BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of a single limb ventilator circuit in accordance with the subject invention.
FIG. 2 is a schematic view of a ventilator for use with the ventilator circuit of FIG.1.
FIG. 3 is a schematic diagram of a single limb ventilator circuit in accordance with the subject invention and incorporating a wye connection to the exhalation valve.
FIG. 4 is a schematic diagram of a dual limb ventilator circuit in accordance with the invention.
FIG. 5 is a schematic view of a ventilator for use with the ventilator circuit of FIG. 4.
FIG. 6 is a schematic diagram of a dual lumen ventilator circuit in accordance with the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
A first embodiment of a ventilator circuit in accordance with the subject invention is identified generally by the numeral 10 in FIG. 1. The ventilator circuit 10 is used with a ventilator 12 as shown in FIG. 2. More particularly, the ventilator 12 of FIG. 2 includes a CPU 14 that controls the operation of the ventilator 12 and its ventilator circuit 10. The ventilator 12 is operative to deliver an air/O2 mixture to the ventilator circuit 10. More particularly, an air/O2 mixer 16 is incorporated into the ventilator 12 and may be controlled by signals generated by the CPU 14. The air/O2 mixer 16 includes an external air input 18 and an external O2 input 20 that communicate respectively with supplies of external air and oxygen. The CPU settings determine the proportion of air and oxygen to create the desired mixture. The air input to the air/O2 mixer 16 can be driven by an internal compressor 22 rather than an external air supply. In this case, a motor speed control and tachometer 24 communicates with the internal compressor 22 and further communicates with the CPU 14 to proportion the air and oxygen to obtain the desired mixture. Thus, the CPU 14 receives speed data from the motor speed control and tachometer 24 for indicating the speed of the internal compressor 22. Additionally, the CPU 14 can generate signals to the motor speed control and tachometer 24 for controlling the speed of the internal compressor 22. The internal compressor 22 further communicates with an air filter for filtering air that is inputted to the air/O2 mixer 16. The air/O2 mixer 16 further includes an output line 28 that delivers the mixture of air and O2 to the ventilator circuit 10 as described further herein. The output line 28 further communicates with an exhalation valve manifold 30 that is operative to generate pneumatic signals for operating valves of the ventilator circuit 10 as described further herein. Other configurations of the ventilator 12 can be used with ventilator circuit 10.
The first embodiment of the ventilator circuit 10, as shown in FIG. 1, includes an O2 fill enable valve 32 that communicates with the outlet line 28 from the air/O2 mixer 16. The O2 fill enable valve 32 also communicates with an exhalation valve control line 34 that extends from the exhalation valve manifold 30 of the ventilator 12.
An inspiratory line 36 extends from the O2 fill enable valve 32 and is operative for delivering the air/O2 mixture from the ventilator 12 towards the patient. In the embodiment of FIG. 1, an exhalation valve 38 is connected to the end of the inspiratory line 36 at a position remote from the O2 fill enable valve 32. The exhalation valve 38 further communicates with a patient connection 40 and with a delivered flow/exhale flow line 42. The outlet end 44 of the patient connection 40 remote from the exhalation valve 38 is configured for connection to the patient via a mask or endotrachal tube (not shown). A pressure line 46 extends from the patient connection 40 at a location between the outlet end 44 of the patient connection 40 and the delivered flow/exhale flow line 42. A delivered flow/exhale flow means for creating a small pressure drop 48 is disposed in the patient line 40 between the delivered flow/exhale flow line 42 and the pressure line 46.
A first check valve 50 is incorporated into the inspiratory line 36 between the O2 fill enable valve 32 and the exhalation valve 38 and in close proximity to the exhalation valve 38. The first check valve 50 is a one way check valve.
The ventilator circuit 10 further includes an O2 fill line 52 that extends from a low pressure low flow oxygen source 54 to a location on the inspiratory line 36 between the O2 fill valve 32 and the first check valve 50 and substantially adjacent to the check valve 50. A second check valve 56 is incorporated into the O2 fill line 52 and allows the ventilator circuit 10 to work if there is no low pressure/low flow source connected.
The exhalation valve control line 34 of the ventilator 12 communicates with both the O2 fill enable valve 32 and the exhalation valve 38 and receives pneumatic signals from the exhalation valve manifold 30 for operating the O2 fill valve 32 and the exhalation valve 38.
