Oxygen mixing and delivery
An adaptive gas mixture controller system. A pulse oximeter interface receives pulse oximeter data. A gas blender interface communicates with a separate externally connected gas blender. A processor receives pulse oximeter data via the pulse oximeter interface and outputs data to the gas blender interface for adaptive feedback control of the gas mixture based upon the SpO 2 level signals from the pulse oximeter interface. When the processor receives data from the gas blender indicating that the gas mixture has been manually changed, enters a manual override mode and halts sending adaptive feedback control signals to the gas blender. This abstract is not to be considered limiting, since other embodiments may deviate from the features described in this abstract.
1 . A system for delivery of a breathing gas mixture to a patient, the system comprising:
a first input for connection with an oxygen source, the first input including a valve controlling the first input, the first input configured to receive an oxygen flow from the oxygen source at a first flow rate;
a second input for connection with a compressed air source, the second input configured to receive an air flow from the compressed air source at a second flow rate;
a blender to form, from the oxygen flow and the air flow, the breathing gas mixture at a third flow rate;
a humidifier for humidifying the breathing gas mixture, the humidifier configured to provide a water consumption rate of the humidifier;
a nasal cannula in fluid communication with the humidifier and configured to deliver the humidified breathing gas mixture to the patient;
a heated wire for heating the breathing gas mixture disposed upstream of the nasal cannula;
a pulse oximeter interface configured to receive signals from a pulse oximeter indicative of a first blood oxygen level of the patient;
a controller coupled to the valve and the pulse oximeter interface and having a memory;
wherein the controller is configured to:
receive, from the humidifier, a water consumption rate of the humidifier;
determine a current humidification level based on the third flow rate and the water consumption rate;
receive, from the pulse oximeter interface, the signals from the pulse oximeter indicative of the first blood oxygen level of the patient;
compare the signals indicative of the first blood oxygen level of the patient to a target blood oxygen level;
determine a first adjustment to be made to the first input;
actuate the valve to adjust the first input based on the first adjustment; and
receive new signals from the pulse oximeter interface indicative of a new blood oxygen level of the patient.
2 . The system of claim 1 , further comprising a delivery tube configured to convey a heated and humidified breathing gas mixture to the nasal cannula.
3 . The system of claim 1 , wherein the heated wire is disposed upstream of the humidifier.
4 . The system of claim 1 , wherein the humidifier comprises a water reservoir and a vaporization mechanism.
5 . The system of claim 4 , wherein the controller is coupled to the humidifier and configured to adjust a humidification level of the humidifier.
6 . The system of claim 1 , wherein the signals received at the pulse oximeter interface from the pulse oximeter include an SpO2 level of the patient.
7 . The system of claim 6 , wherein the signals received at the pulse oximeter interface from the pulse oximeter include a pulse rate of the patient.
8 . The system of claim 6 , wherein the memory stores a lookup table relating SpO2 levels to PaO2 levels, and the lookup table is derived from a sigmoid shaped oxyhemoglobin dissociation curve.
9 . The system of claim 8 , wherein the controller comprises a proportional integral derivative (PID) controller configured to track the sigmoid shaped oxyhemoglobin dissociation curve.
10 . The system of claim 9 , wherein the controller is further configured to:
convert an SpO2 level of the patient to a PaO2 level for calculation of an appropriate gas mixture.
11 . The system of claim 1 , wherein the valve is external to the system.
12 . The system of claim 1 , wherein the compressed air source is external to the system.
13 . The system of claim 1 , wherein first adjustment of the first input by the controller is configured to achieve a change in an oxygen percentage of the breathing gas mixture.
14 . The system of claim 13 , wherein the controller is configured to:
compare the new signals from the pulse oximeter indicative of the new blood oxygen level to the target blood oxygen level,
determine a second adjustment to be made to input of oxygen, and
actuate the valve to further adjust the input of oxygen to the patient based on the second adjustment.