OXYGEN BIOFEEDBACK DEVICE AND METHODS

Abstract

Supplemental oxygen is used by millions of people each year in hospitals and at home. The device and methods described allow people on supplemental oxygen through a feedback loop to optimize their blood oxygen level by measuring oxygen and/or carbon dioxide and/or other related gases in the blood. Because the device and methods optimize the level of supplemental oxygen and/or carbon dioxide and/or other related gases, complications (from too much or too little oxygen and/or carbon dioxide) including death can be prevented. In addition, users can reduce their costs by reducing the amount of oxygen needed as well as labor costs. Additionally, helicopters, ambulance, and mobile surgical sites can reduce weight in critical situations. In addition, the device and methods described also allow patients on ventilators through a feedback loop to optimize ventilation by measuring carbon dioxide in the blood; which can reduce complications, and reduce labor costs. Finally, the device and methods provides a warning system when the oxygen supply is compromised, has or is exhausted.

Claims

1. An apparatus with dual sensing means for automatically controlling and conserving the delivery of oxygen to a patient comprising: an oxygen supply; means having a first non-invasive sensor to measure blood hemoglobin saturation (SpO2) of a patient and a second non-invasive sensor to measure PaCO2 of the patient; means for providing desired range of OVAP saturation for the patient; first control means adapted for identifying a first error signal representing the difference between at least one setpoint level of the range and a signal representing the measurement of the hemoglobin saturation (SpO2)); second control means adapted for identifying a first error signal representing the difference between at least one setpoint level and a signal representing the measurement of the PaCO2; means for responding to the hemoglobin saturation (SpO2) and PaCO2 setpoints to increase or decrease oxygen flow rate.

2. The apparatus of claim 1 wherein the oximeter means comprises a pulse oximeter adapted to be worn on a patients wrist, other body parts, or clothes and having a first probe from the oximeter contacting the patients skin and measure hemoglobin saturation (SpO2) and a second probe form the sensor adapted to adhere to the skin of the thenar eminence, or other appropriate body parts, to measure PaCO2.

3. The apparatus of claim 1 further comprising an alarm means adapted to indicate any default in the operation of the apparatus.

4. The apparatus of claim 1 further compromising au audio and/or visual alarm adapted to indicate loss of oxygen pressure from the oxygen source indicating either a fitting disconnection, exhaustion of the oxygen supply, near exhaustion of the oxygen supply, or inadvertent turning off of the oxygen supply.

5. A method for delivering and controlling oxygen to a patient from an oxygen supply while effectively conserving said oxygen supply, comprising the steps of: a) providing a supply of oxygen from an oxygen source; b) providing a desired range with at least one set point signal for the blood oxygen hemoglobin saturation (SpO2) of a patient; c) measuring the blood oxygen hemoglobin saturation (SpO2) in the patient and providing said measured value as an SpO2 signal; d) generating a first error signal by subtracting the setpoint signal from the measured blood hemoglobin saturation signal; e) providing a desired range with at least one set point signal for the PaCO2 of a patient; f) measuring the PaCO2 in the patient and providing said measured value as a PaCO2 signal; g) generating a second error signal by subtracting the setpoint signal from the measured blood hemoglobin saturation signal; h) generating an oxygen flow setpoint signal by combining the first error signal and the second signal; i) measuring the oxygen flow from the oxygen source and providing an oxygen flow signal; j) generating a third error signal by subtracting the oxygen flow setpoint signal from the oxygen flow signal; and k) adjusting a deliverable amount of oxygen to the patient in response to the second error signal of step.

6. The method of claim 5 wherein sensors are used to measure both the blood hemoglobin saturation (SpO2) and the PaCO2.

7. The method of claim 5 wherein the SpO2 signal and PaCO2 are provided by feed controllers wherein at least one of the controllers comprise analog or digital electrical components providing electrical input and output current signals; mechanical components providing pneumatic input and output signals; computers providing analog to digital and digital to analog converters with analog input and output lines; and artificial intelligence providing input and output signals.

8. The method of claim 5 further comprising the step of; k) indicating any default in any of the signals.

9. The apparatus of claim 1 wherein the oxygen conserver controller is a microcontroller with flash memory.

10. The apparatus of claim 1 wherein the means for detecting and using the control signal is a drive circuit coupled to a solenoid.

