Identification and quantification of the degree of tissue hypoxia

A data processing system for determining the degree of tissue hypoxia of a subject, the data processing system comprising one or more processors configured to:

• a) determine venous blood values by performing at least one of measuring and estimating a blood acid-base status in a venous blood sample that has been obtained from the subject;
• b) receive or provide a value of at least one of measured and estimated arterial oxygenation (SO2AM, SO2AE, SpO2) from the subject;
• c) convert the venous blood values by applying a venous-to-arterial conversion model for deriving blood acid-base status and oxygenation status into first estimated arterial blood values (1_ABGC);
• d) receive or provide second reference acid-base status and oxygenation values of arterial blood (2_ABG) from the subject;
• e) implement a tissue hypoxia model using at least one of a measure of the total buffer base concentration (BB) and a measure of the total carbon dioxide content (tCO2) in the arterial blood, the model having as input, at least the first estimated arterial blood values (1_ABGC) and the second reference values of arterial blood (2_ABG);
• f) wherein the tissue hypoxia model calculates at least one of:
• a. a first measure indicative of the change in the total buffer base concentration (ΔBBT) between the first estimated arterial blood values (1_ABGC) and the second reference values of arterial blood (2_ABG) and
• b. a second measure indicative of the change in the total carbon dioxide content (ΔtCO2,T) between the first estimated arterial blood values (1_ABGC) and the second reference values of arterial blood (2_ABG);
• and
• g) further wherein the tissue hypoxia model is arranged to output a measure indicative of the degree of tissue hypoxia of the subject using at least one of the first and/O second measures.

A method of determining a degree of tissue hypoxia of a subject and treating a determined tissue hypoxia in the subject, the method comprising:

• a) determining venous blood values by at least one of measuring and estimating a blood acid-base status in a venous blood sample that has been obtained from the subject;
• b) providing a value of at least one of measured and estimated arterial oxygenation (SO2AM, SO2AE, SpO2) from the subject;
• c) converting the venous blood values by applying a venous-to-arterial conversion model for deriving blood acid-base status and oxygenation status into first estimated arterial blood values (1_ABGC);
• d) providing second reference acid-base status and oxygenation values of arterial blood (2_ABG) from the subject;
• e) implementing a tissue hypoxia model using at least one of a measure of the total buffer base concentration (BB) and a measure of the total carbon dioxide content (tCO2) in the arterial blood, the model having as input, at least the first estimated arterial blood values (1_ABGC) and the second reference values of arterial blood (2_ABG);
• f) wherein the tissue hypoxia model calculates at least one of:
• a. a first measure indicative of the change in the total buffer base concentration (ΔBBT) between the first estimated arterial blood values (1_ABGC) and the second reference values of arterial blood (2_AB G);
• and
• b. a second measure indicative of the change in the total carbon dioxide content (ΔtCO2,T) between the first estimated arterial blood values (1_ABGC) and the second reference values of arterial blood (2_ABG);
• g) using the tissue hypoxia model to output a measure indicative of the degree of tissue hypoxia of the subject using said at least one of the first and second measures;
• and
• h) treating the subject according to the measure indicative of the degree of tissue hypoxia, the treating comprising at least one of increasing a flow of oxygen to the subject and increasing a ventilation rate to the subject.

A device for determining the degree of tissue hypoxia of a subject, the device comprising a processor configured to:

• a) at least one of measure and estimate values of blood acid-base status in a venous blood sample that has been obtained from the subject;
• b) at least one of receive and provide a value of at least one of measured and estimated arterial oxygenation (SO2AM, SO2AE, SpO2) from the subject;
• c) convert the venous blood values by applying a venous-to-arterial conversion model for deriving blood acid-base status and oxygenation status into first estimated arterial blood values (1_ABGC);
• d) at least one of receive and provide second reference acid-base status and oxygenation values of arterial blood (2_ABG) from the subject;
• e) implement a tissue hypoxia model using at least one of a measure of the total buffer base concentration (BB) and a measure of the total carbon dioxide content (tCO2) in the arterial blood;
• the model having as input, at least, the first estimated arterial blood values (1_ABGC), and the second reference values of arterial blood (2_ABG);
• f) the tissue hypoxia model calculating:
• a. a first measure indicative of the change in the total buffer base concentration (ΔBBT) between the first estimated arterial blood values (1_ABGC) and the second reference values of arterial blood (2_ABG);
• and
• b. a second measure indicative of the change in the total carbon dioxide content (ΔtCO2,T) between the first estimated arterial blood values (1_ABGC) and the second reference values of arterial blood (2_ABG);
• and
• wherein the tissue hypoxia model is arranged to output a measure indicative of the degree of tissue hypoxia of the subject using at least one of the first and second measures to a display of the device.