Self-contained micromechanical ventilator

[0001] Immediate medical care can save the lives of countless accident victims and military personnel. In the emergency medical services arena, there has long been an emphasis on the golden hour during which a patient must receive definitive medical attention. However, definitive medical attention is often limited, because of the lack of necessary equipment. While state of the art medical equipment can be found in medical facilities, such is not the case in emergency situations or military applications. This is particularly true in the area of ventilators.

[0002] Inspiration-only ventilators are known and widely used in hospital settings as they provide useful breathing circuits while minimizing the amount of oxygen utilized in treating the patient.

[0003] Current ventilators are generally designed for stationary, medical facilities. They are heavy, cumbersome and ill suited for portable applications. Most ventilators utilize medical grade air or highly flammable, compressed canisters of oxygen for its oxygen sources. These tanks air/oxygen are heavy, cumbersome, and unsuitable for transport. Prior-art ventilators also require large power sources, making them even less suitable for quick, on-site use. Lastly, most known ventilators require operation by trained personnel in treatment environments, where additional equipment and resources are easily available.

[0004] For example, U.S. Pat. No. 5,664,563 to Schroeder et al disclose a computer controlled pneumatic ventilator system that includes a double venturi drive and a disposable breathing circuit. The double venturi drive provides quicker completion of the exhalation phase leading to an overall improved breathing circuit. The disposable breathing circuit allows the ventilator to be utilized by multiple patients without risk of contamination. This device utilizes canistered oxygen sources. This device also would be rendered inoperable under the conditions anticipated by the present invention.

[0005] Therefore, there is a need for portable ventilators that overcome the disadvantages of the existing stationary ventilators.

[0006] The following portable ventilators address some of the needs discussed above. U.S. Pat. Nos. 6,152,135, 5,881,722 and 5,868,133 to DeVries et al. discloses a portable ventilator device that utilizes ambient air through a filter and a compressor system. The compressor operates continuously to provide air only during inspiration. The DeVries et al devices are utilized in hospital settings and are intended to provide a patient with mobility when using the ventilator. Since these devices are not directed to on-site emergency use, they provide closed loop control, sophisticated valving systems and circuitry that would render them inoperable under the types of emergency conditions anticipated by the present invention.

[0007] The references cited above recognize the need for portable ventilators that provide a consistent breathing circuit. As is the case with most portable ventilators, these devices provide breathing circuits including valve systems and an oxygen source. However, these devices lack the means by which they can be quickly facilitated in emergency situations where there are no stationary sources of power. Secondly, most of these devices depend on canister-style oxygen sources, which are cumbersome, and lessen the ability of the ventilators to be truly portable. Thirdly, the prior art ventilators do not provide breathing circuits that can be continuously used in the absence of stationary power sources. These and other drawbacks are overcome by the present invention as will be discussed, below.

[0008] It is therefore an objective of this invention to provide a portable ventilator that provides short-term ventilatory support.

[0009] It is another objective of the present invention to provide a portable ventilator that includes a pneumatic subsystem, a power subsystem and a sensor subsystem.

[0010] It is another objective of the present invention to provide a portable ventilator wherein the pneumatic subsystem includes two dual head compressor for increased air output.

[0011] It is another objective of the present invention to provide a portable ventilator wherein the pneumatic subsystem includes an accumulator.

[0012] It is another objective of the present invention to provide a portable ventilator that is a disposable one-use device having an indefinite shelf life.

[0013] These and other objectives have been described in the detailed description provided below.

[0019] The present invention is a portable ventilator that provides short-term ventilatory support to one or more patients for the management of trauma or respiratory paralysis. As shown in FIG. 1, the portable ventilator V assures consistent tidal volume and respiratory rate and provides hands free operational capabilities. The portable ventilator V is a fully functional multi-mode device suited for field hospital or forward surgical units, where experienced personnel can utilize the multi-mode capabilities unique to this device. Portable ventilator V is also suitable for use by untrained personnel, and in particularly useful in resource-limited environments. Additionally, the portable ventilator V can be configured as a disposable one-use device that has an indefinite shelf life.

[0020] Also in FIG. 1, the portable ventilator V of the present invention includes a pneumatic subsystem N, a power subsystem P, and a sensor subsystem S. Each of these systems shall be described below.

