INTEGRATED MULTIMODAL ASPIRATION DETECTION AND INTUBATION PLACEMENT VERIFICATION SYSTEM AND METHOD

Abstract

A method of aspiration detection and intubation placement verification for an endotracheal tube comprises: Attempting to intubate the patient with an endotracheal tube; Providing a multimodal aspiration detection and intubation placement verification system for an endotracheal tube having a housing and sensors within the housing, wherein the sensors include at least i) a sensor for a first gastric acid, and ii) a sensor for a second gastric acid different from the first gastric acid; Coupling the housing to the endotracheal tube whereby patient exhalation can flow through an internal passage of the housing, wherein the sensors within the housing come into contact with the patient exhalation; and Utilizing the sensor output for at least one of Detecting aspiration and to verification of intubation placement. The sensors include an electric chemical sensor array which can detect odor molecules at concentrations of less than 10 parts per billion in the gas phase.

Claims

1. An integrated multimodal aspiration detection system for a patient airway device comprising: a) A housing configured to be coupled to the endotracheal tube whereby patient exhalation can flow through an internal passage of the housing; b) sensors within the housing and configured to come into contact with the patient exhalation, the sensors including a chemical sensor array including at least one of i) a sensor for a first gastric acid, and ii) a sensor for a second gastric acid different from the first gastric acid.

2. The integrated multimodal aspiration detection system according to claim 1, wherein the chemical sensor array is a colorimetric chemical sensor array.

3. The integrated multimodal aspiration detection system according to claim 1, wherein one sensor senses butyric acid.

4. The integrated multimodal aspiration detection system according to claim 3, wherein one colorimetric sensor senses hydrochloric acid.

5. The integrated multimodal aspiration detection system according to claim 1, wherein the system is configured for coupling to an endotracheal tube.

6. The integrated multimodal aspiration detection system according to claim 5, wherein the system is configured intubation placement verification system.

7. The integrated multimodal aspiration detection system according to claim 1, wherein the chemical sensor array is an electronic based chemical sensor array.

8. An integrated multimodal bioelectronic based aspiration detection system for a respiratory device comprising: a) A housing configured to be coupled to the respiratory device whereby patient exhalation can flow through an internal passage of the housing; b) Bioelectric based sensors within the housing and configured to come into contact with the patient exhalation, where the bioelectric based sensors include includes an electric chemical sensor array with at least i) a sensor for a first gastric acid, and ii) a sensor for a second gastric acid different from the first gastric acid.

9. The integrated multimodal bioelectronic based aspiration detection system according to claim 8, wherein the electric chemical sensor array can detect odor molecules at concentrations of less than 10 parts per billion in the gas phase and less than 10 parts per million in liquid phase.

10. The integrated multimodal bioelectronic based aspiration detection system according to claim 8, wherein one sensor senses butyric acid.

11. The integrated multimodal bioelectronic based aspiration detection system according to claim 8, wherein one sensor senses hydrochloric acid.

12. The integrated multimodal bioelectronic based aspiration detection system according to claim 8, wherein the housing is configures to be coupled to an endotracheal tube.

13. The integrated multimodal bioelectronic based aspiration detection system according to claim 8, wherein the housing is configures to be coupled to one of a nasal cannula or a face mask.

14. The integrated multimodal bioelectronic based aspiration detection system according to claim 8, further including at least one colorimetric sensor.

15. The integrated multimodal colorimetric based aspiration detection system according to claim 14, wherein one colorimetric sensor senses butyric acid.

16. A method of aspiration detection and intubation placement verification for an endotracheal tube comprising the steps of: a) Attempting to intubate the patient with an endotracheal tube; b) Providing an integrated multimodal aspiration detection and intubation placement verification system for an endotracheal tube having a housing and sensors within the housing, wherein the sensors include at least i) a sensor for a first gastric acid, and ii) a sensor for a second gastric acid different from the first gastric acid; c) Coupling the housing to the endotracheal tube whereby patient exhalation can flow through an internal passage of the housing, wherein the sensors within the housing come into contact with the patient exhalation; and d) Utilizing the sensor output for at least one of Detecting aspiration and to verification of intubation placement.

17. The method of aspiration detection and intubation placement verification for an endotracheal tube according to claim 16, wherein the detection of patient aspiration includes the detection of butyric acid in the patient exhalation.

