System for control of a blood gas exchanger
A demand-adapting and auto-regulatory ECMO system and method is disclosed that may be configured to provide complete cardiopulmonary replacement. The system and method employ a blood gas exchanger having a blood inlet, a blood outlet, a gas inlet, and a gas outlet, an oxygen sensor positioned to detect oxyhemoglobin saturation at the blood inlet, and a carbon dioxide sensor positioned to detect exhaust gas CO2 concentration at the gas outlet. A controller communicates with the oxygen sensor and the carbon dioxide sensor and controls blood flow and gas flow through the blood gas exchanger in response to a sensed oxygen level by the oxygen sensor and a sensed carbon dioxide level by the carbon dioxide sensor, in turn maintaining the sensed oxygen level and the sensed carbon dioxide level within a pre-designated range of values to maintain a patient's metabolic requirements.
1 . An auto-regulatory system for the control of a blood gas exchanger comprising:
a blood gas exchanger having a blood inlet, a blood outlet, a gas inlet, and a gas outlet;
an oxygen sensor positioned to detect oxyhemoglobin saturation at said blood inlet;
a carbon dioxide sensor positioned to detect exhaust gas CO2 concentration at said gas outlet;
a fluid pump in fluid communication with said blood gas exchanger;
a gas delivery system in fluid communication with said blood gas exchanger; and
a controller comprising a microcontroller and memory storage having computer-executable instructions stored thereon, wherein when executed by the microcontroller, the computer-executable instructions cause the controller to:
receive real-time data from the oxygen sensor and the carbon dioxide sensor;
process the received real-time data by using a fuzzy logic control algorithm (FLCA) that (i) reads oxygenator inlet oxyhemoglobin saturation and oxygenator exhaust gas CO2 concentration to determine errors from set-point values and a first derivative of the errors with respect to time, (ii) converts the errors and first derivatives into fuzzy inputs through fuzzification, and (iii) applies membership function evaluation and defuzzification to determine adjustments for maintaining the sensed oxygen and carbon dioxide levels within target ranges to determine optimal adjustment parameters for maintaining physiologic parameters within target ranges; and
dynamically adjust the fluid pump speed and the gas flow rate based on the processed real-time data to maintain the sensed oxygen and carbon dioxide levels within pre-designated target ranges that are adjustable based on a patient's instantaneous metabolic demands.
2 . The system of claim 1 , wherein said computer-executable instructions are further configured to analyze the real-time data to determine an optimal blood:gas ratio and adjust at least one of carbon dioxide flow and blood flow to maintain the optimal blood:gas ratio within the determined optimal target range.
3 . The system of claim 1 , said gas delivery system further comprising a valve, a motor operatively engaging the valve, and a gas flowmeter.
4 . The system of claim 3 , wherein said computer-executable instructions are configured to analyze said sensed oxygen level and said sensed carbon dioxide level to determine optimal valve positioning parameters and adjust operation of said motor to modify a position of said valve based on the determined optimal valve positioning parameters.
5 . The system of claim 1 , further comprising a blood flow regulator having a motor driver in electrical communication with said fluid pump, and a blood flow sensor positioned to measure blood flow within a drainage cannula from a patient.
6 . The system of claim 5 , wherein said computer-executable instructions are configured to analyze at least one of said sensed oxygen level, said sensed carbon dioxide level, and a sensed blood flow level by said blood flow sensor to determine optimal pump operation parameters and adjust operation of said fluid pump through said motor driver based on the determined optimal pump operation parameters.
7 . The system of claim 1 , further comprising an exhaust gas system comprising said carbon dioxide sensor, an air pump, and a dehumidification system.
8 . The system of claim 7 , wherein said computer-executable instructions are configured to analyze said sensed carbon dioxide level to determine optimal exhaust system operation parameters and adjust operation of at least one of said gas delivery system and said fluid pump based on the determined optimal exhaust system operation parameters.