11. A method for weaning supplemental oxygen to a patient that effectively conserves said oxygen supply, comprising the steps of: a) providing a supply of oxygen; b) continuously measuring hemoglobin saturation (SpO2) and/or PaCO2; c) calculating a rate of supply oxygen to reduce blood hemoglobin saturation (SpO2) to 85-95 percent setpoint, or similar; and d) increase the oxygen supply rate if the blood hemoglobin saturation (SpO2) falls below the setpoint.

12. The method of claim 11 wherein the step c) the rate is calculated to achieve a hemoglobin saturation (SpO2) of 92-95 percent in thirty minutes or less. Could do 2-3% increments. Time could be 60-30 minutes; or longer.

13. The method of claim 11 wherein in step d) solenoids are used for adjusting the deliverable amount of oxygen to the patient.

14. A ventilator comprising at least one sensor for sensing OVAP and a controller with setpoints, said controller further connected to an oxygen supply controller that can increase or decrease oxygen supply and/or a controller that an increase or decrease minute ventilation.

15. The device of claim 14 wherein the controller is further connected to a pressure sensor on the oxygen supply and when a pressure in the oxygen supply drops below a predetermined value the controller will alarm.

16. An apparatus with single sensing means for automatically controlling and conserving the delivery of oxygen to a patient comprising: an oxygen supply; means having a first non-invasive sensor to measure blood hemoglobin saturation (SpO2) of a patient; means for providing desired range of OVAP saturation for the patient; first control means adapted for identifying a first error signal representing the difference between at least one setpoint level of the range and a signal representing the measurement of the hemoglobin saturation (SpO2)); means for responding to the hemoglobin saturation (SpO2) setpoints to increase or decrease oxygen flow rate.

17. An apparatus with single or multiple sensing means for automatically controlling and conserving the delivery of oxygen to a patient comprising: an oxygen supply; means having a first non-invasive sensor to measure OVAP #1 of a patient and possible second or more non-invasive sensors to measure additional OVAP #2 (where OVAP #2 represents at least 1 if not more values of OVAP beyond #1) of the patient; means for providing desired range of OVAP #1 levels for the patient; first control means adapted for identifying a first error signal representing the difference between at least one setpoint level of the range and a signal representing the measurement of the one of the OVAP #1 values; possible second or more control means adapted for identifying a first error signal representing the difference between at least one setpoint level and a signal representing the measurement of the OVAP #2 value's; means for responding to the OVAP #1 and/or OVAP #2 setpoints to increase or decrease oxygen flow rate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG. 1 shows a preferred embodiment of a person connected to a sensor on the skin of their hand or other body part, the sensor measuring STO2 and/or SpO2 and/or PCO2 (all 3 are a subset of the entire list of OVAP and are here as examples of OVAP that can be measured), the sensor connected to a controller, the controller connected to an oxygen supply and capable of adjusting the dose of supplemental oxygen to a person.

[0031] FIG. 2 shows a preferred embodiment of a person connected to a sensor in an artery or vein, the sensor measuring STO2 and/or SpO2 and/or PCO2 (all 3 are a subset of the entire list of OVAP and are here as examples of OVAP that can be measured), the sensor connected to a controller, the controller connected to an oxygen supply and capable of adjusting the dose of supplemental oxygen to a person.

DETAILED DESCRIPTION

[0032] Referring now to the drawings wherein the showings are for purposes of illustrating a preferred embodiment of the present invention and not for purposes of limiting the same. The present invention is primarily focused on non-invasive cutaneous gas sensors and methods; however, it should be understood that the sensors and methods disclosed herein could be adapted to measure and monitor blood too. Throughout the detailed description the invention discloses sensors and methods of sensing gases in tissue and blood, the most common measurement being oxygen saturation via an oximeter and often described as SpO2. There are numerous sensors that are capable of measuring other tissue and blood gas concentrations. It should be understood throughout that the present invention may utilize one or more various sensors for measuring oxygen and/or ventilation adjustment parameters (OVAP) in each embodiment and that specific examples are given for clarity and not to limit the scope of the invention unless otherwise expressly stated. It should be understood throughout that the present invention may utilize one or more various sensors for measuring oxygen and/or ventilation adjustment parameters (OVAP). OVAP include at least oxygen saturation, carbon dioxide, partial pressure of oxygen in blood, and other parameters for the fetus, child and/or adult and measured either across the skin (cutaneous), or via invasive blood sampling of venous or arterial blood or via invasive blood measuring of venous or arterial blood. FIG. 1 shows a user 1 with a sensor 2 on the user's skin, the sensor 2 further connected to a controller 3. The controller 3 has an oxygen supply 4 to be delivered to the user via face mask, nasal cannula, ventilator or similar device. FIG. 2 shows a user 11 with a sensor 12 in the user's artery or vein, the sensor 12 further connected to a controller 13. The controller 13 has an oxygen supply 14 to be delivered to the user via face mask, nasal cannula, ventilator or similar device.