18. The method of aspiration detection and intubation placement verification for an endotracheal tube according to claim 17, wherein the intubation placement verification for an endotracheal tube includes the detection of HCL in the patient exhalation.

19. The method of aspiration detection and intubation placement verification for an endotracheal tube according to claim 18, wherein the sensors include an electric chemical sensor array which can detect odor molecules at concentrations of less than 10 parts per billion in the gas phase and less than 10 parts per million in liquid phase.

20. The method of aspiration detection and intubation placement verification for an endotracheal tube according to claim 18, wherein the sensors include an optical chemical sensor array.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0029] FIG. 1A is a schematic sectional view of a subject illustrating swallowing;

[0030] FIG. 1B is a schematic sectional view of a subject illustrating aspiration;

[0031] FIGS. 2 and 3 are sectional views of an integrated multimodal colorimetric based aspiration detection and intubation placement verification system for an endotracheal tube according to one embodiment of the present invention;

[0032] FIG. 4 is a perspective view of an integrated multimodal colorimetric based aspiration detection and intubation placement verification system for an endotracheal tube according to an alternative embodiment of the present invention;

[0033] FIG. 5 is a perspective view of an integrated multimodal colorimetric based aspiration detection and intubation placement verification system for an endotracheal tube according to an alternative embodiment of the present invention;

[0034] FIG. 6 is a schematic view of an integrated multimodal bioelectric based aspiration detection system for a nasal cannula according to an alternative embodiment of the present invention;

[0035] FIG. 7 is a schematic view of the integrated multimodal bioelectric based aspiration detection system of FIG. 6 implemented in a face mask according to an alternative embodiment of the present invention; and

[0036] FIG. 8 is a schematic view of the integrated multimodal bioelectric based aspiration detection and intubation placement verification system of FIG. 6 implemented in an endotracheal tube according to an alternative embodiment of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] FIGS. 2 and 3 show an integrated multimodal colorimetric based aspiration detection and intubation placement verification system 10 for an endotracheal tube including a housing 12 configured to be coupled to the endotracheal tube, such as to a bag valve mask, via inlet/outlet couplings 16. As noted above, the system 10 is referenced as integrated because the system 10 includes multiple distinct sensors 20 (which can collectively be referenced as a multimodal sensor 20) found in a single housing 12. The present system 10 of FIGS. 1-5 is disclosed in connection with endotracheal tubes but is also applicable for coupling to a variety of respiratory assist devices including in the nasal cannula and masks of ventilation systems and also in CPAP devices and Bipap devices.

[0038] The system 10 for an endotracheal tube of FIGS. 1-5 may be coupled to an endotracheal tube through a bag mask valve. A bag valve mask, abbreviated to BVM and sometimes known by the proprietary name AMBU bag or generically as a manual resuscitator or “self-inflating bag”, is a hand-held device commonly used to provide positive pressure ventilation to patients who are not breathing or not breathing adequately. The manual resuscitator device is a required part of resuscitation kits for trained professionals in out-of-hospital settings (such as ambulance crews) and is also frequently used in hospitals as part of standard equipment found on a crash cart, in emergency rooms or other critical care settings.

[0039] The housing 12 of the integrated multimodal colorimetric based aspiration detection and intubation placement verification system 10 of FIGS. 1-5 is configured whereby patient exhalation can flow through an internal passage of the housing 12 through a coupling 16 to a central chamber 14 and into contact with the sensors 20.

[0040] As shown in FIGS. 2 and 3, the inlet/outlet couplings 16 are formed as conventional fluid couplings to facilitate coupling the system 10 to an endotracheal tube or to other respiratory assist device. The inlet coupling 16 has an internal passage that leads to the central chamber 14 to which four distinct colorimetric sensors 20 are mounted within frames 18 and the outlet coupling 16 leads from the central chamber 14. The phrase “multimodal colorimetric based” within the meaning of the specification references a plurality or series of distinct color changing based sensors 20, wherein the distinct sensors are directed to measuring or detecting distinct parameters as detailed below.

