based on the present disclosure. In general, the device should 
have a shape and length so that the device is capable of being employed as 
an in-line humidifier during eye surgery procedures. Nevertheless, 
suitable dimensions include the following. The usable length of the 
housing 22 (length l.sub.h in FIG. 1) suitably may be from about 25 to 
about 50 mm and correspondingly a suitable length for the humidification 
element 24 (length l.sub.f in FIG. 3) maybe from about 20 to about 45 mm. 
Suitable diameters of the housing 22 (diameter d.sub.h in FIG. 1) may be 
from about 10-25 mm and suitable diameters for the humidification element 
24 (diameter d.sub.f in FIG. 3) may be from about 9 to about 20 mm. 
Additionally, the thickness of the housing 22 can be 2 mm or more, more 
particularly in the range of from about 2 to about 4 mm. 
The use of the humidifier 20 and system 10 of the present invention can be 
further understood from the following discussion relating to a method for 
treating a retinal tear or detachment by means of the laser 
photocoagulation technique and with reference to FIGS. 6A-C. Reference 
also shall be made to FIGS. 1-3 and 5 for specific components or elements 
of the in-line humidifier 20 and system 10 of the present invention not 
otherwise shown in FIGS. 6A-C. 
In treating the retinal tear or detachment, the user (e.g. medical 
practitioner) prepares the in-line humidifier 20 and humidification system 
10 for use. As such, the practitioner removes the in-line humidifier 20 
from its sterile packaging and the humidifying element 24 therein is 
charged or hydrated with a liquid such as a saline solution. In a more 
particular embodiment, the humidifying element is hydrated with a 
sufficient quantity of liquid so it is saturated. 
The humidifying element 24 can be charged or hydrated by alternative 
methods. In one technique, the nozzle of a syringe or other such 
instrument containing a predetermined amount of liquid is inserted through 
either of the inlet or outlet connection 26a, b and the liquid is injected 
onto the humidifying element 24. The amount of liquid to be injected and 
the rate of injection preferably is established so the fluid hydrates, 
more preferably saturates, the humidifying element 24 without spillage. 
Alternatively, fluid can be added to the device without disassembly of the 
device or insertion through the above noted gas flow path inlet/outlets , 
e.g. fluid can be introduced through a resealable opening or the like in 
the device. More specifically, a nozzle of the syringe can be passed 
through a resealable port or grommet 41 in the shell or end cap 34 of the 
housing. As is known to those skilled in the art, a resealable grommet 
reseals itself when the nozzle of a syringe is withdrawn. In an exemplary 
embodiment, 10 ml of saline solution when injected onto a corrugated 
paper-humidifying element saturated the element. 
In a further technique for hydrating the element 24, which is particularly 
applicable to a multi-piece housing (see FIG. 3), the housing 22 is 
disassembled by means of the threaded connection 32a, b so the humidifying 
element 24 can be removed from within the housing. The removed humidifying 
element 24 is then hydrated by placing or immersing the element in a 
liquid bath, e.g. a saline solution, until the element is hydrated. 
Alternatively, a syringe is used to inject the liquid directly onto the 
humidifying element 24 to hydrate it. As indicated above, the humidifying 
element 24 (i.e., the hydratable material comprising the element) is 
preferably saturated. After the element has been hydrated the humidifying 
element 24 is re-installed in one housing part 30a and the housing parts 
30a, b are threaded together and re-secured to each other to reform the 
housing 20. The element 24 also can be charged or hydrated by other 
procedures. 
After preparing the in-line humidifier 20 for use, it is interconnected to 
the other components of the system. For example, the female male Luer-Lok 
at the inlet connection 26a receives the male Luer-Lok attached to the 
interconnecting tubing 16 so as to establish a fluid connection between 
humidifier 20 and either the filter 14 or the gas supply 12. Similarly, 
the male Luer-Lok at the outlet connection 26b is inserted into the female 
Luer-Lok provided on the interconnecting tubing 16 being interconnected 
thereto so as to establish a fluid connection between the humidifier and 
the cannula 102 that is inserted into the eye 2. 
