Method and breathing apparatus for assessing pulmonary stress
First Claim
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1. A method for assessing pulmonary stress comprising the steps of:
- generating a pressure controlled flow of respiratory gas, at a pressure conforming to a constant pressure or pre-set pressure profile, associated with a subject having air waves exhibiting resistance and compliance;
measuring said flow;
determining said resistance and said compliance from said pressure and said low; and
determining a stress index value, representative of pulmonary stress of said subject, from said pressure, said flow, said resistance and said compliance said stress index value having a magnitude that indicates whether the compliance is increasing or decreasing during inspiration.
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Abstract
In a method and breathing apparatus for assessing pulmonary stress, wherein pressure controlled flow of respiratory gas is generated, an ensuing flow is measured, resistance and compliance are determined based on measured pressure and flow and a stress index value is determined based on pressure, flow, resistance and compliance. The stress index value is 1 when no stress is present, ≧1 when there is a risk for overdistension and ≦1 when alveolar units are at a risk of being cyclically closed and opened. Implemented in a breathing apparatus the method can be used to assist an operator in diagnostic and therapeutic considerations in relation to a patient.
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Citations
12 Claims
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1. A method for assessing pulmonary stress comprising the steps of:
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generating a pressure controlled flow of respiratory gas, at a pressure conforming to a constant pressure or pre-set pressure profile, associated with a subject having air waves exhibiting resistance and compliance; measuring said flow; determining said resistance and said compliance from said pressure and said low; and determining a stress index value, representative of pulmonary stress of said subject, from said pressure, said flow, said resistance and said compliance said stress index value having a magnitude that indicates whether the compliance is increasing or decreasing during inspiration. - View Dependent Claims (2, 3, 4)
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5. A breathing apparatus comprising:
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a respiratory line adapted for connection to airways of a subject, said airways exhibiting a resistance and a compliance; a regulator connected to said respiratory line that regulates a respiratory gas pressure to maintain said respiratory gas pressure at a pressure in said respiratory line conforming to a constant pressure or a pre-set pressure profile; a flow meter in fluid communication with said respiratory line that measures a flow of said respiratory gas in said respiratory line; and a control unit connected to said gas regulator to control said gas regulator, and said control unit determining said resistance and said compliance from said pressure and said flow and determining a stress index value, representative of pulmonary stress of said subject, from said pressure, said flow, said resistance and said compliance said stress and a value having a magnitude indicating whether the compliance is increasing or decreasing during inspiration. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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Specification