[0041] The housing 12 could take many configurations. Conventional configurations include with the inlet/outlet couplings 16 aligned on opposite sides of the disc shaped central chamber 14, as shown in FIG. 5, or at a right angle or coming in the side and out the bottom as shown. It should be readily apparent that the illustrated embodiment of FIGS. 2-3 is only representative. The housing 12 itself is preferably formed of opaque material to minimize ambient light effecting the colorimetric sensors. Any color for the housing 12 is acceptable as long as the shading of the colorimetric sensors 20 is easily discernable.

[0042] Four distinct colorimetric based sensors 20 are mounted within the housing 12 within frames 18 and configured to come into contact with the patient exhalation. Colorimetric sensors or detectors are well established and are formed to indicate the presence of a target chemical through a chemical reaction that results in a color change. The distinct colorimetric sensors 20 of the system 10 of FIGS. 2-3 include a CO2 colorimetric sensor 20, an HCL colorimetric sensor 20, a butyric acid colorimetric sensor 20, and PH colorimetric sensor 20.

[0043] The colorimetric sensors 20 are formed as a substrate, generally filter paper, impregnated with an indicator that visibly changes color via a chemical reaction in the presence of a present amount of the sensed target substrate. See for example Johnson Test Paper, CBRNE Tech Index (http://www.cbrnetechindex.com/Chemical-Detection/Technology-CD/Colorimetric-CD-T), and Millipore Sigma. For the purpose of the present invention the colorimetric sensors will exhibit a color change generally in less than 2 seconds when exposed to the parameter of interest. For example, the colorimetric paper from Johnson Test paper forming the HCL sensor changes color from blue to pink in the presence of HCl, with the sensitivity of the paper specified to be 0.5 ppm.

[0044] Regarding the CO2 colorimetric sensor 20, colorimetric CO2 sensors or detectors are generally known and have been used to verify proper endotracheal (ET) tube placement and are currently one of the accepted methods of verification. See for example the NELLCOR™ adult/pediatric colorimetric CO2 detector and see generally U.S. Pat. Nos. 4,790,327; 4,928,687; 4,994,117; 5,005,572; 5,166,075; 5,179,002; 5,846,836, 5,965,061 and 6,502,573, which are incorporated herein by reference.

[0045] As discussed above, a critical step in the intubation of a patient is a determination that the breathing tube or intubation tube or endotracheal tube is placed in the trachea and not in the esophagus. If the tube is in the esophagus, there is no return of CO2 from a patient's breath. If the tube is in the trachea, CO2 will be present up to about five percent concentration. Since it is common in emergency situations for less highly skilled technicians to apply endotracheal tubes attached to a cardiopulmonary resuscitator (CPR) to a patient's airway, it is important to confirm the proper placement. The CO2 sensor 20 of system 10 communicating with an endotracheal tube of the invention serves this purpose.

[0046] The hydrochloric acid (HCL) sensor 20 is for measuring HCL concentrations of select samples of the patient exhalation. HCl is the primary acid found in the stomach. Assuming the endotracheal tube has been properly placed, as will be evidenced by the triggered CO2 sensor 20, the HCL sensor 20 activation (or trigger) is used for detecting aspiration of the patient. When the endotracheal tube is not properly placed the CO2 senser will not verify the placement, and the HCL sensor 20 will be triggered giving an active visual indication of improper placement.

[0047] A key aspect of the present invention is the provision of a butyric acid sensor 20. Butyric acid is also known under the systematic name butanoic acid and is responsible for the stench of vomit. Thus, assuming the endotracheal tube has been properly placed, as will be evidenced by activated CO2 sensor 20, the butyric acid sensor 20 is also used for detecting aspiration of the patient. When the endotracheal tube is not properly placed the CO2 senser will not verify the placement, and the butyric acid sensor 20 will be triggered giving an active visual indication of improper placement.

[0048] The HCL sensor 20 and the butyric acid sensor 20 operate on different parameters to achieve the same purpose. In practice it is expected that there will be some situations in which the HCL sensor 20 operates faster at detecting aspiration than the butyric acid sensor 20, and vice versa. The faster detection of one gastric acid over the other may have population dependent parameters, however including both within the system 10 improves response times. In addition to faster response times with two distinct gastric acid sensors 20 there is a possibility that one of the gastric acid sensor 20 sensors is not triggered in an aspiration event and having the second distinct gastric acid sensor 20 essentially eliminates (or significantly further minimizes) undetected aspirations.

