Breath by breath nutritional requirements analyzing system

In a breath by breath analyzer system for assessing the nutritional requirement of an intubated patient receiving a fraction of inspired oxygen up to 100%, said system comprising:

• (a) a pneumotach member coupled to a patient/endotracheal tube/ventilator connection, said pneumotach member including:
• (i) a generally circular passageway having a tapered cross section;
• (ii) a strut extending transverse to the longitudinal dimension of said pneumotach member;
• (iii) a pair of lumens in said strut;
• (iv) a plurality of symmetrically located apertures passing through walls of said strut into said pair of lumens;
• (v) a further pair of apertures passing through a wall of said pneumotach member and individually aligned coaxially with said pair of lumens, with passage of inspired and expired gases through said pneumotach member and over said strut creating pressure differential in said pair of lumens;
• (vi) coupling means for coupling said pneumotach member to a means for measuring the inspired and expired gas flow;
• and
• (vii) means for generating first analog electrical signals proportional to inspired and expired gas flow of said patient;
• (b) gas analyzing means coupled to said pneumotach member for producing second analog electrical signals proportional to a percent concentration of constituent gases in said expired gas flow of said patient;
• (c) flowmeter means coupled to said gas analyzing means for producing third analog electrical signals proportional to a flow rate of said expired gas flow through said gas analyzing means;
• (d) microprocessor means for performing operations in accordance with a stored program of arithmetic instructions, said microprocessor including:
• (i) waveform analyzer means linked to said gas analyzing means, said pneumotach member and said flowmeter means for sampling said first, second and third analog electrical signals in a predetermined sequence and converting said first, second and third analog electrical signals into digital quantities representative of said first, second and third analog electrical signals during a sampling interval of each and storage means for storing said digital quantities as operands for such arithmetic operations;
• and
• (ii) means for dynamically compensating for transit time delays between a time a gas sample is drawn into a sample line and a time said gas analyzing means produce a predetermined output response and for time-wise aligning said measured percentage of concentration of a particular constituent gas with said measured flow rate of inspired and expired gases.