[0033] 1. Feedback Sensor and Method

[0034] The present invention contemplates the use of one or more OVAP sensors to increase accuracy and detect disease states based on known blood and tissue gas parameters that fall outside the normal range. For example, StO2 can be monitored. Tissue oxygenation monitor measures tissue optical attenuation values at 680, 720, 760, and 800 nm. The light in the InSpectra StO2 Cable contains the four wavelengths of light used for the InSpectra StO2 System Measurement. The maximum depth of the tissue volume sampled is estimated to equal the distance between the sensor's send and receive fibers. Cui, Kumar, and Chance (1991) confirmed that the mean measurement depth into the tissue is half of the sensor spacing. The InSpectra StO2 Sensor 1615: 15 mm is designed to measure the proper depth of the tissue sampled in the thenar eminence. There are two light points on the face of the sensor that send and receive a signal from the patient's tissue. The comparison of the receive signal from the patient and the receive feedback signal within the oximitor is processed into a second derivative attenuation spectrum using a fixed wavelength gap point difference calculation. The resultant second derivative attenuation spectrum is sensitive to deoxyhemoglobin and oxyhemoglobin absorption. The absorption spectrum of light returned from a tissue sample varies mainly with oxyhemoglobin and deoxyhemoglobin concentration; other chromophores have less effect.

[0035] Other advanced technology is that developed by Modulate Imaging, Inc. of Irvine, Calif. They have developed non-invasive Spatial Frequency Domain Imaging technology to determine gas levels non-invasively. Harvey, S L et. al. discloses a new platinum/platinum ring-disc microelectrode for monitoring tissue perfusion is a mass transport mechanism that describes the movement of respiratory gases, nutrients and metabolites in tissue. The sensor's capability of detecting perfusion at the cellular level in a continuous fashion is unique. This sensor will provide insight into the way nutrients and metabolites are transported in tissue especially in cases were perfusion is low such as in wounds or ischemic tissue, Conf Proc IEEE Eng Med Biol Soc. 2007; 2007:2689-92. Additional sensor and techniques have been described by Nguyen J T, et al. in A novel pilot study using spatial frequency domain imaging to assess oxygenation of perforator flaps during reconstructive breast surgery, Ann Plast Surg. 2013 September; 71 (3):308-15. The results were Spatial frequency domain imaging was able to measure tissue oxyhemoglobin concentration (ctO2Hb), tissue deoxyhemoglobin concentration, and tissue oxygen saturation (stO2). Images were created for each metric to monitor flap status and the results quantified throughout the various time points of the procedure. For 2 of 3 patients, the chosen flap had a higher ctO2Hb and stO2. For 1 patient, the chosen flap had lower ctO2Hb and stO2. There were no perfusion deficits observed based on SFDI and clinical follow-up.

[0036] In a preferred embodiment, device measures SpO2 and adjusts supplemental oxygen supply upward or downward depending on a physician setting at least one set point for each OVAP used. After a physician sets the device setpoints a PID controller 3 will adjust oxygen delivery based on SpO2 to the setpoint. For example, for a patient with COPD, the physician may target the setpoint of SpO2 to 92-95% but no higher because a high SpO2 could cause injury to the lung alveoli. For example, normal PaCO2 typically ranges from 35 to 45 mm HG; a patient who has had surgery and is recovering could end up with elevated PaCO2 and decreased SpO2 if too much narcotics had been given; the controller would increase the amount of oxygen to return the SpO2 to levels set by the physician and an alarm would go off if the PaCO2 went outside of the set parameters. Another example is a COPD patient in which giving too much oxygen could lead to the CO2 climbing above 45 and then the feedback loop would decrease the oxygen until the CO2 returned to normal.