[0049] The fourth sensor 20 is a PH colorimetric sensor 20 which will effectively respond to the low PH of gastric acids. The normal pH range for stomach acid is between 1.5 and 3.5. The trigger point of the PH sensor 20 may be selected within a range of intragastric PH ranges for humans. See pH dependence of acid secretion and gastrin release in normal and ulcer subjects. Walsh J H. Richardson C T, Fordtran J S J Clin invest. 1975 March; 55(3)462-8. One class of PH colorimetric sensor 20 is a graphene oxide based sensor that exhibits distinctive color response. See “Efficient Colorimetric pH Sensor Based on Responsive Polymer—Quantum Dot Integrated Graphene Oxide”, Kwanyeol Paek, Hyunseung Yang, Junhyuk Lee, Junwoo Park, and Bumjoon J. Kim A C S Nano 2014 8 (3), 2848-2856 DOI: 10.1021/nn406657b.

[0050] When using four colorimetric sensors 20 in frames 18, four 90 degree arcuate segment frames 18 as generally shown in FIGS. 2-3 is effective. Other positions and arrangements are also possible. A clear cover (not shown) can be added over the top of the sensors 20 if desired.

[0051] An alternative version of the invention is shown in FIG. 4 in which three colorimetric sensors 20 are present in the system 10. Specifically, the distinct colorimetric sensors 20 of this system 10 include an HCL colorimetric sensor 20, a butyric acid colorimetric sensor 20, and PH colorimetric sensor 20, and this system 10 design is useful where CO2 monitoring is not needed in the device. The arrangement shown in the system 10 of FIG. 3 works for any combination of three colorimetric sensors 20. For example, the distinct colorimetric sensors 20 in an alternative system 10 embodiment includes a CO2 colorimetric sensor 20, an HCL colorimetric sensor 20, and a butyric acid colorimetric sensor 20, and this could be used where PH measurements are not deemed critical. Further, the distinct colorimetric sensors 20 in an alternative system 10 embodiment includes an CO2 colorimetric sensor 20, a PH sensor 20, and one gastric acid sensor 20 namely one of an HCL colorimetric sensor 20 and a butyric acid colorimetric sensor 20, and this could be used for populations in which either the HCL colorimetric sensor 20 or a butyric acid colorimetric sensor 20 represents dominant response times.

[0052] An alternative version of the invention is shown in FIG. 5 in which the system 10 includes two colorimetric sensors 10 (shown with a transparent cover removed) are present in a slightly distinct housing 12. The housing 10 uses aligned inlet/outlet couplings 16.

[0053] Returning to the embodiment of FIGS. 2-3, consider that intubation of a patient in the emergency room is often verified only by checking for lung sounds after bagging the patient with a bag-mask apparatus. This is not a fool-proof method, and if the endotracheal tube ends up in the esophagus, pumping air into the patient's stomach can lead to additional problems. Another problem frequently associated with emergent intubations is aspiration of gastric contents. This is more common in trauma patients presenting to the emergency room, than a patient being intubated electively. Often it remains undetected until the patient presents with features of pneumonia or fibrosis. Prevention of aspiration before it occurs, or treatment as soon as it is detected is crucial.

[0054] The integrated multi-modal colorimetric sensor system 10 of the invention includes sensors 20 formed of colorimetric pH paper, colorimetric HCl paper, colorimetric butyric acid paper and colorimetric CO2 paper. The system 10 is to be attached to the bag-mask apparatus so that exhaled air comes in contact with it. Air exhaled from the lungs should contain CO2; this will cause the colorimetric CO2 paper to be triggered and to change color if the endotracheal tube is properly positioned. In addition to this, should acidic vapors be present in exhaled air from regurgitation, the pH paper, the colorimetric HCl papers and the colorimetric butyric acid paper will change color, alerting the doctors and nurses to possible aspiration.

[0055] While EtCO2 detectors already exist, this system 10 is different in that it provides an extra layer of confirmation of placement along with the ability to detect aspiration. If the tube is in the esophagus, the pH paper, the HCl paper and/or the butyric acid paper should change color.

[0056] This system 10 is connected to the AMBU bag while ventilating patients and allows instant confirmation of correct placement of the endotracheal tube while also checking if aspiration has occurred by checking gaseous content of exhaled air. The system 10 is particularly useful in trauma patients.

