Respiratory gas flow sensor with sampling port
Inventors
Assignees
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Publication Number
US-9999741-B2
Publication Date
2018-06-19
Expiration Date
Abstract
The accurate measurement of inspired and expired gas volume flow and gas composition are important in respiratory therapy. The invention provides a gas flow sensor for a ventilator comprising: a flow path extending between a first end that connects to a supply of gas and a second end that couples to a patient airway interface; and a constant temperature anemometer sensor arranged within the flow path between those ends. It further comprises a sampling port that may be coupled to a gas analyser device; and an orifice which is in fluid communication with the flow path and the sampling port so that, in use, gas may be drawn from the flow path for analysis, the gas being drawn from the flow path at a position located between the anemometer sensor and the first end.
Core Innovation
The invention provides a gas flow sensor for a ventilator formed from a single component. The sensor comprises a flow path extending between a first end that connects to a supply of gas and a second end that couples to a patient airway interface, with a constant temperature anemometer sensor arranged within the flow path between those ends.
A sampling port is provided for coupling with a gas analyser device. An orifice is in fluid communication with the flow path and the sampling port so that gas can be drawn from the flow path for analysis, the gas being drawn through the orifice from the flow path at a position located between the anemometer sensor and the first end.
A critical separation is defined between the orifice and the anemometer sensor, with the distance in the range of 3-10 mm. This positioning minimizes turbulence/mixing and avoids tidal volume measurement errors and "rogue leak" readings associated with prior separate sampling adapters.
Claims Coverage
The document provides two independent claims, a device claim and a method claim. Across these claims, the inventive coverage is concentrated in the integrated ventilator flow path with a constant temperature anemometer, the sampling port coupled via an orifice, and the defined 3-10 mm upstream distance.
Single-component ventilator flow path with constant temperature anemometer between ends
A gas flow sensor for a ventilator formed from a single component and comprising a flow path extending between a first end that connects to a supply of gas and a second end that couples to a patient airway interface, with a constant temperature anemometer sensor arranged within the flow path between those ends.
Sampling port with orifice drawing gas from a location between anemometer and supply end at 3-10 mm
A sampling port for coupling with a gas analyser device, and an orifice in fluid communication with the flow path and the sampling port so that gas can be drawn from the flow path for analysis, the gas being drawn through the orifice from the flow path at a position located between the anemometer sensor and the first end, wherein the distance between the orifice and the anemometer sensor is in the range of 3-10 mm.
Upstream-side orifice relative to anemometer wires for drawing sampling gas to a gas analyser
A method of drawing sampling gas from the flow path of a ventilator including a constant temperature anemometer sensor arranged within that flow path, comprising providing an orifice in fluid communication with the flow path on the upstream side of the anemometer sensor wires; drawing gas through the orifice from the flow path, the orifice provided at a distance of 3-10 mm from the sensor wires; and passing the drawn gas to a gas analyser device for analysis.
Overall claim coverage focuses on sampling within a ventilator flow path integrated with a constant temperature anemometer, where the sampling orifice is placed between the anemometer and the supply end, or on the upstream side relative to the anemometer wires, with a defined 3-10 mm separation.
Stated Advantages
Minimizes turbulence/mixing associated with sampling.
Avoids tidal volume measurement errors.
Avoids "rogue leak" readings.
Provides advantages over prior separate sampling adapters that cause deadspace increases and measurement errors due to sampling diversion and pressure oscillation.
Documented Applications
Use in ventilator gas flow measurement and gas analysis by drawing sampling gas from the ventilator flow path and passing it to a gas analyser device for analysis.
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