[0037] In an alternative preferred embodiment, device measures SpO2 and PaCO2 and adjusts supplemental oxygen supply upward or downward depending on a physician setting at least one set point for each OVAP used. After a physician sets the device setpoints a PID controller 3 will adjust oxygen delivery based on SpO2 to the setpoint. For example, for a patient with COPD, the physician may target the setpoint of SpO2 to 92-95% but no higher because a high SpO2 could cause injury to the lung alveoli. For example, normal PaCO2 typically ranges from 35 to 45 mm HG; a patient who has had surgery and is recovering could end up with elevated PaCO2 and decreased SpO2 if too much narcotics had been given; the controller would increase the amount of oxygen to return the SpO2 to levels set by the physician and an alarm would go off if the PaCO2 went outside of the set parameters. Another example is a COPD patient in which giving too much oxygen could lead to the CO2 climbing above 45 and then the feedback loop would decrease the oxygen until the CO2 returned to normal.

[0038] In an alternative preferred embodiment, device measures SpO2 and/or PaCO2 and/or other OVAP values and adjusts supplemental oxygen supply upward or downward depending on a physician setting at least one set point for each OVAP used. After a physician sets the device setpoints a PID controller 3 will adjust oxygen delivery based on SpO2 to the setpoint. For example, for a patient with COPD, the physician may target the setpoint of SpO2 to 92-95% but no higher because a high SpO2 could cause injury to the lung alveoli. For example, normal PaCO2 typically ranges from 35 to 45 mm HG; a patient who has had surgery and is recovering could end up with elevated PaCO2 and decreased SpO2 if too much narcotics had been given; the controller would increase the amount of oxygen to return the SpO2 to levels set by the physician and an alarm would go off if the PaCO2 went outside of the set parameters. Another example is a COPD patient in which giving too much oxygen could lead to the CO2 climbing above 45 and then the feedback loop would decrease the oxygen until the CO2 returned to normal.

[0039] 2. Weaning

[0040] In a preferred embodiment of the present invention the device would monitor a patient's SpO2 and/or PaCO2 or other OVAP sensor after an anesthetic procedure or other procedure that requires supplemental oxygen. The PID controller of the device is set by the physician to a setpoint of SpO2, for example, of between 85-95% saturation. The PID controller regulates the rate of oxygen flow from a source. The physician can, for example, make the settings different for patients with different chronic diseases to target weaning a patient form supplemental oxygen from ten to thirty minutes, although up to one hour would be acceptable for patients that have had general anesthesia. The target time will be set by a health care provider such as a physician. When the PID controller detects the rate of oxygen decrease the device can make corrections so that the patient does not under go long periods of SpO2 below 85-92%. This allows hospitals to be more efficient because nurses and doctors do not have to spot check the patient while weaning after a procedure. Additionally, the patient is safe because the device has an alarm if the SpO2 and PaCO2 are out of the specified range for too long or too far out of range that the PID controller predicts the patient needs intervention greater than the maximum supply of oxygen from the oxygen source.

[0041] 3. Mobile

[0042] In a preferred embodiment of the present invention the device is compact and ruggedized for mobile applications. For example, helicopters and ambulance have limited space and limited load capacity. The present invention uses a small PID microprocessor that is robust and can be sealed from the external environment to be water resistant and sand resistant. Because the device is small and does not weigh much, the oxygen that is saved through efficiency can reduce the size of oxygen bottles utilized in mobile applications. Additionally, the device can reduce the costs associated with having to refill oxygen bottles frequently.

[0043] 4. Sleep Apnea and Health Related Monitoring App

[0044] In a preferred embodiment of the present invention the device can be wrist worn or attachable to clothing, i.e. wearable for continuous blood monitoring. Additionally, the device could incorporate Photoplethysmogram sensors to measure pulse rate. The device would additionally have a BlueTooth or other WiFi communication means that would link with a smart device such as an Android or iPhone to monitor and record OVAP levels as well as oxygen usage. This would be very useful for remote monitoring of patients suspected of having obstructive sleep apnea. A software app loaded on the smart device would store the data and create visual data charts for easily understandable conditions. The software app loaded on the smart device may also directly transmit OVAP levels to a physician, hospital or other identified health care provider. For example the American Academy of Sleep Medicine (AASM) was assembled to produce a clinical guideline from a review of existing practice parameters and available literature. Journal of Clinical Sleep Medicine, Vol. 5, No. 3, 2009. The app would incorporate the clinically relevant apnea events and a microphone on the smart device could be used to detect snoring.