[0057] As detailed above the present method utilizing the invention of FIGS. 1-5 can be described as follows: a method of aspiration detection and intubation placement verification for an endotracheal tube comprising the steps of: Attempting to intubate the patient with an endotracheal tube; Providing an integrated multimodal colorimetric based aspiration detection and intubation placement verification system 10 for an endotracheal tube having a housing 12 and colorimetric based sensors 20 within the housing 12, wherein the colorimetric sensors 20 includes a CO2 sensor 20 and at least one of i) a sensor 20 for a first gastric acid, ii) a sensor 20 for a second gastric acid different from the first gastric acid, and iii) a PH sensor 20; Coupling the housing 12 to the endotracheal tube whereby patient exhalation can flow through an internal passage of the housing, wherein the colorimetric based sensors 20 within the housing 12 come into contact with the patient exhalation; and Visualizing the colorimetric based sensors 20 from the exterior of the housing 12 after they have come into contact with patient exhalation to detect aspiration and to verify intubation placement.

[0058] The phrase “patient exhalation” in this application and in this context should be viewed as broader than patient respiration, as if the endotracheal tube is in the esophagus the gas flow though the coupled device of the invention is not conventional patient respiratory exhalation due to the tube misplacement. The present invention will promptly alert the practitioners of any such erroneous placement by a combination of no response/triggering or activation from the CO2 sensor 20 (indicating misplacement) coupled with the detection of the low PH and gastric acid from the remaining sensors 20.

[0059] FIGS. 6-8 show an integrated multimodal bioelectric based aspiration detection and intubation placement verification system 10 implemented within a nasal cannula 100 in FIGS. 6, a face mask 300 in FIG. 7 and in an endotracheal tube 400 in FIG. 8. The intubation placement verification aspects of the system 10 of FIGS. 6-8 are only relevant, of course, where the patient is intubated. Like the system 10 of FIGS. 1-5 discussed above the bioelectric version includes a housing for the sensor 20 (actually a plurality of sensors as discussed below) configured to be coupled to the endotracheal tube 400, face mask 300 and/or nasal cannula 100 whereby patient exhalation can flow through an internal passage of the housing, and bioelectronic based sensors (combining to form the sensor 20) within the housing are configured to come in contact with the patient exhalation.

[0060] The bioelectronic based sensors in the housing shown in FIGS. 6-8 that combine to form the multimodal sensor 20 is a chemical sensor array, specifically an electronic based chemical sensor array. The bioelectronic based sensors use olfactory receptors—proteins, which may be cloned from biological organisms, e.g. humans, that bind to specific odor molecules in emesis (as used herein emesis means stomach contents). The reactive components of the sensors react to volatile compounds on contact, such wherein the adsorption of volatile compounds on the surface of the reactive component (sometimes called the lead) causes a physical change of the reactive component, and this almost immediate response is recorded by the electronic interface transforming the signal into a digital value. The digital value is transmitted over connection 160 to a processor 170. The connection may be a wired connection or a wireless connection like Bluetooth® or the like. The processor 70 can review the data and detect the presence of select volatile compounds in parts per billion and the processor send aspiration detection signal 80 to a display 200, which may be a tablet or smartphone. The aspiration detection signal may be selected when the detected levels reach above a minimal threshold and this threshold may be as low as a few parts per billion. Statistical modeling may be used to adjust the threshold to avoid minimize false positives while detecting aspirations.

[0061] The sensor 20 is multimodal for the system 10 of FIGS. 6-8 because the electronic based chemical sensor array will preferably detect at least two distinct chemicals of emesis, such as preferably HCL and butyric acid. A single chemical sensor detecting ONLY HCL or Butyric acid is possible, but believed to be less effective than the multimodal system 10 disclosed. The multimodal electronic based chemical sensor array for the system 10 of FIGS. 6-8 is analogous to the multimodal colorimetric (or optical) based chemical sensor array for the system 10 of FIGS. 2-5 discussed above.

