WO1998048755A1

WO1998048755A1 - Infant incubator

Info

Publication number: WO1998048755A1
Application number: PCT/AU1998/000294
Authority: WO
Inventors: Stephen James Wilson
Original assignee: The University Of Queensland
Priority date: 1997-04-24
Filing date: 1998-04-24
Publication date: 1998-11-05
Also published as: AUPO639197A0

Abstract

An infant incubator (10) is formed by a canopy (13) placed on a base (11) to define a chamber therebetween. In use, an infant is placed on a platform (12) on top of the base (11) in the chamber. A fan (15) blows air over a generally flat heating element (14). The warmed airflow is introduced into the chamber and recirculated to the fan (15). The flat heating element (14) provides uniform and distributed heating of the airflow, as well as heating of the underside of the platform (12) on which the infant is placed. A control circuit (17) monitors temperature within the chamber, and controls the heating element (14) accordingly.

Description

"INFANT INCUBATOR" THIS INVENTION relates to an infant incubator. In particular, the invention provides an incubator for newborns which provides uniform heating and accurate temperature control .

BACKGROUND ART

It is common practice for premature babies and newborn infants with respiratory or other ailments to be placed in incubators. Such incubators provide a thermally controlled environment for the newborns which places minimal stress on the infant ' s thermoregulatory mechanisms .

The incubators normally comprise a chamber having a transparent cover, a heating mechanism, ventilation means, and a temperature control mechanism. The incubators are designed to control the air temperature within the chamber accurately, while allowing access for nursing care and other therapeutic or diagnostic methods.

Infant incubator design has provided two broad classes of devices; namely, open radiant heaters and closed chambers. Both types of devices consist of a platform or mattress on which the infant is placed and restrained to some degree. In radiant heaters, a heating source located above the infant is used to provide radiative warming of the infant. Examples of incubators with radiant heating can be found in U.S. patents nos. 5,119,467; 5,162,038 and 5,285,519.

In the closed chamber type, a closed transparent canopy covers the platform, and suitably warmed air is introduced from outside the canopy, or recycled from within the incubator. An example of a closed chamber incubator can be found in U.S. patent no. 4,321,913.

Although it is known to use transparent film radiant heat sources in incubators to provide distributed heating, radiant heating incubators still suffer from the disadvantage that the upper side of the infant receives far more heat than the lateral sides and underside of the infant. The heating provided by radiant heaters is generally not as uniform as convection heating used in closed chamber incubators.

Closed chamber incubators, such as that described in U.S. patent no. 4,321,913, typically use a conventional heater to heat an airstream. The heater may be located under the platform on which the infant is placed. Known closed chamber incubators are relatively expensive .

It is an object of the present invention to provide an improved incubator of the closed chamber type.

SUMMARY OF THE INVENTION In one broad form, this invention provides an incubator suitable for newborn infants and the like, comprising a base, a canopy over the base defining a chamber between the canopy and the base, a fan for producing an airflow into or around the chamber, and heating means for heating the airflow, characterised in that the heating means comprises a generally planar heating element.

Typically, a platform is provided on top of the base, on which an infant is laid.

In one embodiment of the invention, the heating element is located within the base, and under the platform. The fan blows air across the heating element and into the chamber. The heating element not only warms the air, but also warms the platform on which the infant rests. The distributed nature of the heating avoids "hot spots" .

Further, the planar nature of the heating element allows it to be inserted in a horizontal orientation under the platform, thereby permitting the base to be of low compact design.

Advantageously, the incubator includes means for humidifying the air passing into the chamber. The humidifying means comprises water placed in the airflow path and heated by the heating means. In the preferred embodiment, the water is fed by capillary action from a reservoir to an absorbent pad or sponge in contact with the face of the heating means. As the airflow passes over the heated water in the pad or sponge, it picks up warmed moisture. In this manner, warmed and humidified air is delivered to the chamber. Moreover, by incorporating the humidifying means with the heating means, an additional heating source for humidification is not required.

