Non-invasive estimation of arterial blood gases

A computer controlled data collection and processing method for monitoring arterial gas values, comprising the steps of:

• sampling a patient's exhaled breath to determine a partial pressure of said arterial gas and total breath volume as a function of time during an exhale cycle;
• convening said partial pressure data to a volumetric domain;
• segregating said partial pressure data into three distinct phases;
• extracting functional variables from said distinct phases in terms of slope and intercept values;
• recalling from memory a matrix of stored weighting parameters associated with said extracted values;
• creating a vector based on said extracted values modified by said stored weighting parameters;
• and
• determining arterial gas value based on said vector.

A non-invasive method of determining the blood gas content based on volume domain, comprising the steps of:

• a) taking time domain measurements of a plurality of a patient's expiratory breaths using a pneumotachometer and gas sensor, said measurements being at a frequency approximately between 10 and 1000 Hz;
• b) mapping said time domain measurements to form a curve;
• c) converting said curve to the volume domain;
• d) determining a threshold point having a value, where said curve transcends from a value below said threshold point value to a value above said threshold point value;
• e) calculating a Phase II curvature wherein said threshold point is an initial curvature point, linearly plotting subsequent points until said points deviate from said linearity, said deviation indicating a termination of Phase II;
• f) calculating a Phase III curvature by taking a last data point of expiration and progressing toward the termination point of Phase II;
• g) extracting Phase II and Phase III curve values to create a linear expiratory relationship;
• h) combining said linear expiratory relationship with stored arguments into at least one vector;
• and
• i) using said at least one vector to produce an estimate of an amount of said blood gas, wherein said blood gas content is visually displayed.

A non-invasive method of determining a dissolved gas content of an arterial portion of an adult patient's pulmonary vasculature expressed as a partial pressure comprising the steps of:

• a) taking time domain measurements of a plurality of said adult patient's expiratory breaths using a pneumotachometer and gas sensor, at a frequency of about 100 Hz;
• b) converting said time domain measurements to a volume domain;
• c) mapping a curvature relationship of gas partial pressure v gas volume;
• d) determining a threshold point, said threshold point being the point where said curvature relationship transcends from a value below 0.5% to a value above 0.5%;
• e) calculating a Phase II curvature wherein said threshold point is an initial curvature point;
• f) linearly plotting subsequent points until said points deviate from said linearity, said deviation indicating termination of Phase II;
• g) calculating a Phase III curvature by taking a last data point of expiration and progressing toward the termination of Phase II;
• h) using the Phase II and Phase III curves to quantify an expiratory gas relationship;
• i) combining said relationship with stored arguments into at least one vector;
• j) using said at least one vector to estimate the partial pressure of said gas of said arterial portion of said adult patient's pulmonary vasculature;
• and
• k) visually displaying said partial pressure of said arterial gas.