Method and apparatus for changing the concentration of a target gas at the blood compartment of a patient's lung during artificial ventilation
First Claim
1. Method for changing the concentration of a target gas at the blood compartment of a patient'"'"'s lung from an actual target gas concentration to a desired target gas concentration during artificial ventilation with an inspiratory gas composition by a respirator being controlled via a set of ventilation parameters, by varying the fraction of the target gas supplied to the inspiratory gas composition, and/or the fraction of the re-breathed gas supplied to the inspiratory gas composition, and/or the set of ventilation parameters being responsible for the ventilated lung volume, wherein a) the lung is ventilated in a first ventilation stage by setting a fraction of target gas, a fraction of re-breathed gas and a set of ventilation parameters, wherein said setting results in the actual target gas concentration, and b) the lung is ventilated in a second ventilation stage in which at least once the set of ventilation parameters is varied for yielding an increased ventilated lung volume compared to the first ventilation stage and on the basis of the increased ventilated lung volume the fraction of target gas and/or the fraction of re-breathed gas is varied such that the target gas concentration is changed towards the desired target gas concentration.
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Abstract
The invention refers to a method and apparatus for changing the concentration of a target gas at the blood compartment of a patient'"'"'s lung from an actual target gas concentration to a desired target gas concentration during artificial ventilation with an inspiratory gas composition by a respirator being controlled via a set of ventilation parameters. In order to decrease the negative effects of general anaesthesia during artificial ventilation even further, the method according to the invention comprises the following steps: a) ventilating the lung in a first ventilation stage, and b) ventilating the lung in a second ventilation stage in which alveolar recruitment is promoted.
34 Citations
16 Claims
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1. Method for changing the concentration of a target gas at the blood compartment of a patient'"'"'s lung from an actual target gas concentration to a desired target gas concentration during artificial ventilation with an inspiratory gas composition by a respirator being controlled via a set of ventilation parameters, by varying
the fraction of the target gas supplied to the inspiratory gas composition, and/or the fraction of the re-breathed gas supplied to the inspiratory gas composition, and/or the set of ventilation parameters being responsible for the ventilated lung volume, wherein a) the lung is ventilated in a first ventilation stage by setting a fraction of target gas, a fraction of re-breathed gas and a set of ventilation parameters, wherein said setting results in the actual target gas concentration, and b) the lung is ventilated in a second ventilation stage in which at least once the set of ventilation parameters is varied for yielding an increased ventilated lung volume compared to the first ventilation stage and on the basis of the increased ventilated lung volume the fraction of target gas and/or the fraction of re-breathed gas is varied such that the target gas concentration is changed towards the desired target gas concentration.
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9. Apparatus for changing the concentration of a target gas at the blood compartment of a patient'"'"'s lung from an actual target gas concentration to a desired target gas concentration during artificial ventilation with an inspiratory gas composition by a respirator being controlled via a set of ventilation parameters, comprising
target gas varying means for varying the fraction of the target gas supplied to the inspiratory gas composition, re-breathed gas varying means for varying the fraction of the re-breathed gas supplied to the inspiratory gas composition, parameter varying means for varying the ventilation parameters being responsible for the ventilated lung volume, and controlling means for controlling the target gas varying means, the re-breathed gas varying means and the parameter varying means such that a) the lung is ventilated in a first ventilation stage by setting a fraction of target gas, a fraction of re-breathed gas and a set of ventilation parameters, wherein said setting results in the actual target gas concentration, and b) the lung is ventilated in a second ventilation stage in which at least once the set of ventilation parameters is varied for yielding an increased ventilated lung volume compared to the first ventilation stage and on the basis of the increased ventilated lung volume the fraction of target gas and/or the fraction of re-breathed gas is varied such that the target gas concentration is changed towards the desired target gas concentration.
Specification