In a second embodiment, the canopy has a double wall, and the planar or membrane heating element is located between the twin walls of the canopy. Air is blown by the fan between the twin walls, and is heated by the heating element before passing around and/or in the chamber.

Typically, the incubator also includes electronic temperature control means, responsive to sensors in the chamber and/or on the infant's body. The temperature is monitored by the control means which then controls the heating element and/or fan to maintain the temperature at a desired level .

In order that the invention may be more fully understood and put into practice, preferred embodiments thereof will now be described.

BRIEF DESCRIPTION OF THE DRAWING Fig. 1 is a perspective view of an incubator according to an embodiment of the invention; Fig. 2 is a schematic sectional elevation of the incubator of Fig. 1; and

Fig. 3 is a schematic block diagram of the electrical control circuit of the incubator of Fig. 1.

DESCRIPTION OF PREFERRED EMBODIMENTS

As shown in the drawings, an infant incubator 10 comprises a base 11 having a platform 12 thereabove on which an infant may be placed. Typically, the infant is placed on a thin mattress, blanket or similar cushioning layer on the platform.

The base 11 is covered by a transparent canopy

13, which preferably is double-walled. The platform 12 and canopy 13 define a substantially closed environment for the infant. Access openings 18 may be provided in the canopy 13, or the canopy may be hinged to the base 11 and opened to allow access for nursing care and other therapeutic or diagnostic treatment. A flat or planar heating element 14 is provided in the base 11 and located under the platform 12. The heating element is typically in the form of a flat membrane and comprises a planar electrically resistive element which on application of suitable voltage, will provide warming by ohmic heating.

In one embodiment, the flat heating element comprises a carbon layer encased or sandwiched in electrically insulating plastics sheeting.

A fan 15 is provided in the base to pass air over the heating element 14. The warmed air then passes through outlet 16 into the chamber within the canopy 13.

Air is drawn from the chamber to the fan 15 through outlet

19.

Humidifying means may be incorporated in the incubator. In the illustrated embodiment, the humidifying means comprises a damp layer, such as a thin sponge or absorbent pad 20, on the face of the heating element 14 in the airflow path. Capillary action keep^'s the sponge 20 moist with water fed from a reservoir 21 via a tube 22. In this manner, the airflow is not only heated by the heating element but also humidified. The use of such humidifying means obviates the need for an additional heating source for humidification.

In use, temperature sensors (not shown) are placed within the chamber, preferably both on the infant and at selected locations within the chamber. An electronic control circuit and display 17 are provided on a printed circuit board mounted near the front of the base 11.

As shown in Fig. 3, the electrical control circuit includes a microprocessor 25 which is programmed to detect hazard states, such as overheating or under- temperature, or component failure. The microprocessor 25 is connected to the output of a two channel temperature sensor which senses air temperature within the chamber and the infant skin temperature . In response to the sensed temperatures, the microprocessor 25 controls the operation of the heater panel 14, via a triac switch 27. A thermostat 28 provides feedback information regarding the actual temperature. Preferably, the control circuit controls not only the heater temperature, but also the fan speed, to maintain the temperature uniformly in the chamber at the desired level. The temperature is shown on the display 17 at the front of the base.

Several light emitting diodes 29 are also provided at the front of the base 11, and controlled by the microprocessor 25, to indicate various operating modes and alarm conditions. For example, in the event that a sensor 30 detects failure of the fan 15, the microprocessor 25 makes appropriate adjustment to the operation of the heater panel 14, and activates an alarm LED 29. An audible alarm is also actuated in addition to the visual alarm.

The abovedescribed incubator has a number of advantages, including:

• The planar heating element 14 can be housed in a low base 11, thereby enabling a compact design for the incubator.