[0062] The system 10 of FIGS. 6-8 above, coupled with the airway device (the nasal cannula 100 of FIG. 6, the face mask 300 of FIG. 7 and the endotracheal tube 400 of FIG. 8), can be considered to form a type of “electronic nose” as the term in known in the art. An electronic nose is an electronic sensing device intended to detect odors (or flavors). Since at least 1982, research has been conducted to develop technologies, commonly referred to as electronic noses, which could detect and recognize odors and flavors. Electronic noses traditionally include three major parts: a sample delivery system, a detection system, a computing system. Here the sample delivery system is the nasal cannula 100 of FIG. 6, the face mask 300 of FIG. 7 and the endotracheal tube 400 of FIG. 8 coupled with the attached housing of the sensor array. The detection system is the reactive components of the sensor 20, while the computing system is the processor 70 (although a display 200 is often deemed important to show results).

[0063] The integrated multimodal bioelectric based aspiration detection and intubation placement verification system 10 of FIGS. 6-8 can be easily integrated with the integrated multimodal colorimetric based aspiration detection and intubation placement verification system 10 of FIGS. 2-5 simply by incorporating the housing holding the bioelectronic based sensors of the system 10 of FIGS. 6-8 with the housing 12 of integrated multimodal colorimetric based aspiration detection and intubation placement verification system 10 of FIGS. 2-5. The merged embodiments would operate independently and yield electronic (display 200) and visual (colorimetric) indication of aspiration detection and proper intubation placement.

[0064] One aspect of this invention is directed to an integrated multimodal bioelectronic based aspiration detection and intubation placement verification system for an endotracheal tube including a housing configured to be coupled to the endotracheal tube whereby patient exhalation can flow through an internal passage of the housing, and bioelectronic based sensors within the housing and configured to come in contact with the patient exhalation, where additional colorimetric based sensors may be visible from the exterior of the housing, and wherein the bioelectronic sensors include i) a sensor for a first gastric compound, and ii) a sensor for a second gastric compound different from the first gastric compound. Utilizing the bioelectric sensors to measure trace gases of emesis (e.g. HCL and butyric acid) coupled with early detection of pre-emesis or emesis could substantially lower mortality and morbidity associated with the deleterious sequalae of aspiration/aspiration pneumonitis.

[0065] Early detection and/or prevention of aspiration of emesis or other chemical/organic compounds via bioelectronic analysis of volatile organic compounds (VOCs) including butyric acid can decrease mortality and morbidity. Detecting exhaled or passively released VOCs (including butyric acid and/or other compounds readily found in emesis) facilitates timely early interventions, such as establishing airway protection (intubation), suctioning, pharmacological intervention (opiate and/or benzodiazepine reversal), elevating the head of the bed, and/or improving the level of consciousness, etc.

[0066] As shown in FIGS. 6-8, bioelectronic analysis can be adapted to a variety of platforms, such as: endotracheal tubes, facemasks, nasal cannulas, CPAP machines, etc. The bioelectronic analyzer can be a portable unit or adapted to preexisting modules (e.g. the display can be via a downloadable app on a user's handheld device). The bioelectronic analyzer will use variations in baseline detection of products of emesis and/or precursors of aspirant and may give visual data on the display via numeric valves and/or positive indication, as well as a possible audible warning when predetermined thresholds are met. These alarm mechanisms/warnings can be transmitted via Bluetooth, Wi-fi or direct connection to a display on a hand held device or to a dedicated module with visual display. Predictive algorithms would be used from compiled data to establish patterns and protocols, followed by standardized interventions which would be initiated after positive detection of emesis or a precursor of emesis.

[0067] The effective “bioelectronic nose” of the integrated multimodal bioelectric based aspiration detection and intubation placement verification system 10 can detect odor molecules at extremely low concentrations of less than 10 parts per billion in the gas phase and less than 10 parts per million in liquid phase. The apparatus is configured to discriminate the smells of emesis, preemptively avoiding aspiration or detecting aspiration earlier in the process. In short, binding the odorants of interest to the olfactory receptors of the bioelectronic nose electronic chemical array, the odorant products of emesis are timely recognized and an audiovisual alarm may be effectively and timely triggered.

[0068] Presented above are a few versions of the bioelectronic analyzer designs and described operations. Note that the preceding descriptions are not exhaustive, and do not restrict the applicability of the approach presented here and are meant to serve as illustrations. Further embodiments of the apparatuses will become obvious after study of the apparatuses presented here by persons with experience in the art or area.

[0069] While the invention has been shown in several particular embodiments it should be clear that various modifications may be made to the present invention without departing from the spirit and scope thereof. The scope of the present invention is defined by the appended claims and equivalents thereto.