[0045] 5. IOC Anti Doping Monitor

[0046] In a preferred embodiment of the present invention the device could be used by agencies like USADA, the United States Anti-Doping Agency to create a standard of normal recovery times for oxygen saturation recovery. For example, an athlete could be placed in a hypo baric (or reduced oxygen atmosphere) chamber for ten minutes to thirty minutes and determine if the athletes response is outside the normal range of responses in order to detect artificial treatments. Also, the chamber could be introduced with normal air or hyper oxygenated or under hyperbaric conditions and the response to OVAP responses would be indicative of artificial treatments. For example, the hypo baric chamber could have a preconditioning setting between ten to thirty minutes. Then the introduction of normal air, hyperbaric air, or oxygen enriched air would be introduced into the chamber. If the athletes OVAP fell outside of the normal recovery of oxygen saturation or other OVAP metrics it would signal an artificial treatment.

[0047] 6. Ventilators

[0048] Health care providers often use elevated arterial pCO2 (PaCO2) as an indicator of incipient respiratory failure. In this regard, the determination of PaCO2 is useful in optimizing the settings on ventilators and detecting life-threatening OVAP changes in an anesthetized patient undergoing surgery. In a preferred embodiment of the present invention the device is configured for continuous monitoring of SpO2 and/or PaCO2 or other OVAP sensor. Oxygen delivered to the patient directly through the ventilator circuit would be continuously adjusted to optimize the set point or range of SpO2 and/or PaCO2 or other OVAP sensor set by the medical provider. Minute ventilation, via its subsets such as tidal volume and/or respiratory rate per minute, would be continuously adjusted to optimize the set point or range of SpO2 and/or PaCO2 or other OVAP sensor set by the medical provider. Thus, the invention can continuously regulate supplemental oxygen delivery as well as minute ventilation by constant biofeedback from OVAP. Acute maintenance.

[0049] 7. Continuous Monitoring

[0050] In a preferred embodiment of the present invention the device could continuously monitor a patient admitted to an air or ground ambulance, clinic, emergency room or acute care facility and the amount of oxygen delivered to the patient directly through the face mask, nasal cannula or similar device wound be continuously adjusted to optimize the set point or range of SpO2 and/or PaCO2 or other OVAP sensor set by the medical provider. In this case the patient may or may not be on supplemental oxygen but the data from the continuous monitoring could be stored on flash memory in the device and available for real-time transmission to a facility server for alarm monitoring. Alternatively, the stored data could be download and charted just prior to a patient's examination with a physician, nurse or other health care provider.

[0051] 8. Fail-Safe Mechanism

[0052] In all of the above disclosed embodiments the controller would have a fail-safe mechanism for detecting failure (either exhaustion of the oxygen supply or a disconnection of the fittings) of supplemental oxygen delivery. The controller default position in the fail-safe mode would be to open up oxygen from the source and alarm. The alarm would be audible and/or visual. The alarm would be at the site of the device use as well as remote alarm via communication technology such as WiFi and BlueTooth. An additional safety feature is the ability to test oxygen delivery in line from the oxygen source on route to the patient and alarm if the oxygen source were depleted or close to being depleted, for example if there was a pressure drop in a pressure regulator at the oxygen source that would trigger an alert that the oxygen supply was getting low.

[0053] 9. Energy Supply, Recording and Data Sharing

[0054] It should be understood from the context that the above embodiments could be powered by hardwire, disposable battery, rechargeable battery, USB compatible for rechargeable battery. Additionally, the embodiments could incorporate various memory for recording data and either sharing in real time or saved on an SD memory card for later transmission.

[0055] Additional modifications and improvements of the present invention may also be apparent to those skilled in the art. Thus, the particular combination of parts described and illustrated herein in intended to represent only one embodiment of the invention, and is not intended to serve as limitations of alternative devices within the spirit and scope of the invention.