• The flat heating element 14 not only warms the air passing into the chamber, but also provides radiant/conductive heating of the underside of the platform 12. In this manner, the infant is heated from all sides. The broad area over which heat is produced provides uniform heating of the infant bed. Unlike known closed chamber incubators with heated air, the incubator of this invention precludes the build-up of local areas of intense heat. Such focal hot areas, or "hot spots", act as a fire risk, and also as an explosive risk in the presence of oxygen which is commonly used in such devices.

• The membrane heating element is electrically safe, robust and of economical manufacture.

• The heating and control unit is easily removed from the incubator base, permitting easy cleaning and sterilisation.

• The heating means may also be used for humidification, avoiding the need for separate heating means for humidifying the air.

The foregoing describes only one embodiment of the invention, and modifications which are obvious to those skilled in the art may be made thereto without departing from the scope of the invention.

In a further embodiment of the invention (not shown) , a membrane heating element is located between the spaced walls forming the canopy 13. This membrane heating element may be a transparent film heat source such as the type described in U.S. patents nos. 5,119,467 and 5,285,519. Instead of providing predominantly radiant heating however, the membrane heat source within the double-walled canopy is used to provide convection heating. Namely, air is blown between the walls of the double-walled canopy 13 by the fan 15, and is heated by the heating film or membrane. The heated air may be used to heat the canopy directly, and the interior of the chamber indirectly. Alternatively, the heated air may be passed into the chamber for convection heating of the infant .

Claims

CLAIMS :

1. An incubator suitable for newborn infants and the like, comprising a base, a canopy over the base defining a chamber between the canopy and the base, a fan for producing an airflow into or around the chamber, and heating means for heating the airflow, characterised in that the heating means comprises a generally planar heating element.

2. An incubator as claimed in claim 1, wherein the heating element is a membrane-type heating element.

3. An incubator as claimed in claim 1, wherein the heating means comprises an electrically resistive carbon layer interposed between electrically insulating layers.

4. An incubator as claimed in claim 1, further comprising a platform on top of the base on which an infant may be laid, in use.

5. An incubator as claimed in claim 4, wherein the heating element is located within the base, and under the platform.

6. An incubator as claimed in claim 1, wherein the fan is located within the base, and blows air over the heating element and into the chamber through an opening in the top of the base, the air being recirculated from the chamber to the fan through another opening in the top of the base .

7. An incubator as claimed in claim 1, further comprising humidifying means for humidifying the airflow into the chamber.

8. An incubator as claimed in claim 7, wherein the humidifying means comprises a water retaining material placed in the airflow and in heat exchange relationship with the heating means.

9. An incubator as claimed in claim 1, further comprising at least one temperature sensor located within the chamber, an electrical control circuit connected to the output of the temperature sensor (s), the control circuit being connected to the heating means and/or fan for controlling the temperature in the chamber in response to the output of the temperature sensor (s) .

10. An incubator as claimed in claim 9, further comprising alarm means connected to the control circuit .

11. An incubator as claimed in claim 9, further comprising a display panel at the front of the base, the display panel being connected to the control circuit.

12. An incubator as claimed in claim 1, wherein the canopy comprises an interior wall and an exterior wall in close proximity thereto, the heating means being located in an air space between the interior wall and the exterior wall, and the airflow passes between the interior and exterior walls of the canopy before passing into the chamber .

13. An incubator as claimed in claim 1, wherein the base has a short vertical dimension relative to the canopy.

14. An incubator suitable for newborn infants and the like, comprising a base having a platform thereon for supporting an infant, a canopy over the base forming a chamber containing the platform, fan means in the base for creating an airflow into the chamber, and a distributed heating element located in the airflow in the base under the platform.

15. An incubator suitable for newborn infants and the like, comprising a base having a platform thereon for supporting an infant, a canopy over the base forming a chamber containing the platform, fan means in the base for creating an airflow into the chamber, a distributed heating element located in the airflow in the base under the platform, a heating element located in the airflow in the base under the platform, and a water retaining layer of material in the airflow and in heat exchange relationship with the heating element .