Automated Oxygen Delivery Method

• US 20100224192A1
• Filed: 03/06/2009
• Published: 09/09/2010
• Est. Priority Date: 03/06/2009
• Status: Abandoned Application

• Current Assignee: CareFusion 207, Inc. (Becton Dickinson & Co)
• Original Assignee: Cardinal Health 200 Incorporated (Cardinal Health, Inc.)
• Inventors: Dixon, Paul, Westfall, Thomas
• Application Number:
  US12/399,360
• Publication Number:
  US 20100224192A1
• Time in Patent Office: Days
• US Class Current: 128/204.230
• CPC Class Codes: A61B 5/0205 Simultaneously evaluating both cardiovascular conditions and different types of body conditions, e.g. heart and respiratory condition
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/145 Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissuemeasuring of blood pressure or blood flow A61B5/02; non-radiation detecting or locating of foreign bodies in blood A61B5/06
• CPC Class Codes: A61B 5/14539 for measuring pH
• CPC Class Codes: A61M 16/1015 using a gas flush valve, e.g. oxygen flush valve
• CPC Class Codes: A61M 16/107 in the inspiratory path
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2016/1025 the O2 concentration
• CPC Class Codes: A61M 2202/0208 Oxygen
• CPC Class Codes: A61M 2205/3368 Temperature
• CPC Class Codes: A61M 2205/505 Touch-screens; Virtual keyboard or keypads; Virtual buttons; Soft keys; Mouse touches
• CPC Class Codes: A61M 2205/581 by audible feedback
• CPC Class Codes: A61M 2205/583 by visual feedback
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/202 partial carbon oxide pressure, e.g. partial dioxide pressure (P-CO2)
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/208 pH-value
• CPC Class Codes: A61M 2230/432 partial CO2 pressure (P-CO2)

Abstract

The present invention advantageously provides a method of automatically delivering oxygen to a patient. A desired concentration of oxygen in a bloodstream of a patient is received from a user. Data, including a measurement of the amount of oxygen in the bloodstream of the patient, as well as status information associated with the measurement, is received from a sensor. The measured data are determined to be valid or invalid based on the measurement value and the status information, and, based on this determination, a delivered fraction of inspired oxygen is delivered to the patient. If the measured data are determined to be valid, then the delivered fraction of inspired oxygen is based on the desired oxygen concentration and the measured data. On the other hand, if the measured data are determined to be invalid, then the delivered fraction of inspired oxygen is set to a predetermined value.

Claims

1. A method of automatically delivering oxygen to a patient, comprising:

receiving, from a user, a desired concentration of oxygen in a bloodstream of a patient;

receiving, from a sensor, data including a measurement of the amount of oxygen in the bloodstream of the patient and status information associated with the measurement;

determining whether the measured data are valid or invalid based on the value of the measured data and the status information;

controlling a delivered fraction of inspired oxygen, FiO₂, to the patient, including;

if the measured data are valid, controlling the FiO₂ based on the desired oxygen concentration and the measured data, and

if the measured data are not valid, setting the FiO₂ to a predetermined value; and

delivering the FiO₂ to the patient.

2. The method of claim 1, wherein the FiO₂ is not less than an FiO₂ threshold.

3. The method of claim 2, wherein the FiO₂ is increased if the measured S_PO₂ is below a lower S_PO₂ threshold, and the FiO₂ is decreased if the measured S_PO₂ is above an upper S_PO₂ threshold.

4. The method of claim 1, wherein the sensor is a pulse oximeter, and the sensor data include a saturation of peripheral oxygen measurement, S_PO₂, a perfusion index and a signal quality index.

5. The method of claim 1, wherein the sensor is a transcutaneous gas tension sensor, and the sensor data include an arterial oxygen partial pressure measurement, PtcO₂, and an arterial carbon dioxide partial pressure measurement, PtcCO₂.

6. The method of claim 1, wherein the sensor is an invasive catheter blood analyzer, and the sensor data include a dissolved oxygen in the blood measurement, pO₂, a dissolved carbon dioxide in the blood measurement, pCO₂, a blood acidity pH measurement, and a blood temperature measurement.

7. A method of automatically delivering oxygen to a patient, comprising:

receiving, from a user, a desired concentration of oxygen in a bloodstream of a patient;

receiving, from a pulse oximeter sensor, data including a measurement of the saturation of peripheral oxygen, S_PO₂, in the bloodstream of the patient, a perfusion index and a signal quality index;

determining whether the S_PO₂ is valid or invalid based on the S_PO₂ value and at least one of the perfusion index and the signal quality index;

controlling a delivered fraction of inspired oxygen, FiO₂, to the patient, including;

if the S_PO₂ is valid, categorizing the S_PO₂ within a hypoxemia range, a normoxemia range or a hyperoxemia range, and controlling the FiO₂ based on the desired oxygen concentration, the S_PO₂ and the respective range, and

if the S_PO₂ is invalid, setting the FiO₂ to a predetermined value; and

delivering the FiO₂ to the patient.

8. The method of claim 7, wherein the FiO₂ is not less than an FiO₂ threshold.

9. The method of claim 8, wherein the FiO₂ is increased if the measured S_PO₂ is below a lower S_PO₂ threshold, and the FiO₂ is decreased if the measured S_PO₂ is above an upper S_PO₂ threshold.

10. The method of claim 7, further comprising identifying measurement artifacts, including optical interference and electrical interference, wherein said determining whether the S_PO₂ is valid or invalid is based on at least one of the perfusion index, the signal quality index, and one or more of the measurement artifacts.

11. The method of claim 7, wherein the perfusion index is a fractional variation in the optical absorption of the S_PO₂ between the systole and diastole periods of an arterial pulse.

12. The method of claim 7, wherein the signal quality index provides a confidence metric for the S_PO₂.

13. The method of claim 12, wherein the signal quality index is based on variations in the optical absorption of the S_PO₂.

14. The method of claim 7, wherein hypoxemia is excessively-low blood oxygen saturation, normoxemia is a clinically-appropriate blood oxygen saturation, and hyperoxemia is excessively-high blood oxygen saturation.

15. The method of claim 7, further comprising applying a transformation to the S_PO₂ values to normalize frequency distribution, and applying one or more linear filters to the transformed S_PO₂ values.

16. The method of claim 15, wherein the transformation is an inverse transform of an oxyhemoglobin saturation curve.