The invention will now be described with reference to the drawing figures, in which like reference numerals refer to like parts throughout. An embodiment in accordance with the present invention provides a respiratory breathing circuit that prevents heat loss and condensation in a flow of humidified air supplied through a conduit from a humidification system to a patient interface, such as a nasal cannula. The circuit is part of an overall gas humidification system that supplies a high flow of respiratory breathing air to a patient through a patient interface. The present invention directly impedes heat loss and/or insulates the flow of a humidified gas through the circuit, and in one embodiment provides a heating source inside the circuit along the length of the circuit to prevent net heat loss from the circuit tubing. A temperature, humidity, or other flow quality measuring probe can be disposed at the distal end of the circuit near the patient interface to actively measure the corresponding quality of the humidified gas flow so as to provide feedback and information to the system. An additional safety device in the form of a pressure relief valve is provided on the circuit architecture to prevent a pressure build-up and/or structural failure, as well as to alert the surroundings of such an event.
An embodiment of the present inventive apparatus is illustrated in
The system 10 further includes at least two flow quality monitoring ports where a flow quality monitor or probe can be added. A first proximal probe 30 is provided at the proximal end portion of the circuit 12. In accordance with conventional practice, as used herein, the term “proximal” or “proximal end” shall refer to the specified end of a device or its component which is closer to the medical personnel handling or manipulating the device as it is intended to be used, and the term “distal” or “distal end” shall refer to the specified end of a device or its component which is closer to the patient. Another distal probe 32 can be provided at the distal end or distal end portion of the circuit 12. Either probe 30 or probe 32 can be a temperature measuring device or a moisture or relative humidity measuring device. A clip 34 is also provided at the proximal end portion of the circuit 12, which can be used to secure and attach a cable or wire, such as that connecting the distal end probe 32.
The “circuit” 12, as defined herein, shall be any arrangement of one or more tubular conduits connecting the supply of humidified gas, which can extend from the column all the way to a patient interface 36, where respiratory breathing is directly aided or enabled by the supply of the gases. The patient interface 36 can be any device which the patient wears or touches, which is directly proximate the patients mouth, nose, or throat. In the embodiment shown in
By measuring the quality of the supplied gases to the patient at the distal end of the circuit 12, proximate the probe 32, the temperature or relative humidity of the supplied gases can be directly measured right before the gases are administered to the patient. This more effectively prevents any rain-out from occurring, since an undesirable temperature or moisture condition can be immediately measured at its more critical point, that is, just before the patient breathes the gases supplied.
The present invention is also supplied with a heating element. In the embodiment of
This is not the only way of preventing or impeding heat loss in the flow in the circuit 12. An alternative embodiment of the present invention can include a multi-lumen tube for circuit 12, having an inner lumen which carries the flow of gas to the patient, and one or more outer lumens that radially enclose or surround the inner flow lumen. A fluid such as heated water can be supplied through the one or more outer lumens, thereby insulating the flow of gas in the inner lumen, to thus prevent or impede the loss of heat from the gas flow in the circuit 12. Any prevention of heat loss will accordingly prevent condensation in the system, so as to prevent rain-out from occurring. A number of lumen configurations is possible, as is well known in the art, including outer lumens that completely surround the inner lumen, or individual lumens that supply fluid to and from the distal end portion of the circuit 12.
The patient interface 36 can be a loop shaped nasal cannula, which can include two halves, a proximal half 60 and a distal half 62. Passive insulation can be added to the proximal half 60 to prevent or impede heat loss or condensation in the flow lumen inside the cannula loop. This insulation is therefore a “passive” means, whereas the heater wire 38 or alternative multi-lumen arrangements discussed above for the circuit 12 are active means of impeding heat loss in the fluid flow in the circuit 12.
The circuit 12 can also include a pressure relief valve 44 at its proximal end, such as part of the junction 40, although the pressure relief valve 44 can be at any position along the circuit 12.
Turning now to
As disclosed herein, the present invention efficiently and effectively supplies air to a patient for respiratory breathing that is at the correct temperature, humidity, and pressure conditions. The device can deliver up to 40 liters per minute, which is less for pediatric and neonatal patients. The system 10 can deliver to an adult patient a range of 5 to 40 liters per minute, a pediatric patent a range of 5 to 20 liters per minute, and a neonatal patient a range of 1 to 8 liters per minute. Patients will thus benefit from a high flow rate of heated, humidified oxygen, which can be used to alleviate hypoxemia, dyspnea, or other respiratory conditions in a hospital or home care setting.
The many features and advantages of the invention are apparent from the detailed specification, and thus, it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope of the invention. Further, since numerous modifications and variations will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.