This invention relates generally to devices for supplying fluids to patients and more particularly to devices for supplying warm, humidified oxygen gas to patients.
Oxygen is commonly delivered in the practice of medicine to patients as a gas. The oxygen flows from a source to a delivery device such as a nasal cannula, for delivery to the patient""s respiratory tract.
The administration of oxygen to patients, including neonatal, pediatric and elderly patients, requires the selection of an oxygen delivery system that suits the patient""s size, needs and therapeutic result. Typically, the oxygen gas delivered directly from a hospital oxygen delivery system is dry and cold. Delivering dry and cold oxygen to an infant, for example, can undesirably lower body temperature and promote dehydration. Accordingly, it is often preferred to warm and humidify the oxygen so that the patient inhales a warm gas-liquid mixture.
It has proved difficult to supply warm oxygen having sufficient humidity at flow rates of less than about 2 liters/minute. Standard equipment available for both warming and humidifying oxygen is suitable for use with adults and is adjustable to deliver a volumetric fluid flow of from about 2 to about 15 liters per minute. These devices, however, generally require a minimum flowrate of at least about 2 liters per minute in order to operate. Pediatric patients, particularly neonatal patients, require a flow rate of less than about 2 liters per minute, sometimes only slightly above zero liters per minute (e.g. about xe2x85x9 liter per minute).
Accordingly, there is a need in the art for a device which enables warm, humidified oxygen to be supplied to pediatric/infant patients at flow rates of from about 2 liters per minute and below.
It is therefore an object of the invention to provide a system for controlling the flow rate of fluid, such as warm, humidified oxygen, from a fluid source.
An additional object of the invention is to provide a system of the character described that is compatible with existing equipment, such as oxygen humidifiers.
A further object of the invention is to provide a system of the character described that is suitable for use with pediatric patients.
It is another object of the invention to provide a system of the character described that is selectively adjustable to enable an oxygen flow rate of from about 0 to about 2 liters per minute.
A further object of the invention is to provide a system of the character described that is uncomplicated in configuration and convenient to use.
A still further object of the invention is to provide a system of the character described that is economical and suitable for use with conventional oxygen delivery systems.
With regard to the foregoing, the present invention is directed to a system for use with standard humidification equipment having a flow rate of at least about 3 liters/minute for delivering fluids such as oxygen, preferably warm, humidified oxygen to patients at a flow rate of from about 0 to about 2 liters/minute. As used herein, the term xe2x80x9cwarm/humidified oxygenxe2x80x9d refers to oxygen gas having a temperature of from about 30xc2x0 C. to about 37xc2x0 C. (about 86xc2x0 F. to about 98.6xc2x0 F.) and a relative humidity of from about 80 to about 100%.
The system includes a conduit having an inlet connected to a source of humidified oxygen at a flow rate of at least about 3 liters/minute and an outlet end for delivering humidified oxygen to a neo-natal patient at a flow rate of from about 0 to about 2 liters/minute. A first aperture extends through the sidewall of the conduit for bleeding oxygen from the conduit so that the flow in the conduit is reduced to about 2 liters/minute. A second aperture is provided downstream from the first aperture and extends through the sidewall for bleeding oxygen from the conduit at a rate of from about 0 to about 2 liters/minute. A substantially solid member is movably positionable adjacent the second aperture for defining a variably dimensionable flow path to enable control over the amount of oxygen bled through the second aperture.
In another embodiment, the invention is directed to a system for controlling the flow rate of fluid from a fluid source, such as humidified oxygen, for delivery to a patient.
In a preferred embodiment, the system includes a conduit having an interior and an exterior separated by a substantially continuous sidewall, an inlet end in flow communication with an outlet end for flow of fluid from the fluid source through the conduit from the inlet end toward the outlet end, the inlet end being in flow communication with the source of fluid at a first flow rate and the outlet end being in flow communication with a fluid delivery device for delivering fluid to the patient at a second flow rate that is lower than the first flow rate.
A first aperture extends through the sidewall for passage of fluid from the interior to atmospheric regions adjacent the exterior of the conduit and for reducing the flow rate of fluid within the conduit to a third flow rate that is less than the first flow rate and greater than or equal to the second flow rate. A second aperture is provided downstream from the first aperture extends through the sidewall. A substantially solid member is movably positionable adjacent the second aperture for defining a variably dimensionable flow path for passage of fluid from the interior to atmosphere regions adjacent the exterior of the conduit. Variation of the dimension of the variably dimensionable flow path selectively enables escape of fluid from the interior of the conduit to provide the second flow rate of fluid.
In another embodiment, the invention relates to a system for delivering humidified oxygen to a patient. The system preferably includes a conduit having an inlet connected to a source of humidified oxygen at a first flow rate and an outlet end for delivering humidified oxygen to a patient at a second flow rate that is less than the first flow rate. A first flowpath extends through a sidewall of the conduit for continuously bleeding oxygen from the conduit. A second flowpath is located downstream from the first flowpath and extends through the sidewall of the conduit for continuously bleeding oxygen from the conduit at a rate of from about 0 liters/minute or above. A substantially solid member is movably positionable adjacent the second flowpath for selectively blocking and unblocking portions of the second flowpath for defining a variably dimensionable flow path in order to control over the amount of oxygen flowing through the second flowpath.
In yet another aspect, the invention relates to a method for delivering treatment fluids, such as humidified oxygen, to pediatric patients from a source of fluid of the type used for adults and having a flow rate above about 3 liters per minute. The method includes the steps of providing the oxygen source, placing it in flow communication with a delivery system in accordance with the invention and manipulating the delivery system to achieve a desired flow rate to the patient of from about 0 to about 2 liters per minute.
The invention advantageously enables warm, humidified oxygen to be delivered at low flow rates heretofore unobtainable by conventional hospital equipment. The invention thus enables the use of standard oxygen and other delivery and humidification systems in the treatment of pediatric and other patients having treatment flow rate requirements below those available from standard treatment equipment. The system also advantageously adapts to fit pediatric output components, such as pediatric cannulas having smaller tubing size, while connecting to adult or standard input components having larger tubing sizes.