The Pneumatic Subsystem:

[0021] As shown in FIG. 2, the pneumatic subsystem N includes two dual head air compressors 1a and 1b for increased air output. Ambient or NVC filtered air is drawn into the dual head compressors 1a and 1b and compressed. The compressed air exits 1a and 1b and enters into the accumulator tank 2. An accumulator tank 2 is connected to each of the compressors 1a and 1b to act as a pneumatic holding area for the combined outputs (4 in total) of compressors 1a and 1b. The accumulator tank 2 overcomes the inconsistent nature of the phasing of the pressure waves inherent with dual head air compressors and prevents compressors 1a and 1b outputs from canceling each other. The accumulator tank 2 is further connected to a connector system 3. Since the compressors 1a and 1b function as constant-flow rates over a wide range of physiologic pressures, the connector system 3 provides constant, total airflow through the accumulator 2 to the user, for a necessary period of time. The periods of time are controlled through a timing circuit T that is part of a logic board B.

The Logic Board:

[0022] The logic board B includes timing circuit T and is connected to the power subsystem P. Logic board B controls power to compressors 1a and 1b in order to turn 1a and 1b on and off. Duration of the on-time of compressors 1a and 1b determines the amount of air that is delivered to the user. The logic board B utilizes analog logic and does not require microprocessor control. The logic board B is also connected to the sensor subsystem S.

The Sensor Subsystem:

[0023] As shown in FIG. 3, the portable ventilator V includes a sensor subsystem S that provides critical care monitoring and support critically ill patients in the emergency situations. The sensor subsystem S includes an airflow sensor 4 that detects loss of connection of the portable ventilator V from the patient's face mask or endotracheal tube. The sensor subsystem S also includes an airway pressure sensor 5. The pressure sensor 5 provides the desirable function of detecting the end of a previous breath (inhaled) in the user, so that air delivery can be delayed until the completion of the previous breath. An airflow sensor 6 is used to detect the cessation of exhalation of the previous breath if the scheduled start time for the next breath is not completed. The sensor subsystem S may be located within the ventilator V or be exterior to ventilator V.

The Power Subsystem:

[0024] As shown in FIG. 4, the power subsystem P of the portable ventilator V include disposable or rechargeable batteries 7 that are capable of operating under high capacity, wide temperature ranges and are compatible with the pneumatic subsystem N and the sensor subsystem S. In a preferred embodiment, the portable ventilator V of the present invention utilizes conventional lead-acid rechargeable batteries 7. The batteries 7 must provide at least 30 to 60 minutes of operating time.

The Portable Ventilator:

[0025] As shown in FIG. 5, the pneumatic subsystem N is connected to the sensor subsystem S and the power subsystem P and enclosed within housing 8 of the portable ventilator V. Housing 8 includes an rigid frame structure 8a that is made of either plastic or metals and capable of withstanding physical and mechanical pressures. Portable ventilator V includes an input port 8b which allows rechargeable batteries 7 to be powered using an external power source or an AC power source. Alternatively, batteries 7 may include disposable type batteries.

[0026] Housing 8 also a recessed control panel 8c. Control panel 8c includes ports for providing air to the user through known means. The panel 8c also includes a switch for selecting desired air flow rates, an on/off switch and can include a switch for recharging the batteries 7. The control panel 8c is recessed to prevent damage to any instrumentation positioned thereon.

[0027] The portable ventilator V of the present invention implements controlled ventilation and assists control ventilation to a patient. Example 1 below shows functionality and performance of two portable ventilators V described above.

[0028] The Sekos 2 and 3 ventilators were tested. All tidal volumes, respiratory rates and other parameters were within Ý10% of the settings existing on the ventilator V.

[0029]

PERFORMANCE
PARAMETER	SEKOS 2	SEKOS 3
APPROX. WEIGHT	12	<6
(lb0
APPROX. SIZE (in.)	10.75W × 9 75D × 7 H	5.7W × 11 5D × 3 5H
PHYSICAL	733	230
VOLUME
(in3)
BATTERY	3.4 Ah lead acid	1.3 Ah lead acid
TYPE/SIZE
OPERATING LIFE	1.5–3	0.3–1
(h)
COMPRESSORS	2	2
CONTROLLABLE	No	No
I:E RATIO
RESP. RATE	6–30	10 OR 20 ONLY
ADJUSTMENT (bpm)
TIDAL VOLUME	200–1200	300, 900, OR 1200
(ml)
MAX MINUTE	20 (NOT YET TESTED)	20 (NOT YET
VOLUME (L/m)		TESTED)
INSPIRATORY	No	No
FLOW
MEASUREMENT
EXPIRATORY	Yes	Yes
FLOW
MEASUREMENT

[0030] The portable ventilators tested above, have been shown to be superior in performance to traditional ambu-bags. These and other portable ventilators having the features discussed above are within the scope of this invention.