Automatic control method for supplying anaesthetic to a low flow-type closed circuit
First Claim
1. A method of automatic control for the supply of a volatile anaesthetic to a closed anaesthetic circuit of low flow, which comprises the stage of mixing fresh gas and volatile anaesthetic before introducing the mixture into the patient, the method comprising the steps of:
- a) setting a ventilatory rate (VR) of the patient;
b) automatically setting a flow of fresh gas (FFG) to 10% of the VR;
c) determining a fraction inhaled (% IF) and exhaled (% EF) by the patient of volatile anaesthetic;
d) setting a dial of an anaesthetic vaporiser to a value resulting from multiplying by 10 a differential of the inhaled fraction (% IF) and exhaled fraction (% EF) of volatile anaesthetic by the patient, wherein a concentration of anaesthetic at an output of the anaesthetic vaporizer (% dial) is equal to (% IF−
% EF)×
10, and changing, in a same proportion, the opening of said dial every time that said differential of inhaled fraction (% IF) and exhaled fraction (% EF) of volatile anaesthetic by the patient varies;
e) supplying a quantity of anaesthetic to a circuit (QASC) that covers at least a total quantity of anaesthetic consumed by the patient (TQAC) by means of opening of the dial of the anaesthetic vaporizer; and
f) mixing the quantity of anaesthetic with the FFG before introducing said mixture into the patient.
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Abstract
The method comprises the stages of a) setting the ventilatory rate (VR) for the patient; b) automatically setting the flow of fresh gas (FFG) to 10% of the VR; c) determining the volatile anaesthetic fractions inhaled (% IF) and exhaled (% EF); d) opening the dial of the anaesthetic vaporiser to the value resulting from multiplying the differential (% IF−% EF) by 10; e) supplying the circuit with a quantity of anaesthetic that covers, at least, the total quantity of anaesthetic consumed by the patient, by means of opening the dial of the anaesthetic vaporiser; and f) mixing the quantity of anaesthetic with the FFG before introducing the mixture into the patient. The method has application in the administration of inhaled anaesthetics in low-flow anaesthetic systems.
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Citations
4 Claims
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1. A method of automatic control for the supply of a volatile anaesthetic to a closed anaesthetic circuit of low flow, which comprises the stage of mixing fresh gas and volatile anaesthetic before introducing the mixture into the patient, the method comprising the steps of:
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a) setting a ventilatory rate (VR) of the patient;
b) automatically setting a flow of fresh gas (FFG) to 10% of the VR;
c) determining a fraction inhaled (% IF) and exhaled (% EF) by the patient of volatile anaesthetic;
d) setting a dial of an anaesthetic vaporiser to a value resulting from multiplying by 10 a differential of the inhaled fraction (% IF) and exhaled fraction (% EF) of volatile anaesthetic by the patient, wherein a concentration of anaesthetic at an output of the anaesthetic vaporizer (% dial) is equal to (% IF−
% EF)×
10, and changing, in a same proportion, the opening of said dial every time that said differential of inhaled fraction (% IF) and exhaled fraction (% EF) of volatile anaesthetic by the patient varies;
e) supplying a quantity of anaesthetic to a circuit (QASC) that covers at least a total quantity of anaesthetic consumed by the patient (TQAC) by means of opening of the dial of the anaesthetic vaporizer; and
f) mixing the quantity of anaesthetic with the FFG before introducing said mixture into the patient. - View Dependent Claims (2, 3, 4)
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3. A method according to claim 1, wherein the QASC is determined by the equation QASC=FFG×
- % dial.
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4. A method according to claim 1, wherein the QASC is determined by the equation:
Specification