In treating a retinal tear or detachment using a photocoagulation technique 
employing a laser, a cutting/aspirating instrument 100, a cannula 102 and 
a light transmitting instrument 104 are inserted through the sclera so one 
end of each resides intraocular. The light transmitting instrument 104 is 
configured so the light from the laser (not shown) can be directed to 
specific locations on the retina. The cutting/aspirating instrument is 
disposed so an end thereof is proximate the retinal tear. 
Initially, the vitreous gel, especially all strands causing traction on the 
retinal tear are removed or aspirated by means of the cutting/aspirating 
instrument 100. As the vitreous gel is being aspirated, the intraocular 
volume is maintained by a continuous infusion of a fluid, such as a 
balanced salt solution (BSS), through the cannula 102. Any subretinal 
fluid is also aspirated through the retinal tear. Thereafter, the vitreous 
fluid is aspirated and exchanged with a humidified gas such as air passing 
through the cannula 102. In the method of the present invention, the gas 
or air being exchanged is humidified by means of the in-line humidifier 20 
and humidification system 10 as herein above-described. 
The retina surrounding the tear is then repeatedly exposed to the laser 
light from the light transmitting instrument 104 so as to form a plurality 
of heat spots on the retina surrounding the retinal tear. In particular, 
the practitioner manipulates the light transmitting instrument 104 so that 
a plurality of rows of a plurality of such heat spots surrounds the 
retinal tear. In this way, the retinal tear is photocoagulated with a 
laser to achieve a thermal adhesive injury. The heat spots also produce 
scars that prevent fluid from passing through and collecting under the 
retina. 
Thereafter, the intraocular gas or air, infused while exposing the retina 
surrounding the retinal tear to laser light, is totally exchanged for a 
longer-lasting gas, such as sulfur hexafluorine or perfluoro propane. This 
gas allows an adequate tamponade time for the therapeutic chorioretinal 
scar to develop. Preferably, the longer lasting gas being infused is 
humidified using the in-line humidifier 20 and system 10 of the present 
invention. After completing the "in eye" portion of the treatment 
procedure, the inserted instruments and cannula are removed from the eye 
and the spent or used in-line humidifier 20 is disposed of in accordance 
with normal and usual practices. 
During the treatment procedure and, in particular when infusing the 
humidified gas into the eye, the practitioner, by visual observation 
through the clear area 28 of the housing 22, determines if the humidifying 
element 24 or humidifier should be replaced. For example, the practitioner 
visually observes the humidifying element 24 through the clear area 28 to 
see if the element appears to be dried out as a means for making such a 
determination. If it is determined that the humidifying element 24 is no 
longer sufficiently hydrated and thus is no longer capable of performing 
its humidifying function, then the spent in-line humidifier is replaced 
with a freshly charged or hydrated in-line humidifier. 
For purposes of easily maintaining sterility of the field, the preferred 
action is to replace the spent element with a new humidifier that has been 
properly charged with liquid. This course of action also allows a 
practitioner to prepare a humidifier in advance to minimize the time 
amount of time required to return the humidified air supply back to 
service. It is within the scope of the present invention, however, to 
re-charge the humidifying element 24 of an in-line humidifier 20 that is 
in use by either injecting additional liquid onto or into the humidifying 
element or by re-immersing the element in a liquid bath as described 
above. 
The invention also includes device kits that comprise an in-line humidifier 
20 in an assembled configuration with or without interconnecting tubing 
packaged in a sterile condition. Alternatively, the humidification element 
24 and housing 22 can be supplied together in the sterile packaging for 
later assembly by the practitioner. Preferably the in-line humidifier 20 
is provided in its assembled condition. 
Although a preferred embodiment of the invention has been described using 
specific terms, such descriptions are for illustrative purposes only, and 
it is to be understood that changes and variations may be made without 
departing from the spirit or scope of the following claims.