Control of respiratory oxygen delivery

Abstract

Methods and systems for supplying respiratory oxygen to users when the users are inhaling are disclosed. The methods and systems may rely on delivery devices that are selectively placed in fluid communication with either a respiration sensor or a source of oxygen. The methods and systems may actively monitor for exhalations, as well as monitor for oxygen in the oxygen source. The respiration sensor may preferably be a flow sensor.

1 . A method of controlling oxygen delivery comprising: 
 continuously measuring blood oxygen content of a patient to obtain a measured blood oxygen content level;    delivering oxygen from an oxygen source to the patient if the measured blood oxygen content level is below a desired value;    restricting the delivery of oxygen to the patient if the measured blood oxygen content level of the patient is above the desired value;    determining if the measured blood oxygen content level is invalid; and    delivering a default amount of oxygen to the patient if the measured blood oxygen content level is invalid.    
   
   
       2 . A method according to  claim 1 , wherein the oxygen is delivered through a nasal cannula.  
   
   
       3 . A method according to  claim 1 , further comprising determining when the patient is inhaling.  
   
   
       4 . A method according to  claim 1 , further comprising providing an alarm if the measured blood oxygen content level is invalid.  
   
   
       5 . A method according to  claim 1 , further comprising providing an alarm if the patient experiences hypoxemia.  
   
   
       6 . A method of controlling oxygen delivery comprising: 
 continuously measuring blood oxygen content of a patient to obtain a measured blood oxygen content level;    delivering a variable dose of oxygen from an oxygen source to the patient, wherein the variable dose is at least partially determined based on the measured blood oxygen content level;    determining if the measured blood oxygen content level is invalid; and    delivering a default amount of oxygen to the patient if the measured blood oxygen content level is invalid.    
   
   
       7 . A method according to  claim 6 , wherein the variable dose of oxygen is at least partially based on a trend in measured blood oxygen content as measured at different times.  
   
   
       8 . A method according to  claim 6 , wherein the variable dose of oxygen is at least partially based on a difference between a desired value for the measured blood oxygen content and the measured blood oxygen content, and wherein the method further comprises changing the desired value for the measured blood oxygen content level.  
   
   
       9 . A method according to  claim 8 , wherein changing the desired value for the measured blood oxygen content level comprises monitoring the patient's heart rate and changing the desired value for the measured blood oxygen content level in response to change in the patient's heart rate.  
   
   
       10 . A method according to  claim 6 , wherein the variable dose includes a zero dose.  
   
   
       11 . A method according to  claim 6 , wherein the oxygen is delivered through a nasal cannula.  
   
   
       12 . A method according to  claim 6 , further comprising determining when the patient is inhaling.  
   
   
       13 . A method according to  claim 6 , further comprising providing an alarm if the measured blood oxygen content level is invalid.  
   
   
       14 . A method according to  claim 6 , further comprising providing an alarm if the patient experiences hypoxemia.  
   
   
       15 . A method of controlling oxygen delivery comprising: 
 continuously measuring blood oxygen content of a patient to obtain a measured blood oxygen content level;    delivering a variable dose of oxygen from an oxygen source to the patient, wherein the variable dose is at least partially determined based on the measured blood oxygen content level;    determining if the measured blood oxygen content level is invalid; and    replacing the invalid measured blood oxygen content level with a value based on a recent trend in blood oxygen content level.    
   
   
       16 . A method according to  claim 15 , wherein the variable dose of oxygen is at least partially based on a trend in measured blood oxygen content as measured at different times.  
   
   
       17 . A method according to  claim 15 , wherein the variable dose of oxygen is at least partially based on a difference between a desired value for the measured blood oxygen content and the measured blood oxygen content, and wherein the method further comprises changing the desired value for the measured blood oxygen content level.  
   
   
       18 . A method according to  claim 17 , wherein changing the desired value for the measured blood oxygen content level comprises monitoring the patient's heart rate and changing the desired value for the measured blood oxygen content level in response to change in the patient's heart rate.  
   
   
       19 . A method according to  claim 15 , wherein the variable dose includes a zero dose.  
   
   
       20 . A method according to  claim 15 , wherein the oxygen is delivered through a nasal cannula.  
   
   
       21 . A method according to  claim 15 , further comprising determining when the patient is inhaling.  
   
   
       22 . A method according to  claim 15 , further comprising providing an alarm if the measured blood oxygen content level is invalid.  
   
   
       23 . A method according to  claim 15 , further comprising providing an alarm if the patient experiences hypoxemia.  
   
   
       24 . A system for delivering respiratory oxygen to a patient, the system comprising: 
 a blood oxygen content level sensor;    a oxygen source;    a valve in fluid communication with the oxygen source;    a controller capable of operating the valve, the controller restricting oxygen flow through the valve when the blood oxygen content level measured by the blood oxygen content level sensor is above a desired value; and    means for determining when the blood oxygen content level measured by the blood oxygen content level sensor is invalid, wherein the controller operates the valve to deliver a default amount of oxygen to the patient when the measured blood oxygen content is invalid.    
   
   
       25 . A system according to  claim 24 , further comprising means for determining when the blood oxygen content level measured by the blood oxygen content level sensor is valid after being invalid, wherein the controller operates the valve to restrict oxygen flow through the valve when the blood oxygen content level measured by the blood oxygen content level sensor is above a desired value.  
   
   
       26 . A system according to  claim 24 , wherein the controller variably restricts oxygen flow through the valve to deliver a variable dose of oxygen from the oxygen source to the patient, wherein the variable dose of oxygen is at least partially determined based on the measured blood oxygen content.  
   
   
       27 . A system according to  claim 24 , wherein the controller determines the variable dose of oxygen at least partially based on a difference between a desired value for the measured blood oxygen content level and the measured blood oxygen content level.  
   
   
       28 . A system according to  claim 24 , wherein the controller determines the variable dose of oxygen at least partially based on a trend in measured blood oxygen content level as measured at different times.