9 . An auto-regulatory system for the control of a blood gas exchanger comprising:
a blood gas exchanger having a blood inlet, a blood outlet, a gas inlet, and a gas outlet;
an oxygen sensor positioned to detect oxyhemoglobin saturation at said blood inlet;
a carbon dioxide sensor positioned to detect exhaust gas CO2 concentration at said gas outlet; and
a controller comprising a microcontroller and memory storage having computer-executable instructions stored thereon, wherein when executed by the microcontroller, the computer-executable instructions cause the controller to:
receive real-time data from the oxygen sensor and the carbon dioxide sensor;
process the received real-time data by analyzing the real time data to determine using a fuzzy logic control algorithm (FLCA) that (i) reads oxygenator inlet oxyhemoglobin saturation and oxygenator exhaust gas CO2 concentration to determine errors from set-point values and a first derivative of the errors with respect to time, (ii) converts the errors and first derivatives into fuzzy inputs through fuzzification, and (iii) applies membership function evaluation and defuzzification to determine adjustments for maintaining the sensed oxygen and carbon dioxide levels within target ranges to determine optimal adjustment parameters for maintaining physiologic parameters within target ranges; and
dynamically adjust blood flow and gas flow through the blood gas exchanger based on the processed real-time data to maintain said sensed oxygen and carbon dioxide levels within pre-designated target ranges that are adjustable based on a patient's instantaneous metabolic demands.
10 . The system of claim 9 , wherein said computer executable instructions are further configured to analyze the real-time data to determine an optimal blood:gas ratio and adjust at least one of carbon dioxide flow and blood flow to maintain the optimal blood:gas ratio within the determined optimal target range.
11 . The system of claim 9 , further comprising a gas delivery system having a valve, a motor operatively engaging the valve, and a gas flowmeter.
12 . The system of claim 11 , wherein said computer executable instructions are configured to analyze said sensed oxygen level and said sensed carbon dioxide level to determine optimal valve positioning parameters and adjust operation of said motor to modify a position of said valve based on the determined optimal valve positioning parameters.
13 . The system of claim 9 , further comprising:
a fluid pump; and
a blood flow regulator having a motor driver in electrical communication with said fluid pump, and a blood flow sensor positioned to measure blood flow within a drainage cannula from a patient.
14 . The system of claim 13 , wherein said computer-executable instructions are configured to analyze at least one of said sensed oxygen level, said sensed carbon dioxide level, and a sensed blood flow level by said blood flow sensor to determine optimal pump operation parameters and adjust operation of said fluid pump through said motor driver based on the determined optimal pump operation parameters.
15 . The system of claim 9 , further comprising an exhaust gas system comprising said carbon dioxide sensor, an air pump, and a dehumidification system.
16 . The system of claim 15 , wherein said computer-executable instructions are configured to analyze said sensed carbon dioxide level to determine optimal exhaust system operation parameters and adjust operation of at least one of gas delivery to said blood gas exchanger and blood delivery to said blood gas exchanger based on the determined optimal exhaust system operation paramters.
17 . A method for autoregulation of a blood gas exchanger, comprising the steps of:
providing a blood gas exchanger having a blood inlet, a blood outlet, a gas inlet, and a gas outlet; an oxygen sensor positioned to detect oxyhemoglobin saturation at said blood inlet; a carbon dioxide sensor positioned to detect exhaust gas CO2 concentration at said gas outlet; and a controller comprising a microcontroller and memory storage having computer-executable instructions stored thereon, wherein when executed by the microcontroller, the computer-executable instructions cause the controller to:
receive real-time data from the oxygen sensor and the carbon dioxide sensor;
process the received real-time data by using a fuzzy logic control algorithm (FLCA) that (i) reads oxygenator inlet oxyhemoglobin saturation and oxygenator exhaust gas CO2 concentration to determine errors from set-point values and a first derivative of the errors with respect to time, (ii) converts the errors and first derivatives into fuzzy inputs through fuzzification, and (iii) applies membership function evaluation and defuzzification to determine adjustments for maintaining the sensed oxygen and carbon dioxide levels within target ranges to determine optimal adjustment parameters for maintaining physiologic parameters within target rangers; and
dynamically adjust blood flow and gas flow through the blood gas exchanger based on the processed real-time data to maintain said sensed oxygen and carbon dioxide levels within pre-designated target ranges that are adjustable based on a patient's instantaneous metabolic demands;
receiving at said controller a blood flow rate of blood flowing to said blood gas exchanger and a sweep gas flow rate of sweep gas flowing to said blood gas exchanger;
receiving at said controller a blood oxygen concentration from said oxygen sensor;
receiving at said controller an exhaust gas CO2 concentration from said carbon dioxide sensor; and
causing said controller to modify at least one of said blood flow rate and said sweep gas flow rate in response to and based upon said blood oxygen concentration and said exhaust gas CO2 concentration.
18 . The method of claim 17 , further comprising the step of determining at said controller an estimated blood CO2 concentration based upon said exhaust gas CO2 concentration.
19 . The method of claim 18 , further comprising the step of causing said controller to modify a blood:gas flow ratio in response to and based upon said determining an estimated blood CO2 concentration.