System and method for automatically maintaining a blood oxygen saturation level

• US 5,682,877 A
• Filed: 04/15/1994
• Issued: 11/04/1997
• Est. Priority Date: 12/30/1991
• Status: Expired due to Fees

• Current Assignee: Adolph J. Mondry
• Original Assignee: Adolph J. Mondry
• Inventors: Mondry, Adolph J.
• Primary Examiner(s): Asher, Kimberly L.
• Application Number:
  US08/228,092
• Time in Patent Office: 1,299 Days
• Field of Search: 128/204.18, 128/204.21, 128/204.23, 128/204.26, 128/205.24, 128/205.23, 128/716-719, 128/632
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/0627 with sealing means on a part of the body other than the face, e.g. helmets, hoods or domes
• CPC Class Codes: A61M 16/0672 Nasal cannula assemblies for oxygen therapy
• CPC Class Codes: A61M 16/10 Preparation of respiratory gases or vapours
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 2016/1025 the O2 concentration
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/205 partial oxygen pressure (P-O2)
• CPC Class Codes: A61M 2230/435 partial O2 pressure (P-O2)

Abstract

A system and method for automatically selecting an appropriate oxygen dose to maintain a desired blood oxygen saturation level is disclosed. The system and method are particularly suited for use with ambulatory patients having chronic obstructive lung disease or other patients requiring oxygenation or ventilation. In one embodiment, the method includes delivering a first oxygen dose to the patient while repeatedly sequencing through available sequential oxygen doses at predetermined time intervals until the current blood oxygen saturation level of the patient attains the desired blood oxygen saturation level. The method then continues with delivering the selected oxygen dose to the patient so as to maintain the desired blood oxygen saturation level.

Claims

1. A method for maintaining a desired blood oxygen saturation level within a first predetermined range of values having an upper limit and a lower limit so as to reduce variation of the blood oxygen saturation level, the method being adapted for use with an oxydosimeter including an electronic control unit (ECU) having memory, a pulse oximeter attached to a patient for measuring a current blood oxygen saturation level of the patient, and an oxygen delivery system controlled by the ECU for delivering a selected oxygen dose to the patient, the oxygen delivery system having a plurality of sequential oxygen doses ranging from a first oxygen dose to a second oxygen dose, the method comprising:

delivering the second oxygen dose to the patient while repeatedly sequencing through the plurality of sequential oxygen doses beginning with the first oxygen dose and proceeding to an adjacent oxygen dose in the sequence after a predetermined time interval has elapsed until the current blood oxygen saturation level of the patient attains the desired blood oxygen saturation level at which point a corresponding oxygen dose is selected from the plurality of sequential oxygen doses;

delivering the selected oxygen dose to the patient so as to maintain the desired blood oxygen saturation level; and

energizing an alarm when a predetermined number of oscillations between any two nonadjacent oxygen doses is detected.

2. The method of claim 1 wherein the current blood oxygen saturation level is determined by:

storing a sequence of blood oxygen saturation values in the memory, the sequence containing at least three measurement values obtained from the pulse oximeter;

determining the median value of the at least three measurements; and

calculating a mean value using the sequence values which are within a predetermined range of the median value, the predetermined range depending upon characteristics of the oxydosimeter, the mean value representing the current blood oxygen saturation level.

3. The method of claim 1 wherein the current blood oxygen saturation level is determined by:

storing a sequence of blood oxygen saturation values in the memory, the sequence containing at least three measurement values obtained from the pulse oximeter;

determining the median value of the at least three measurement values; and

selecting the most recently stored value, which is within a predetermined range of the median value, from the sequence of values, the predetermined range depending upon characteristics of the oxydosimeter, the most recently stored value representing the current blood oxygen saturation level.

4. The method of claim 1 wherein the plurality of sequential oxygen doses comprises a plurality of discrete oxygen flow rates.

5. The method of claim 1 wherein the plurality of sequential oxygen doses comprises a plurality of discrete oxygen concentrations.

6. A system for maintaining a desired blood oxygen saturation level within a first predetermined range of values having an upper limit and a lower limit so as to reduce variation of the blood oxygen saturation level, the system including an electronic control unit (ECU) having memory, a pulse oximeter attached to a patient for measuring a current blood oxygen saturation level of the patient, and oxygen delivery apparatus controlled by the ECU for delivering a selected oxygen dose to the patient, the oxygen delivery apparatus having a plurality of sequential oxygen doses ranging from a first oxygen dose to a second oxygen dose, the system comprising:

means for delivering the second oxygen dose to the patient while repeatedly sequencing through the plurality of sequential oxygen doses beginning with the first oxygen dose and proceeding to an adjacent oxygen dose in the sequence after a predetermined time interval has elapsed until the current blood oxygen saturation level of the patient attains the desired blood oxygen saturation level at which point a corresponding oxygen dose is selected from the plurality of sequential oxygen doses;

means for delivering the selected oxygen dose to the patient so as to maintain the desired blood oxygen saturation level; and

an alarm for indicating when a predetermined number of oscillations between any two nonadjacent oxygen doses is detected.

7. The system of claim 6 wherein the current blood oxygen saturation level is determined by:

means for storing a sequence of blood oxygen saturation values in the memory, the sequence containing at least three measurement values obtained from the pulse oximeter;

means for determining the median value of the at least three measurements; and

means for calculating a mean value using the sequence values which are within a predetermined range of the median value, the predetermined range depending upon characteristics of the oxydosimeter, the mean value representing the current blood oxygen saturation level.

8. The system of claim 6 wherein the current blood oxygen saturation level is determined by:

means for storing a sequence of blood oxygen saturation values in the memory, the sequence containing at least three measurement values obtained from the pulse oximeter;

means for determining the median value of the at least three measurement values; and

means for selecting the most recently stored value, which is within a predetermined range of the median value, from the sequence of values, the predetermined range depending upon characteristics of the oxydosimeter, the most recently stored value representing the current blood oxygen saturation level.

9. The system of claim 6 wherein the plurality of sequential oxygen doses comprises a plurality of discrete oxygen flow rates.

10. The system of claim 6 wherein the plurality of sequential oxygen doses comprises a plurality of discrete oxygen concentrations.

11. A method for maintaining a desired blood oxygen saturation level within a first predetermined range of values having an upper limit and a lower limit so as to reduce variation of the blood oxygen saturation level, the method being adapted for use with an oxydosimeter including an electronic control unit (ECU) having memory, a pulse oximeter attached to a patient for measuring a current blood oxygen saturation level of the patient, and an oxygen delivery system controlled by the ECU for delivering a selected oxygen dose to the patient, the oxygen delivery system having a plurality of sequential oxygen doses ranging from a first oxygen dose to a second oxygen dose, the method comprising:

delivering the second oxygen dose to the patient while sequencing through the plurality of sequential oxygen doses beginning with the first oxygen dose and proceeding to an adjacent oxygen dose in the sequence after a predetermined time interval has elapsed until the current blood oxygen saturation level of the patient attains the desired blood oxygen saturation level, at which point a corresponding oxygen dose is selected from the plurality of sequential oxygen doses; and

delivering the selected oxygen dose to the patient so as to maintain the desired blood oxygen saturation level, wherein the predetermined time interval is based on circulation time of the patient, the predetermined time interval being adjusted when a predetermined number of oscillations between any two nonadjacent oxygen doses is detected.

12. The method of claim 11 wherein the predetermined time interval is adjusted by about one second.