In operation, the O2 fill enable valve 32 normally is open and allows oxygen fill gas from the O2 fill line 52 to fill the inspiratory line 36 during the exhalation cycle. Pressure from the exhalation valve control line 34 closes the O2 fill enable valve 32 during the inspiratory cycle and the patient will inhale the air/oxygen mix that has accumulated in the inspiratory line 36 during the previous exhalation cycle. During the exhalation cycle, the exhalation valve 38 permits the exhaled air to exit from the ventilator circuit 10.
As noted above, the mechanical characteristics of the ventilator permit some of the exhaled air to accumulate in the inspiratory line of the prior art system and the subject invention. As a result, each subsequent inspiratory cycle in the prior art system and the subject invention permits part of the most recently exhaled gas to be inhaled again by the patient. This retention of exhaled gas in the ventilator circuit also adds to the exhaled volume that is simultaneously retained in the patient's anatomical dead space. In the prior art, this effect is mitigated partially by designs that reduce circuit dead space. Whereas the prior art delivers a breathing gas mixture for each successive breath that consists of essentially a uniform mixture, approximately one-third of the oxygen used to create this mixture never gets to the distal alveoli in the lungs where gas exchange actually takes place. In contrast, the subject invention hyper-oxygenates the part of the inspiratory line 36 that is closest to the patient to raise the O2 content of the retained gas more effectively by mixing with it in the anatomical dead space on its way to the distal alveoli during the next inspiratory cycle.
FIG. 3 shows an alternate embodiment of the ventilator circuit identified generally by the numeral 200. This design typically has less circuit dead space than the single limb circuit design of FIG. 1. More particularly, the ventilator circuit 200 is a single limb ventilator circuit similar to the ventilator circuit 10 described above with respect to the FIG. 1. However, the ventilator circuit 200 includes a wye fitting 60 between the check valve 50 and the patient connection 44. The exhalation valve 38 then is connected to one branch of the wye fitting 60, and hence is in an off line position from the inspiratory line 36. All other aspects of the ventilator circuit 200 shown in FIG. 2 are substantially the same as in the FIG. 1 embodiment. Furthermore, the ventilator circuit 200 of FIG. 2 achieves the same functional advantage of filling the inspiratory line 36 with oxygen that flows through the O2 fill line 52 from the low pressure low flow O2 source 54. Hence, the patient is assured of receiving the proper volume of oxygen at the start and throughout each inspiration cycle.
FIGS. 4 and 5 show a third embodiment of the ventilator circuit. The ventilator circuit of FIG. 4 is a dual limb circuit and is identified generally by the numeral 300 in FIG. 3. The FIG. 4 embodiment is structurally and functionally very similar to the FIG. 2 embodiment. In particular, a wye fitting 60 is in substantially the same position depicted in the FIG. 2 embodiment. However, the FIG. 4 ventilator circuit 300 further includes an expiratory line 62 that extends from wye fitting 60 to the exhalation valve 38. This embodiment further has the O2 fill enable valve 32 and the exhalation valve 38 as being parts of the ventilator 12, as shown in FIG. 5. However, the ventilator circuit 10 and the ventilator 12 cooperate to function substantially the same as in the first two embodiments.
FIG. 6 shows a further variation of the ventilator circuit, and specifically depicts a dual lumen circuit identified generally by the numeral 400. In particular, the ventilator circuit 400 of FIG. 6 has a dual lumen line 80 with an inspiratory segment 82 and an expiratory segment 84. The inspiratory segment 82 of the dual lumen line 80 extends from the O2 fill enable valve 32 to the patient connector 40. The expiratory segment 84 of the dual lumen line 80 extends substantially from the patient connection 40 to the exhalation valve 38. The check valve 42 is disposed in the inspiratory segment 82 in proximity to the patient connection 44. The O2 fill line 52 communicates with the inspiratory segment 82 at a location near the check valve above the check valve 42 and between the check valve 50 and the O2 fill enable valve 32. The ventilator circuit 400 of FIG. 6 functions exactly the same as the ventilator circuit 300 as shown in FIG. 3.
Patent Application
20070272243
